Feasibility of Using Wastewater Treated by Activated Sludge Method and Microfiltration for Agricultural Irrigation

To explore the suitable treatment level for the resource utilization of domestic wastewater, an indoor potted plant experiment was conducted. In the experiment, three differently treated wastewater were used to water vegetable planting pots. The three differently treated wastewater include: effluent from aerated sand settling, effluent from anaerobic activated sludge method and microfiltration, effluent from aerobic activated sludge method and microfiltration, and tap water was as a control. The feasibility of using different treatment levels of domestic wastewater for vegetable irrigation and their impact on the physicochemical properties of sandy soil, such as pH, organic matter content, electrical conductivity, and permeability, were studied. The results showed that the anaerobic activated sludge method combined with microfiltration effectively removed chemical oxygen demand (COD) and fecal coliform (E. coli) from domestic wastewater. The pH, total salt content (TSC), COD, and E. coli indicators of the effluent met the requirements of the "Water Quality Standards for Irrigation in Farmland" (GB5084-2021). The irrigated wastewater had no inhibitory effect on seed germination, and nutrients in the wastewater treated by anaerobic activated sludge method could meet the needs of plant growth, and the impact on soil physicochemical properties, such as pH and permeability coefficient, was relatively low. Moreover, wastewater irrigation could increase the organic matter content in the plant soil. Therefore, "anaerobic activated sludge method and microfiltration” process is an economically feasible way for the resource utilization of domestic wastewater.