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Cost-effective wastewater treatment in a continuous manner by a novel bio-photoelectrolysis cell (BPE) system

Sun, Han, Zhao, Weiyang, Mao, Xuemei, Ren, Yuanyuan, Wu, Tao, Chen, Feng
Bioresource technology 2019 v.273 pp. 297-304
biomass, cell growth, cost effectiveness, electric current, energy, harvesting, lipid content, lipids, microalgae, models, nitrogen, phosphorus, wastewater, wastewater treatment
Approaches to improve wastewater treatment by microalgae have objectives of greater culture control, efficient nutrient removal and increased lipid content. This work designed a bio-photoelectrolysis cell (BPE) system to modulate wastewater treatment by electric current. The electric current had the capacity to enrich entrapped cell weight with a 0.72-fold increase, which resulted in high daily nutrient removal, with 6.78 mg/L/d for nitrogen and 2.14 mg/L/d for phosphorus at 0.6 A/m2. As the nutrient removal was mostly dependent on cell growth, the 1.17-fold increase of lipid productivity was achieved. The harvesting at 6 A/m2 required lower energy input of 1.77 KWh/kg. For the recyclability of treatment, BPE system could continuously treat the fresh wastewater for at least three cycles with biomass and lipid productivities of 68.67 and 22.04 mg/L/d, respectively. The nitrogen removal model of Cst = 45.52–5.52exp(0.45 t) and phosphorus removal model of Cst = 12.54–1.48exp(0.45 t) were established to evaluate the stability of BPE system.