Integrated nutrient removal and biogas production using microalgal and anaerobic microbial cultures

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2013
Çalıcıoğlu, Ayşe Özgül
Following industrialization and urbanization, there have been significant impairments in key nutrient cycles, affecting both ecosystems and human well-being. Urban sewage is rich in nutrients such as nitrogen and phosphorus, which cause eutrophication in receiving water bodies, if not removed. Microalgal nutrient removal is a viable alternative for biological wastewater treatment, considering their high nutrient uptake capabilities of microalgae. These systems are also advantageous in terms of nutrient recycling and conversion into microalgal biomass, which, in turn, is a beneficial resource for biofuel production. In this study, a semi-continuous photo-bioreactor was operated for investigation of nutrient removal efficiency of unialgal culture, Chlorella vulgaris. Maximum N and P removal efficiencies of 99.6% and 91.2% were achieved in the photobioreactor. Biogas production from biomass obtained from semi-continuous photobioreactor was investigated via Biochemical Methane Potential (BMP) assays. The results illustrated that maximum biogas yield of 442 mL/g VS added could be achieved in untreated microalgal slurry reactors. Evaluation of pretreatment options indicated that the highest biomethane yield could be achieved after heat pretreatment. However, considering that autoclave pretreatment is less energy intensive, this method was found to be more feasible for enhanced biogas production. The results of BMP assay conducted for co-digestion of microalgal slurry with model kitchen waste or waste activated sludge indicated that maximum biogas yield of 785 mL/ g VS added could be achieved when model kitchen waste was used as co-substrate. Outcomes of this study reveal that microalgal biotechnology is a feasible alternative for integrated nutrient removal and biofuel production applications.

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Citation Formats
A. Ö. Çalıcıoğlu, “Integrated nutrient removal and biogas production using microalgal and anaerobic microbial cultures,” M.S. - Master of Science, Middle East Technical University, 2013.