Mikroalgal ve anaerobik mikrobiyel kültürlerin kullanımı ile entegre besiyer madde giderimi, sera gazı mitigasyonu ve biyo-yakıt ve biyo-ürün eldesi

TÜBİTAK ÇAYDAG15.08.2015Mikro algal kültürlerin kullanımı ile önemli bir sera gazı olan CO2’in mitigasyonu çok yeni bir araştırma alanıdır. Mikro algal kültürler ile besiyer madde giderimi ve atık mikro algal biyokütleden biyogaz, hidrojen ve gübre eldesi çeşitli araştırmalara tek başına ya da birlikte konu olmuş uygulamalardır. Ancak, bu projenin konusunu oluşturan mikro algal ve anaerobik mikrobiyel kültürlerin entegre besiyer madde giderimi, sera gazı mitigasyonu ve biyo-yakıt ve biyo-ürün eldesi için birlikte kullanıldığı entegre bir biyoproses konfigürasyonun geliştirilmesi özgün bir yaklaşımdır. Bu inovatif konfigürasyon sadece atık su arıtımı ve CO2 mitigasyonu gibi önemli atık yönetimi sorunlarına bir katkıda bulunmakla kalmayacak, biyoyakıt (biyogaz ve biyohidrojen) ve biyoürün (gübre) eldesi de sağlayabilecektir. Bu projenin en önemli çıktısı hem evsel hem de endüstriyel atık suların atık CO2 kaynakları (örneğin endüstriyel baca gazları) ile birlikte arıtılabilmesini sağlayan özgün bir biyoteknolojik proses konfigürasyonunun geliştirilmesi olacaktır. Bu sürece paralel olarak sağlanacak olan biyoyakıt ve biyoürün eldesi, sadece atık valorizasyonuna değil, sürdürülebilir atık yönetimine de önemli bir örnek oluşturabilecektir. Atık sulardan azot ve fosforun %90-100 arasında değişen verimle giderimi, fotobiyoreaktörlerde sağlanan 0,16-0,26 g/L.gün CO2 tutma hızı, mikro algal biyokütleden elde edilen metan verimi (249 mL CH4/g TUKM), hidrojen verimi (2,47 mL H2/g TUKM) ve detayları bu raporda sunulan projemizin diğer sonuçları hipotezimizi destekler bir ilk adım niteliğindedir. Diğer bir deyişle, mikro algal ve anaerobik mikrobiyel kültürlerin entegre besiyer madde giderimi, sera gazı mitigasyonu ve biyo-yakıt ve biyo-ürün eldesinde birlikte kullanımı olasıdır. Bu üç farklı amaca aynı anda hizmet edecek olan bir inovatif biyoproses konfigürasyonunun optimizasyonu çalışmalarımızın bundan sonraki aşamasını oluşturacaktır.The mitigation of CO2 which is an important greenhouse gas by using microalgal cultures is a very new research area. Nutrient removal by microalgal cultures and anaerobic digestion of waste microalgal biomass and subsequent biogas, biohydrogen and fertilizer production were relatively investigated in the past. However, the research on these areas concentrated on only one or two of these tasks. Therefore, the integrated bioprocess configuration which is investigated in this project to provide integrated nutrient removal, greenhouse gas mitigation and bio-fuel and fertilizer production by using both microalgal and anaerobic microbial cultures is an innovative approach. This innovative configuration will not only contribute to nutrient removal from wastewaters and CO2 mitigation but also generate bio- fuels (biogas, biohydrogen) and bio-products (fertilizer). The impact of this project will be a cost-efficient biotechnological process configuration for the treatment of both domestic and industrial wastewaters as well as waste CO2 sources such as flue gas. Moreover, the parallel bio-fuel and bio-product generation will be a good example of waste valorization and sustainable waste management approach. Nitrogen and phosphorus removal from wastewaters with 90-100% efficiency, achievement of significant CO2 mitigation rates (0,16-0,26 g/L.day) in photobioreactors, methane production from microalgal biomass with a yield of 249 mL CH4/g VS, dark fermentative hydrogen production with a yield of 2.47 mL H2/g VS and other results of our project which are presented in this report not only support our initial hyphothesis but also constitute the first step toward its realization. In other words, an integrated approach enabling nutrient removal, greenhouse gas mitigation and bio-fuel and fertilizer production by using microalgal and anaerobic cultures is possible. Optimization of an inovative bioprocess configuration which will serve for all these three objectives will be the next phase of our research

Karışık mikroalg kültürünün kullanılması ile entegre besiyer madde giderimi ve karbondioksit tutulması.

Microalgae can remove nitrogen (N) and phosphorus (P) in domestic and industrial wastewaters, which cause eutrophication in rivers, lakes and seas. Microalgae have also been recognized as a promising alternative for carbon dioxide (CO2) sequestration from flue gas. However, it is necessary to design flexible and low-cost cultivation systems and, use suitable operating conditions to achieve enhanced biomass productivities and high CO2 fixation efficiencies. The aims of this study were: (i) to determine optimum hydraulic retention times (HRTs) for cultivation of microalgae in different types of wastewaters; (ii) to compare the microalgal productivities and nutrient removal rates at different N:P ratios (iii) to propose an integrated system for the utilization of wastewater and CO2 in flue gas for the production of microalgae. Within this context, a mixed microalgae culture collected from Araç Creek in Karabük Province in Turkey was grown under batch and semi-continuous operation modes. Two types of culture mediums were used in the experiments: (i) primary treated domestic wastewater from Ankara Tatlar WWTP and (ii) KARDEMIR Coke Plant wastewater diluted with supernatant of sludge thickener tanks of Ankara Tatlar WWTP. While ambient air (0.03% CO2) was supplied to the cultures grown with primary treated domestic wastewater, CO2 enriched air (4% CO2) was sparged into the cultures grown with diluted industrial wastewater. Light and mixing (aeration) conditions were the same in all set-ups. The optimum inoculum volume was determined as 10% (v/v) conducting a batch study and was used in all experiments. The optimum HRT was found to be 2 days for cultivation of microalgae in primary treated domestic wastewater. Mixed microalgae culture was able to remove 94.7% of Total Ammonia Nitrogen (TAN) and 93.8% of orthophosphate (PO4-P) from domestic wastewater at a HRT of 2 days. Although almost complete nutrient removal efficiencies were observed during steady conditions of the cultures with 4- and 8-day HRT, the steady-state conditions could not be maintained and cell washout was observed in the reactors due to nutrient limitation. The TAN/PO4-P (g/g) ratio of 6 resulted in the maximum nutrient removal efficiency when the diluted coke plant wastewater was used in the batch-mode operation. Results of the semi-continuous study conducted with diluted coke plant wastewater revealed that HRT should be kept 8 days at minimum in order to achieve efficient TAN and PO4-P removal (>98%) and high steady-state biomass concentrations (>2.4 mg TS/L). The CO2 removal rates were highest in the culture with 12 day-HRT and, it was obtained as 0.436 g CO2/h. The results demonstrated both effectiveness and potential application of the coupled system to remove nutrients from domestic and industrial wastewaters and simultaneous CO2 removal from a point source.  M.S. - Master of Scienc