Simultaneous removal of ammonium and manganese in slow sand biofilter (SSB) by naturally grown bacteria from lake water and its diverse microbial community

Abstract

Ammonium and manganese may cause the aesthetic deterioration of drinking water quality if their penetration into the water intake is not controlled. The current physical chemical methods may be unable to treat polluted raw water alone, so a biological method is used to bolster the current physical capabilities. In this study, the biological removal of ammonium and manganese was performed using a slow sand biofilter (SSB) and optimized based on a central composite design (CCD) with response surface methodology (RSM). RSM was used to study the interaction among the process variables, namely, the feed concentration of ammonium (NH4-N) and manganese (Mn), the aeration rate (AR) and retention time (RT). The optimum conditions suggested by the response model were 2.01 mg NH4-N/L and 3 mg Mn/L feed concentrations, a 6 L/min AR and a 9.45 h RT. The condition resulted in an 89% and 98% reduction of ammonium and manganese, respectively. The microbial community attached on the SSB was identified using a polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) method. Eight strains were obtained and identified as closest to Clostridium sp., Desnuesiella sp., Aeromonas sp., Pseudoalteromonas sp., Romboutsia sp., and Plasticicumulans sp. Of the bacteria identified in the community, Aeromonas sp. is known to have the ability to oxidize ammonium, and Pseudoalteromonas sp. is involved in oxidation of soluble Mn2+ to insoluble Mn4+.