LEE- Çevre Biyoteknolojisi-Yüksek Lisans

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http://hdl.handle.net/11527/24005

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Simulation of water resource recovery facilities with an open source software

(Graduate School, 2022-02-11) Binay, Doğa ; Özgün Karahan, Özlem ; 501181808 ; Çevre Biyoteknolojisi

Digitalization is in an uprising trend for more than a decade on many aspects of wastewater treatment processes and these days we are coming across with the term more than ever. Simulation softwares are virtual platforms, a projection of a particular configuration created by the users that can process the data provided with the help of consistent mathematical model implementations. By doing this, environmental engineers are able to control and optimize the operational parameters and use if for finding the most cost-efficient treatment configuration while upgrading an existing facility process scheme or even before constructing it. In other words, engineers can prevent excessive construction and operational costs along with excessive energy consumptions. The motivations of this thesis study is to emphasize the need for popularizing creating functionable softwares with user friendly interfaces, creating specific softwares for divergent configurations and usage of modelling in academy as it is so benefitial for the students to familiarize with the fundamentals of modeling during their undergraduate lectures in terms of the convenience it provides for operational and kinetic parameters. An open-source software able to perform simulations of water resource recovery facilities with Modified Ludzack-Ettinger configuration has been developed within the scope of this study. Python programming language has been chosen for the development of the software due to its easy to learn syntax and its open-source libraries that contain powerful packages such as NumPy, SciPy, PySide2, Matplotlib and Pandas. The data handling of inputs and outputs have been achieved with the help of useful built-in functions of NumPy and Pandas, whereas the graphical user interface of the software have been created with PySide2. SciPy.integrate's solve_ivp function has been used for performing computations of ordinary differential equations with the backward differentiation formula (BDF) method which is a multi-step variable-order implicit method used in solving stiff problems. Lastly for the development phase, figure canvas class of Matplotlib package has been integrated to the interface for visualizing the results of performed simulations. A biochemical process model, consisting of 10 processes and 2 operational parameters defined for 15 state variables, have been created for the specific configuration that includes hydrolization processes of rapidly hydrolyzable COD, slowly hydrolyzable COD, soluble organic nitrogen and particulate organic nitrogen along with the growth and decay processes of heterotrophic and autotrophic biomasses. Activated Sludge Model No. 1 (ASM1) has been taken as a base model for the creation of software model meanwhile endogenous respiration process definitions for two different heterotrophic organism species were adopted from the Activated Sludge Model No. 3 (ASM3). Modifications have been made to the hybrid process model as the ammonification of soluble organic nitrogen process from Activated Sludge Model No. 1 and the storage mechanism of Activated Sludge Model No. 3 were removed from the process model in this thesis study. Once the process model was created, mass balance equations of each state variable were implemented in the software. Configuration reactors were considered as Continuously Stirred Tank Reactors (CSTR) and therefore were assumed as ideal reactors. The reactant concentrations were considered to be distributed homogenously through the reactors meaning that the reactant concentrations within the reactor are assumed to be equal to the effluent concentrations of the reactors. Rate of accumulation in the reactors were computed for each state variable for defining the mass balance equations of the specific configuration. Cofefficients and stoichiometric parameters defined on process model matrix were multiplied by the process rates of each component for calculating the rate of accumulation in the reactors. Operational processes like constant feed of dissolved oxygen and sludge disposal process for the particulate matter that are going to be wasted were included in the matrix. Computation of sludge disposal was achieved by a sludge retention time input parameter and correction factors for the process rates of denitrifiers were also included to kinetic parameters alongside the coefficients of heterotrophic and autotrophic growth and decay processes. Lastly, hydrolysis rates and coefficients were appended to the model. Calibration and validation of the process model have been achieved by using the data set of an existing WRRF. First 220 days of the data set of 363 days were used for the calibration and last 143 days were used for the validation of the parameter coefficients. Root Mean Square Error (RMSE) and Janus Coefficient methods have been selected for evaluating the precision of model simulation outputs. The most precise predictions in the calibration were achieved for the NH4-N and the NO3-N parameters with Root Mean Square Error values of 1,73 and 2,01, respectively while in the validation phase, the most precise predictions were achieved for the NH4-N and the TKN parameters with Root Mean Square Error values of 0,65 and 0,78, respectively. The least precise predictions were computed for the COD and pCOD parameters on both of the calibration and validation processes with Root Mean Square Error values of 14,41 and 14,14, respectively for the calibration and 5,82 and 7,93, respectively for the validation processes. The verification of the developed software was achieved by implementing the Modified-Ludzack Ettinger model in AQUASIM, an acknowledged simulation software used in environmental science, and comparing the results obtained from AQUASIM and the developed software created in this thesis study. Several simulations were done using the same operational parameters, kinetic and stoichiometric coefficients in each software while changing the parameters and coefficients each time a simulation was performed. Similarly, simulation outputs of each software were compared with simulations having different step sizes like 10-1, 10-2 and 10-3. On all of the simulations mentioned, it was seen that the outputs of the developed software matched the outputs of AQUASIM software. In conclusion, a useful tool to predict the performances of nitrogen removal process schemes for different water quality and treatment requirements was created in this thesis study. Considering a decent automation integration is achieved to the software, the developed software will increase the control of facility operators over the operation of the systems. The need for specific case studies on the modeled configuration will reduce with the efficient use of the software and younger generations of environmental engineers will be provided a better mean of comprehension for the operational, kinetic and stoichiometric parameters and their impacts on the processes.
Environmental impacts of Golden Horn dredgings

(Graduate School, 2022-02-17) Barut, Anıl Sıla ; İskender, Fatma Gülen ; 501181801 ; Environmental Biotechnology

It is possible to pollute water resources with domestic, industrial and surface materials, and in some cases, water resources may begin to fill up. Depending on the water pollution, the sediment can be polluted and even if the water pollution is controlled, it continues to be a source of pollution. One of the most frequently applied methods to control sediment pollution is dredging. This method is also used to prevent water bodies from being filled with materials such as sediment brought in by the water sources that feed them. The management of dredged materials depends on their contamination status. Dredged materials with high pollutant content can be treated by physical, chemical and biological methods or disposed of in specially established facilities for the removal of these materials. During the implementation of the dredging project, it is possible for pollutants leaking from the sediment pore water or present in the fine-grained particles of the sediment to diffuse into the water body, and emissions to water and air depending on the equipment used in the dredging works. It is possible that the environmental impacts of a dredging project that is not implemented carefully will result in adverse impacts. In this study, an evaluation was made on the environmental effects of the dredging works applied both for pollution control and to prevent the Golden Horn from being completely filled. The study includes dredging studies conducted between 2016-2020. The management status of the dredged materials, which were applied at the beginning of the dredging works in the Golden Horn, in the sludge dams established in the quarries, and the dewatering of the dredged materials, which started to be applied later, and their disposal in the sanitary landfill facilities were examined. In addition, the effects of producing bricks with dredged material as an alternative method were investigated. In order to evaluate the environmental impacts of the dredging works, 1 m3 of dredged material was chosen as the functional unit. The system boundaries have been chosen to cover the extraction and transportation of the raw materials to be applied in each process, starting with the removal of the dredged material, its transportation, dewatering, removal and beneficial use. As a result of the life cycle assessment applied, it has been shown that the environmental impact of the disposal method in the sludge dams, which is the first method applied in the Golden Horn, is the most depending on the preparation of the removal area. As a result of the introduction of the landfill method, it has been concluded that although the applied methods require electricity consumption, it is more advantageous than the disposal case in sludge dams. Furthermore, the impacts of brick production with dredged material were compared with traditional clay brick production, and it was concluded that brick production with sediment was an advantageous method.
Determination of biogas potential of banana harvestingwaste and environmental life cycle assessment of utilizingstem waste for banana production in greenhouses in Türkiye

(Graduate School, 2022-09-26) Adsal, Kardelen Afrodit ; Arıkan, Osman Atilla ; Üçtuğ, Fehmi Görkem ; 501171807 ; Environmental Biotechnology

In Türkiye, 548,323 tons of banana fruit were produced in 2019. Banana fruit mainly grows in the Mediterranean Region due to the favorable temperature conditions. The year-long average temperature, humidity, and specifications of the soil are the parameters that make this region preferable for banana production. However, the environmental conditions in the Mediterranean Region have disadvantages when the region is compared with the countries that are the motherland of bananas such as India, Uganda, Ecuador, and Brazil. The ideal growing temperature for bananas is 27° C. In the case of a production environment at this temperature, an average of 100 kg of fruit can be collected from a plant for each harvest, although it varies according to the type of banana plant. It is not possible to capture this temperature regime during the year in Türkiye. For this reason, 77% of the current banana production is made in greenhouse areas. Greenhouse areas are production areas designed to keep the indoor temperature as high as possible, especially in winter. However, with existing methods, producers cannot increase the indoor temperature above 15 ° C in winter. This situation leads to the 40-50 kg range of production yield in each harvest per tree in Türkiye. Although this amount, which was half the current yield in the previous periods, is accepted; when the increasing banana consumption is considered, producers have tried various methods to increase this yield even more. However, most of them have failed. One method that has been tried frequently has been to use a heat source to increase the temperature of the covered areas. Some producers have installed wood, coal, and even natural gas stoves in greenhouses, also known as greenhouses, and tried to heat the interior in this way. The average size of the greenhouses densely located in Mersin and Alanya regions is 3 decares; In greenhouses covering these and larger areas, heating by setting up a stove has not been an effective method since it could not heat the entire area homogeneously. The most effective method for increasing the yield of banana production in Türkiye is to spray the groundwater into the greenhouse to improve the indoor temperature to a higher level than the ambient temperature. In Alanya, where the average air temperature is 11.8 °C in winter, groundwater temperatures are around 15 °C. Therefore, the usage of groundwater by spraying is an effective method of heating the greenhouses during the winter period. While some producers feed the groundwater directly into the greenhouses, some producers use the boiler systems they have installed to heat the groundwater and give it into the greenhouse. Fossil and nonrenewable energy sources are widely used in the heating process. This study, aims to evaluate the wastes generated during banana production and harvest and to measure the environmental effects of this method to handle the banana production process with a more circular approach, which will be an alternative to fossil fuels. The banana harvest takes place approximately 9 months after the plant sprouts. Depending on the type of banana plant, the plant's height could reach 8-10 meters during that time. The main planted banana plant species in Türkiye are Azman, Dwarf Cavendish, and Grande Naina can grow up to 6 to 8 meters. When the fruit harvest is completed, the strongest sprout is left from the newborn roots of the banana plant, and the whole plant is cut and left as waste. During the production of every 1 kg of banana fruit, 4 kg of harvest waste is generated. Banana harvest waste consists of leaves, stems, roots, root stems, flowers, and raw fruits. These completely organic wastes contain a high yield of carbon, nitrogen, phosphorus, and potassium. Currently, some producers leave these wastes in greenhouses and wait for the rich nutrient content to return to the soil. Although leaving these wastes to decompose in an uncontrolled way has a positive effect on nutrient recovery, generally, the application of a non-homogeneously distributed dose to a certain area has a negative effect. In addition, a disease that occurs in harvested plants can pass into the soil as a result of decomposition and damage healthy or newly budded plants. The banana harvest waste is quite suitable for energy and nutrient recovery by anaerobic digestion method when all the mentioned effects and properties are evaluated. In the anaerobic digestion method, banana harvest wastes are digested in a controlled reactor in the absence of oxygen at constant temperature and pH. During the digestion process, various bacteria consume organic matter and pathogens in the harvest waste and produce biogas, the content of it mostly methane (CH4) and carbon dioxide (CO2) gases. The produced biogas has a flammable feature due to the CH4 gas content and thus can be used as a renewable fuel. This study was carried out in two stages. In the first stage, the biogas potential of banana harvesting waste that occurred in Türkiye was measured in a pilot-scale anaerobic biogas reactor built in Lüleburgaz, Kırklareli. Thus, the potential of banana waste as a renewable source was measured for the greenhouse production areas which use groundwater as the heating source. However, due to different reasons (logistics, technical problems, etc.), the reactor could only be operated for 30 days, and the system could not reach a steady state during this time. However, the results and experiences obtained, albeit for a short time, are given to shed light on future studies. It is not recommended that these results be used for design purposes as the steady state is not reached. The reactor design was completed based on the results of the characterization of banana harvesting waste samples collected from southern Türkiye. The reactor volume is calculated as 10 m3. Anaerobic digestion was carried out in mesophilic conditions for 30 days. The results collected in the 30-day experiment were verified by comparison with literature data. Then, parameters in the design of the pilot scale reactor and biogas production quantities were used as inputs in the life cycle assessment. In the second stage of the thesis, the life cycle environmental impacts of banana production and then its supply to the end user in Türkiye were investigated. The low groundwater temperatures in Türkiye inhibit the yield of banana trees in Türkiye and literature suggests that it is possible to double the yield of a single tree by increasing the irrigation water temperature to 27 °C. Hence, three different scenarios were studied. The first scenario, also known as the business as usual case was considered; in the second scenario heating the irrigation water by using natural gas was studied, and in the third scenario heating the irrigation water by using biogas produced on-site via the anaerobic digestion of banana stem waste was analyzed. The functional unit was chosen as 2 tons of bananas produced throughout the lifetime of the biogas production system. CCaLC2TM was used as software, and CML2001 methodology was used. A cradle-to-grave approach was employed. The production processes were modeled based on real-life data acquired from a real greenhouse in Türkiye. Six impacts (global warming potential, acidification potential, eutrophication potential, photochemical oxidant creation potential, ozone layer depletion potential, and human toxicity potential) were calculated. Results show that four of the six impacts decreased when biogas was used, suggesting that this practice has the potential to reduce the environmental footprint of banana production. The results were found to be in good agreement with the values reported in the literature. It was concluded that to reduce the environmental footprint of banana production, utilizing stem waste instead of the conventional practice of burning is essential, and special emphasis should be given to treating or utilizing the bioreactor digestate to further reduce the environmental footprint.
Investigation of grey water treatment performance in a vertical subsurface flow constructed wetland

(Graduate School, 2023) Kılıç, Ömer Furkan ; Karpuzcu, Mahmut Ekrem ; 790907 ; Environmental Biotechnology Programme

The depletion and unconscious consumption of water, which is an indispensable element for vital activities, has become a global problem due to the increasing world population and industrialization. The decrease in precipitation as a result of climate change has made this problem even more challenging. A significant portion of the world's population currently has difficulty in accessing potable clean water resources. Moreover, it is reported that there will be a further increase in this human population deprived of this water in the coming years. Although countries put forward strategic plans on a national and international scale so that this problem does not turn into a serious crisis, they will face this crisis unless more measures are taken. The sustainability goals of the United Nations are a part of the solution proposals put forward against this problem. As resources should be used correctly and efficiently, making these resources reusable is one of the most important solutions. The reuse help reduces the risks of negativity in the process leading to the water crisis. Treatment of GW, which constitutes a large part of domestic WW and has a low pollution load, for reuse will reduce the burden on existing facilities and contribute to sustainable wastewater management. Thus, treated WW, which is discharged into water bodies and has the potential to cause environmental pollution to a certain extent, will turn into a valuable input. The treatment of these GWs, which do not require advanced treatment, using natural treatment technologies will further increase this positive contribution. Because natural purification technologies; They can imitate natural processes and offer an effective treatment performance without requiring energy, reinforced concrete structure and mechanical equipment. For all these reasons, in this thesis, the conversion of gray water into reusable water using a natural treatment technology has been examined. GWs, which are characterized as weak or strong according to their type, have a great potential for reuse. GWs can become usable water directly or indirectly by removing the disease-causing pollutants and pathogens in its content. Thus, the pressure on water resources may decrease somewhat. Moreover, since the load on WW treatment plants will decrease, a serious economic loss will be prevented. In this study, the treatment of GW, which is a valuable resource, by collecting it with discrete systems for reuse in CWs, which is one of the natural treatment systems, was investigated. Thus, it is aimed to fill this gap by offering a sustainable and environmentally friendly treatment method for Türkiye, which is also under water stress. Presenting it as a realistic solution to prevent environmental disasters such as mucilage will also be decisive in terms of Türkiye's environmental policies. By obtaining effective treatment efficiencies, an incentive will be created for the use of these technologies, especially in areas with low urbanization. In this direction, the GW of a large hotel in Taksim, Istanbul, was collected and then characterized, and these GWs were treated in the vertical subsurface flow constructed wetland (VFCW) installed in the laboratory. The quality of the treated GW in the reactor was determined and thus the GW treatment performances of the wetland were investigated. Characterization results were compared with a previous study by TÜBİTAK and no big difference was observed. However, the decrease in the number of guests due to the pandemic caused a decrease in N and P values. On the other hand, higher than average values were obtained in some COD measurements due to their lower water consumption. The VFCW bed, where filtration and adsorption will take place, was created by considering the design concepts in the literature. The system was fed with gray water for 2 weeks before the main experiment plan was carried out. Thus, biofilm growth was provided for the activity of microorganisms. The reactor in which Cyperus alternifolius was planted was fed with GW for 4 hours until saturation throughout the operation.
Relating microbiome profiles to removal of non-steroidal anti-inflammatory drugs in sequencing batch reactors along a sludge retention time

(Graduate School, 2023) Sercan, Melis ; Balcı Zengin, Gülsüm Emel ; 807315 ; Environmental Biotechnology Programme

Non-Steroidal Anti-Inflammatory Drugs (NSAIDs) are medications commonly used for pain and inflammation treatment. The residues generated from their use can contaminate water sources. The primary concern regarding these pollutants is their insufficient removal in wastewater treatment plants, leading to their release into the environment. In recent years, studies investigating the presence of NSAIDs in aquatic environments at critical levels and their long term effects have increased. The environmental impacts of these pollutants are not yet fully understood, raising concerns. In March 2015, the Water Framework Directive initiated by the European Commission listed some NSAIDs on the Watch List under Decision 2015/495/EU. The concept of harnessing the activities of adaptable microorganisms in low-cost and conventional systems, instead of expensive advanced wastewater treatment plants, is important for the treatment of micropollutants. Activated sludge based treatment processes have the potential to partially remove micropollutants; however, there is insufficient knowledge regarding which microorganisms play an active role. Furthermore, there have been limited studies on determining the appropriate sludge retention time for the biological treatment of micropollutants. The microbial communities in activated sludge can vary depending on the different chemicals present in the wastewater, which can adversely affect the system's performance. In this study, the impact of a mixture of six NSAIDs (diclofenac, ibuprofen, ketoprofen, naproxen, indomethacin, and mefenamic acid) on microbial population and composition in activated sludge systems was investigated using advanced molecular biotechnology and bioinformatics tools. This study mainly focused on (i) the impact of sludge age (SRT) on the treatability of the selected mixture of NSAIDs in activated sludge systems, (ii) a comparison of the microbiome analysis of samples collected from an advanced wastewater treatment plants in Istanbul and three lab scale sequential batch reactors operated at sludge retention times (SRTs) of 5, 10, and 20 days, (iii) the impact of reference database selection on the analysis of the activated sludge microbiome, (iv) the analysis of the impact of the selected NSAIDs on the microbial population and composition using bioinformatics tools and software, and (v) the correlation of the changing microbial population and composition with the treatment efficiency of the wastewater and selected NSAIDs. In the laboratory scale study, a total of six parallel sequential batch activated sludge reactors were operated with three different SRT: 5, 10, and 20 days. Among these reactors, three served as control reactors, while the remaining three were designated as micropollutant added reactors. Each SRT had a corresponding pair of control and micropollutant added reactors. The control reactors were operated under normal conditions without the addition of micropollutants, while the micropollutant added reactors were operated with the addition of a specific mixture of selected NSAIDs in predetermined proportions. The operating performance of the reactors was monitored regularly by measuring various parameters including suspended solids (SS), volatile suspended solids (VSS), pH in the reactor and chemical oxygen demans (COD), ammonia (NH4+), nitrite (NO2-) and nitrate (NO3-) in the effluent. The result of these analysis showed that these chemicals did not have a long term inhibitory effect on biological degradation in all six reactors. There was no significant change in COD removal efficiency in reactors where NSAIDs were added. The nitrification efficiencies were found to be better in the micropollutant added reactors with sludge retention times of 5 and 20 days compared to the control reactors. The removal efficiencies of the six NSAIDs were individually determined in all sludge retention time reactors. Ibuprofen exhibited removal efficiencies exceeding 99% in all micropollutant added reactors operated for 5, 10, and 20 days. Ketoprofen showed average removal efficiencies above 75% in reactors operated for 5 and 20 days. Naproxen had removal efficiency above 90%, with the highest removal efficiency observed in the reactor operated for 20 days. Indomethacin exhibited removal efficiencies above 90% in all micropollutant added reactors. Mefenamic acid had the highest removal efficiency observed in the reactor operated for 5 days, but its removal efficiency decreased in reactors with longer sludge retention times. Diclofenac removal efficiency was adversely affected in reactors with longer sludge retention times. This study aimed to understand the impact of micropollutants on the diversity and activity of microbial communities within activated sludge, which play a crucial role in wastewater treatment. Using next generation sequencing technology, the microbial communities involved in the degradation of six NSAIDs were investigated in laboratory scale activated sludge reactors, along with the potential adverse effects of these drugs on the communities. The sequenced data obtained from the Illumina MiSeq platform were analyzed using the QIIME2 software package to assess microbial diversity. A comparison between the NCBI and SILVA databases revealed that the NCBI database provided more taxonomic information at the species level. The addition of NSAIDs was found to affect microbial diversity in the 5 and 10 day sludge retention time systems, reducing species richness at the taxonomic level. However, in the micropollutant added 20 day sludge retention time system, an increase in diversity was observed. The observed operational taxonomic unit (OTU) numbers in the clone libraries for the sludge samples collected from the control and micropollutant added reactors were 203 and 145 for 5 day sludge retention time, 171 and 106 for 10 days sludge retention time, and 100 and 182 for 20 days sludge retention time, respectively. In this study, it was determined that Proteobacteria, Actinobacteria, and Bacteroidetes phyla were dominant in raw sludge, control, and micropollutant added reactors. The presence of NSAIDs at a sludge retention time of 5 days increased the abundance of the Verrucomicrobia phylum, while it decreased at a sludge retention time of 10 days. In the control reactor, Verrucomicrobia was not detected at a sludge retention time of 20 days, but its abundance increased with the addition of NSAIDs. In the micropollutant added reactors, different species became dominant at different sludge retention times. Prosthecobacter and Paracoccus species were dominant at a sludge retention time of 5 days, Chryseobacterium and Niabella species at a sludge retention time of 10 days, and Niabella and Parafilimonas species at a sludge retention time of 20 days. The presence of these species can be associated with their capacity to degrade NSAIDs in the micropollutant added reactors. In contrast, the presence of NSAIDs led to the disappearance of more than 80% of species such as Frigidibacter albus and Prosthecobacter vanneervenii in the reactor with a sludge retention time of 5 days, Thauera terpenica in the reactor with a sludge retention time of 10 days, and Intrasporangium oryzae in the reactor with a sludge retention time of 20 days. These species were unable to adapt to the new conditions created by the addition of NSAIDs. Changes in bacterial abundance in functional groups were also observed in the presence of NSAIDs. Specifically, an increase in the abundance of species involved in the nitrification process was observed in the reactor with a sludge retention time of 20 days with NSAID addition.
Comparative evaluation of nutrient, land, water and energy requirements of hydroponic vs. conventional agricultural methods: Case study for lettuce, basil, and arugula

(Graduate School, 2023-02-07) Aktuğ, İlayda ; Sözen, Seval ; Kutman, Ümit Barış ; 501181809 ; Environmental Biotechnology

The rapidly growing world population needs more environmental resources, mainly water and food, to the limit of extinction and defunctionalize traditional solution methods. Available water resources are decreasing day by day, moving to a value below the previously determined rate in researches as 3%. The most powerful reason for this is the increase in the carbon footprint created by industrialization. Global warming, changes in climate lead to insufficient water and food resources for the existing population. The amount of water per capita in year for our country is around 1500 m3, this amount is projected to decrease to 1.100 m3 in 2030. In this direction, efforts to prepare watershed protection action plans including long term conservation programs and measures to protect water resources for all types of use, prevent pollution, improve the quality of contaminated water resources, as well as project works to effectively use the community water resources by reducing losses and leaks in the water supply system have been initiated. Using water resources in our country general directorate of state water works for irrigation datas, other water use datas based on Turk Stat in Turkey as of 2016, 71,3% of the water in agricultural irrigation, 18,4% in industry, 10,3% in drinking and using water was determined. Based on these datas, it is concluded that the amount of agricultural irrigation should be under more controlled, considering the percentage of agricultural water use. In agricultural irrigation, 70% surface, 17% sprinkler, 13% drip irrigation methods are used. New method is used as an another alternative to conventional agricultural food production and also other modern greenhouse food production as the amount of water usage, more efficiently by 95% called "hydroponic farming" technology of food production simultaneously in both climate commitment reduction, reducing production time, while eliminating the problem of transportation into the city in conformance with the installation, reduce your carbon footprint. Dissolved nitrogen (N) and phosphorus (P) are the two main elements that trigger eutrophication. When the elements are above the limit concentrations, it is the result of water pollution and threatens aquatic life. As a result of uncontrolled fertilization in traditional agriculture, these pollutants, which are mixed into the soil release through irrigation water and then into groundwater, threaten the available water resources and the aquatic ecosystem. In the hydroponic vertical farming method, on the other hand, the amount of water used is reduced and fertilizer is used as much as the plant needs, so that there is no uncontrolled release into natural water resources. Comparative evaluation researches of plants grown in a controlled environment have proven that the plant is able to retain more nitrogen and phosphorus. Plants grown in hydroponic agriculture are healthy and nutritious for human health and consumption, while at the same time reducing the higher amount of nitrogen and phosphate in the water. Hydroponic farming systems are agricultural production methods made with only water without using soil. Plants get the minerals they need from the water in a usable form. The effects of technology on agriculture have reached to the inclusion of mechanization in time, then the development of sensor technologies, and finally the automated soilless vertical farming systems in the closed area, where lighting and air conditioning technologies can be realized by replicating nature. Vertical agricultural products, in which almost all leafy greens and some fruits can be grown, are nutritious in terms of content and can be grown in a shorter time. If the plants are grown in these systems, need much less nutrient use, can be carried out indoors and with automation systems, then the compliance of the plants grown with the increasing food requirement and the principle of "food safety and sustainability" is determined. Since the importance of growing indoors will be independent of the effects that may come from outside, chemicals used for pests are not required in these systems. With the development of lighting technologies, sunlight that will operate the photosynthesis mechanism of plants can also be imitated in these systems. The light spectra required by the plant vary at different rates depending on the type of plant. For the most efficient lighting, plants can be tested continuously and the highest yield can be given at any time of the year with full commitment. With advanced technology; automation systems, air conditioning, lighting, dosing, circulation and disinfection processes are monitored by sensors. In addition, the high quality tastes and images of fruits and vegetables grown hydroponically are better quality since the products grown in traditional agriculture are generally used both chemical usage and stress factors such as wind, irregular nutrients distribution and raining. However, in the literature, the nutrient and oil content of plants can be changed without affecting their naturalness by changing the ambient conditions given. Based on studies in literature, it is planned to prepare a thesis that can be examined under the title of Environmental Biotechnology within the scope of the hydroponic system consuming 95% less water compared to traditional agriculture within the principle of sustainability; examining nitrogen, phosphorus and energy consumption; obtaining quantity and plants are grown faster and under the principle of higher yield compared to the climate and arable area problems encountered in traditional agriculture. The aim of the thesis is to realize the reuse of wastewater, higher nitrogen and phosphorus consumption, energy consumption and area usage in the hydroponic system in Gebze Technical University (GTU) Institute of Biotechnology in collaboration with Plant Factory Inc. In the thesis, the prototype installed by Plant Factory Bitki ve Gıda Sistemleri A.Ş. at GTU, Biotechnology Institute; trials of automation will be carried out in which plants will grow in suitable conditions, healthy, higher yield plants. Generally, there are hydroponic studies with lettuce, basil and arugula plants in the literature. The contribution of the study to the literature is a more comprehensive examination of five parameters, in five different experiments, in four different experimental area, with three different leafy greens in a single study. In the study, energy, area, nitrogen, phosphorus and water consumption results were obtained by using three soil experiments and two hydroponic experiments (nutrient film technique, deep water culture) in open field (OF), greenhouse (GH), growth chamber (GC) and container (C) experimental areas that were carried out simultaneously with lettuce, basil and arugula plants. According to the datas obtained from the growing conditions, the nitrogen and phosphorus consumption rates in the hydroponic "Nutrient Film Technique (NFT)" and the "Deep Water Culture (DWC)" experiments are higher than soil agricultural studies. As plants grow, the growing medium only acts as a carrier for nutrients. For this reason, the environment of plants in traditional agriculture is soil, while hydroponic systems' is water, so plants take nutrients and transport them to tissues faster. In this case, because of providing homogeneity in water faster; homogeneous growth of plants is higher than soil agriculture by the way. Hydroponic systems are supportive alternative to traditional agriculture for efficient use of water in addition to efficient nitrogen and phosphorus consumptions. In the study conducted with NFT, it was observed that the water consumption rates were the lowest was more higher than others followed by DWC. High area use efficiency can be achieved successfully with the NFT hydroponic system in plant cultivation followed by DWC. In addition to that, another reason for the different responses of grown plants to different environmental conditions is the positive effect of lighting technology on plant growth. In addition, the importance of climatic conditions for the plant is as valuable as the lighting technology. As a result of the temperature and humidity conditions being adjusted where the plant does show required stress conditions to balance both the root and upper parts of the plant under the effect of transpiration and photosynthesis. The amount of energy consumption, which is another parameter obtained from datas, calculated as per gram dry leaf weight, is from low to high, respectively; in soil-based experiments as OF, GH, GC experimental areas; in hydroponic studies, NFT, DWC systems. NFT consumes less energy than the DWC hydroponic system but more than greenhouse production. In today's conditions, energy is provided from fossil sources. For this reason, although the carbon emission rate due to transportation is much less than traditional agriculture with its establishment in city centers, the energy used during production, especially due to lighting technologies, is quite high. Renewable technologies should be used to prevent energy-related carbon emissions. Solar, geothermal, wave, wind, biomass, hydroelectric, hydrogen energies are among the renewable energy sources that can be used. Considering the advantages and disadvantages, indoor hydroponic systems in green leafy plant cultivation is considered as an alternative method to support soil agricultural methods, both in terms of water, area, nitrogen-phosphorus use efficiency and the yield per square meter area.
Biopolymer production potential from pickle brine effluent through microbial processes

(Graduate School, 2023-09-14) Demir Aşkın, Merve ; Balcı Zengin, Gülsüm Emel ; 501211807 ; Environmental Biotechnology

The use of plastics is increasing every year around the world. This increase brings along both the waste problem and the raw material problem. Due to the waste problem, political and environmental problems are experienced worldwide. Since conventional plastics cannot be degraded in nature, their disposal is being more challenging and costly. When they are discarded, they can take hundreds of years to decompose, leading to a buildup of plastic waste in landfills and oceans. This plastic waste poses a threat to wildlife and the environment. In addition, the raw material for conventional plastics in which petroleum derivatives are non-renewable sources and they will eventually be depleted one day. In this context, use of alternative sources is critical for sustainable development. It is especially important that these resources, which can be offered as alternatives, should be biodegraded in nature and renewable sources. Biopolymers have been considered as new generation bioplastics however studies for optimum cost with high efficiency is still required. In this thesis, the production of polyhydroxyalkanoate (PHA) biopolymers, which are categorized as both biodegradable and bio-based, with pickle brine effluent was studied. PHA is a type of natural biopolymer that is produced by microorganisms and is known for being eco-friendly. PHAs have several advantages over conventional plastics with their characteristics of biodegradibility, renewable, biocompatibility and versatility. Metabolic production of PHA can be done by both pure culture microorganisms and mixed culture microorganisms. Pure culture microorganisms necessitate specific substrates, sterile environments, and cause high cost. There is a high risk of contamination, and the sterilization is required to prevent this contamination. Mixed microbial culture can be a more sustainable and cost-effective approach compared to pure culture methods. Mixed microbial cultures are less prone to contamination and more suitable for large-scale production. They have a higher diversity of microorganisms, which can lead to a wider range of PHA types and properties. And they can utilize low-cost carbon sources, such as wastewater and organic waste, which can reduce the overall production costs and contribute to circular economy. In this thesis, the production of PHA from pickle industry wastewater is studied with mixed microbial culture. In PHA production with mixed microbial culture (MMC), the carbon feedstock is fermented to produce a mixture of soluble fermentation products (SFP). Then, a community of PHA-storing bacteria is selected and enriched with various enrichment methods. Lastly, the selected culture is utilized to produce PHA, whereby SFP is added to the culture under conditions that limit growth to ensure the culture reaches its highest PHA capacity. In this thesis, the pickle brine effluent was used as feedstock for PHA production. In this context food waste is used for biopolymer production in which waste will be converted to high-value added product. This approach will both minimize the use of non-renewable resources and contribute to circular economy. The featuring characteristics of the pickle brine effluent is that it contains high organic acid content and high salinity. In order to ease the acclimation of the mixed microbial culture to saline conditions, the inoculum was obtained from the pickle industry wastewater treatment plant. The mixed microbial culture (MMC), was first acclimated to high salinity and further enriched for PHA producing MMC with aerobic dynamic feeding (ADF) regime. High salinity of the pickle brine effluent is used for the stress condition for ADF regime. Since the fermented pickle brine effluent includes various organic acids with high concentration, fermentation step was not required for PHA production. The pickle brine effluent had high organic and chloride content, with an average of 19,050±700 mg/L chemical oxygen demand (COD) and 39,175±1,155 mg/L chloride (Cl-), respectively. Total kjeldahl nitrogen (TKN), total phosphorus (TP) concentrations and pH values were 445 ± 18 mg N/L, 32± 46 mg P/L and 2.95±0.15, respectively. The organic acid content of the pickle brine effluent was 1,035±290 mg/L of acetic acid, 8,365±300 mg/L of lactic acid, 5,680±550 mg/L of propionic acid and 490±155 mg/L of succinic acid. In this study, for the experimental set-up, working volume of the the sequencing batch reactor (SBR) was selected as 2 L. Initially, SBR was operated as 1 cycle/day for the acclimation of the MMC to high salinity. The total suspended solids (TSS) concentration and volatile suspended solids (VSS) concentration of the inoculum was 8,065±605 mg/L, and 5,775±240 mg/L, respectively. After the inoculum was adapted to the pickle brine effluent, the culture enrichment process was started. Aerobic dynamic feeding (feast/famine regime) was used for the enrichment. SBR was fed with pickle brine effluent with 3,800 mg COD/L and 7,850 mg Cl-/L per cycle. The organic loading rate (OLR) of the reactor was 7.6 g COD/L.day. Also the pH of the feeding solution was adjusted to 6 to provide optimum environmental conditions and the SBR was kept in an isothermal room at 22°C. One cycle duration was 720 minutes (12 hours) consisted of 7 minutes of feeding, 630 minutes of aeration, 80 minutes of settling and 10 minutes of discharge. Waste sludge was discharged once per day as 500 mL to sustain a sludge retention time of 4 days. The ratio of initial volume to the total volume was 0.5. The SBR was operated for 209 days. The performance of the system was monitored by taking samples weekly from the SBR. Within the scope of SBR performance monitoring studies, volatile suspended solids, organic acid and PHA measurements were done in regular terms. The average volatile solids concentrations in the SBR were measured as 5,200±1,175 mg MLVSS/L at steady state conditions. In order to see the maximum PHA storage potential of the system, in-cycle monitoring studies were carried out. Thus, the SBR was monitored during a whole period of a cyle time (12 hours). The PHA content of the biomass was were found to be 0.48 mg COD/mg VSS, 0.52 mg COD/mg VSS and 0.59 in mg COD/mg VSS, respectively. These results are comparable with the literature. According to in-cycle analysis, HB and HV monomers of PHA biopolymer were found to be 98% (w/w) and 2% (w/w), respectively, and HB was observed as the major monomer. The polymer composition depends on the substrate composition, and it is known that HB is synthesized as a precursor, usually with acetic acid lactic acid-containing substrate. In this study, acetate and lactate were the main organic acid fraction utilized by the enriched culture for PHA production, while the propionic acid was used for growth. In addition, a batch experiment was also carried out to observe the effect of the organic loading rate on PHA storage yield. In this experiment, the organic feeding was 9,500 mg COD/L and the PHA content of the biomass was measured as 0.42 mg COD/mg VSS. The chloride concentration was quite high as 19,600 mg Cl-/L compared to the SBR with 3,800 mg COD/L and 7,850 mg Cl-/L feeding. It was observed that, high salinity reduced the reactor performance with lower PHA productions. Consequently, the results indicate that pickle brine effluent is a promising alternative for PHA biopolymer production with the optimization of the system.
Uncertainty analysis in the measurement of nitrification kinetics in urban wastewater treatment plants in Türkiye

(Graduate School, 2024-06-28) Leblebici, Berker ; Çokgör, Emine ; 501211801 ; Environmental Biotechnology

In this study, relation between the maximum growth rate of nitrifiers and the initial amount of active biomass placed at the beginning of the nitrification experiment was investigated by using parameter estimation and uncertainity analysis for four different wastewater treatment plants, taking into account local conditions. By focusing on these parameters, critical importance of the effects of initial conditions on the nitfication experiment is investigated. To designing and optimising the performance of wastewater treatment plants, nitrification kinetics play a decisive role. Nitrification directly affects aerobic sludge age, which is one of the most important parameters to obtain volume calculations. Understanding of nitrification kinetics will enable predict and control the rates of these biochemical transformations with greater sensitivity and, in turn, increase the effectiveness of future nitrogen removal processes. Nitrification is important for the alleviation of aquatic eutrophication and the minimization of the toxic ammonia concentration to meet the ever-increasing stringent environmental discharge regulations. In addition, it has significant impacts on designed advanced treatment technologies and sustainable practices along the pathways to ensure minimal anthropogenic impact on the natural ecosystems. Four different advanced biological wastewater treatment plants across the Marmara Region of Türkiye are taken into account to highlight the importance of the local conditions. From these plants daily samples were taken and nitrification experiment was carried on, and with the results of the experiments and the data generated by the model are used in this study. Some assumptions such as assuming the respiration and growth as constant are made in order to reduce the complexity of the initial conditions and to improve practical identifiability and lesser uncertainity between the focused parameters. The nitrification experiment results of the plants, that were modeled using Microsoft Excel program, used and with the help of sum of squared method, parameter estimations are performed, and the effect of the initial conditions of the experiment, and uncertainties are investigated. According to the results, approximate confidence intervals were visualized as contour plots based on critical values calculated at a 95% confidence level for each plant. The effects of local conditions on nitrification kinetics experiments were discussed based on observed similar trends in approximate confidence intervals. Nitrifiers growth rates in Türkiye found to be lower than that of standard values, and errors in maximum growth rate of nitrifiers are calculated to be in the order of 5-10%, which is acceptable according to the general design margins which is typically range between 20% to 25%. Also, for the practical applications overdesign is very general approach for construction of wastewater treathment plant design and oftenly varies between 10-30%. Thus, the importance of factors that may arise from the initial conditions of the experiment was emphasized, and the most suitable experimental conditions were examined. In many studies, the significance test of the data can be overlooked; however, this study focuses on the uncertainty analysis between the maximum growth rate of nitrifiers and the initial active biomass placed at the beginning of the experiment. Meanwhile, it is important to acknowledge that this study may be one of the first investigations to explore this specific aspect.
Investigation of toxicity of antiviral drugs in the presence of microplastics and their removal through ozonation and LDH-based catalytic ozonation

(Graduate School, 2024-06-28) Chavoshi, Nasim ; Doğruel, Serdar ; 501201814 ; Environmental Biothechnology

Following global outbreaks such as SARS-CoV-2 and influenza, the heightened use of pharmaceuticals to treat infected individuals has led to the presence of antiviral drugs and their metabolites in wastewater at significant levels. Since wastewater treatment plants (WWTPs) are not designed to remove antiviral drugs, these contaminants are discharged into receiving environments without treatment. If these substances are not adequately degraded during wastewater treatment, they could potentially harm human and ecosystem health when released into aquatic systems. To address this concern, tertiary treatment applications have to be employed. In this study, in order to assess the treatability of two commonly used antivirals, Oseltamivir (OSE) and Favipiravir (FAV), advanced oxidation processes, involving ozonation and catalytic ozonation were applied. Additionally, the potential ecotoxicological impacts of treated wastewater effluent were investigated on soil and aquatic environments. Moreover, the efficiency of the applied processes was also explored in the presence of microplastics (MPs). In this study, the concentrations of OSE and FAV were selected based on the occurrence of these antivirals in environment ranging from low (500 ng/L) to high (50 µg/L). A biologically treated synthetic wastewater sample, mirroring a typical domestic effluent, was exposed to ozonation with three different ozone dosages: 0.2, 0.6, and 1 mg O3/mg DOC (dissolved organic carbon) at pH values of pH: 7±0.1 and pH: 10±0.1. The degradation of these compounds was also assessed in the presence of catalyst 0.1 g/L of ZnFe LDH (layered double hydroxide), which is a nanocomposite catalyst. The widely found polyethylene (PE) microplastic (0.1 mg/L) was introduced into samples during the ozonation and catalytic ozonation applications. Antiviral compounds and their corresponding removal rates were assessed using liquid chromatography tandem mass spectroscopy (LC-MS/MS), employing the isotope dilution method. Solid phase extraction was employed to facilitate accurate quantification of antivirals in samples. Finally, to assess the potential reusability of treated wastewater, soil organisms Enchytraeus crypticus and acute organisms Vibrio fischeri were exposed to ozonated and catalytic ozonated samples according to OECD and ISO 11348-3 methods. According to the findings, by evaluating conventional parameters in ozonated and catalytic ozonated effluent samples, it was concluded that both ozonation and catalytic ozonation can effectively decrease the amount of organic matter in wastewater, while MPs had a negligible effect on the wastewater characterization. In this regard, the maximum removal rates in chemical oxygen demand (COD), dissolved organic carbon (DOC), and ultraviolet absorbance at 254 nm (UV254) parameters were achieved by catalytic ozonation at pH 10 with 1 mg O3/mg DOC, reaching approximately 27.2%, 17.7%, and 71%, respectively. Additionally, particle size distribution (PSD) analysis was conducted for non-ozonated and ozonated samples revealed an 11% decrease in the COD fraction within the particle size interval of <2nm, contributing to an overall removal efficiency of 21%. This finding underscores the significance of the soluble fraction (<2nm) in COD removal, constituting 54% of the total COD removed. In the case of antiviral removal, it was observed that in single ozonation and without the presence of MPs, both OSE and FAV showed a removal efficiency of 85% at high antiviral concentrations, regardless of the specific ozone dose. However, at low antiviral concentrations, while FAV was completely removed with 100% efficiency, OSE only exhibited a 26% removal under the same conditions. At high concentrations of antiviral compounds, catalytic ozonation did not perform as effectively as single ozonation. When considering the presence of MPs, it can be concluded that they negatively impact the removal efficiency of antiviral compounds. To assess the effectiveness of the treatment process and the potential reusability of ozonated and catalytic ozonated effluent samples, ecotoxicological analysis was conducted on Enchytraeus crypticus and Vibrio fischeri. The soil experiments carried out on high antiviral concentrations did not indicate any toxic effect on E. crypticus organisms; instead, the reproduction rate of organisms increased. Moreover, when these organisms were exposed to the samples containing MPs, their reproduction rate increased significantly. The toxicity evaluation using Vibrio fischeri bacteria indicated that biologically treated synthetic wastewater exhibited higher toxicity compared to ozonated wastewater. Furthermore, ozonated wastewater demonstrated slightly higher toxicity than catalytic ozonated wastewater. The leaset toxicity was observed in distilled water. The presence of individual antivirals in the wastewater resulted in lower toxicity compared to their combined presence, revealing the synergistic effect of FAV and OSE. Since antivirals were not completely removed during ozonation and catalytic ozonation at the high initial concentration (50 µg/L), they contributed considerably to the observed toxicity. The experimental results indicated that ozonation and catalytic ozonation could serve as favorable options to upgrade existing wastewater treatment plants. These processes not only contributed to the reduction in the release of antivirals from domestic effluents, but also significantly enhanced the suitability of treated wastewater for irrigation of agricultural areas.
Anaerobic digestion of lignocellulosic waste usingphysico-chemical pretreatment methods interms of performance, microbial community, and cost analysis

(Graduate School, 2024-09-26) Güven Beyaz, İrem ; İnce, Orhan ; 501211805 ; Environmental Biotechnology

Increasing population and energy demand emphasize the global need to use energy resources more effectively and responsibly. Specifically, reliance on fossil fuels and the repercussions of climate change have hastened the hunt for renewable energy. However, current sustainable energy supplies are insufficient to fulfill rising demand alone. In this context, transforming organic solid waste into a sustainable resource and energy solves the environmental pollution problem while also creating new resource prospects. Although anaerobic treatment is a well-known and widely utilized method, it remains a field for further improvement. However, the lignocellulosic structure of organic solid wastes makes hydrolysis, the first stage in anaerobic digestion, more difficult than with other forms of waste. The use of lignocellulosic wastes in anaerobic digestion systems offers significant waste management potential. However, biodegradation of such wastes is challenging due to their complicated structure, hence several pre-treatment procedures have been devised. Physicochemical pretreatment procedures, particularly microwave and acid treatments, speed up the breakdown of lignin and cellulose structures, allowing microorganisms to operate more efficiently with the waste. As a result, the anaerobic process becomes more efficient, and important chemicals like methane and volatile fatty acids are produced in greater quantities. Sunflower waste is a major raw material source for anaerobic treatment procedures in Turkey and across the world. Turkey is one of the world's largest sunflower producers, with sunflowers growing across vast agricultural regions, particularly in the Thrace region. Stem, head, and other biomass wastes from sunflower cultivation are typically left on agricultural areas or disposed of using inefficient ways. However, these wastes have a significant potential in biogas production thanks to their high cellulose and lignin content. Integrating these wastes into the circular economy makes significant contributions to both environmental sustainability and economic gains. Agricultural wastes have great potential for biomass energy production and can be converted into various products such as biogas, bioethanol, compost. In addition, by utilizing agricultural waste, farmers' income sources diversify and contribute to the strengthening of the rural economy. Products obtained by recycling agricultural wastes both ensure efficient use of resources within the scope of the circular economy model and contribute to meeting Turkey's energy needs with sustainable resources. As a result of these reasons, sunflower was chosen as organic waste in the study. Even though pretreatment methods are basically divided into physical, chemical, biological and combined pretreatment, research has shown that combined pretreatment can be more successful. Combined pretreatments are preferred to ensure more effective breakdown of lignocellulosic wastes, because methods used alone often cannot adequately break down the complex structure of the waste. Combined pretreatments are generally applied by combining physical, chemical or biological methods, whereby the advantages of each method create a synergistic effect, providing more efficient results. For example, the combination of microwave and acid-based pretreatment disrupts the structure of biomass both thermally and chemically, resulting in higher biogas and volatile fatty acid production. While these methods increase energy efficiency, they also provide sustainable solutions in terms of cost effectiveness. In this study, physico-chemical pretreatment was chosen to break down the lignocellulosic structure most successfully. For a physicochemical process, microwave was used for physical pretreatment and hydrochloric acid was used for chemical pretreatment. In this way, a more effective hydrolysis process was achieved with combined pretreatment. The substrate was microwave pretreated in 0.8%, 1.2% and 1.6% HCl solutions for 30 minutes at 120oC and 140oC. After pre-treatment, sCOD values were examined to understand under which condition the efficiency was more successful. Compared to the control sample without pretreatment, it was observed that 47% higher sCOD was obtained in the sample that underwent combined pretreatment in 1.2% HCl solution at 120oC for 30 minutes. The sCOD value measured without pretreatment is 22395 mg/L sCOD, and with 1.2% HCl 120oC pretreatment, the sCOD value is 32908 mg/L. In this way, the most effective pretreatment method was obtained in the study. At the same time, TS and VS values for seed sludge, control sample and the most efficient pretreatment were determined by standard methods. When comparing control samples and pretreated samples, TS degradation increased by 45% and VS by 52%. An increase in the TS and VS values of the solid material is a sign of effective deterioration. Thus, lignocellulosic wastes can be shown to decompose more efficiently, meaning that a more efficient hydrolysis will result in a larger VFA output. In recent years, it has become quite common to suppress the presence of archaea in the anaerobic digestion process and to ensure the formation of volatile fatty acids. The main reason for this is that although methane is used as an energy source, it is an important source of greenhouse gases. At the same time, CO2 is also formed as a byproduct in addition to methane (CH4) in semi-anaerobic digestion. The most important motivation of this study is to obtain volatile fatty acids. In addition to the development of pre-treatment technologies, the production of volatile fatty acids, which have an important place in the circular economy and are used in many different sectors, has become very popular. In this study, sunflower used as lignocellulosic waste was kept at pH 5.5 after being exposed to combined pretreatment. While archaea, that is, microorganisms that provide methane formation, cannot survive in this pH range, only the formation of volatile fatty acids is possible with acidogenesis microorganisms. At this pH value, microorganisms produce volatile fatty acids, but these volatile fatty acids do not turn into methane because the archaea cannot survive. Once the archaea were inhibited and the pH was checked every day, samples were taken on certain days. The formation amount of volatile fatty acid types, which are used in various sectors and have different usage purposes, on determined days was measured in mg/L sCOD. Cumulative VFA formation was determined for acetic acid, propionic acid, butyric acid, isobutyric acid, valeric acid and isovaleric acid. The 1st day sCOD value for the pretreated sample was 32908 mg/L; At the end of the 30th day, it was observed to be 19324 mg/L. It is showed that a success rate of volatile fatty acid formation of approximately 40%. In summary, the acid types, from most produced to least produced, are as follows: Propionic Acid: 3089 mg/L, Isovaleric Acid: 2993 mg/L, Isobutyric Acid: 2700 mg/L, Butyric Acid: 2137 mg/L, Isocaproic Acid: 2421 mg/L, Caproic Acid: 760 mg/L, Acetic Acid: 539 mg/L, Valeric Acid: 245 mg/L. Another important aspect of the study is the generation of genomic sequences of microbial communities for taxonomy categorization. The aim is to fully characterize microbial species using Oxford Nanopore MinION technology in combination with fast and long-read approaches. After DNA isolation, PCR and sequencing were performed under appropriate conditions. 16S, 18S and archaeal microorganism communities were classified and compared as phylum, class and species. Genetic sequencing of microbial communities has revealed a diverse spectrum of microorganisms involved in the anaerobic digestion process, including many species of bacteria and archaea. The most dominant species in microbial communities were observed as follows: Armatimonadota, Caloramator sp. E03, Dysgonomonadaceae:, Stephanoeca, Prototheca ciferrii, Prototheca wickerhamii, Tetramitus dokdoensis, Methanosarcina vacuolata, Methanothrix soehngenii, Methanosarcina barkeri. These findings will provide resources for future studies on understanding the microbial community of the anaerobic digestion process and improving system efficiency. Finally, a cost analysis was performed using all collected data. The economic values according to the types of volatile fatty acids obtained from 1.5 grams of substrate are as follows: Acetic Acid: $17, Propionic Acid: $250, Isobutyric Acid: $476, Butyric Acid: $247, Isovaleric Acid: $673, Valeric Acid: $24, Isocaproic Acid: $385, Caproic Acid: $122. Microbial analysis is very important to check system success efficiency. Archaea were shown to persist in this manner. Anaerobic digestion is an extremely sensitive process. Although successful pretreatment was used and archaea were predicted to be absent, their continued presence indicated that a more precise process application could yield more efficient VFA synthesis. At the end of this entire study, the following conclusions can be made: Increasing population and energy demand increases the need to replace traditional energy sources with sustainable alternatives. In this context, the use of organic solid wastes, especially those with a lignocellulosic structure, in the production of biogas and volatile fatty acids is important. However, the complexity of the lignocellulosic structure makes biodegradation difficult. Therefore, physicochemical pretreatment methods such as microwave and HCl enable waste to be hydrolyzed more easily and increase biogas yield. Studies show that combined pretreatment methods disrupt the structural integrity of wastes, leading to higher methane and volatile fatty acid production. In countries where sunflower production is intense, such as Türkiye, these wastes offer a great energy potential. While volatile fatty acid production in anaerobic treatment stands out as a more environmentally friendly and economical option, effective taxonomic analysis of microbial communities has the potential to further increase process efficiency.
Anaerobic digestion of lignocellulosic waste using alkali pretreatment method interms of performance, microbial community, and cost analysis

(Graduate School, 2024-09-26) Kazancı, Canberk ; İnce, Orhan ; 501211803 ; Environmental Biotechnology

Agricultural residues with lignocellulosic structures play a crucial role among renewable bioenergy sources and are abundantly available in nature. Anaerobic digestion (AD) is considered an ideal technology for agricultural waste stabilization/treatment and the production of renewable energy carriers. However, the overall economic value of the produced methane remains low, especially when compared to the potential value of waste streams. In this project, the aim is to facilitate the transition to anaerobic fermentation using agricultural waste, specifically sunflower stalks and heads with lignocellulosic structures, to increase the production of volatile fatty acids (VFA). An alkali pretreatment method will be employed as a chemical pretreatment process to investigate the yield from the selected agricultural waste and assess its impact on acidification efficiency. The purpose of using a pretreatment process is to make lignocellulosic material which is difficult to biologically degrade, more easily digestible thereby enhancing process efficiency. Wastes subjected to pretreatment with Potassium Hydroxide (KOH) at various dosages will be thoroughly examined for VFA yield. During the research process, the taxonomic classification of the microbial community active throughout the process will be conducted using the third-generation sequencing technology provided by Oxford Nanopore MinION, targeting the 16S and 18S rRNA gene regions. Finally, a cost analysis will be developed based on the obtained data. This analysis aims to contribute significantly to research in this field by providing practical guidelines to enhance the effectiveness of anaerobic treatment systems and transform organic waste into a sustainable energy source

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