LEE- Çevre Biyoteknolojisi Lisansüstü Programı

Bu topluluk için Kalıcı Uri

http://hdl.handle.net/11527/24003

Gözat

Yazar "Balcı Zengin, Gülsüm Emel" ile LEE- Çevre Biyoteknolojisi Lisansüstü Programı'a göz atma
  • Öge
    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.
  • Öge
    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.