Isolation of heterotrophic bacteria used in drinking water treatment and their ammonium removal characteristics

Two heterotrophic bacteria, named YX1 and YX2, were isolated from Songhua River. They were identified to be Microbacterium sp. and Acinetobacter sp. by morphological, physiological, biochemical and molecular analysis. The generation times of strain YX1 and YX2 were 3.03 h and 3.87 h at 5°C. Ammonium removal characteristics of strain YX1 and YX2 were analyzed by bio-enhanced activated carbon technology. The results showed that the strains started to degrade ammonium after 3-4 days accommodation. The environmental parameters affected ammonium removal by the isolates. Strain YX1 and YX2 were aerobic bacteria with higher ammonium removal efficiency under high dissolved oxygen concentration (above 5 mg/L). The optimal temperature for ammonium removal was 12~15°C. Two strains were mesophilic bacteria to endure low temperature. Alkalescence condition (pH of 7.5 to 8.0) was propitious to improve the ammonium removal efficiency. When the carbon source was acetate sodium, the ammonium removal rate was the highest, followed by glucose, trisodium citrate, calcium carbonate and glycerol.