Performance assessment of solar photovoltaic-based constructed wetland for sustainable rural wastewater treatment

Water pollution poses a significant challenge to the development of rural human settlements in China, necessitating the development of wastewater treatment systems tailored to the local economic conditions and discharge characteristics. This study introduces a novel wastewater treatment process, namely solar photovoltaic power generation-constructed wetland (SPPG-CW) and conducts a comprehensive evaluation of its performance on rural domestic sewage treatment. The findings reveal that the solar photovoltaic power generation unit ensures stable off-grid operation, providing a reliable power supply to the wetland unit. Simulation results demonstrate that the LAB achieves stable energy output and absorption during SPPG unit operation, thus avoiding energy loss. Long-term monitoring experiments confirm that the SPPG-CW efficiently treats real wastewater. Upon stabilization, the system consistently achieves over 90 % removal efficiency for turbidity, chemical oxygen demand (COD), linear alkyl-benzene sulfonates (LAS), and petroleum. The influent concentrations of COD and petroleum were identified as critical water quality indicators. Post-treatment, the SPPG-CW reduces COD and petroleum concentrations to as low as 5.49 mg/L and 0.02 mg/L, respectively, meeting the irrigation water quality standards. The average removal rates for total nitrogen (TN) and total phosphorus (TP) were 88.38 % and 79.41 %, respectively. Further investigation into the purification pathways reveals that microbial activity primarily drives the degradation of LAS and TN, while TP removal is largely attributed to plant uptake. Remarkably, the SPPG-CW, incurring only 20.37 % of the total cost of existing rural wastewater treatment facilities, demonstrates promise for applications in areas endowed with abundant solar energy resources.