Immobilization of Nitrifying Bacteria in Waterborne Polyurethane Hydrogel for Removal of Ammonium Nitrogen from Wastewater

A gelation of a material for immobilization, waterborne polyurethane (WPU). Using the WPU gel as the carrier and nitrifying bacteria as the microbe, we have tested the feasibility of the proposed immobilization method. The effects of WPU prepolymer and gelation process on the activity of nitrifying bacteria were investigated by relative respiratory activity. The microbial growth and distribution of immobilized nitrobacteria were observed with a scanning electron microscope (SEM) before and after acclimation. The nitrogen removal efficiency of immobilized acclimated nitrifying bacteria from inorganic synthetic wastewater was estimated in batch experiment and continuous experiment in up-flow inner circulation reactor. Also the maximum specific ammonia utilization rate, Ka, could reach 300 mg-N/(L-pellet-h). The results have verified the fact that the waterborne polyurethane entrapped-cell method developed in this study has a great potential for a variety of biological wastewater treatment applications.