Research On Characteristic Of Nitrogen Removal By Integrative Hybrid MBR

Membrane bioreactor (MBR) is a reasonable combination process of biological treatment technology and membrane technology, having many advantages such as high removal efficiency of pollutants, fewer sludge products and stable and high quality effluent. And it has been becoming a promising wastewater treatment. In the study, the wastewater with low C/N ratio was treated by an integrative hybrid membrane bioreactor. And the performance of the reactor in removing carbon and nitrogen in the influent, as well as those indexes influencing the performance were mainly studied. Furthermore, the mechanism of nitrogen removal was studied. Finally the influences of operating conditions, such as HRT, water temperature and C/N in the influent on the reactor's removal efficiencies were investigated. And the following conclusions can be obtained.(1)As the water temperature was 20℃~30℃, both removals of COD and NH3-N were increasing appreciably with the prolonging of HRT. But when the HRT was as long as more than 21h, though the removal of NH3-N kept on increasing, the removal of COD was decreased.(2)When the water temperature was 20℃~30℃, HRT was 9h, COD and NH3-N removals were increased as temperature rising. The NH3-N removal was obvious influenced by water temperature; the NH3-N removal was only 39.4% when the temperature was 10℃.(3)As the water temperature was 20℃~28℃, HRT was 9h, the influent COD was in the range of 103.9~776.3 mg/L, the NH3-N in the range of 98.1mg/L～146.7mg/L and C/N ratio was 0.8~5.7, COD, NH3-N and nitrogen removals were increased with C/N ratio increasing. And when C/N ratio was 5.7, COD, NH3-N and nitrogen removals were 92.0%, 93.1%, 70.0% respectively.(4)The research indicated that contamination removal mainly took place in aerobic section and anoxic section and the nitrogen removal process of hybrid MBR was based on the following two aspects. The first was that nitrification was mainly displayed in the aerobic section and denitrification was dominantly carried out in the anoxic section. Another was that nitrification and denitrification could be displayed simultaneously in each section. Sedimentation basin and membrane pool had little contribution to contamination removal.