Nitrification of high levels of ammonia in groundwater using fixed‐bed biofiltration technique

Abstract

Groundwater ammonia pollution is well investigated worldwide as well as in Viet Nam. The products of its conversion process, namely nitrite and nitrate, cause the toxicity of ammonia in water. In addition, the existence of ammonia in water causes the modification of water taste and smell, increases the risk of heterotrophic and contagious microorganism presence. Biofilm technique has been being applied to treat the ammonia in the groundwater recently. In this present study, fixed‐bed biofiltration technique was implemented to remove the ammonia at high concentration of 20‐50 mgN/L. The results indicated that the effluent reached the standard of domestic and drinking water quality (the ammonia concentration < 3 mgN/L) at all investigated ammonia concentrations. The specific nitrification rate of the microbial carrier used reached the maximum value of about 3.76 kgN.m‐3.day‐1 with the hydraulic retention time lower than 0.4 h and feed ammonia concentration of about 50 mgN/L. The biomass density in biofiltration column before experimental implementation was about 1000 mg/L.