Study On Nitrogen And Phosphorus Removal In A Integrated Reactor

In recent years, situation of water environment is severe, and the issue of eutrophieation in the water body is still serious. However, nitrogen and phosphorus which are key nutrients that result in water eutrophication has become the major pollutants in the diacharge of all kinds of waste water, the discharge of nitrogen and phosphorus in domestic sewage is increasing at present especially. With the development of biological nitrogen and phosphorus removal technology, a new technology with advantages of small investment, low cost, easy management, high efficiency and less energy consumption will be prevalent in domain of nitrogen and phosphorus removal technology.Based on the research progress on the biological nitrogen and phosphorus removal, a novel continuous flow integrated reactor which combines airlift circulation bioreactor and biofilm technology was explored in this paper. After the biofilm acclimatization and the start-up of the reactor, biosystem and operation parameters were adjusted and optimized, nitrogen and phosphorus removal ability and contaminants removal mechanism of the reactor were investigated under the optimum operation process.The main conclusions of the study show that, early biofilm cultivation was completed and COD removal efficiency reached to85%after the operation of the reactor for15days. After the biofilm cultivation for40days, the biofilm with good nitrification and denitrification was cultivated, effluent NH4+-N and TN removal efficiencies reached to95%and80%, respectively. Through the comparative studies on fixed bed biofilm system and moving bed composite biosystem, effluent outflow through a sedimentation basin and a membrane module, continuous exchange and cycle exchange respectively, the basic process conditions of using moving bed composite biosystem and intermittent circulation operation mode, effluent withdraws through a hollow fiber membrane module, and operation cycle of185min was determined.Under the operation process, influent PO43-P maintained at20mg/L, gradient increased influent COD and TN load, COD gradient increased from450mg/L to1125mg/L, TN gradient increased from46mg/L to121mg/L, COD removal efficiency was above90%, nitrification efficiency was above94%, and TN removal efficiency was above80%. Sludge retention time (SRT) was maintained at17days through regular sludge discharge, phosphorus (PO43--P) removal efficiency increased gradually and stabilized at95.4%.The analyses on contaminants concentration variation of single operation cycle, and nitrification rate and denitrification rate of microbes in each zone of the reactor show that, the reactor has obvious function distribution of each zone, biofilm can fix different preponderant bacterial flora, whereas activated sludge have similar bacterial flora in anaerobic zone and aerobic zone. Traditional nitration-denitrification, simultaneous nitrification denitrification, anaerobic phosphorus release and aerobic phosphorus excessive uptake is the major approach of nitrogen and phosphorus removal. Biofacies in the reactor is rich, microbes show different growth state in respective environment, which provide a guarantee to the realization of the function of each zone and high efficiency.