Start-up Of EGSB Reactor Under Different Conditions And Study On Microbial Flora

With the increas of industrial waste water discharge,the problem of water pollution is becoming more and more serious.Water treatment has become the main problem of environmental protection workers.EGSB reactor(Anaerobic granular sludge bulking bed)is widely used because of its high operating load,low sludge yield and high treatment efficiency.And the clean energy generated in the anaerobic biological treatment process makes the whole wastewater treatment process to achieve a kind of environmental protection effect,and saves manpower and material resources comparing aerobic biological treatment.At present,there are more and more studies on EGSB reactor,but there are few studies on its mechanism and microbial community.In this paper,the effects of startup of EGSB reactor were studied under the condition of glucose as carbon source,sodium acetate as carbon source and lean nutrient,respectively.Then the effect of simultaneous methane production and denitrification process in the reactor was investigated.Meanwhile,the biodiversity and flora distribution of microbial community in the EGSB reactor was analysized with high throughput sequencing technology.The concrete results are as follows:1)The successful start-up of poor nutrition simulated wastewater was investigated with sodium acetate carbon source in an EGSB reactor,and EGSB reactor inoculated the flocculent sludge from the anoxic zone in the municipal sewage treatment plant.The results demonstrated the COD removal efficiency can also achieve more than 80%,even reaching above 95%,when the COD concentration of influent was improved from 200,500 to 1000 mg/L in the continuous operation of 73 days.Furthermore,the microbial communities of seeding source,sludge samples collected on the 43 th day and at the end of operation were investigated with the next generation sequences(NGS)tool in the EGSB reactor.Analysis results showed that it indicated that the microbial diversity decreased.At the bacterial phylum level,there was an apparent increase in relative sequences of Chloroflexi and Euryarchaeota(33.01% and 0.63% in AWN1,and 44.03% and 7.14% in AWN2),which was 19.40% and 0.54% in the inoculum.At the genus level,except unclassified genus,Methanosarcina,Clostridium and WCHB1-05 were found to be the main members,whose sum occupied 16.13% and 18.41% of the total sequences in AWN1 and AWN2,respectively.2)EGSB reactor can start successfully under the condition of glucose as carbon source.After the EGSB reactor was started,pH remained at about 7.5 and ORP was about-340 mv.In the whole operation process,the removal rate of COD gradually increased,and finally reached about 90%.Proteobacteria,Bacteroidetes and Firmicutes account for 70.00%,12.96% and 10.09% of the microbial colonies after the start-up of the EGSB reactor,respectively.However,after the start-up of the EGSB reactor,the distribution of generic microorganisms is relatively uniform,and there is no special dominant generic microorganisms.The EGSB reactor with glucose as carbon source is not suitable for the growth of the original biologically grown bacteria in the sludge.3)EGSB reactor can be activated successfully under conditions of sodium acetate as carbon source.During the whole operation process,the removal rate of COD gradually increased,and finally reached about 85% in the EGSB reactor.The biodiversity of the microbial in the reactor decreased because of the anaerobic environment.After the start-up of EGSB reactor,the dominant phylum of bacteria was Bacteroidetes,Firmicutes,Chloroflexi,Synergistetes and Proteobacteria,accounting for 22.05%,19.37%,14.91%,13.61%,10.98% respectively.VadinCA02 and Clostridium accounted for 9.89% and 5.01% respectively.4)Simultaneous methanogenesis and denitrification process was successfully operated in the EGSB reactor.After the start-up of EGSB reactor,the COD removal rate was 80%,and after adding nitrate,the COD removal rate was 85%,and the nitrate removal rate was over 95%.The denitrifying bacteria in the granular sludge coexist with methanogens in the reactor.Bacteroidetes,Chloroflexi and Firmicutes were the dominant groups in the sludge after the start-up of EGSB reactor,accounting for 30.39%,22.17% and 15.88% respectively.After startup,the genera were evenly distributed,and the larger proportion were T78 genera,Anaerovorax genera,vadinCA02 genera,E6 genera and Clostridium genera.