Enhancing Nitrogen And Phosphorus Removal From Municipal Wastewater With Pilot-scale MBBR

The nitrogenous and phosphorus pollutants discharged into water body from urban wastewater are increasing along with the rapid development of urbanization as well as improvement of human's living, so improving the efficiency of wastewater treatment plant is the key to solving the problem. This study innovatively adopted pilot-scale MBBR(Moving Bed Biofilm Reactor) process to strengthen nitrogen and phosphorus removal, this thesis also studied the process parameters optimization, process removal capacity and microbial structure so that the treatment performance of pilot-scale MBBR were investigated to lay a theoretical foundation for the modification project of the wastewater treatment plant(WWTP).In the condition of HRT 8.9h,30% ratio of the fillers, DO 2-3mg/L, after 52 d's cultivation, the removal efficiency of COD was 53.6±6.5%, COD volumetric removal loading rate was 599.5±127.3 g·m-3·d-1; the removal efficiency of NH4+-N was more than 98%, NH4+-N volumetric removal loading rate was 67.75 g·m3·d-1. During the biofilm startup period, the biofilm thickness increased gradually, structure changed a tight and the variety of microbes increased.Shorten HRT could improve the volumetric COD removal rate, but reduce the volumetric NH4+-N removal rate. The average removal efficiency of COD, NH4+-N and TP for united MBBR-Activated sludge process were 71.2±8.5%,94.9±10.3%, 71.5±10.8%, respectively, water quality can reach the discharge standard of pollutants for municipal WWTP.Compared the treatment effect of MBBR with activated sludge method, analysis the feasibility of the WWTP modification project combind with full-scale oxidation ditch operation effect. The results showed that the COD and ammonia nitrogen removal efficiency of two phase activated sludge method were worse than united MBBR-Active sludge process. The ammonia nitrogen removal efficiency of full-scale oxidation ditch process and two phase activated sludge process were both lower than MBBR-active sludge process obviously, and the treatment effect is not stable. Using MBBR technique can improve the nitrification performance to ensure that ammonia nitrogen in effluent can meet the emission standard. Furthermore, MBBR could enhance biological phosphorus removal, reducing chemicals dosage and sludge production.