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Net-Zero-Energy Model for Sustainable Wastewater Treatment

Yan, Peng, Qin, Rong-cong, Guo, Jin-song, Yu, Qiang, Li, Zhe, Chen, You-peng, Shen, Yu, Fang, Fang
Environmental Science & Technology 2017 v.51 no.2 pp. 1017-1023
bioenergy, electricity, energy balance, models, recycling, sludge, wastewater, wastewater treatment, China
A large external energy input prevents wastewater treatment from being environmentally sustainable. A net-zero-energy (NZE) wastewater treatment concept based on biomass energy recycling was proposed to avoid wasting resources and to promote energy recycling in wastewater treatment plants (WWTPs). Simultaneously, a theoretical model and boundary condition based on energy balance were established to evaluate the feasibility of achieving NZE in WWTPs; the model and condition were employed to analyze data from 20 conventional WWTPs in China. A total of six WWTPs can currently export excess energy, eight WWTPs can achieve 100% energy self-sufficiency by adjusting the metabolic material allocation, and six municipal WWTPs cannot achieve net-zero energy consumption based on the evaluation of the theoretical model. The NZE model offset 79.5% of the electricity and sludge disposal cost compared with conventional wastewater treatment. The NZE model provides a theoretical basis for the optimization of material regulation for the effective utilization of organic energy from wastewater and promotes engineering applications of the NZE concept in WWTPs.