A technology to achieve stable and high ammonia nitrogen removal rates for corn distillery wastewater （ethanol fuel production） treatment has been designed.The characteristics of nitrifying bacteria entrapped in a waterborne polyurethane （WPU） gel carrier were evaluated after acclimation.In the acclimation period,nitrification rates of WPU-immobilized nitrobacteria were monitored and polymerase chain reaction （PCR） was also carried out to investigate the change in ammonium-oxidizing bacteria.The results showed that the pellet nitrification rates increased from 21 to 228 mg-N/（L-pellet·hr） and the quantity of the ammonia oxidation bacteria increased substantially during the acclimation.A continuous ammonia removal experiment with the anaerobic pond effluent of a distillery wastewater system was conducted with immobilized nitrifying bacteria for 30 days using an 80 L airlift reactor with pellets at a fill ratio of 15% （V/V）.Under the conditions of 75 mg/L influent ammonia,hydraulic retention time （HRT） of 3.7-5.6 hr,and dissolved oxygen （DO） of 4 mg/L,the effluent ammonia concentration was lower than 10 mg/L and the ammonia removal efficiency was 90%.While the highest ammonia removal rate,162 mg-N/（L-pellet·hr）,was observed when the HRT was 1.3 hr.
