Rural Septic Tank Wastewater Treatment Based on Enhanced Microalgae Growth in a Photosynthetic Electrochemical System

AbstractThe three-chamber septic tank has become essential in the middle rural areas of China, although its drainage serves as a potential source of groundwater contamination. A photosynthetic electrochemical system using Chlorella vulgaris was developed to treat synthetic sewage, and the impact of environmental factors on treatment performance was investigated. The results showed that the removal efficiencies of chemical oxygen demand (COD), NH4+-N and PO43−-P reached maximum value under 1.00 times/day−1 hydraulic circulation, 0.3·g L−1 initial algae dosage and 4,350 Lux light intensity. When the optimal condition were applied to treat the effluent of three-chamber septic tank, the removal efficiencies of COD, NH4+-N, and PO43−-P were 61.95%, 88.32%, and 95.36%, respectively. This study provided an optional treatment technology of rural sewage, and future research should focus on the algae separation and recovery in practical applications.