Effectiveness of ammonia removal by recirculating sand filters

This study examines the ability of in-service domestic wastewater treatment facilities, as opposed to controllable laboratory experiments, to remove ammonia utilising recirculating sand filters (RSFs). Permitted facilities in Missouri, USA, are required to regularly sample, analyse and report discharged water quality. The Missouri Department of Natural Resources stores the results in a central database, which was queried and analysed to assess the performance of these facilities in both the summer and winter seasons and to determine if a correlation exists between ammonia removal and flow capacity. The RSFs were found to discharge ammonia under 44 mg/l 95% of the time in winter and under 30 mg/l in summer. No correlation between performance and flow was found. The results of the study suggest that RSF technology is presently unable to treat ammonia in domestic wastewater to meet acceptable water quality standards for surface discharge.