Study On Treatment Of Domestic Sewage By PVA Biological Process On Normal Temperature

With the constant improvement of Chinese urbanization rate,small towns sewage emissions increased rapidly year by year.Currently,domestic sewage treatment processes were enhanced primary treatment,combined process of biofilm and constructed wetland,anaerobic hydrolysis and high loading biological filter,ecological pond and so on.However,these processes have many shortcomings such as lower volume load,high sludge yield,high cost,complicated to operate and so on.Therefore,new high efficient biological treatment technology was desiderated to research.PVA biological treatment process was developed by Kurary company of Japan,which was to use the PVA-gel beads to be carrier with the high technical advantages of volumetric load and high efficent treatment effect and low sludge production.The recent domestic researchers using PVA processing sewage biological systems had obtained the good effect.However,the whole process which required under 30 conditions leaded to process operation energy consumption and controlling cost being significantly increased.Therefore,in order to solve the difficult technology problem,this paper by using PVA biological system volume doubled was to operate PVA biological treatment process with sewage on normal temperature aiming to establish a foundation for the popularization and application of this technology.The main research contents and conclusions were as follows:?1?Under the conditions of pH value from 6.5 to 8.5,DO from 2 to 4 mg·L^-1 and volume load 0.5 kgCOD·m^-3·d^-1,operate the PVA biological treatment process on normal temperature.After 8 d running,the system of COD and NH₄⁺-N removal rate steadied at78%and 71%above,the effluent COD and NH₄⁺-N concentration was in 46 mg·L^-1 and8.25 mg·L^-1 below respectively.The result showed that after 8 d running of the system PVA biological treatment process had meant reactor started-up successfully.?2?At volumetric loading rate of 1.5 kgCOD·m^-3·d^-1,normal temperature.During 11days continuous operation,the system showed that the average removal rate of COD and NH₄⁺-N was 72.6%and 81.6%,the effluent COD and NH₄⁺-N reduced to 55.6 mg·L^-1 and7.19 mg·L^-1 respectively.?3?From the appearance and microcosmic changed of PVA-gel beads,the main reasons for the processing ability of PVA biological systems were as follows:a)PVA-gel ball had good biological affinity,and its internal contained a lot of pore structure,to which had big specific surface area with a plenty of place for large number of microorganism;b)Enrichment of microorganisms in gel ball forming an approximation of the granular sludge microbial community of high concentration,as a consequence,the biological treatment process would markedly enhance its capability of impact resistance to volume load and improve the stability of the system.