Study On Efficient Anaerobic Reactor And Denitrification With Deodorization Process Of Small-Sized And Decentralized Domestic Wastewater

In recent years, the discharge of rural domestic sewage has become an important factor for water pollution.So.it’s important to develop technologies and processs applied to rural decentralized wastewater treatment. The research group of Southeast University proposed a bio-ecological combined process, anaerobic baffled reactor - anoxic deodorization tank aerobic biological rotating disc(waterwheel driving) - constructed wetland. The process has the characteristics of simple operation, low energy consumption, good treatment effect, recyclable nitrogen and Phosphorus resources etc.Through the research on treatment and operation parameters of anaerobic unit, anoxic unit and the overall process, efficient degradation of pollutants and effectively elimination of the odor of surface structures from sewage treatment had been achieved, as well as the aim of ornamental and gardening wasteater treatment. The main conclusions are as followed:(1) In summer and spring-autumn, the COD removal rate of ABR (anaerobic baffled reactor) rised with HRT increasing. When HRT was 72h in summer and 96h in spring-autumn, the COD removal rate reached 72% and 67% respectively. The four compartments of ABR degradated the most degradable organic compounds. Biogas production increased with the increase of volume load. The TON of effluent decreased with the increase of HRT, and the effluent TON dropped to 220 when HRT was 72h in summer and TON dropped to 210 when HRT was 96h in spring-autumn.72h was suggested as the appropriate HRT for summer and 96h was suggested for spring-autumn. The anerobic reactor compartment number was suggested 4.(2) In winter, low temperature had a significant effect on the treatment of ABR. When the HRT was 120h, the COD removal rate could reach 60%. The front four compartments completed most removal of organic compounds in ABR. Gas production reduced prominently with the decrease of the volume load and decrease of temperature. What’s more, the TON of effluent decreased with the increase of HRT. When HRT was 120h, the TON dropped to about 275. In autumn and winter, HRT was suggested 96h and compartment number was suggested 4.(3) In summer and autumn, the effect of nitrification and deodorization was improved with the reflux ratio increased in anoxic deodorization tank. When the reflux ratio was 100%, the removal rate of TON reached above 90%, the sulfide removal rate reached 96.1% and total nitrogen removal rate reached 40.1%. Secondly, with the increasing load of nitrate and dissolved oxygen of influent, deodorization effect was improvd and denitrification effect decreased. When nitrate and dissolved oxygen load was respectively 20g/(m3·d) and 2.5mg/L, the best denitification and deodorization effect can be obtained.N/S ratio and C/N ratio were also important factors that affecting the effect of denitrification and deodorization. With the increase of the N/S ratio, the deodorization effect increased while denitrification rate decreased. However, when C/N ratio deodorization effect significantly reduced, and the denitrification rate increased. In conclusion, when N/S and C/N were 1.0 and 6.0 respectively, the best deodorization rate and denitrification rate can be achieved.(4) In spring-autumn with the reflux ratio at 150%, the TON removal rate reached at 87.2%, the sulfide removal rate was 91.3% and TN removal rate was 33.7%. When the influent nitrate and dissolved oxygen load were 25g/(m3·d) and 3.2mg/L, the best deodorization and denitrification effect can be achieved,while N/S and C/N were 1.5 and 4.0 respectively.(5) In winter, affected by low temperature denitrification rate and deodorization effect decreased. With the reflux ratio at 200%, the TON removal rate reached at.4%, the sulfide removal rate was 85.6% and TN removal rate was 88.5%. When the influent nitrate and dissolved oxygen load were 30g/(m3·d) and 3.8mg/L, the best deodorization and denitrification effect can be achieved,while N/S and C/N were 2.0 and 3.5 respectively.(6) The whole system ran stably, with the COD, ammonia, TN and TP concentration of effluent were 10.4～28.7 mg/L,3.6～11.5mg/L,0.5～4.6mg/L,0.21～0.48mg/L respectively. The quality of the effluent reached A level of the national discharge standard of pollutants for municipal wastewater treatment plant. At the same time, the effluent gas from the anoxic tank, hydrogen sulfide and ammonia gass which were 0.043～0.058 mg/m3 and 0.320～0.378 mg/m3, reached the second grade of the national discharge standard of ordor pollutants for wastewater treatment plant.