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Continuous energy recovery and nutrients removal from molasses wastewater by synergistic system of dark fermentation and algal culture under various fermentation types
- Ren, Hong-Yu, Kong, Fanying, Ma, Jun, Zhao, Lei, Xie, Guo-Jun, Xing, Defeng, Guo, Wan-Qian, Liu, Bing-Feng, Ren, Nan-Qi
- Bioresource technology 2018 v.252 pp. 110-117
- acetates, algae culture, biomass, butyrates, byproducts, chemical oxygen demand, energy, energy recovery, fermentation, hydrogen, hydrogen production, lipid content, microalgae, molasses, nitrogen content, nutrients, wastewater, wastewater treatment
- Synergistic system of dark fermentation and algal culture was initially operated at batch mode to investigate the energy production and nutrients removal from molasses wastewater in butyrate-type, ethanol-type and propionate-type fermentations. Butyrate-type fermentation was the most appropriate fermentation type for the synergistic system and exhibited the accumulative hydrogen volume of 658.3 mL L−1 and hydrogen yield of 131.7 mL g−1 COD. By-products from dark fermentation (mainly acetate and butyrate) were further used to cultivate oleaginous microalgae. The maximum algal biomass and lipid content reached 1.01 g L−1 and 38.5%, respectively. In continuous operation, the synergistic system was stable and efficient, and energy production increased from 8.77 kJ L−1 d−1 (dark fermentation) to 17.3 kJ L−1 d−1 (synergistic system). Total COD, TN and TP removal efficiencies in the synergistic system reached 91.1%, 89.1% and 85.7%, respectively. This study shows the potential of the synergistic system in energy recovery and wastewater treatment.