Immobilization of Micro-Organism on Macroporous Polyurethane Carriers

Abstract

The micro-organism B500 was immobilized on macroporous carriers by linking and adsorption methods, placed into a bioreactor that consists of an electric controlling system and employed in the treatment of wastewater from a campus. Under the conditions of dissolved oxygen (DO) = 2.5 mg/L, temperatures ranging from 25°C to 27°C, pH values from 8.2 to 8.3, and an hydraulic retention time (HRT) = 4.0 h, the results showed the removal rates for chemical oxygen demand (COD_Cr) and NH₄⁺-N were 90 and 92%, respectively. The macroporous structure of the carrier offers a better microenvironment for micro-organisms' activation and substrate diffusion during nitrification and denitrification, such that the removal efficiency for contaminants in wastewater was enhanced. To meet the criteria for the effluent COD_Cr <100 mg/L and NH₄⁺-N <10 mg/L, the maximum applied COD_Cr load and the applied ammonium load in the immobilized bioreactor should be 11.72 kg/m³ · day and 0.29 kg/m³ · day, respectively. Results of the continuous operation of the equipment for half a month showed that the resulted immobilized micro-organism held excellent stabilization and endurance to the wastewater fluctuation.