LEE- Çevre Bilimleri Mühendisliği ve Yönetimi-Doktora

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Application of different strategies to improve aerobic granular sludge process performance for treatment of municipal wastewater

(Graduate School, 2022-09-29) Koşar, Şadiye ; Erşahin, Mustafa Evren ; 501162714 ; Environmental Sciences, Engineering and Management

Aerobic granular sludge (AGS) process is an energy-efficient alternative biological wastewater treatment process to the conventional activated sludge (CAS) process which requires high energy and big space. In CAS systems, flocs sized above 0.2 mm are referred as granule. So far flocs and granules could be easily differentiated by size clustering as well as their capabilities of removal for organic matter and nutrients. Surface of the granule has porous morphology, and this allows the substrate penetration and as well as oxygen diffusion into the inner layers of the granule. The diffusion of oxygen is somehow can be a limiting factor for the simultaneous carbon and nutrient removal due to structure of the granule. In many cases, granule has a compact and dense structure that limits the oxygen transfer to the inner core layers of the granule which improves the denitrification and allows better phosphorus (P) removal within the granule. Whereas in some situations, granules have amorphous structure which do not improve any core inside the granule so affects the removal of substrate. Aerobic granules are heavier than flocs formed in waste sludge, so they settle faster, and this improves the settleability of the sludge which further allows to operate in one reactor. For this reason, large sedimentation tanks are not required in AGS systems. Since aerobic, anoxic and anaerobic biological activities take place inside the granule, AGS process offers 25-75% less space and consumes 20-50% less energy compared to conventional activated sludge plants. Nitrification takes place on the surface of the granule during aeration phase and denitrification occurs in the inner layers of the granule under anoxic conditions. P removal is maintained by polyphosphate accumulating organisms (PAOs) that are located in the core part of the granule. PAOs and denitrifiers which are responsible for the denitrification are both heterotrophic organisms and compete for the carbon sources as substrate. For this reason, it is important to have sufficient amount of organic matter for nitrogen (N) and P removal. Since PAOs are located in the inner layer of the granule they are only capable of using organic that are in dissolved form. In municipal wastewater, organic matter is particulate and dissolved forms. Particulate matter reduces N and P removal up to 40% and 46% respectively. Particulate organic matter is turned into dissolved form in the presence of extracellular polymeric substances (EPS) which are hydrolyzing them further. Hydrolysis ends up in anaerobic phase when the attached particulate matter on the surface of the granules hydrolyzed and it is uptaken by PAOs and denitrifiers. If dissolved organic matter cannot be consumed by these species, then it would be consumed by the aerobic heterotrophic bacteria on the surface of the granule which further causes filamentous microorganisms' overgrowth. This leads to amorphous structure and disintegration of the granule. In this thesis, the treatability municipal wastewater by AGS process was investigated under different circumstances. Four separate studies were conducted within the scope of this study. In the first study, two different sludge were comparatively investigated as inoculum: (a) waste activated sludge (WAS) taken from the return activated sludge line of an advanced biological wastewater treatment plant (WWTP), (b) WAS taken from the return activated sludge line of a pilot scale high-rate activated sludge (HRAS) system. This study was conducted in two stages: AGS system was seeded with the WAS taken from the return activated sludge line of an advanced biological wastewater treatment plant in the first stage; in the second stage, AGS system was seeded with the mixture of WAS taken from the return activated sludge line of an advanced biological WWTP and WAS of pilot scale HRAS process as volume in proportion of 1:1. This study was performed to reveal the contribution of microorganisms found in the flocculent sludge to the granulation process. Since HRAS process sludge has high settleability and the mixture of WAS with HRAS process as inoculum was expected to enhance the settling properties of granular sludge as well as achieving good treatment performance. Although at the start-up period sludge wash-out occurred and mainly fluffy waste sludge wasted, HRAS process sludge settles faster, and it remained in the reactor. So, in this case especially denitrifiers were mostly washed out of the system which deteriorated system performance compared to the AGS system operated solely with WAS. At the end of this study, WAS waste sludge was chosen as seed sludge for the further studies to obtain aerobic granulation based upon AGS system treatment performance. In the second study, WAS taken from the return activated sludge line of an advanced biological WWTP was used as seed sludge. Study was conducted in two stages: (a) AGS system was fed directly with the synthetic municipal wastewater, (b) AGS system was fed with the pre-settled synthetic municipal wastewater (30 min of settling) to simulate pre-sedimentation tanks in the full-scale wastewater treatment plants (WWTPs). With pre-settling application, it was proposed that particulate matter would settle so mainly dissolved organic matter could be introduced to the AGS system. Since AGS system is anaerobically fed, this would improve the nutrient removal by allowing the uptake of organic matter easily by PAOs and denitrifiers. It was shown that up to 60% of particulate matter was removed by settling and as a result carbon/nitrogen (C/N) ratio decreased 20% lead deterioration of the AGS system treatment performance. It was apparent that a combination of pre-sedimentation in AGS process didn't improve the system. In the third study, AGS system was operated in three different stages continuously following each other without having different start-up periods: (a) AGS system was fed directly with raw municipal wastewater, (b) AGS system was fed with the pilot scale HRAS system's effluent (treated wastewater), (c) AGS system was fed with the mixture these two flows: raw municipal wastewater (20%) and HRAS process effluent (80%). Waste sludge taken from the return activated sludge line of an advanced biological wastewater treatment plant was used as inoculum. Firstly, aerobic granulation was maintained by introducing municipal wastewater than HRAS process effluent fed to the system and AGS system performance was followed thoroughly. It was shown that the granule stability remained somehow same, but AGS system performance was affected by decreased C/N ratio. AGS system was fed with the mixture the raw municipal wastewater and HRAS process effluent to improve the system performance. As a result, AGS system performance was improved with the increase in C/N ratio (20% increase compared to feeding with only HRAS process effluent). Thus, HRAS process integration with AGS process was found to be energy efficient configuration. Both systems comparably occupy less space than conventional treatment systems and their integration will definitely improve the effluent quality. In the fourth study, digestibility of AGS which was obtained from the third study was compared to the WAS taken from the return activated sludge line of an advanced biological wastewater treatment plant. It is known that AGS process sludge has low digestibility than WAS. Thus, ultrasonication was applied to improve the solubilization of organic matter for increasing sludge digestibility. Since aerobic granules are clusters of microorganisms that are attached together, they are bigger in size and more compact than WAS flocs. Therefore, relying on their physical differences, it was assumed that ultrasonication would enhance digestibility of the AGS. It was shown that ultrasonication as pre-treatment method led to solubilization for both sludge sources in terms of volatile fatty acids (VFAs), protein and carbohydrates besides causing decrease in particle size. A direct relation found between the release of organic compounds, ammonium, phosphorus and heavy metals with the increase in ultrasonication intensity. Overall results obtained from this thesis showed a comprehensive approach to treat municipal wastewater by AGS process while improving the treatment performance by focusing on inoculum source as well as feeding strategy. Besides, sludge from AGS process was evaluated in terms of soluble products release by applying ultrasonication process compared to the WAS. This thesis would enhance the knowledge on AGS technology in terms of seeding and feeding regimes beneath giving clues for full-scale AGS process applications.
Application of different strategies to improve anaerobic digestion for organic fraction of municipal solid waste

(Graduate School, 2024-06-24) Kabakcı, Yağmur ; Arıkan, Osman Atilla ; Üçtuğ, Fehmi Görkem ; 501152707 ; Environmental Sciences, Engineering and Management

Municipal Solid Waste (MSW) management is a worldwide issue with significant effects on public health, community welfare, environmental sustainability, and economic progress which includes items like packaging, food scraps, newspapers, and more, coming from homes, businesses, and industries. Effective MSW management is vital for sustainable urban development, emphasizing waste segregation, recycling, and treatment to minimize landfill reliance and harness waste-to-energy technologies. Tailoring waste management systems to local contexts is crucial, considering factors like waste composition and financial resources. From this perspective, this thesis focused on the characterization of MSW and increasing biogas production by applying different pretreatment strategies to organic fraction of MSW (OFMSW). Due to increasing population worldwide, it is essential to understand the MSW characteristics to apply efficient waste management strategies. The organic fraction of MSW (OFMSW) holds potential for energy recovery through anaerobic digestion (AD), offering municipalities economic opportunities besides environmental benefits. In the first study, waste composition and physiochemical of the mechanically separated OFMSW (ms-OFMSW) at a full-scale AD plant in Türkiye was evaluated. ms-OFMSW predominantly comprised of organic matter (76.45 ± 1.71%), alongside recyclable (8.99 ± 1.56%) and non-recyclable (14.56 ± 1.69%) components according to the findings of this study. Environmental assessment was conducted using Environmental Protection Agency's online tool (Recyculator tool) underscored the substantial energy and water savings associated with segregating recyclable materials (metal, glass and plastic) from the waste stream. Moreover, this study highlighted the importance of efficient pre-separation units in enhancing OFMSW digestibility and maximizing environmental benefits. AD is recognized as an effective waste management strategy for different types of waste with the potential to mitigate greenhouse gas emissions (GHGs) while concurrently generating renewable energy. The physicochemical characteristics of OFMSW can significantly influence the AD process's efficiency and biogas production. Hydrolysis, a pivotal step in AD, is often rate-limiting for degradation of waste, particularly for substrates like OFMSW. In the second and third studies, electrohydrolysis and enzyme pretreatment were explored to improve hydrolysis efficiency. Experiments showed that doubling electrohydrolysis treatment time (from 30 minutes to 60 minutes) led to notable improvements in methane production, with a significant reduction in the lag phase. Methane production increased by 3–10% following electrohydrolysis pretreatment, underscoring its potential to expedite the AD process and enhance biogas yields. While in the enzyme pretreatment, anaerobic degradation of organic waste was investigated by employing alpha amylase enzyme which was obtained from Aspergillus oryzae. According to the results, a significant increase in the methane yield and a decrease in the lag phase was observed. Optimum results were obtained with the addition of 0.5 mg of enzyme per g volatile solids (VS) added, highlighting the effectiveness of alpha amylase in enhancing the biodegradability and biogas production of OFMSW. In summary, this thesis sheds light on the importance of understanding and managing OFMSW characteristics to optimize AD efficiency and maximize environmental benefits. Efficient pre-separation units, electrohydrolysis and enzyme pretreatment emerge as promising strategies for enhancing OFMSW digestibility and biogas production in AD processes. However, further research is warranted to fully explore and optimize these approaches for practical implementation on a larger scale. By leveraging these advancements, the waste management sector can move towards more sustainable practices, reducing environmental impact and contributing to the transition to a circular economy.
Concentrate treatment via membrane distillation/crystallization method

(Graduate School, 2023-08-23) Salmanlı Mutlu, Öykü ; Koyuncu, İsmail ; Wiesner, Mark R. ; 501152708 ; Environmental Sciences and Engineering

Boron is an important semimetal element that is found in water, soil and rocks. Boron is widely used in a variety of industries such as glass, semi-conductors, detergents, cosmetics, drugs and fertilizer. Boron is also an essential nutrient for animals, plants and humans that needs to be found in dietary intake. Although it is beneficial the excessive amount of boron can lead to some health problems for humans and growth problems or death for plants. The boron content in wastewater is increasing due to the increasing industrial activities. Boron can also be found naturally from rocks, salt deposits or rainfalls and approximately 75% of the boron reserves of the world are found in Turkey. In the second chapter of this thesis study a literature review was prepared comprehensively. Boron removal and recovery techniques were reviewed. The increasing demand for clean water resources makes boron removal from water resources much more important. However, the removal is not enough alone in the aspect of sustainability. The removal and recovery techniques both conventional methods like precipitation, adsorption, coagulation, ion exchange and membrane processes are examined to juxtapose the states of the science in these two related—and increasingly important—processes. In the third chapter, the optimization studies of the membrane distillation process used in the thesis study were conducted. 2 different MD configurations, 3 different vacuum pressures, 6 different membranes and 3 different feed water were used to determine the optimum conditions. VAGMD had the higher fluxes since vacuum assistance enhanced fluxes while decreasing specific energy consumption. The boron content in permeate waters was lower than the 0.5 mg/L. In the fourth chapter hydrophobic and superhydrophobic membrane production methods were investigated. Different fabrication techniques as phase inversion and electrospinning were utilized while coating was applied to modify commercial and fabricated membranes. Different coagulation bath mediums for phase inversion method, nanoparticle additives and different coating solutions were compared. It was possible to obtain a superhydrophobic membrane that has a contact angle of 153. A novel hydrophobic blend membrane was fabricated to use in VAGMD within the scope of the fifth chapter. NaCl, synthetic boron solution and real RO concentrate supplied from the boron mining area were tested. A fluoro-containing benzoxazine monomer (Bz) was blended with our base polymer PVDF. The cross-linking of Bz is provided by thermal curing. According to the results, the BisF-Bz membrane showed higher hydrophobicity, more durability and physical stability compared to the pristine membrane. Boron rejection was highest for the BisF-Bz blended and two times thermally cured nanofiber membrane. In chapter six VAGMDC system was utilized to remove and recover boron from the concentrate stream. The concentrate problem is the main drawback of membrane processes so needs additional treatment and management. To address this problem VAGMDC system was tested. Synthetic boron solution was used to optimize process conditions such as concentration, pH and membrane type. Real RO concentrate was tested in the following experiments. Flux values, boron concentration and boron rejections, SEM-EDS analysis and XRF analysis for obtained crystals were conducted. The results showed that VGMDC could be successfully used for the removal and recovery of boron. The pilot scale VAGMDC system was tested in the scope of chapter seven. Different recovery ratios and operating modes were tested. Highly boron-contented raw river water and RO concentrate of that water were fed to the pilot scale MD system. Conductivity, flow rate and vacuum pressure were observed during the experiments. Boron, arsenic, hardness and conductivity removals were analyzed and determined. After VAGMD operation crystallization was applied to the obtained concentrate. 43.9% B2O3 contented crystals could be obtained. In conclusion, the relatively new VAGMDC process is an effective method for boron removal and recovery.
Coupling ozone with GAC, AIX and biochar: Removal of pharmaceuticals from the biologically treated wastewater and fate of their transformation products

(Graduate School, 2024-09-24) Kutlu Fakıoğlu, Malhun ; Öztürk, İzzet ; 501172707 ; Environmental Science, Engineering and Management

In order to prevent water pollution in the water bodies, there has been a rising interest in improving cost-efficient quaternary treatment technologies to efficiently remove pharmaceuticals from the effluents of wastewater treatment plants. Various methods, including physical, biological, and chemical processes, are being utilized to eliminate organic micropollutants (OMPs) which include pharmaceuticals and persistent pollutants such as per- and polyfluoroalkyl substances (PFAS). Among these advanced techniques, ozonation and activated carbon adsorption are currently suggested as the most feasible options for substantially decreasing pharmaceutical concentrations in the wastewaters. Carbon-based materials such as activated carbon are notably effective adsorbents used for removing pharmaceuticals. Likewise, ozone is a highly potent oxidizing agent capable of oxidizing micropollutants directly via O3 itself or indirectly through the generation of hydroxyl radicals. However, after ozonation, instead of being mineralized, compounds can be converted into other substances known as transformation products, which may pose greater toxicity than the original compound. Additionally, the reaction between bromide and ozone produces bromate which is a toxic and carcinogenic by-product. To mitigate potential adverse effects from ozonation, it is often recommended to implement post-treatments such as biological or adsorptive systems like granular activated carbon (GAC) to eliminate potential transformation products and by-products. When combined with activated carbon adsorption, ozonation acts as an additional method for removing compounds that are resistant to adsorption. Crucially, activated carbon, with its extensive specific surface area and high concentration of functional groups, has demonstrated its ability to eliminate transformation products and by-products that may be generated during ozonation. While the effectiveness of the O3-GAC pairing is well-documented in literature, less attention has been given to combinations like ozonation with anion exchange (AIX) or other potentially more sustainable sorption materials such as biochar. The O3-AIX combination is particularly intriguing for this study, as many wastewater treatment plants, including the WWTP that provided wastewater for this research, are grappling with the challenge of removing PFAS. The treated wastewater from the aforementioned WWTP is released into the Fyrisån River, which flows into Ekoln Lake, Mälaren Lake, and eventually to the Baltic Sea. Fyrisån River also contributes to replenishing a groundwater source used for the city's drinking water. Consequently, the conventionally treated wastewater, containing untreated micropollutants, is discharged into a river that ultimately serves as a drinking water source. Thus, this study aims to simulate a potential combined advanced treatment step for the wastewater treatment plant. This research is particularly noteworthy as it not only provides guidance for implementing advanced techniques to remove micropollutants in full-scale wastewater treatment plants, but also investigates the fate of transformation products within three different combined systems: ozone and granular activated carbon filtration, ozone and ion exchange, and ozone and biochar. The objective of this thesis was both to examine the effectiveness of removing 24 selected pharmaceuticals and to monitor the fate of 7 of their metabolites, including oxidation transformation products. This investigation utilized a combination of processes, namely O3-GAC, O3-biochar (with two different types of biochar), and O3-AIX, in laboratory-scale experiments using actual effluent from a full-scale WWTP. The entire system was operated with three different O3 dosages, each maintained continuously for two weeks. Various sorption filters, including two types of biochar (one derived from forest biomass and the other from sewage sludge), reactivated GAC, and an AIX resin, were assessed. The evaluation of results focused not only on micropollutant removal but also on the generation of transformation products and by-products. 23 out of the 24 pharmaceuticals examined were detected in the effluent wastewater collected from the Kungsängsverket WWTP in total. The findings revealed that concentrations of sertraline, trimethoprim, fluconazole, atenolol, and sulfamethoxazole were below 500 ng/L, whereas the average concentrations of venlafaxine, desvenlafaxine, fexofenadine, bicalutamide, and lamotrigine were above 5,000 ng/L. According to the study findings, the average removal of selected pharmaceuticals varied between 8.8% and 97% with an O3 dosage of 0.28 g O3/g DOC, while it ranged from 86% to 99% for higher O3 dosages (0.96 and 2.17 g O3/g DOC). Pharmaceuticals such as fluconazole, atenolol, metoprolol, and tramadol exhibited relatively lower removal rates (9-15%) with the specific O3 dosage of 0.28 g O3/g DOC compared to furosemide, propranolol, clindamycin, and clarithromycin, which showed high removal rates (>90%). Tertiary amines like cetirizine and fexofenadine, known for their high reactivity with ozone, achieved removal rates of 79% and 89%, respectively, via 0.28 g O3/g DOC in this study. Furthermore, highly reactive compounds such as carbamazepine, diclofenac, sulfamethoxazole, and trimethoprim were removed by 70%, 85%, 70%, and 88%, respectively, with 0.28 g O3/g DOC, consistent with existing literature. Conversely, fluconazole exhibited a removal rate of 9% with an O3 dosage of 0.28 g O3/g DOC, while atenolol had an average removal rate of 15%. Among all materials tested, GAC emerged as the top-performing sorbent, effectively removing nearly all compounds below the limit of quantification (LOQ) even after continuous operation for two weeks (BV=864). The potential efficacy of biochar 2 for pharmaceutical removal, which was derived from sewage sludge, was particularly significant for the overall sustainability of the WWTP. Although biochar 1 exhibited better performance than biochar 2, both sorption materials showed decreased sorption capacity over the two-week period (BV=864) for most target compounds, including carbamazepine, fexofenadine, tramadol, fluconazole, sulfamethoxazole, and erythromycin. By the end of the continuous two-week operation, biochar 1 achieved removal rates ranging between 30% and 89% (mean 68%), while biochar 2 removed selected compounds at rates of 8.5% to 82% (mean 38%). Conversely, AIX that has been included for PFAS removal, demonstrated lower removal rates as expected after two weeks compared to biochars 1 and 2, ranging between 2% and 55% (average: 20%) for positive removal rates (BV= 3,264). Based on the findings, GAC exhibited the highest performance when paired with ozone (>99%), followed by biochar 1. Generally, the combination of ozone with biochar 1 proved to be more effective (mean=91%, range: 42-99%) than with biochar 2 (mean=79%, range: 29-99%). As anticipated, the combination of ozone with AIX yielded the lowest removal rates for pharmaceuticals (mean=58%, range: 6-98%). Based on the findings, six out of seven metabolites were identified in samples both pre- and post-ozonation. The results suggested that while the concentrations of certain metabolites decreased during ozonation, some metabolites, including oxidation transformation products like citalopram N-oxide, exhibited an increase over the two weeks of continuous operation. On average, citalopram concentration decreased by 81%, whereas the concentration of citalopram N-oxide increased by 19% with an O3 dosage of 0.28 g O3/g DOC. With the system operating at 2.17 g O3/g DOC, citalopram's average removal reached the LOQ, while the increase in citalopram N-oxide exceeded to 33%. Furthermore, all detected metabolites were eliminated to below the LOQ using GAC after two weeks of operation. Concentrations of most metabolites exhibited a linear decrease over time for biochar 1 and biochar 2, while for AIX, concentrations of certain metabolites increased over time. During all three O3 dosages (0.28, 0.96, and 2.17 g O3/g DOC), bromate concentrations remained below 5 µg/L. At the lower O3 dosage of 0.28 g O3/g DOC, the bromide concentration in the utilized WWTP effluent was 1.03 mg/L, whereas at the higher O3 dosages of 0.96 and 2.17 g O3/g DOC, the bromide concentrations were 0.52 and <0.50 mg/L, respectively. This variation resulted in an inability to assess the potential formation of bromate. Removal of DOC via different O3 dosages ranged from 19% to 26%, while GAC removed over 90% of DOC under all operational conditions. Conversely, AIX only removed less than 10% of initial DOC across all operational conditions, while in all cases, biochar 1 and biochar 2 removed within the range of 18-23% and 5-10%, respectively. In summary, ozonation exhibited high removal efficiency of pharmaceuticals and their metabolites at higher O3 dosages (>0.96 g O3/g DOC), while at lower O3 dosages (0.28 g O3/g DOC), a post-treatment became necessary for effective pharmaceutical removal. However, higher O3 dosages entail increased operational costs and pose a risk of transformation product formation. Therefore, employing combined systems for pharmaceutical and metabolites elimination is suggested as a preferable alternative to sole reliance on ozonation as the advanced treatment method. Comparative analysis of different post-treatment filter sorbents indicated that GAC yielded the most favorable results for pharmaceutical and metabolite removal. Conversely, the adsorption capacities of two distinct biochar types diminished over the continuous two-week operation, whereas GAC's performance remained consistent throughout. Biochar 1 outperformed biochar 2 in terms of pharmaceutical removal. AIX exhibited the lowest removal efficiencies, suggesting it may not suffice as a polishing step for ozonation when simultaneous removal of pharmaceuticals and PFAS is targeted. Overall, the combination of O3 with GAC demonstrated the most effective performance for pharmaceutical removal. Biochar holds promise as a more sustainable substitute for GAC, as it can be sourced from renewable materials like wood. However, there is a need for ongoing development to better understand the efficacy of combined O3-filter systems, with a focus on considering long-term operation. Before scaling up to a full-scale WWTP, conducting a life cycle assessment and feasibility analysis would be prudent steps to take.
Degradation of industrial micropollutants with sulfate radical–based advanced oxidation processes

(Lisansüstü Eğitim Enstitüsü, 2021) Montazeri, Bahareh ; Arslan Alaton, İdil ; 693111 ; Çevre Mühendisliği

Occurrence of micropollutants in wastewaters from the industries poses a serious threat to the environment and many of these contaminants are recalcitrant and/or toxic and/or biologically non-degradable. Therefore, the major concern is to treat the wastewater before being discharge into the environment. Among all these industrial micropollutants, in particular 3,5-dichlorophenol (3,5-DCP) from chlorophenols (CPs), 2,4-dichloroaniline (2,4-DCA) from chloroanilines (CAs) and iprodione (IPR) from hydantoins, have been drawn specific attention due to their commercial importance as raw materials, potential toxicity and refractory nature. 3,5-DCP is directly released to the aquatic environment through various waste streams such as wood pulp bleaching processes. 2,4-DCA is extensively used in manufacturing of pigments, optical brighteners and pharmaceutical agents. IPR as a fungicide is used to prevent gray mold on crops; however, its usage has been banned recently by the European Food Safety Authority. Considering the wide spread usage of the above-mentioned micropollutants and their incomplete removal in conventional industrial and urban wastewater treatment plants; they may end up in the aquatic environment, becoming threats to wildlife. Sulfate radicals (SO4●-)-based advanced oxidation processes (AOPs) have demonstrated that they have the potential to be efficiently applied in removing many organic pollutants from wastewater. In the first part of this study, three persulfate (PS)-mediated AOPs including one homogenous photochemical oxidation processes; ultraviolet-C (UV-C)-activated PS oxidation process (UV-C/PS), and two heterogeneous catalytic oxidation processes; zero-valent iron-activated persulfate oxidation process (ZVI/PS) and zero-valent aluminum-activated persulfate oxidation process (ZVA/PS) were employed in order to investigate the three micropollutants removal in distilled water (DW) and examine the influence of initial PS concentration (0.00 mM-1.00 mM) and pH on the treatment performances. UV-C/PS treatment of 3,5-DCP for all studied PS concentrations resulted in complete 3,5-DCP removal and the 3,5-DCP degradation rate increased by increasing the initial PS concentration which can be explained by an increase in the steady-state concentration of SO4●- generation in reaction solution. Increasing the initial pH to values more than 7.5, resulted in rapid 3,5-DCP degradation. Maximum 3,5-DCP removal efficiency was as 59% by 120 min ZVI/PS (PS=1.00 mM; pH=5.0); however, complete 3,5-DCP removal was obtained by decreasing pH to more acidic value after 20 min ZVI/PS (PS=0.50 mM; pH=3.0) treatment. ZVA/PS could not provide complete 3,5-DCP removal after 120 min treatment such that for the highest tried PS concentration.(1.00 mM; pH=3.0) resulted in only 31% 3,5-DCP removal. 2,4-DCA degradation by UV-C/PS, at all studied initial PS concentrations and pH values resulted in complete pollutant removal. PS activation with ZVI resulted in complete 2,4-DCA removal for initial PS concentration exceeding 0.50 mM such that after 80 min ZVI/PS (PS=0.75 mM; pH=5.0) treatment, complete 2,4-DCA was obtained; however, the required time to achieve complete 2,4-DCA with initial PS of 1.00 mM was longer (100 min) most probably as a result of SO4●- scavenging reaction with excess PS and/or ferrous ion. The highest 2,4-DCA removal (47%) by 120 min ZVA/PS (pH=3.0) treatment was obtained with initial PS concentration of 0.25 mM, below or beyond which the 2,4-DCA removal decreased. 2,4-DCA removal by 120 min ZVA/PS (PS=0.50 mM) treatment increased remarkably from 20% to 89% , when pH decreased from 3.0 to 1.5 suggesting that more acidic pH facilitated effective removal of 2,4-DCA due to ZVA corrosion. Complete IPR removal was achieved by UV-C/PS at all studied initial PS concentrations such that even with low PS (0.03 mM), complete IPR was obtained in 20 min. Increasing initial PS concentration in the range of 0.01 mM to 1.00 mM led to higher SO4●- concentrations and consequently faster IPR degradation rates. Alkaline hydrolysis of IPR was observed at initial pH of 9.0 and 11.0 during UV-C/PS treatment; however, complex pH effect on IPR degradation rate was observed at neutral and acidic pH values. ZVI/PS (pH=5.0) treatment of IPR, demonstrated that increasing initial PS concentration to more than 0.50 mM, appreciably improved ZVI/PS treatment of IPR. ZVA/PS was an efficient treatment only in IPR degradation such that even low PS concentrations (0.10 mM and 0.25 mM) with initial pH of 3.0 resulted in almost 80% IPR removal after 120 min treatment and for higher PS concentrations, complete IPR was obtained. In both heterogeneous treatments of all three model industrial micropollutants acidic pH values showed a better performance. Those oxidation processes from treatability of the micropollutants in DW resulted in complete micropollutant removal, were investigated under selected PS and pH conditions to correlate each micropollutant removal with chloride ion (Cl-) release, metal ion release, dissolved organic carbon (DOC) removal and PS consumption. Experiments conducted in DW indicated that for all three model industrial micropollutants, complete removals were achieved by UV-C/PS accompanied with dechlorination and appreciable mineralizations. 3,5-DCP was completely degraded by UV-C/PS (PS=0.30 mM; pH=6.3) treatment in 40 min accompanied with 95% DOC removal that was achieved after 120 min treatment. Maximum Cl- concentrations of 3.91 mg/L was obtained after 120 min UV-C/PS treatment of 3,5-DCP corresponding to practically 90% of the highest possible theoretical Cl- release of 4.35 mg/L. Practically complete 2,4-DCA removal was achieved after 10 min UV-C/PS (PS=1.00 mM; pH=6.0); however, with the progress of the treatment, dechlorination and DOC removal were proceeded such that 93% DOC removal and Cl- concentration of 3.64 mg/L were obtained after 40 min treatment. Beyond this treatment time, both DOC removal and dechlorination were practically stopped and remained constant probably due to PS depletion. IPR degradation was accompanied with rapid dechlorination and PS consumption. UV-C/PS (PS=0.30 mM; pH=6.2) treatment was also effective in IPR mineralization; 78% DOC was removed after 120 min treatment and maximum Cl- concentrations of 1.50 mg/L was obtained at the end of the reaction. For all three studied industrial micropollutants, complete/near-complete removals were achieved by ZVI/PS accompanied with iron (Fe) release; however, their mineralizations were partially (21%-50% DOC removal) after 120 min treatment. ZVA/PS was only effective in IPR removal; however poor mineralization was obtained after 120 min treatment. Treatability of the selected micropollutants was also examined in a synthetic tertiary treated urban wastewater (SWW) during the studied treatments due to the fact that the presence of different water constituents in the reaction solution may inhibit the oxidation performance. Experimental results of three model industrial pollutants by the selected treatments (UV-C/PS and ZVI/PS) in SWW, revealed complete micropollutant removals; however, their mineralizations were partially and different compared to DW. UV-C/PS treatment of 3,5-DCP in DW that exhibited appreciable mineralization of 3,5-DCP, demonstrated worse treatment performance compared to ZVI/PS when applied in SWW (26% DOC removal and 41% DOC removal in SWW after 120 min treatment by UV-C/PS and ZVI/PS, respectively). Partial mineralizations of 2,4-DCA in SWW by 120 min UV-C/PS and ZVI/PS treatments were obtained as 57% and 35% DOC removals, respectively which were lower compared to DW revealing performance of both treatments decreased in complex medium. The experiments in DW exhibited the superior performance of the UV-C/PS for IPR mineralization (78% DOC removal after 120 min); however, the oxidation performance of UV-C/PS in SWW decreased appreciably and resulted in 24% DOC removal after 120 min. 40% DOC removal after 120 min was observed with ZVI/PS being the most efficient process in SWW. UV-C/PS treatment of all three selected micropollutants, was most negatively affected when apply in SWW most probably due to UV-C light absorption of SWW constituents hindering effective absorption by the target pollutant. Vibrio fischeri (V. fischeri) and Pseudokirchneriella subcapitata (P. subcapitata) were employed as the organism tests to assess changes in acute toxicity during application of the studied treatments. Responses of the two mentioned test organisms were rather different; higher inhibition rates were observed on P. subcapitata than V. fischeri. While the percent relative inhibition of the original 3,5-DCP on P. subcapitata was almost 20%, the inhibitory effect increased after 80 min UV-C/PS treatment reaching to 47%. After 80 min ZVI/PS treatment of 3,5-DCP, the percent relative inhibition of treated samples on P. subcapitata did not change appreciably. The percent relative inhibition of the original 2,4-DCA on P. subcapitata was in the range of 20%-28%; however, the inhibitory effect increased and reached 72% after 120 min UV-C/PS treatment. The percent relative inhibition of original IPR samples on P. subcapitata was obtained as <10%; however, it reached 56% and 39% after 120 min UV-C/PS and ZVI/PS, respectively. During the application of selected treatments in DW, the genotoxicity of original micropollutants and their AOPs-treated samples were explored using a mutant strain of Salmonella typhimurium TA 1535; however, no significant genotoxic effect was observed. At the final stage of this study, the type and nature of possible evolved degradation products during the selected treatments of three model industrial pollutants in DW were examined by ion chromatography, liquid chromatography and mass spectrometry analysis in order to gain a deeper insight into the formed radical reactions with the target pollutants. Hydroquinone, acetic acid and Cl- could be detected and quantified in the reaction solution during UV-C/PS and ZVI/PS treatments of 3,5-DCP. Aniline and acetic acid formations were evidenced during UV-C/PS treatment of 2,4-DCA accompanied with dechlorination; however only acetic acid was identified during ZVI/PS. LC analysis confirmed the formation of 2,4-DCA, hydroquinone, acetic acid and formic acids as the major aromatic and aliphatic degradation products of IPR during UV-C/PS while hydroquinone, lactic acid and acetic acid was evidenced for ZVI/PS treatment of IPR.
Dynamic membranes in aerobic membrane bioreactor systems for municipal wastewater treatment

(Graduate School, 2021-06-08) Işık, Onur ; Demir, İbrahim ; Özgün, Hale ; 501142704 ; Environmental Sciences Engineering and Management ; Çevre Bilimleri Mühendisliği ve Yönetimi

The amount of municipal wastewater produced around the world is expected to increase parallel to the increase in population. Therefore, the treatment of municipal wastewater is very crucial for public health. Conventional activated sludge systems have been used for the treatment of municipal wastewater for a long time. Due to limited area availability and stringent discharge standards in most cases, compact treatment systems enabling high effluent quality have become attractive recently. Membrane bioreactor (MBR) technology is a good alternative to conventional activated sludge systems. There are several advantages of MBR technology over conventional biological treatment systems. Low footprint and high permeate quality can be considered as the most distinguishing features of the MBRs. Due to the retention of high suspended solids concentration in the bioreactor, smaller reactor volume and low sludge production can be achieved by the MBR process. However, some constraints have been observed during the operation of MBRs including membrane fouling and membrane costs. Dynamic membrane (DM) technology is a promising solution for problems encountered during the operation of MBRs for wastewater treatment. Membranes can be substituted with coarse-pore filters made of low-cost materials such as meshes or fabrics in dynamic membrane applications for cake (DM) layer formation. DM is a secondary layer formed on a low-coast porous support material. DM layer acts like a Microfiltration (MF) or Ultrafiltration (UF) membrane and keeps the sludge particles inside the bioreactor providing high permeate quality. Besides, physical cleaning, without using chemical reagents, may be enough for cleaning in dynamic membrane bioreactors (DMBRs), thus, the operational costs can be reduced. Flat sheet submerged module configurations were mostly used for aerobic DMBR studies for municipal wastewater treatment in the literature. Also, few studies used tubular modules in DMBRs. However, no studies reported using hollow fiber modules in the literature. The main aim of this thesis was to investigate the applicability of hollow fiber DM for municipal wastewater treatment in an aerobic DMBR. This thesis was conducted in 6 Stages. In stage 1, a hollow fiber polyester fabric support material was used for DM formation and compared with a commercial hollow fiber UF membrane. The system was fed with medium strength synthetic municipal wastewater to keep the characteristics of the wastewater same, and to evaluate the treatment and filtration performances of both membranes clearly. Morphological analyses were also carried out for DM and UF surfaces. The system was operated continuously at a flux of 5 L/m2·h for 85 days. High chemical oxygen demand (COD) removal efficiency and total suspended solids (TSS) rejection were achieved by the DM. Transmembrane pressure (TMP) of the DM was higher in comparison to the UF membrane, which was related to the formation of the cake layer in DM. In Stage 2, impact of support material type on DMBR performance was investigated for municipal wastewater treatment. A hollow fiber polyester support material was compared with a glass fiber support material in terms of treatment and filtration performances. Medium strength synthetic municipal wastewater was used for a stable feed characteristics. Similar treatment performances were obtained with each membrane achieving high removal efficiencies for COD(>97%) and TSS (>99%) parameters. Higher TMP was observed for glass fiber material in comparison to polyester material. Based on morphological analyses, dynamic layers formed on both support materials had similar compositions, organic and inorganic materials. A homogeneous layer was formed on a polyester support material, while fine particles were deposited between the filaments of glass fiber support material, which caused clogging. In Stage 3, a hollow fiber polyester fabric support material was used for DM formation for raw municipal wastewater treatment. The wastewater had average COD concentration of 413 mg/L, sCOD concentration of 208 mg/L and TSS concentration of 259 mg/L. Treatment and filtration performances were evaluated. High treatment performance was obtained in the permeate achieving over 93% of COD removal efficiency and low TSS concentration (<10 mg/L) in the permeate. The average TMP value was observed as around 598 mbar after the system reached stable conditions. In Stage 4, effect of different TSS concentrations on the DM layer was evaluated in terms of biological treatment and filtration performances. Hollow fiber polyester support material was used for DM layer formation. Treatment and filtration performances of the DMBR were investigated at two different TSS concentrations (5 g/L; 10 g/L). The DMBR was operated at a flux of 18 L/m2·h at each condition. High treatment performance and permeate quality were achieved at each sludge concentration. However, a shift to a relatively higher range in particle size distribution of permeate was observed at high sludge concentration. Furthermore, higher TMP was observed at the sludge concentration of 10 g/L, resulting in a rapid clogging. Overall, results indicated that selection of the optimum sludge concentration played a significant role in achieving homogeneous and stable DM layer in DMBRs. In stage 5, hollow fiber polyester support material was used for DM formation and compared with a commercial UF membrane in terms of micropollutant and heavy metal treatment performance from raw municipal wastewater, also biological treatment and filtration performances were evaluated. The removal of different micropollutants; sulfamethoxazole, ciprofloxacin, trimethoprim, caffeine and acetaminophen, was assessed for both membranes. The membranes were operated at a flux of 10 L/m2·h. High TSS (>99%) and COD (> 91%) removal efficiencies were achieved with both membranes. Similar high removal efficiencies of micropollutants (>68.3->99.7%) were achieved with both membranes. DM was operated at higher TMP compared to UF membrane, since DM layer was formed on the support material. Morphological analyses were conducted for both membranes to get insight to the DM layers which accumulated on the membranes. In Stage 6, effect of using different inoculum on DMBRs performance was investigated. Excess sludge from HRAS and conventional activated sludge system retuned activated sludge were used as inoculums. Conventional UF membrane was used in parallel with a dynamic membrane (DM) in the same reactor to be operated at the same conditions. Both sludges were characterized to understand the changes during the operational period. Biological treatment and filtration performances of both membranes were investigated. High TSS (>99%) and COD (> 86%) removal efficiencies were achieved with both membranes for both inoculum sludge. Because of the inoculum sludge characteristics, lower TMP values were observed for DM at Phase-2. Morphological analys (ESEM measurement) was conducted to understand the effect of different inoculum on the sludge cake on the surface of the membranes.
Effect of different precursors and disinfection processes on the formation of nitrosamines

(Graduate School, 2023-07-18) Coşkun, Burçin ; Mantaş Pehlivanoğlu, Elif ; 501112704 ; Environmental Sciences and Engineering

In drinking water treatment, it is important to focus on public health and ensure the quality of the treated water. Disinfection is a must-process which is applied before supply of drinking water to the water supply system. Disinfection byproducts such as Trihalomethanes (THM), Haloacetic acids (HAA), and Nitrosodimethylamine (NDMA) are present in different water media, i.e., drinking water in treatment facilities, rivers, and wastewaters. The effect of NDMA on human health has become an important issue in recent years, and investigations are planned to define NDMA precursors and the conditions that lead to the formation of NDMA. Nitrosamines, the group of compounds NDMA belongs to, are carcinogenic and toxic compounds with negative effects even at low concentrations. Peter Magee's discovery led to investigations to determine their carcinogenic properties. Nitrosamines are found in industrial products and food industry, and can also form during disinfection of potable water. Although the MCL in drinking water are usually set as the concentration that increases cancer risk one in a million, the concentration of NDMA at which the public has to be warned is set to be 10 ng/L by California Department of Public Health (CDPH, 2022) since the concentration of NDMA causing a one in a million increase in cancer risk 0.7 ng/L (EPA IRIS 1993) is hard to measure properly. NDMA is a disinfection by-product of chlorination, chloramination and ozonation processes, with chloramination producing the highest amount. Precursors are organic nitrogen containing compounds that are converted to nitrosamines during these processes. This thesis aims to reveal the formation potential of NDMA at the end of disinfection processes from selected precursors in different types of water media. It is also aimed to compare the disinfection processes based on the NDMA concentration formed from the potential of precursors in different water matrices. The main steps of this thesis are NDMA method optimization, precursors potential determination, swimming pool monitoring, and surface water monitoring. Optimization of method used for NDMA includes the change of parameters such as mobile phase content and the gradient of them, and LC-MS/MS parameters such as tube lens offset, collision energy. Pharmaceuticals, swimming pool, and surface water were investigated to determine their potential to form NDMA. In addition to target analysis measuring NDMA, non-target analysis was also performed. Transformation products that formed during chloramination of Doxylamine were investigated and the compounds that lead to formation of other products and not NDMA were determined using LC-Q Exactive Hybrid Quadropole-Orbitrap MS and Compound Discoverer Programme version 2.1. NDMA formation in presence of pharmaceuticals which are known precursors resulted with a concentration of 1380 ng/L for Ranitidine, 344 ng/L for Sumatriptan, 156 ng/L for Doxylamine and 4 ng/L for Metformin. The mixture of all four pharmaceuticals resulted in formation of 1896 ng/L NDMA. The highest amount of NDMA was formed by Ranitidine as it was expected from the previous studies in the literature. In order to research the possibility of synergistic or antagonistic effects of the pharmaceuticals in terms of NDMA formation, binary combinations were also examined under formation potential test conditions and 1841 ng/L, 1623 ng/L, 1548 ng/L, 513 ng/L and 322 ng/L NDMA was formed respectively for the couples of Ranitidine-Sumatriptan, Ranitidine-Doxylamine, Ranitidine-Metformin, Sumatriptan-Doxylamine and Metformin-Doxylamine. Ranitidine dominated the formation of NDMA as it was the same with the single formation potential test. To simulate real conditions in the water treatment plants and water supply networks, chloramination was performed in lower concentrations of chlorine than formation potential test. As expected, the NDMA concentration formed during chloramination (Cl2/N ratio of 4:1; Cl2: 2 mg/L) was lower than the NDMA concentration obtained during the formation potential test. The time dependent change of NDMA concentration for each single pharmaceutical was observed and 3 different time intervals were chosen; 30 min, 2 h and 6 h. At the end of the 6h- period the highest amount of NDMA was formed for each of every pharmaceutical except Metformin. Metformin behaved differently and NDMA formed at the second hour decreased at the end of 6 h. In ozonation, the same behavioural trend for Metformin was observed and the concentration of the NDMA formed during ozonation was decreased after a while. Also for the ozonation process the other pharmaceuticals behaved same with Metformin and NDMA was degraded in the second period of application time. The possible effects between pharmaceuticals during formation of NDMA was also investigated under formation potential test conditions. The results from the tests conducted with binary combinations of pharmaceuticals suggested that the relationship between Doxylamine and Metformin was synergistic as they formed higher amount of NDMA when they were together. Other binary combinations of pharmaceuticals did not have synergistic or antogonistic effect when they were together during formation potential test. Sakarya river was investigated as an example of a surface water for the existence of NDMA and its precursors.
Enhancing wastewater treatment efficiency through laccase-mediated biodegradation of trace organic contaminants

(Graduate School, 2023-09-07) Yüksek, Gülten ; Çokgör Ubay, Emine ; 501122708 ; Environmental Sciences and Engineering

Recently, concerns have been raised about trace organic contaminants (TrOCs) in wastewater and their potential adverse effects on human health and the environment. TrOCs found in wastewater are a cause for concern due to their ability to contaminate drinking water sources and the environment. Consuming contaminated water with TrOCs can pose health risks to humans. It can also harm aquatic life, leading to ecosystem disruptions and potential entry into the food chain. Additionally, certain TrOCs have properties that can disrupt endocrine systems, which can further impact human health and the stability of the environment. Researchers have explored various treatment methods, including fungal treatments and laccase enzymes. However, there needs to be more literature regarding selecting fungal strains and optimizing laccase-based biodegradation mechanisms for efficient TrOC removal. This thesis aims to fill that gap by delving into laccase production, purification, immobilization, and its impact on degrading TrOCs. By exploring various aspects of this process, we can work towards developing more efficient and sustainable methods of reducing the negative impact of TrOCs on our environment. The current study encompasses a comprehensive examination of different fungal strains, including Trametes hirsuta, Pleurotus dryinus, Tramates versicolor, and Coriolopsis polyzona, to evaluate their laccase productivity and response to trace elements. The sorption mechanisms of laccase-mediated fungal treatment on targeted TrOCs were also explored. Furthermore, the study investigated free Laccase's purification and removal efficiency and the potential of laccase mediator systems (LMS) and immobilization techniques for enhanced biodegradation. The findings from this study provided valuable insights into the optimization and cost-effectiveness of laccase-based bioremediation strategies for sustainable wastewater treatment and environmental protection. Throughout experiments, fungal strains have been found to play a crucial role in producing external laccase activities. One of the advantages of using fungi is its high adsorption capacity, thus making it an effective pollutants-removal method. It is interesting to note that the reactions of internal and external enzymes on selected compounds differ from one compound to another. It has been observed that Laccase does not affect all types of TrOCs. It is essential to establish reasonable system control measures to prevent the release of adsorbed contaminants or enhance laccase activities to optimize the fungal treatment. It also highlights the importance of degradation by external enzyme activity and/or adsorption mechanisms as a primary step in removing TrOCs, followed by internal enzyme activities that remove some of the existing compounds after reaching a specific limit of adsorption capacity. Following these experiments, the study focused on the efficiency of laccase-mediator systems in removing recalcitrant organic contaminants. The results showed that laccase-mediator systems efficiently removed recalcitrant organic contaminants such as atrazine (ATZ) and carbamazepine (CBZ) in individual compound solutions, even at environmentally relevant concentrations. The removal efficiency of ATZ and CBZ in single compound solutions sets was observed up to 100% during the first 36h, and no significant difference was observed for all the tested mediators. Regardless of single compound sets, ATZ and CBZ in mixed compound sets removal were less than 65%. Also, the phenolic contaminant acetaminophen (APAP) is examined as a potential mediator candidate for laccase, and the results showed positive results. The study on laccase mediator systems led to a sub-study on "Laccase Catalyzed Iodine Synthesis as Disinfectant." Results showed that acetophenone was a more efficient mediator than APAP for iodine synthesis. Increasing APAP concentration increased iodine synthesis with a maximum of 0.5 mM. High concentrations of KI (>20 mM) inhibited laccase activities. Under 10 U/L, 20 mM KI concentration was most efficient for enzyme activity, chemical consumption, and contaminant removal efficiency. APAP and other phenolic compounds in real wastewater could serve as a mediator and increase the system's efficiency. Laccase-catalyzed iodine demonstrated high disinfection performance in fecal coliform tests, with the optimal concentrations observed at 15 and 20 mM KI. The study examined the effectiveness of laccase immobilization and optimization. The immobilization was achieved by bonding and adsorbing on mesoporous silica-covered packing. The results showed that the immobilized laccase was more efficient and stable in harsh conditions than the free enzyme. It had broader optimal temperature and pH ranges and better storage stability. This study suggests that immobilization can be a promising solution for industries that rely on sensitive biological enzymes. Particularly noteworthy is the use of mesoporous silica-covered packing and laccase-abundant broth instead of pure laccase for the immobilization, which offers substantial financial benefits. This approach facilitates the immobilized enzyme at any desired time, allowing for multiple cycles of re-utilization. Such a strategy holds tremendous potential for enhancing the efficiency and sustainability of enzymatic processes in various industries. The resulting enzyme immobilization yield on the support was between 56-74 %, and the highest immobilization efficiency, 1.8 U/g packing, was achieved in the sets where initial laccase activity was limited (15 U). The unique part of this study was that the silica-covered mesoporous packing was immobilized by contacting with 15000 U laccase-abundant broth without the purifying step, which consumes many chemicals. The immobilization yield was 60%, and the highest activity was 346 U/g packing. The immobilization process remained consistent after 2 days, indicating that most laccase molecules were adsorbed within the pores without undesired lateral interactions. The immobilized laccase exhibited good reusability and retained more than 50 % of its initial activity after being stored at 4ºC for 5 months. It was addressed that the best pH was selected as 7 to condition silica-covered packing with glutaraldehyde, while the optimum pH was 3.5 or 5.5 to immobilize laccase on the silica-covered packing. The optimum glutaraldehyde concentration was also selected as 3%. Unfortunately, it is not enough to immobilize laccase; it requires a high amount of laccase immobilization, so it requires a high amount of laccase production. It examined the potential of non-polar solvent hexane and polar solvents, methanol, and ethanol, as inducers for laccase production and the established inducer copper. Also, the abundant hexane effluent from silica production is tested as an inducer to diminish the ecological footstep of the study. The impact of mesoporous silica-coated plastic packing on free laccase production and concomitant immobilization was evaluated under both sterilized and unsterilized conditions to understand if the costly step-sterilization can be avoided. The study revealed that copper and ethanol were the most effective inducers, with the highest total laccase activity achieved at a copper concentration of 0.5 mM under sterilized conditions. The groups treated with copper and ethanol also showed immobilized laccase activity under unsterilized conditions. Our evaluation of concomitant laccase immobilization showed that the sterilized waste hexane sets had the highest activity of immobilized laccase, with a value of 1.25 U/mg packing. The hexane sets under sterilized conditions had the second-highest immobilized enzyme activity. It was found that even though a small amount of immobilized laccase activity was detected in the packings of the copper and inducer sets in the unsterilized sets, the desired levels of free and immobilized laccase activity were not achieved in comparison to the sterilized sets. These results likely are because the sets were not sterilized, which could have led to other species due to planned -microbial contamination from the laboratory. This presence of several fungal species could have had a significant impact on the reduction of laccase activity. Using pure cultures and ensuring a sterilized system is essential to avoid contamination. This step of the study focuses on one of the most remarkable outcomes of the current research: the successful application of waste hexane as an inducer for concomitant immobilized laccase activity. This innovative approach to laccase production could lead to a promising method for decreasing running costs and improving the cost-efficiency of enzymatic processes in wastewater treatment plants, both industrial and domestic.
Environmental and economic assessment of zero waste management

(Graduate School, 2023-12-08) Maçin, Kadriye Elif ; Arıkan, Osman Atilla ; Damgaard, Anders ; 501172716 ; Environmental Sciences Engineering and Management

The waste management (WM) approach for the protection of resources known as "zero waste" (ZW) has become popular in recent years. A number of measures have been taken and facilities have been installed to facilitate improved management of municipal solid waste (MSW). ZW to landfill targets have gained significant traction worldwide, including in Turkiye. The aim of this thesis is to assess the environmental and economic results of WM pathways within the context of an increasingly applied ZW approach.This study evaluates the sustainability of municipal solid WM through the ZW goal on multiple scales (Istanbul and Ayazağa Campus). The thesis provide a framework that enables institutions to develop a goal-oriented WM strategy using material flow analysis (MFA) and life cycle assessment (LCA). In addition to presenting the framework, a case study was conducted on a campus scale by using primary and secondary data. The framework assumes that no prior data is available, and the study will begin by collecting primary data on campus. For providing primary data; waste characterization and recycling potential of the Istanbul Technical University (Turkiye) Ayazağa Campus before (2019) and after (2022) the ZW management strategy the campus was divided into four distinctive groups, which are (i) academic (ii) administrative (iii) residential/dormitory and (iv) cafeteria. First, initial field study was conducted afterwards (for waste characterization and recycling potential), the new containers were placed. Students and campus personnel have been trained in within the scope of ZW management practices through both in-person and online seminars. The final phase of the study, the second field work, was completed. The results demonstrate that the waste generation rate in the pilot areas fluctuates between 0.045-0.190 kg/cap/day, but it decreases to 0.011-0.117 kg/cap/day in the second field study. The first field study had a potential recycling rate of 76.3%, but then it dropped to 68.2% in the second study. The MFA results indicate that landfill diversion ranges between 29.8% to ~99-100%, some residuals or ash from the incineration plant will still be disposed in landfill. Furthermore, simply diverting waste from landfill does not necessarily lead to circularity or directly address sustainable consumption and public attitudes towards ZW goals. The study framework aims to address potential challenges in campus-based, goal-oriented WM studies. Future case studies from other institutions and their campuses could help validate and improve this methodology. Based on the Ayazağa waste characterization results, the efforts to establish a ZW management system also led to a reduction in waste generation and increase in recycling performance. However, further studies are still required to assess the ZW's public awareness activities. In addition, a case example was developed based on ITU Ayazağa campus, Turkiye, with annual separated food waste of 577 tonne per year to provide a more circular and decarbonised economy. A LCA was conducted using the EASETECH software. Four scenarios were evaluated: anaerobic digestion, composting, incineration, and landfill. Of these, incineration resulted in the highest CO2-eq savings (-192 kg CO2-eq/tonne FW), but lacked decoupling and circularity of resources. Conversely, anaerobic digestion demonstrated the highest circularity and lowest toxicity. Based on these findings, anaerobic digestion was selected for further investigation. Economic transactions for the anaerobic digestion system's business models were analysed,including revenues, municipality fees and operating costs. The new economic model is expected to align with circular economy strategies and promote stakeholder collaboration as a significant social outcome.
Fabrication of thin film nanocomposite pressure retarded osmosis (PRO) membranes using cellulose nanocrystal (CNC) and evaluation of performances in the processes

(Graduate School, 2021-02-02) Paşaoğlu, Mehmet Emin ; Koyuncu, İsmail ; 659118 ; Environmental Engineering

Nowadays, owing to quick world population growth and abrupt economy, high water demands desire innovative technologies in order to ensure clean and safe water with lower energy use. Severe environmental emissions arising by the consumption of fossil fuels often needs us to build energy harvesting technology which are environmentally sustainable. As an advanced technology, osmotic membrane processes consisting of forward and pressure-retarded osmosis, are conceived to be conspicuous technologies for the treatment, recycling and reuse of wastewaters and the harvesting of salinity gradient energy which is called "Blue Energy". Nevertheless, forward osmosis (FO) and pressure retarded osmosis (PRO) are at the level of growth yet. It is difficult piece of work to fabricate osmotic membranes obtaine high water permeability and perfect ion retention. The ideal osmotic membrane candidate can be a thin film composite membrane satisfy the conditions which has high water permeation and as soon as low reverse salt flux ratio. Furthermore, for the membrane to endure relatively high hydraulic pressures in PRO systems, certain mechanical properties are vital. Thankfully, membranes that are fabricated with electrospinning method have an excellent capability to overcome all specifications of the perfect support layer in consequence of porous structure characteristics and simplicity with that nanomaterials may be integrated to enhance the nanofibers mechanical strength. Apart from this, interfacial polymerization (IP) may be accomplished to electrospun nanofiber membrane to achieve a very thin selective polyamide coating. TFN membranes may show tremendous potential in osmotically driven membrane processes after integrating nano additives into their support layer. The aim of this thesis to carry out and design a comprehensive study on the development of reinforced pressure retarded osmosis membranes. Specifically, this thesis presents the development of novel nanofiber supported thin film composite membranes with high water permeability and excellent selectivity for solvents, while showing an excellent mechanical strength for PRO processes. Interfacial polymerization reactions were used to construct very thin polyamide selective layer on the support, and electrospinning process was used to fabricate a number of support layers. Initially, we investigated the potential to use flat sheet electrospun polyacrylonitrile nanofibers as support support layer to fabricate PRO membranes. Polyamide TFCs were successfully applied on five different substrate containing 0,1,2,5,10% crystal nanocellulose (CNC) in 16% PAN polymer solution. PRO membranes successfully fabricated via tailor-made flat sheet fabrication unit. It is concluded that PAN and CNC generated a complete mixture according to SEM, FTIR, DMA & contact angle analysis findings.The addition of CNC improved the mechanical strength of PAN support layers which is the main phenomenon in PRO applications. The newly developed membrane can achieve a higher PRO water flux of 300 LMH, using a 1 M NaCl draw solution and deionized water feed solution. The corresponding salt flux is only 1.5 gMH. The reverse flux selectivity represented by the ratio of water flux to reverse salt flux (Jw/Js) was able to be kept as high as 200 L/g for PRO operation. Following the success of flat-sheet TFN PRO membrane fabrication, improvements need to be done to increase packing density of fabricated final membrane modules. In this point, we used a novel technique to fabricate tubular membranes for PRO applications. The newly fabricated membrane achieves a higher PRO water flux of 405.38 LMH with using a 1 M NaCl and a DI as feed water. The corresponding salt flux is found as 2.10 gMH which is higher than flat sheet membranes. The selectivity of the reversed flux represented by the ratio of the water flow to the reversed salt flux (Jw/ Js) was able to be kept as high as 193.03 L/g for PRO operation.As far as we know, the performance of the work developed membrane in this study has shown better performance than all PRO membranes reported in the literature previously.
High-rate activated sludge process for energy efficient wastewater treatment

(Graduate School, 2023-10-25) Gülhan, Hazal ; Öztürk, İzzet ; 501172704 ; Environmental Sciences Engineering and Management

The conventional activated sludge (CAS) process used in wastewater treatment is inefficient in terms of energy and requires a large space. CAS plants can only recover around 33% of the energy in wastewater, which is a significant drawback. The growing urban population and wastewater volume pose a challenge in land-constrained areas like Istanbul. Therefore, it is important to adopt innovative treatment processes that minimize land requirements, maximize organic matter capture, and reduce carbon dioxide (CO2) losses. This approach, known as carbon capture, redirection, or harvesting, focuses on diverting carbon from wastewater to the sludge line for biogas production in anaerobic digesters. High-rate activated sludge (HRAS) systems, developed in the 1980s, aim to redirect carbon from wastewater to anaerobic digesters for energy production, offering an alternative to primary sedimentation in wastewater treatment plants (WWTPs). They are operated at high organic loading rates and have short sludge retention times (SRTs) and hydraulic retention times (HRTs). In the B-stage, pollutant removal primarily occurs through biological oxidation at lower organic loading rates. The HRAS process has proven to be superior to CAS and primary sedimentation units with regard to carbon redirection and methane generation during anaerobic digestion. However, several areas for improvement have been identified based on existing literature. Firstly, there is a lack of information regarding the performance of HRAS systems when equipped with lamella clarifiers, which can enhance the performance of solid-liquid separation in WWTPs. Secondly, existing mathematical modeling studies of the HRAS process are either overly complex or overly simplistic, often overlooking important processes like adsorption and focusing primarily on carbon removal. Furthermore, sensitivity and uncertainty analyses, commonly employed to assess the robustness of models, have not been extensively applied to HRAS system models. Thirdly, despite its potential, there is a scarcity of literature on integrating the HRAS process into water reclamation practices, which could benefit from its smaller spatial footprint, lower energy consumption, and nutrient-rich effluent. Lastly, it is essential to address the fact that the use of coagulants in the HRAS process improves phosphorus removal efficiency while increasing operational costs. Limited research has been conducted on the impact of using water treatment plant (WTP) sludge on the anaerobic digestion of waste sludge in WWTPs and its influence on HRAS process performance and energy recovery. This thesis explores the potential of the HRAS process in sustainable wastewater treatment and investigates the following research topics: Study 1, optimum operational conditions for the HRAS process with a lamella clarifier, Study 2, mathematical modelling of the HRAS process to provide a practical tool for future implementations of HRAS plants, Study 3, integration of membrane filtration for reclaimed water production for industries, Study 4, post-treatment alternatives for HRAS process effluent for irrigation purposes, and Study 5, the reuse of WTP sludge to enhance treatment performance and resource circularity. These topics were investigated through pilot and laboratory scale studies using real municipal wastewater. A pilot-scale HRAS plant with a lamella clarifier was constructed in a full-scale preliminary WWTP (PWWTP) in Istanbul. The plant was operated under various conditions for two years to address the research topics. Laboratory-scale experiments involving membrane filtration and chemical precipitation were conducted using real municipal wastewater collected from the same PWWTP. Study 1 focused on determining the optimal operational conditions for the pilot-scale HRAS system coupled with a lamella clarifier. The study found that using a lamella clarifier resulted in lower total suspended solids (TSS) concentrations in the effluent and required a smaller footprint compared to a conventional clarifier. The optimum operational condition was identified as Stage 1, with an HRT of 75 minutes and a dissolved oxygen (DO) concentration of 0.5 mg/L. This condition demonstrated the best effluent quality, highest carbon capture, and highest production of extracellular polymeric substance (EPS). The study also found that reducing the HRT increased biosorption but led to increased chemical oxygen demand (COD) loss through the effluent. Lower DO concentrations promoted carbon redirection but resulted in weak floc formation and increased particulate COD (xCOD) loss. Meanwhile, higher DO concentrations enhanced COD oxidation but allowed more particles to escape through the effluent. Overall, the HRAS process with a lamella clarifier showed promising particulate matter removal efficiency and the potential for reclaimed water production. Studies 3 and 4 further investigated the inclusion of the HRAS process in reclaimed water production systems. Study 2 developed and calibrated a mathematical model for HRAS systems by integrating Activated Sludge Models No. 1 and 3 (ASM1 and ASM3), accounting for substrate adsorption and storage. The calibration utilized dynamic data from the pilot-scale HRAS plant and identified influential parameters like maximum specific growth rate (µ), growth yield (YH), storage yield (YSTO), storage rate (kSTO), decay rate (b), and readily biodegradable substrate half-saturation coefficient (KS1). The calibrated model demonstrated satisfactory efficiencies for mixed liquor suspended solids (MLSS), total COD (tCOD), soluble COD (sCOD), xCOD, total nitrogen (TN), ammonia nitrogen (SNH), total phosphorus (TP), soluble TP (sTP), and particulate TP (xTP), all above 70%. However, an uncertainty analysis exposed discrepancies in sCOD. The study also highlighted the potential to enhance sTP dynamic behavior estimation. The low model efficiency is likely due to variations in wastewater characteristics, especially the phosphorus (P) fractions, which were not dynamically considered in the model. Another reason could be the precipitation of phosphate salts, which was not included in the model. Overall, the study offers valuable insights into influential parameters and opportunities for refining the HRAS process modeling. Study 3 encompassed both experimental and cost analyses to evaluate different treatment configurations for water reclamation. Six configurations were examined, incorporating pre-treatment options like direct membrane filtration (DMF) via microfiltration (MF) and ultrafiltration (UF) membranes, and HRAS, and final treatment alternatives such as nanofiltration (NF) and reverse osmosis (RO). The performance of NF and RO membranes ensured that the reclaimed water from each scenario met the required quality standards for cooling tower makeup water. Despite HRAS producing effluent with higher turbidity compared to MF and UF membranes, the cost analysis revealed that the HRAS+NF configuration (C3) offered the most cost-effective treatment, with a cost of 0.38 €/m3 of wastewater. This cost advantage was due to the lower expenses associated with the HRAS process compared to MF and UF membranes.
İstanbul'da ulaştırma sektörünün iklim değişikliğine etkisinin belirlenmesi

(Lisansüstü Eğitim Enstitüsü, 2021-09-16) Güzel Doğan, Tuğba ; Alp, Kadir ; 501142712 ; Çevre Bilimleri Mühendisliği ve Yönetimi

İklim değişikliği, günümüzde küresel ölçekteki en önemli problemlerden biri haline gelmiştir. İklim değişikliğinin temel sebebi olarak gösterilen küresel ısınma ise, atmosferde bulunan sera gazları (CO2, CH4, N2O, HFCs, PFCs ve SF6) tarafından dünyadan yansıtılan ışınların tutulması sonucu yerkürenin ısınması şeklinde tanımlanmaktadır. Sanayileşme öncesi dönemden bu yana, küresel ortalama yüzey sıcaklığı 1°C artış göstermiştir. Ayrıca, insan faaliyetleri günümüzdeki atmosferik CO2 konsantrasyonunu sanayi devrimi öncesi seviyenin neredeyse %50 üzerine çıkarmıştır. İklim değişikliğinin olumsuz etkilerine karşı küresel düzeyde çözüm bulunabilmesi amacıyla çeşitli adımlar atılmaktadır. Bu doğrultuda, 2015 yılında 21. Taraflar Konferansı'nda kabul edilen ve küresel ısınmanın sanayi öncesi seviyelere kıyasla 2°C'nin çok altında, tercihen 1,5°C ile sınırlandırılmasını hedefleyen Paris Anlaşması küresel emisyonların en az % 55'ini oluşturan 55 ülkenin onayı ile 4 Kasım 2016'da yürürlüğe girmiştir. Tarihi Paris Anlaşması'nın kabul edildiği COP21 öncesinde ülkeler, kendi yerel koşulları ve yeteneklerini dikkate alarak hazırladıkları sera gazı emisyonlarını azaltma isteklerini BMİDÇS Sekreteryası'na iletmiştir. Niyet Edilen Ulusal Olarak Belirlenmiş Katkı olarak nitelendirilen bu iyi niyet beyanını ülkemiz 30 Eylül 2015 tarihinde Sekreterya'ya iletmiş olup, sera gazı emisyonlarında 2030 yılında artıştan %21 oranında azaltım katkısı hedeflemiştir. Bu kapsamda, ulaştırma sektörü sera gazı salımına katkıda bulunan önemli bileşenlerden birini oluşturmaktadır. Ülkemizde ulaştırma sektörü birincil enerji tüketimi 27,7 milyon TEP ile sektörel tüketimler arasında sanayi tüketiminden sonra ikinci sırada yer almaktadır. Ulaştırma sektörü birincil enerji tüketiminin yaklaşık %93'ünü karayolları oluşturmaktadır. Sera gazı salımına katkıda bulunan motorlu kara taşıtı sayısı ülkemizde gün geçtikçe artmaktadır. Türkiye'nin 2019 yılı motorlu kara taşıtı sayısı yaklaşık 23,2 milyon olup, bu değerin 4,2 milyonu İstanbul'daki araç sayısıdır. 5.461 km2 ile ülke yüzölçümünün yalnızca %0,7'sini oluşturan İstanbul, küçük bir il olmasna rağmen nüfus ve ekonomik çıktı açısından ulusal olarak baskın bir rol oynamaktadır. İstanbul, 15,52 milyon nufusu ve 15.285 ABD Dolar kişi başı gayri safi yurtiçi hasıla (GSYİH) değeri ile Türkiye'nin en büyük ve en gelişmiş metropol şehridir. Ayrıca, 2987 kişi/km2 nüfus yoğunluğu ile zirvede yer almaktadır. İstanbul'da şehir içi ulaşım karayolu, raylı sistem ve denizyolu ile sağlanmaktadır. İstanbul Boğazı şehir içi ulaşımda olduğu kadar uluslararası ulaşımda da önemli bir rol oynamaktadır. İstanbul'un Anadolu ve Avrupa Yakası'nda toplamda 2 adet havalimanı bulunmaktadır. Bu doğrultuda, bu çalışma kapsamında İstanbul'da ulaştırma sektörünün iklim değişikliğine olan etkisinin incelenmesi amaçlanmıştır. Türkiye'de trafik yoğunluğunun en fazla olduğu şehirlerinden biri olan İstanbul için ulaştırma sektörü kaynaklı sera gazı emisyonlarının mevcut durum için hesaplanması, ileriye yönelik sera gazı emisyonu projeksiyonlarının yapılması ve farklı senaryolar altında gelecekte sera gazı emisyonları üzerinde ne gibi etkiler olacağının değerlendirmesi yapılmıştır. Tez çalışması kapsamında TIMES (The Integrated MARKAL-EFOM System) Modeli kullanılmıştır.
Kimyasal oksijen ihtiyacı deşarj limitlerinin sağlanmasında inert ve mikrobiyal ürünlerin rolü : Organize sanayi bölgesi örneği

(Lisansüstü Eğitim Enstitüsü, 2022) Kılıçarpa, Ayça ; İnsel, Güçlü ; 769461 ; Çevre Bilimleri, Mühendisliği ve Yönetimi Programı

Atıksularda biyolojik olarak arıtılabilirlik özelliği açısından oranları çok geniş aralıkta değişebilen organik maddeler bulunmaktadır. Endüstriyel atıksularda, atıksu karakterizasyonunun doğru olarak yapılmaması, diğer bir deyişle organik madde bileşenlerinin doğru bir şekilde saptanmaması, arıtılabilirlik deneylerinin sonuçlarının yanlış yorumlanmasına ve deşarj kriterlerinin sağlanmasında problemlere yol açabileceğinden büyük önem arz etmektedir. Endüstriyel atıksu arıtma tesisi çıkış atıksuyundaki Kimyasal Oksijen İhtiyacı (KOİ) parametresi deşarj standartlarının sağlanması açısından önemli bir yere sahiptir. Sadece toplam KOİ veya çözünmüş KOİ'nin tespit edilmesi yeterli olmayabilir. Çıkış atıksuyunda organik maddelerin biyolojik olarak parçalanabilirliğinin tespitinde KOİ'nin biyolojik olarak ayrışabilen kısmının ve inert KOİ bileşenlerinin tespit edilmesi gerekmektedir. Çevre biyoteknoloji alanındaki son gelişmelere ve modelleme alanındaki ilerlemeler sayesinde, tesislerin tasarım aşamasında arıtma verimlerinin hesaplanmasında özellikle inert ve yavaş ayrışan organik madde bileşenlerinin miktarlarının ve toplam organik maddeye oranının doğru belirlenmesi, kolay ayrışabilir organik madde kinetiğinden daha önemli bir hale gelmiştir. Bu gelişmeler modelleme anlayışına da yansımış ve arıtma kinetiğinin substrat ve biyokütleden oluşan iki bileşenli matematik modeller ile ifade edilmesi son yıllarda geçerliliğini yitirmiş ve günümüzde çok bileşenli modelleme yaklaşımları uygulanmaya başlamıştır. Bu yaklaşıma göre atıksu karakterizasyonunun biyolojik olarak ayrışamayan, yavaş ayrışan ve hızlı ayrışan organik madde bileşenlerini içerecek şekilde yapılması ve tasarımda kullanılacak olan stokiyometrik ve kinetik parametrelerin doğru belirlenmesi gerekmektedir. Bu çalışmada kimya kategorisinde yeralan bir organize sanayi bölgesi (OSB) atıksu arıtma tesisinin giriş atıksu örneği üzerinde çok bileşenli modellemeye imkan tanıyacak karakterizasyon yaklaşımı içinde, konvansiyonel atıksu karakterizasyonunun belirlenmesini, inert, yavaş ve hızlı ayrışan organik madde bileşenlerinin, kinetik ve stokiyometrik katsayıların deneysel yöntemler ile saptanmasını ve elde edilen bulgular yardımı ile karbon giderimine yönelik bilgisayar destekli modelleme çalışmalarını içermektedir. Ayrıca, elde edilen veriler yardımıyla tabi olunan deşarj limitlerinin sağlanmasında çözünmüş inert ve mikrobiyal ürün oluşumunun etkisinin değerlendirilmesini de kapsamaktadır. Mevcut atıksu arıtma tesisine 182 – 1761 m3/gün aralığında debi gelmekte olup ortalama 1014 m3/gün değerini almıştır. Endüstriyel atıksuların biyolojik olarak arıtılabilirliğinde önemli bir husus reaksiyon sonunda geriye kalan inert organik madde miktarıdır. İncelenen OSB atıksularında biyolojik arıtma sonrasında geriye kalan çözünmüş (arıtılamayan) inert organik madde konsantrasyonu %6-8 arasındadır. Bu tez kapsamında; birinci bölümde konunun önemi ve amacı hakkında bilgi verilerek yapılan çalışmanın kapsamı anlatılmıştır. İkinci bölümde konu özelinde literatürde yer alan bilgiler özetlenirken üçüncü bölümde ise çalışmaya konu mevcut endüstrinin tanıtımına ve materyal/metod bilgilerine yer verilmiştir. Dördüncü bölümde, deneysel ve modelleme çalışmalarının değerlendirilmesi yapılmış ve son olarak, beşinci bölümde genel sonuçlar ve öneriler sunulmuştur.
Life cycle assessment of package and ultrafiltration systems and four disinfection technologies for a full-scale water treatment plant

(Graduate School, 2024-08-02) Demir, Mehmet Zahid ; Koyuncu, İsmail ; 501152714 ; Environmental Science Engineering and Management

A growing global population underscores the urgent need for access to adequate drinking water, a basic human need. As recognized by the United Nations, access to safe and clean drinking water is a basic human right and obliges governments to ensure this right. To meet this need, various treatment and disinfection methods are used depending on the water source. The materials and equipment used in these processes are sourced from different sectors and discarded after use, potentially leading to significant environmental consequences such as depletion of natural resources, emissions and waste generation. To comprehensively assess these environmental impacts, Life Cycle Assessment is one of the most comprehensive and accuratemethodologies available. Today's approaches to improving drinking water quality are mainly based on physical and chemical processes as well as combination of those. Package treatment systems offer several advantages over conventional plants by treating water through pre-built treatment tanks using both physical and chemical processes. These systems are characterized by relatively low initial investment cost, minimal spatial footprint, quick installation and ease of operation. Furthermore, the materials used in these systems are recyclable, reducing their environmental impact. In contrast, ultrafiltration systems rely on physical processes which provide advantages such as reduced chemical use, minimal space requirements, operational simplicity and potential for capacity expansion. Regardless of the treatment method, disinfection of water is essential to ensure safety for consumption. Drinking water must be free of pathogenic microorganisms to be considered safe for human consumption. Common water disinfection techniques include chemical methods such as chlorination and ozonation, physical methods such as ultraviolet (UV) irradiation, advanced oxidation processes and electrochemical methods. UV irradiation is increasingly preferred because it is effective against a wide range of microorganisms and easy to use. From an economic point of view, chemical disinfection methods are generally more cost-effective, with the exception of ozone due to its high investment and operational costs. Although the adoption of UV systems has been increasing, it is supported by installations that utilize a variety of UV sources despite its relatively high investment cost. The aim of this thesis is to present a comparative analysis of the environmental impacts of the most widely used disinfection systems, including gas chlorine, ultraviolet and ozone, as well as package treatment and ultrafiltration water treatment systems, using the Life Cycle Assessment methodology. This study aims to achieve a thorough comprehension of the ecological consequences associated with both water treatment and water disinfection systems, with the objective of facilitating knowledgeable decision-making in the pursuit of environmentally sustainable water treatment and disinfection alternatives. The comparisons were made by following the steps of ISO 14040 "Environmental management - Life cycle assessment - Principles and framework" standard. ISO 14040 specifies the steps to be applied in LCA studies and how they should be, and ISO 14044 "Environmental management - Life cycle assessment - Requirements and guidance" explains these steps in detail. The treatment and disinfection systems examined in this thesis include phases i) Goal and scope definition ii) Life cycle inventory analysis (LCI) iii) Life cycle impact assessment (LCIA) and iv) Life cycle interpretation. The data used for the environmental impact calculations were collected through site visits, literature and market researchThe data collected were arranged in accordance with the functional unit and utilized in the computational process.. For the calculation of environmental impact values, SimaPro, an LCA software, was used to evaluate 18 impact categories together with the ReCiPe LCA methodology. The results of the water treatment and disinfection systems examined within the scope of the thesis were analyzed and the results were compared with the existing studies in the literature in line with the thesis subject. The water treatment systems were compared in terms of their environmental impacts from both operation and construction. Although more material is used to produce package water treatment system than ultrafiltration water treatment system, it is seen that the environmental impact of package treatment systems is less in all impact categories. The main reason for this is the high environmental impact of the production of materials used in the production of ultrafiltration systems and the high energy consumption required for operation. Another important aspect is that the materials used in the production of the treatment tanks used in package treatment systems (e.g. stainless steel, galvanized sheet) can be reused instead of being disposed of at the end of their useful life. The comparison of water disinfection systems considers only the impacts caused by the operational phase. Environmental impacts caused by the production of the water disinfection equipment are not included in the calculations. The reason for this is that there is no literature information about the production of the disinfection equipment examined and the manufacturers do not share this information. Among the water disinfection equipment compared, the systems with the lowest environmental impact were the UV system using low pressure amalgam ultraviolet lamps and the gas chlorine system. The ozone system and the UV system using LED ultraviolet lamps had the highest environmental impact. The main reason for this result is the amount of energy required for operation. The results show that the environmental impacts of the water treatment and disinfection processes are important for the source of the energy and material production steps used in the plant. When utilizing two separate sets of electricity generation data - one encompassing global electricity generation and the other focusing on local electricity generation - no alteration was observed in the ecological impact rating of water disinfection systems. However, variations were evident in each impact category, both showing increases and declines. The use of renewable energy sources will reduce the environmental impacts of drinking water treatment and disinfection systems.
Monitoring and assessing the temporal changes of natural lakes of Türkiye via satellite images

(Lisansüstü Eğitim Enstitüsü, 2023-10-02) Fıratlı, Ertuğ ; Tanık, Ayşe Gül ; 501162704 ; Environmental Sciences, Engineering and Management

Bu tezin amacı, fiziksel özelliklerine, türlerine, yüksekliklerine, derinliklerine ve konumlarına göre sınıflandırılmış 2000 hektarın üzerindeki seçilmiş doğal göller için Türkiye genelinde uydu verileri ile doğal göllerin su yüzey alanı değişimlerini izlemek ve su durumunu değerlendirmektir. Su yüzey alanı (SYA) iklimsel ve/veya insan kaynaklı faktörlerle değişmektedir. Bu kapsamlı çalışmada izlenen tüm yöntem ve adımlar dikkate alınarak, karar vericiler, bilim adamları, uygulayıcılar ve diğer paydaşlar gibi ilgili taraflar için bir rehber görevi görecek bir metodoloji geliştirilmiştir. SYA değişikliklerinin arkasındaki temel nedeni anlamak, sorunu çözmenin en önemli adımıdır. Son zamanlarda, doğal göllerin çoğu, özellikle bazı havzalarda kuraklık koşullarıyla karşı karşıyadır. Dramatik SYA değişikliklerinin nedenleri dikkatlice araştırılmalı ve gelecekte bölgesel değişikliklerdeki düşüşü durdurmak veya azaltmak için ilgili önleyici tedbirler alınmalıdır. Bu çalışma karar vericilerin bu konularda gerekli eylemleri başlatmalarına yardımcı olacaktır. Önlem alınmadığı takdirde, bu son derece hassas göl alanlarının ve yakın çevrelerinin ekolojik dengesi bozulacaktır. Bu çalışma, su tipi, havza, rakım, derinlik, konum, arazi kullanımı/arazi örtüsü (AKAÖ) değişimi, baraj inşaatları, meteorolojik durum ve tarımsal faaliyetler ile ilgili olarak SYA değişikliklerinin arkasındaki sebep-sonuç ilişkilerini açıklamayı amaçlamaktadır. Tezin her bölümünde göllerin farklı özelliklerine odaklanılmakta ve ilgili faktörler arasındaki bağlantılar ve ilişkiler sunulmaktadır. Bu tezde öncelikle doğal göllerin SYA değişimleri ile ilgili çalışmalar için uluslararası literatür taranmıştır. Ardından, doğal göllerin bir envanterini oluşturmak için ulusal raporlar taranmıştır. Orman ve Su İşleri Bakanlığı tarafından yayımlanan bir yayında, 302 doğal gölün de dahil olduğu uzun bir doğal göl listesi bulunmuştur. Buna ek olarak, benzer sayıda gölden oluşan bir başka resmi veri olan Sulak Alan Bilgi Sistemi (SAYBİS) temin edilmiştir. Bu iki ana envanter, SAYBİS veri tabanına göre 2000 hektardan fazla SYA'na sahip 302 göl tarandıktan sonra, 27 doğal göl seçilmiş ve kısa (son 5 yıl) ve uzun vadede (son 35 yıl) SYA değişimlerinin arkasındaki nedenleri anlamak için çalışmaya dahil edilmiştir. Türkiye'deki 25 havzadan 15'ine dağılmış en büyük 27 göl için SYA değişikliklerini araştırmak için uzaktan algılama enstrümanları, meteorolojik veriler, CORINE verileri, raporlanan SYA bilgileri ve diğer bazı ilgili veriler kullanılmıştır. Coğrafi olarak, kuzey havzalarında (Batı Karadeniz, Doğu Karadeniz) büyük ölçekli (>2,000 ha) göl yoktur, ancak bunların dışında seçilen göller, ülke ölçeğinde bir çalışmayı temsil etmesi için tüm Türkiye'ye dağılmıştır. 27 göl ile envanter oluşturulduktan sonra, uzaktan algılama verilerinin elde edilmesi ve analizi, meteorolojik verilerin elde edilmesi ve analizi, CORINE verilerinin elde edilmesi ve analizi, baraj inşaatları ve tarımsal faaliyetler gibi WSA değişikliklerinin diğer olası nedenleri adım adım değerlendirilmiştir. Farklı veri setlerinin yanı sıra göllerin yükselti, derinlik, konum, havza, koruma durumu ve su tipi ayrı ayrı incelenmiş ve tüm bilgiler göl envanterine dahil edilmiştir. Bu özellikler, göllerin SYA değişikliklerini değerlendirmek için kabul edilmiştir. Su tipi, çalışmanın en önemli kısımlarından biridir. Sonuçları değerlendirdikten sonra, su türlerine göre göller için bazı modeller bulunmuştur. Örneğin, Türkiye'de diğer tüm göller (acı, soda, tuzlu) yüksek rakımlarda (>750 m) bulunurken, alçak rakımlarda acı, soda ve tuzlu göl yoktur. Ayrıca tuzlu göllerin, farklı su tiplerine sahip diğer göllere göre genel olarak SYA değişikliklerine en duyarlı olduğu bulunmuştur. Tuzlu göllerin çoğu, çalışma süresi boyunca dikkat çekici SYA değişiklikleriyle uğraştığı gözlenmiştir. Başlangıçta, kısa vadeli (2016-2020) ve uzun vadeli (1985-2020) SYA değişikliklerinin analizi, Sentinel-2, Landsat-5 ve Landsat-8 gibi farklı uydu verileri kullanılarak analiz edilmiştir. Mevsimsel değişimleri anlamak için kısa vadeli analizler kullanılırken, göllerin farklı özelliklerine göre 35 yıllık değişim ve örüntüleri değerlendirmek için uzun vadeli analizler kullanılmıştır. Elde edilen veriler her bir göl için SAYBİS, ulusal veri tabanı ve gerektiğinde diğer resmi yayınlardan bildirilen verilerle karşılaştırılarak değerlendirilmiştir. Analizler göllerin su tipine göre tatlısu ve diğer (tuzlu, acı, sodalı) göller olarak yapılmıştır. İkinci olarak, özellikle uzun vadeli SYA değişikliklerinde iklim değişikliği etkilerini anlamak için meteorolojik veriler çalışmaya dahil edilmiştir. Yağış, buharlaşma ve sıcaklık verileri, varsa göllere en yakın meteoroloji istasyonlarından toplanmıştır. Bazı durumlarda, sistematik verilerde eksiklik olduğu durumlarda en yakın ikinci veya üçüncü meteoroloji istasyonu seçilmiştir. Buna göre tüm havzalarda çalışma süresi boyunca sıcaklıklarda artış olduğu sonucuna varılmıştır. Bir sonraki adımda, göllerin havzaları için AKAÖ'yi anlamak üzere CORINE verileri çalışmaya entegre edilmiştir. 1990, 2000, 2006, 2012 ve 2018 verileri indirilerek 5 ana CORINE kategorisi altında analiz edilmiştir; yapay yüzeyler, tarım alanı, orman ve yarı doğal alan, sulak alanlar ve su kütleleri. Temsili görüntüler oluşturmak için veriler CBS araçlarında göllerin havzasının coğrafi konumu ile kesiştirilmiştir. Genel olarak, havzaların çoğunda yapay alanlar (yerleşimler) önemli ölçüde arttığı ve birçok havzada tarım alanlarının önemli ölçüde arttığı, orman ve yarı doğal alanların azaldığı tespit edilmiştir. Su kütlelerinin alanları, havzaların çoğunda önemli ölçüde azalmıştır. Bazı göllerin sulak alanlarının azalması, bazılarının artması nedeniyle sulak alanlar bir ortak trend göstermemiştir. Genel olarak, bu çalışma kapsamında değerlendirilen havzaların çoğunda orman ve yarı doğal alanların ve bazı durumlarda su kütlelerinin yapay yüzeylere ve tarım alanlarına dönüştürüldüğü sonucuna varılmıştır. Artan yapay alanlar ve tarım alanları çoğu zaman göllerin SYA'nını olumsuz etkilemektedir. Bu durum aynı zamanda artan insan kaynaklı faaliyetlere işaret etmektedir ve onu birçok havzadaki dramatik SYA değişikliklerinin ana itici gücü yapmaktadır. Göller daha sonra rakımlarına ve su türlerine göre sınıflandırılmıştır. Sonuçlar yorumlanırken göllerin derinliği, rakımı ve konumu dikkate alınmıştır. Derinlik, rakım ve konum bilgileri, göllerin SYA değişimleri üzerinde doğrudan etkiye sahip olabileceğinden, çalışmaya entegre edilmiştir.
Nitrogen removal and microbial community shift in oxic-settling-anoxic sludge reduction process

( 2020) Karlikanovaite Balıkçı, Agne ; Yağcı, Nevin ; 618662 ; Çevre Mühendisliği ; Environmental Biotechnology

Nitrifikasyon ve biyolojik azot giderme mekanizmalarını içeren sürekli araştırma çalışmalarıyla aktif çamur işleminin performansı arttırıldı. Ancak, uygulanan bu işlemden kaynaklanan aktif çamurun rutin israfı nedeniyle, sürekli olarak fazla biyokütle üretimi olmaktadır, bu da daha fazla arıtma ihtiyacıyla beraber çamurun uygun bir bölgeye atılmasını veya yakılmasını gerektirdiğinden dolayı fazla çamurun arıtımı ve imha edilmesi hala zorlayıcıdır. Fazla çamurun arıtılması ve imha edilmesi, toplam işletme maliyetinin % 25-65'ini oluşturmaktadır. Bu nedenle, aşırı çamur üretimini en aza indirmek için stratejilerin uygulanması hem çevresel hem de ekonomik açıdan ideal bir çözüm olabilir. Şimdiye kadar çamurun en aza indirilmesi için yaygın olarak Anaerobik sindirim kullanılsa da, üretilen aşırı çamur hacminin dünya çapında hala artması, biyolojik atık su arıtma proseslerinde aşırı çamur üretimini azaltmak için daha yeni, daha umut verici stratejiler ve yöntemlerin keşfedilmesi gerekmektedir. Literatürdeki mevcut bilgiler ve bu alanlardaki uzmanlıkların ışığında, nitrojen giderimi ve çamuru en aza indirgemek için uygun işlem alternatiflerinin belirlenmesi ve çamur üretimini azaltmak adına anaerobik/anoksik yan akım reaktörleriyle besin giderimi için modifiye edilmiş alternatif işlemlerin uygulanması gibi seçenekler mümkün olabilir. Literatüre göre, OSA sürecinin avantajlarına ek olarak, OSA arıtma performansını en üst düzeye çıkarmak için operasyonel ve tasarım parametrelerini belirlemek hala büyük bir ihtiyaçtır; Daha da önemlisi, OSA süreci ile ilgili çalışmaların çoğunda sentetik atık su kullanıldı, bu çalışmanın orijinal tarafı, gerçek evsel atık su kullanılarak yapılmış olmasıdır. Bu özel araştırmada, konular uluslararası bir düzeyde ele alınacaktır, çünkü OSA sürecinin entegrasyonu ile kademeli besleme SBR sistemi toplam azot giderimi açısından oldukça verimlidir, çamur imhası ve arıtımı gerekli olmayacaktır. Yine de, mevcut literatürdeki araştırmacılar arasında çamurun azaltılmasına neden olan kilit mekanizma halen çok tartışmalıdır, bu nedenle ASM1 bu çalışmada OSA sürecinde çamur azaltmaya neden olan mekanizmayı araştırmak için kullanılmıştır. Buna ek olarak mikrobiyal topluluğu değerlendirmek için literatürde ilk kez bakteriyel 16S rRNA gen amplikonları Yeni Nesil Dizileme (NGS) kullanılmıştır. Özet olarak, OSA sistemi ile ilgili multidisipliner bir yaklaşım ve yoğun araştırma gerektiren bir zorluk yaratan birçok darboğaz vardır. Bu çalışmanın amacı, OSA sürecinin uygulanmasından önce ve sonra SBR sistemlerinin performansını göstermektir. Gerçek atık su kullanan OSA sürecindeki bilgi eksikliği, OSA sistemlerinin uygulanmasından sonra toplam azot giderimi, aşırı çamur azaltımı, mikrobiyal topluluk değişikliklerine odaklanan bu çalışmayı güçlü bir şekilde motive etmiştir. Bu çalışma, gerçek atık suyun tam ölçekte arıtılmasında OSA sistemlerinin uygulanmasının daha iyi anlaşılmasına katkıda bulunacaktır. Kentsel atıksu arıtımı sırasındaoluşan fazla çamurun uzaklaştırılması ve besi maddesi giderimi konusunda son yıllarda uygulanan standartların sıkılığı,pekçok atıksu arıtma tesisinin çıkış suyu standartlarını sağlama ve çamuroluşumu konusunda ciddi zorluklarla karşı karşıya kalmasına neden olmuştur. Bu çalışmada, yukarıda belirtilensorunların giderilmesi konusunda gelecek vaad eden bir proses olanoksik-çökeltim-anaerobik (OSA) üzerine odaklanılarak, azot giderimi ve çamur azalmasının birlikte gerçekleştirildiği bir sistemin değerlendirilmesi amaçlamıştır. Yan akım reaktöründe en yüksek çamur azalması iç geri devir oranının %7,7 olduğu durumda %58 olarak gerçekleşmiştir. Diğer sistemlerde ise iç geri devir oranının %5,9 ve 5,0 olması durumlarında bu değer sırasıyla %37 ve %35 olarak elde edilmiştir. Bu doğrultuda, bu sistemlerde, yan akım reaktöründen gelen çamur girişi nedeniyle ana reaktörde gerçekleşen yüksek biyokütle konsantrasyonunun ve çamur bekletme süresinin etkisiyle mikrobiyal ölüm fazının çoğalmaya görece daha yüksek gerçekleştiği düşünülmektedir. Bu sistemlerde, aynı zamanda, yüksek (%85'e kadar) azot giderim verimlerinin gerçekleştiği gözlenmiştir. Buna göre, iç geri devir oranının, literatürde genellikle kullanılan %10 oranı yerine %8 olarak gerçekleştirilmesinin hem çamur azalması hem de azot giderimi açısından, muhtemelen daha düşük maliyetli, bir seçenek olacağı düşünülmektedir. OSA prosesi, biyolojik atıksu arıtımı sırasında kaçınılmaz olarak oluşan, susuzlaştırılıp stabilize edildikten sonra uzaklaştırılması gereken fazlabiyolojik çamur miktarının azaltılmasına yönelik olarak fazla çamur yan akımına anaerobik reaktör ilavesi ile gerçekleştirilmektedir. İlave edilen yan akım anaerobik reaktörde, fazla çamur hattındaki biyolojik çamurun bir kısmı belirli bir süre oksijensiz koşullara maruz bırakıldıktan sonra biyolojik arıtma ünitelerinin girişine biyokütle girdisi olarak verilmektedir. Bu sayede, yan akım reaktöründe kısmi stabilize olan çamur biyolojik ünitelerde besi madde olarak kullanılmak suretiyle özellikle azot giderimi için karbon kaynağı olma potansiyeli taşımaktadır. Aynı zamanda, yan akımda stabilizasyon nedeniyle sistemin çamur yaşı artmakta, dolayısıyla gözlenen dönüşüm oranları düşmektedir. Bunun sonucu olarak da biyolojik sistemde çamur üretimi azalmakta ve uzaklaştırılacak çamur miktarı düşmektedir. Bu çalışmada, çamur azalmasına yönelik olarak geliştirilen OSA sistemi kullanılarak farklı işletme koşullarında çamur azalması oranları ve azot giderimine yoğunlaşılmıştır. Bu sistemlerin aktif çamur modelleri ile modellenmesi ve gerçek sistemlere yönelik modelleme çalışmalarına esas oluşaturacak kinetik katsayı belirleme çalışmaları gerçekleştirilmiştir. Ayrıca, bu sistemlerde farklı işletme şartlarında mikrobiyal topluluğun değişimi ortaya konulmaya çalışılmıştır. Mikrobiyal kinetiğin değerlendirilmesi ve çamur azaltma mekanizmasının daha iyi anlaşılması için bir dizi respirometrik test tasarlanmıştır. Kalibrasyon çalışmasının sonuçlarına göre mikrobiyal ölüm oranının, sistem konfigürasyonuna bağlı olarak, en değişken kinetik parametre olduğu görülmüştür. Bu kinetik katsayının sistemler OSA konfigürasyonunda işetilmeye başlandıktan sonra önemli ölçüde arttığı, buna karşılık -diğer model parametrelerinin neredeyse sabit kaldıkları görülmüştür. Bu durumun, mikrobiyal topluluktaki veya mevcut topluluğun metabolizmasındaki değişimden kaynaklanıyor olabileceği düşünülmektedir. Bu çalışmada işletilen klasik aktif çamur sistemlerinde, yürütülen respirometrik analizler sonucunda, aktif biyokütle oranı% 75 civarında elde edilmişken yan akım reaktöründe bu değer 2 kat daha düşük olarak belirlenmiştir. Sonuç olarak, respirometrik analizlerden elde edilen veriler doğrultusunda, OSA prosesininölüm fazını teşvik ettiği, bunun sonucu olarak reaktördeki biyokütle canlılığını azaldığı ve aşırı çamur azalmasının sağladığı sonucuna varılmıştır. Bu çalışmanın en önemli yönlerinden birisi de gerçek evsel atık su kullanılmasıdır. Literatürdeki çalışmalar sentetik olarak hazırlanmış atıksuların kullanımı ile gerçekleştirilmişken, tüm deneysel çalışma bir atıksu arıtma tesisi kum tutucu çıkışından alınan ham atılsu ile yürütülmüştür. Böylelikle, OSA prosesinin pratik uygulanabilirliği yönünde önemli sonuçlar elde edilebilmiştir. Elde edilen veriler, OSA sistemlerinde çamur azalmasının ve azot gideriminin birlikte gerçekleştirilebilirliğinin mümkün olduğunu göstermiştir. Mikrobiyal topluluğun ölüm fazına yakın çalışması ve biyolojik çamur girdisi nedeniyle biyolojik reaktörde yüksek biyokütle konsantrasyonları elde edilmiş, bu çalışma süresinde sistemden normal biyolojik atıksu arıtma tesislerinde yapılan rutin çamur atma işlemi yapılmamıştır. Yürütülen deneysel çalışmada, kurulan OSA sistemleri farklı değişim oranlarında işletilmiştir. Bu amaçla, biyolojik sistemden yan akım reaktörüne beslenen çamur miktarları değiştirilmiştir. Bu sistemlerde çamur azalması, gözlenen dönüşüm oranları ve azot giderim yüzdeleri belirlenmiştir. Mikrobial topluluk kompozisyonu başlangıç biyolojik çamuru ve farklı işletilmiş OSA sistemlerinden alınan biyolojik çamurlarda belirlenerek sonuçlar karşılaştırılmıştır. Literatürde ilk kez kapsamlı olarak, bu sistemlerde, bakteriyel 16S rRNA gen sekanslama analizi (Yeni Nesil Sekanslama) ile mikrobiyal topluluk profili ortaya konulmuş ve değerlendirilmiştir. Bu çalışmada, çamur azalması oranlarının değerlendirilmesi ve mikrobiyal topluluktaki değişimin ortaya konulması amacıyla farklı iç geri devir oranlarında işletilen sistemlerin gözlenen dönüşüm oranları hesaplanarak, aynı koşullarda işletilen kontrol sistemleri ile karşılaştırılmıştır. Buna göre, en yüksek çamur azalması (%52,1) iç geri devir en yüksek olduğunda elde edilmiştir. 16S rRNA gen amplikon sekans analizi, benzer filogenetik gruplardan, Proteobakteriler, Acidobacteria ve Bacteroidetes türlerinden oluşan bakteri topluluğunun baskın olduğunu göstermiştir. Değişen iç geri devir oranlarına bağlı olarak bu toplulukların baskınlığı da farklılık göstermiştir. OSA sistemlerindeThiothrixtürünün baskın olduğu ve sistemlerde önemli rolü olabileceği görülmüştür. Çamur üretiminin en aza indirilmesinin, Intrasporangiaceae türlerinin baskınlığı ile de ilgili olabileceği elde edilen bulgular arasındadır.
Optimization of anaerobic membrane bioreactors for sludge treatment

(Graduate School, 2023-02-01) Abdelrahman, Amr Mustafa ; Erşahin, Mustafa Evren ; Volcke, Eveline ; 501182702 ; Environmental Sciences, Engineering and Management

Wastewater treatment is an energy intensive process. The energy balance is positively affected by anaerobic sludge digestion, especially primary sludge. The inclusion of a primary clarifier before the biological reactors results in a higher sludge total production compared to the direct treatment of raw wastewater. Conventional anaerobic digesters for sludge treatment are designed as completely mixed reactors operated at long solid retention times (SRTs) for enhanced solids conversion and to maintain the methanogenic activity in the reactor. Consequently, anaerobic digesters are commonly built with large volumes to ensure sufficient reduction of volatile solids (Xu et al., 2011). Anaerobic membrane bioreactor (AnMBR) is a promising alternative to conventional anaerobic digesters for sludge digestion. AnMBRs are operated at long SRTs independent from hydraulic retention time (HRT) by means of physical separation of the membrane. Thus, slow growing methanogenic biomass can be kept longer in the reactor, resulting in enhanced methane production. Moreover, a smaller footprint of the anaerobic reactor can be achieved since the HRT can be controlled by manipulating the flux. To understand the rationale behind the thesis, Chapter 1 presents a brief description about the energy consumption for wastewater treatment and its distribution in the wastewater treatment plant (WWTP). The organic matter removal mechanism in the conventional WWTP is explained. Novel process configurations for organics capture are presented. Anaerobic digestion process and the design parameters of the anaerobic digester are explained as well. The advantages of using AnMBR for sludge treatment are defined. The chapter ends with research gap and an outline of the thesis. The current status and perspectives of the AnMBR technology for sludge treatment are critically reviewed in Chapter 2. It discusses the historical development of the AnMBR for sludge treatment, and factors influencing the AnMBR performance reported in the literature. The operational conditions such as SRT, HRT and temperature have a noticeable effect on the methane production and permeate quality. Volatile fatty acids (VFAs) can be recovered simultaneously during sludge treatment, which can improve the economics of the WWTP. However, there are still problems, such as membrane fouling, which hinder the adoption of AnMBR technology for sludge management, as well as a lack of studies demonstrating the economic benefits of using AnMBRs for sludge treatment. Suggestions for research perspective are given, aiming for overcoming the challenges and for optimization of the AnMBR for sludge treatment. The aim of this thesis was to investigate the applicability of the AnMBR for sludge treatment in the view of energy-positive WWTPs. The objectives of this thesis were met through four different studies. Chapter 3 explains the material used and methods followed during these studies. The results of these studies are explained and disscussed in Chapter 4. In order to maximize organic capture and thus energy recovery from wastewater, novel configurations including an A-stage and CEPT have been proposed as alternatives to primary settling. However, it remains to be investigated to which extent these configurations affect the sludge characteristics, which may affect the economic feasibility of the integrated systems. Therefore, the first study focuses on the effect of these primary treatment methods on sludge characteristics and digestibility, and on plant-wide economics of wastewater treatment. A detailed characterization of sludge obtained from primary settling (primary sludge), A-stage treatment (A-sludge) and CEPT showed significantly different sludge characteristics. The organic compounds in primary sludge consisted mainly of 40% carbohydrates, 23% lipids, and 21% proteins. A-sludge was characterized by a high amount of proteins (40%) and a moderate amount of carbohydrates (23%), and lipids (16%), while in CEPT sludge, organic compounds were mainly 26% proteins, 18% carbohydrates, 18% lignin, and 12% lipids. The biomethane potential test showed that primary sludge and A-sludge had the highest methane yield (347 and 333 mL CH4/g VS, respectively), while methane yield of CEPT sludge was lower(245 mL CH4/g VS). A plant-wide economic evaluation for the three systems, indicated that energy surplus was the highest with CEPT. The inclusion of an A-stage had the lowest positive net energy due to the relatively high energy consumption in aeration. Considering the effluent quality of the three systems, CEPT had the highest benefits, followed by A-stage. Overall, integration of CEPT or A-stage, instead of primary clarification in existing wastewater treatment plants, has the potential to improve the effluent quality and energy recovery. AnMBRs have been applied as compact alternatives for anaerobic digesters for sludge treatment in conventional WWTPs. However, there is no information about the impact of integrating an A-stage, instead of primary clarifier, on sludge digestion in an AnMBR. The second study examines the performance of lab-scale AnMBRs, in terms of treatment and filtration performances, for both digestion of primary sludge and A-sludge. The results showed that anaerobic digestion of A-sludge yielded more methane and improved methanogenic activity in the AnMBR compared to primary sludge. The permeate of the AnMBR fed with A-sludge contained higher nitrogen and phosphorous concentrations due to higher nitrogen and dissolved phosphorous concentrations of A-sludge. No coliforms were detected in the permeates, which showed that from the hygienic point of view, the permeate had the potential to be directly used for irrigation purposes. A higher EPS concentration was observed during the digestion of A-sludge compared to the primary sludge, which accumulated on the surface of the membrane and caused an increase in transmembrane pressure (TMP) and filtration resistance. On a plant-wide level, the integration of an A-stage increased the amount of organic matter (COD) recovered from wastewater in the form of methane gas by about 15% compared to a WWTP configuration with a primary clarifier. Anaerobic digesters are operated at either mesophilic (35°C) or thermophilic (55°C) conditions. In general, it is known that higher amounts of biogas are produced from digesters operated at thermophilic conditions because of higher biochemical reaction rates. However, the specific effect of temperature on AnMBR performance for A-sludge digestion has not yet been assessed. Therefore, the third study evaluates the treatment and filtration performances of lab-scale AnMBR under mesophilic and thermophilic conditions. Higher biogas and VFAs were produced under thermophilic conditions, which were 23% and 47% higher than those under mesophilic one, respectively. Besides, the membrane could be operated at lower TMP under thermophilic conditions. However, taking into account the energy consumption and production, operating the AnMBR under mesophilic conditions would result in a more than three-fold higher net energy production than operating under thermophilic conditions, whereas surplus energy recovery under thermophilic conditions was less than the additional energy consumption. Therefore, despite the advantages of thermophilic conditions, operating AnMBR for sludge digestion under mesophilic conditions has a higher potential to improve the energy balance in the WWTPs. As found during the review (Chapter 2), there is a lack of studies demonstrating the economic benefits of using AnMBRs for sludge treatment in the WWTP. Therefore, the feasibility of the AnMBR for sludge (primary and waste activated sludge) treatment in a conventional WWTP is evaluated in the fourth study, through mathematical modeling and simulation, on unit process and plant-wide levels. The impact of HRT and SRT as control handles on the performance of the AnMBR was assessed. The amount of COD converted into methane could be increased by increasing the SRT or lowering the HRT, the former having a higher positive impact. The nitrogen and phosphorous load in the permeate increased by increasing the SRT or lowering the HRT, while the COD concentration in the permeate was hardly affected. As for the energy balance, increasing the SRT was more efficient than lowering the HRT. Indeed, increasing the SRT caused a significant increase in energy production while lowering the HRT only slightly reduced the energy consumption and did not affect the energy production. On a plant-wide level, the integration of an AnMBR instead of the anaerobic digester decreased the operational costs of the WWTP by 27%, but led to a worse effluent quality. The latter could be remedied by post-treatment of the permeate by struvite recovery and nitrogen removal through partial nitritation/anammox, at the same time further decreasing the operational costs - with 35% compared to a conventional WWTP. Overall, applying AnMBR for sludge treatment combined with post-treatment of the permeate provides effluent quality that meets the EU regulations and implies significant operational cost savings for wastewater treatment. Finally, Chapter 5 summarizes the main findings of the previous chapters and gives perspectives for further research inspired from the thesis.
Organik atıklardan sürdürülebilir enerji geri kazanımı: Biyolojik ve termal geri kazanım proseslerinin analizi

(Lisansüstü Eğitim Enstitüsü, 2022-04-28) Altan, Hasan Suphi ; Sözen, Seval ; 501152712 ; Çevre Bilimleri, Mühendisliği ve Yönetimi

Yürütülen tez çalışması kapsamında farklı kaynaklarda üretilen enerji potansiyeli yüksek olan organik atıklardan, alternatif teknolojiler kullanılarak sürdürülebilir şekilde yenilenebilir enerji geri kazanımının fizibilitesi ortaya konmaktadır. Çalışma kapsamında ele alınan organik karakterdeki evsel katı atıklar, endüstriyel içeriğe sahip olmayan arıtma çamurları, ülke genelinde yaygın olarak yürütülen hayvancılık faaliyetlerinden kaynaklanan atıklar ve ülke genelinde bölgesel olarak majör tarımsal faaliyetler neticesinde açığa çıkan atıkların enerji geri kazanımı ile ülke enerji arz çeşitliliğine ve enerji ekonomisine önemli bir katkı sağlanabileceği tahmin edilmektedir. Çalışmanın temeli kapsamlı bir literatür araştırmasına dayanmaktadır. İlk olarak ülke genelinde enerji üretimine uygun olan katı atık potansiyeli araştırılmış ve evsel katı atıklar, endüstriyel içeriğe sahip olmayan arıtma çamurları, majör hayvancılık faaliyetlerinden kaynaklanan atıklar ve her bir coğrafi bölgede yaygın olan tarım faaliyetlerinden kaynaklanan atıklar için literatür kaynaklı miktar tespiti yapılmıştır. Bir sonraki basamakta ise organik madde muhtevası yüksek olan katı atıkların enerji geri kazanımı için yaygın olarak kullanılan prosesler detaylı araştırılmış ve termal geri kazanım prosesleri kapsamında yakma, gazifikasyon (gazlaştırma), piroliz ve biyolojik enerji geri kazanım prosesleri kapsamında ise anaerobik çürütme (digestion) prosesi simüle edilerek, bu proseslerin modellenmesine yönelik parametreler tespit edilmiştir. Evsel katı atık miktarlarının tespitinde TÜİK verilerinden faydalanılmış, her bir il için yıllara bağlı miktarlar tespit edilmiştir. Evsel/Kentsel atıksu arıtma tesislerinden kaynaklanan arıtma çamurlarının miktarı, TÜİK veri tabanında ilan edilen atıksu arıtma miktarları ile ilişkili olarak hesaplanmıştır. Söz konusu hesaplamada coğrafi bölge özellikleri ve arıtma tesislerinin konfigürasyonları dikkate alınmış ve her bir il için oluşan arıtma çamurlarının miktarı tespit edilmiştir. Hayvancılık faaliyetlerinden kaynaklanan atıkların miktarının tespitinde ise Enerji ve Tabii Kaynaklar Bakanlığı, Yenilenebilir Enerji Genel Müdürlüğü tarafından oluşturulan Biyokütle Potansiyel Atlası veri tabanından faydalanılmıştır. Buna göre çalışma kapsamında ele alınmak üzere büyükbaş, küçükbaş ve kanatlı hayvan yetiştirme faaliyetlerinden kaynaklanan atık miktarları il bazında tespit edilmiştir. Tarım faaliyetlerinden kaynaklanan atıkların tespitinde ise ülke genelinde tarım faaliyetlerinin değişken olması nedeniyle bölgesel yaklaşım ile ilerlenmiştir. Yapılan literatür çalışmasının kaynağını hayvancılık faaliyetlerinden kaynaklanan atıklarda olduğu gibi Biyokütle Potansiyel Atlası oluşturmaktadır. Çalışma genelinde her bir coğrafi bölge için o bölge içerisinde en fazla miktarda üretilen üç farklı atık tipi esas alınmıştır.
Plant-wide process analysis targeting reliable estimation of biogas production from anaerobic sludge digestion

(Graduate School, 2024-05-17) Özyıldız, Gökşin ; İnsel, H. Güçlü ; 501172714 ; Environmental Sciences Engineering and Management

Anaerobic sludge digestion is a critical and widely used technology employed in wastewater treatment plants for the stabilization of solids generated during the treatment process and for the production of biogas as a renewable energy source. This process typically involves the treatment of mixed primary and biological sludge in digesters. Primary sludge comprises inorganic solids and organic matter, whereas biological sludge is rich in active biomass and residues from biochemical reactions. The process faces challenges, such as the lower organic degradation efficiency of waste activated sludge (WAS) under both aerobic and anaerobic conditions, necessitating extended sludge retention times. Hydrolysis, identified as the rate-limiting step in microbial degradation across various environmental conditions, significantly influences the efficiency of the anaerobic digestion process. Therefore, the nature of the degradation of the hydrolysable matter directly influences the efficiency of the anaerobic digestion process. Traditional activated sludge models, which conceptualize COD turnover through a single hydrolysable matter component (XB), do not adequately account for the range of hydrolysis kinetics observed in practice. Despite a plethora of parameter values proposed for anaerobic hydrolysis, research into the kinetic analysis of anaerobic sludge digestion, particularly considering varying mixes of primary and waste activated sludge, remains sparse. The appropriate selection of wastewater treatment and sludge disposal methods depends on specific aspects, including the organic matter components in the influent wastewater and the kinetic parameters specific to the biomass. Therefore, the integration of experimental studies with plant-wide modeling tools is becoming an important strategy for selecting suitable treatment systems and executing reliable process calculations. In this study, seven large-scale wastewater treatment plants were analyzed for operational parameters and dynamic modeling was combined with plant-focused batch experiments to uncover deviations from the calculated data during the design phase. The long-term performance of three full-scale carbon and biological nutrient removal plants with anaerobic sludge digestion systems was rigorously monitored. This approach aimed to improve the understanding of process kinetics for carbon removal, nutrient removal, and anaerobic digestion. It involved COD fractionation, nitrification and denitrification kinetics, and anaerobic batch experiments. Plant-specific kinetic parameters were determined experimentally and integrated with plant-wide SUMO model simulations. The research revealed that anaerobic hydrolysis rates are significantly lower than the available literature values. The study identified this stage as a critical point in optimizing biogas production. Anaerobic digestion batch experiments and plant-wide model calibration showed that anaerobic hydrolysis rate is the critical parameter for biogas production. In parallel, anaerobic digestion performance and modeling studies in full-scale plants showed low biogas production efficiency. The innovative use of plant-wide model calibration, in conjuction with anaerobic digestion tests in the study, illuminated the significant challenges posed by low anaerobic hydrolysis rates for efficient biogas production. This was demonstrated by the poor performance and low biogas yields in full-scale plants. The study also discovered that the degradation rate of primary sludge through anaerobic hydrolysis is significantly higher compared to the hydrolysis rate of biological sludge, shedding light on areas for process improvement. In the second stage of the study, the effect of anaerobic hydrolysis rate on biogas production was investigated with mesophilic digesters in seven large-scale wastewater treatment plants. This phase was critical in understanding how the process parameters underpinning anaerobic digestion could be optimized to enhance biogas production.
Profile of priority substances and toxicity assessments of wastewater treatment plants in Istanbul

(Graduate School, 2023-05-31) Birtek, Rahime İclal ; Öztürk, İzzet ; 501122704 ; Environmental Sciences, Engineering and Management

Wastewaters formed due to anthropogenic activities around urban areas pose a threat to aquatic environments. The growth in industrial activity along with the worldwide urban migration, as well as the threat posed by climate change, increase the extent of pollution. The discharge of the treated or untreated wastewaters is reported to cause a threat to their receiving water environments. Conventional wastewater treatment plants (WWTPs) are constructed to minimize the nutrient loads of macropollutants (C, N, and P) entering the receiving water bodies. As, removal of some of the emerging contaminants (ECs) or micropollutants present in wastewaters is found to be incomplete in conventional wastewater treatment processes, traces of those non-biodegradable ECs were reported to be found in the receiving environments. The presence of ECs, even in very low concentrations (pg/L - ng/L) in the water environments could cause adverse effects on humans and the ecosystem. In addition to industrial emissions, domestic discharges along with urban runoffs are main contributors of ECs in WWTPs. Understanding the presence, sources and transport of the micropollutants and ECs in wastewaters is important for assessing their impacts, and hence can help their reduction and management in the receiving environment. Micropollutants that have shown toxic, persistent, bioaccumulative, and ubiquitous properties and have been identified in aquatic environments, are designated as priority substances (PSs) by the EU Water Framework Directive (WFD). EU Member States are required to identify the presence of PSs in surface waters, in order not to exceed threshold levels specified by the Environmental Quality Standards (EQS) dictated by WFD. The Turkish Ministry of Forestry and Water Affairs adopted the aforementioned quality standards for the PSs in surface waters in 2012, and updated them in 2016. Since WWTPs are known to be main point sources of ECs entering the receiving water bodies, investigating the occurrence of PSs in wastewaters of Istanbul has generated valuable information. This thesis aims at understanding the occurrences of PSs in the wastewaters of the megacity of Istanbul as well as assessing WWTP effluents as sources of PSs in receiving environments. The thesis also includes the acute toxicity assessment of the same wastewaters. The scope of the study includes the wastewaters of the seven largest WWTPs, a hospital wastewater and leachate of a landfill treatment plant in Istanbul. The results of the PSs analyses allowed estimation of risks posed by the PSs in the WWTP effluents. Lists were formed to PSs showing sufficient risk (RQ>1), and their inclusions are recommended in the surveillance monitoring programs for the effluents of advanced treatment, as well as mechanical treatment. The regulators undertaking environmental risk assessments in the initiation of monitoring programs for the protection of the Sea of Marmara, Bosphorus and the Black Sea may utilize the findings of this study. Chapter 2 provides general information on the background of the study that is related to the aim and objective of the study. Chapter 3 comprises of information regarding the study area as well as methods on the description of all the experiments conducted through this study, namely analyses of PSs, toxicity analyses and physiochemical analyses. Chapter 4 Results and Discussion, provides information on the results of the experiments conducted through this study (PSs analyses, toxicity analyses and physiochemical analyses), as well as discussion of those results. Chapter 5 provides a summary of the whole thesis. The References section includes the complete bibliography. The Appendix includes tables, figures and pictures.

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