Simultaneous biological removal of ammonia, iron and manganese from potable water using a trickling filter

A pilot-scale trickling filter with dual layer support material was constructed and tested for simultaneous biological removal of ammonia, iron and manganese from potable water. The performance of the trickling filter was tested at constant hydraulic loading of 226 m3/m2 d while feed concentrations of iron, ammonia and manganese were varied between 0.5 and 4.0, 0.5 and 3.0, and 0.5 and 1.3 mg/l, respectively. The system was inoculated with a mixed culture and a series of experiments was performed to investigate the interactions among ammonia, iron and manganese removal when simultaneously present in the trickling filter. The oxidation reduction potential increased along the filter depth from about 150 to 600 mV, depending on the feed concentrations, thus enabling one-stage simultaneous removal of the three pollutants. Ammonia and iron drastically affected manganese oxidation and manganese was found to be the rate-limiting pollutant. The results are presented using an operating diagram of the system, that determines the range of operating conditions resulting in optimal operation, keeping iron, ammonia and manganese concentration under the maximum permitted limits in potable water.