Research Of Moving Bed Biofilm Reactor On Suspended Medium Selection And Its Treatment Of Low Concentration Wastewater

Taihu Lake is an important drinking water resource, the pollution in Taihu has seriously affected people's life and development of regional economic, so controll of pollutants in total effectively is a necessary prerequisite for improving the water quality of Taihu. Due to the level of general nitrogen removal process in sewage treatment plants is not high, developing a floating bed biological process based on the conventional treatment to achieve enhanced wastewater denitrification is necessary. In this paper, we applied the joint process of moving bed biofilm reactor (MBBR) and A/O for wastewater treatment, enhancing the nitrogen removal technology. The major conclusions were described as follows:1) In this paper, the polyethylene and sponge fillers were used as the MBBR's medium, then considering the two fillers' effects on the removal of COD, TN and NH4+-N. According to the overall treatment results, it's obtained that the sponge filler was better than the polyethyene filler. As the biofilm could penetrate into the inside of sponge filler, it was more conductive to attachment for microbes.2) In order to control the flow pattern of filling in the reactor while saving costs, the aeration tank was divided into three cells, then selecteing the better filling position by experiments. In the same water quality and system operation conditions, considering the removal efficiency of COD, TN and NH4+-N, it's obtained that the fillers in the inlet segment had better treatment effect.3) The experiment studied the major factors affecting the MBBR:hydraulic retention time (HRT), temperature, reflux ratio, influent concentration and dissolved oxygen(DO). As the conclusion, the optimum operating conditions:HRT was 6h, the reflux ratio was 3:1, DO was from 2 to 3.5mg/L, temperature was above 25℃.4) MBBR reactor had a great resistance to the changing of influent concentration.The reasons were as followed:besides the biomass was high, the microbe was growing in the form of fixation. When subjected to shock loading change, due to the outer membrane's buffer, the inner membrane suffering the toxic effects should be small and the recovery was quick.5) When the temperature was low, pollutants (COD, NH4+-N, TN) treatment effect was significantly reduced. Extending the hydraulic retention time, increasing the response time between microbes and organic pollutants, then the removal of pollution could be improved.