Using slow sand filter for organic matter and suspended solids removal as post-treatment unit for wastewater effluent

Certain applications of wastewater after treatment necessitate the implementation of a post-treatment system (PTS) to elevate effluent quality, especially in cases where human exposure, such as irrigation, is a possibility. Slow sand filters (SSF) have emerged as a pivotal technology in PTS; these systems offer the advantage of significantly enhanced effluent quality. This research endeavors to assess the efficiency of a supply pond by incorporating top-surface funnel units at its outlets. Additionally, it comprehensively evaluates the overall performance of a PTS that was designed to serve as tertiary treatment for secondary-treated effluent originating from the Rafah Wastewater Treatment Plant in the Gaza Strip, Palestine. The PTS design demonstrated substantial efficacy, including a 70% reduction in biochemical oxygen demand, a 60% reduction in chemical oxygen demand, and an impressive 79.5% reduction in fecal coliform levels. Furthermore, this unit eliminates 53% of total suspended solids (TSS). However, despite these achievements, the presence of residual biological pollutants presents challenges regarding the water's suitability for agricultural applications.