Development And Application Of Advanced Stacked Assembly Bioreactor For Wastewater Treatment

This study aims to develop a new reactor for efficient removing of nitrogen and phosphorus in the domestic sewage of rural area.Considering the features of integrated sewage treating reactor,the study developed an advanced stacked assembly bioreactor.Generally,the reactor is easily to assemble,processing superior capacity of denitrification,dephosphorization,aeration/water permeability and pollutant removal performance.For the sake of practical use,reactor’s performance and operating parameters were subsequently discussed in the study.The main research contents and conclusions are as follows:1.The study has analyzed the influence of different reflux rates on reactor performance.It was found that reactor’s pollutant removal capacity gradually decreased along with decrease of the reflux rate.The optimum removal efficiency was achieved when the reflux rate was 40L/h.Average removal rates of COD,NH3-N and TN could reach 86%,88%and 87%,respectively,under aforementioned rate.2.The study explored effect of aeration manner,including natural oxygenation and artificial aeration,on the reactor’s pollutant removal performance.Artificial aeration exhibited positive effect on the COD removal efficiency,mild effect on the NH3-N removal efficiency and negative effect on the TN removal efficiency.After artificial aeration,the reactor’s COD removal efficiency rose from 86%to 94%,whereas,TN removal efficiency shrank from 87%to 65%,which is speculated with inhibition of denitrification under aerobic environment.3.The study discussed the effect of cycle time on reactor’s performance.It was found that concentration of effluent COD,NH3-N,TN and TP all fell to minimum,corresponding to removal efficiency of 91.5%,86.9%,72.9%,and 64.8%,respectively,after 12h treatment under a circumstance of 40L/h reflux rate and natural oxygenation.At this time,the reactor hydraulic load can be increased to 1.6m3/m2/d,indicating properly reduction of cycle time will not only be a good strategy for some pollutant removal but also help to improve the hydraulic load of the reactor.4.The study employed FeSO4 and a self-developed agent as filler to enhance phosphorus removal by placing them on the top of reactor.The resulted showed that the maximum removal rate of TP were up to 64.4%and 80%after the addition of two different fillers,respectively.And,the utilization ratio of two different fillers were 87.1%and 94.2%,respectively.Generally,the self-developed agent displayed a more stable and higher performance comparing with its component,demonstrating its feasibility in the practical use.5.The research analyzed microbial diversity of different layers within reactor.The result revealed that Chloroflexi,Oxyphotobacteria,Acidobacteria,Diapherotrites,Bacteroidetes,Actinobacteria,Firmicutes,Thaumarchaeota,Proteobacteria,and Nitrospira dominated in different fillers.Among them,Nitrospira was only in the top 10 genus list of anaerobic layer filled with zeolite.Chloroflexi in both aerobic and anaerobic zone validated the existence of phosphorus biodegradation in the reactor.Generally,all these mentioned bacteria constituted the main population and contributed to the outstanding removal of COD,NH3-N,TN and TP in sewage.6.The reactor was amplified and applied on the treatment of domestic sewage in Dianjietang Village,Tongxiang City.Although,issues caused by unstable controlling systems frequently happen to the amplified reactor,it still displayed good removal capacity of COD,NH3-N and TN in the field.On this basis,another reactor,whose structure was optimized and operation mode was modified,was applied to treat domestic sewage in Maojiawan Village,Changxing County,Huzhou City.The results showed that modification of reactor improved its nitrogen and phosphorus removal performance.The reactor’s effluent NH3-N,TN and COD concentration had satisfied the requirement of the class one A standard,and TP concentration had meet class one B standard in the "Emission Standards for Pollutants in Urban Sewage Treatment Plants"(GB 18918-2002).Meanwhile,the reactor has its edge over regular one by occupying a smaller area and a shorter time for construction.This study will provide a basis for the subsequent engineering application of developed reactor.