Preparation of Polyurethane Immobilized Nitrifying Bacteria Pellets and Application to Treatment of Micro-polluted Source Water

The preparation and application of polyurethane immobilized nitrifying bacteria pellets for surface water treatment was studied. The removal of ammonia nitrogen from micro-polluted source water by polyurethane immobilized nitrobacteria pellets with a stuffing ratio of 10% in volume in an up-flow inner circulation reactor was investigated with the system operated continuously under the following conditions: temperature 20 degrees C--30 degrees C, DO 3--5 mg/L, and pH 7.1--7.3. The continuous removal rates of NH4+-N remain above 90% and NH4+-N concentration in the produced water was less than 0.5 mg/L with the hydraulic reaction time (HRT) controlled at 0.5 h. The results verified that polyurethane immobilized nitrobacteria pellets have a great potential for micro-polluted source water treatment applications.