Experimental Study On Enhanced Aerobic Biological Treatment Of VC Wastewater By Salt-tolerant Bacteria

High-salinity organic wastewater is a common type of industrial wastewater with a complex chemical composition.Achieving the discharge standard through direct biochemical methods poses a significant challenge.Intensive treatment of high-salt organic wastewater by salt-tolerant bacteria is a current focus in biological treatment.A lot of work has been done in this study.Firstly,the predominant salt-tolerant bacteria were isolated and cultured in activited sludge.Secondly,for the removal effect of organic matter,the biological enhancement effect of salt-tolerant bacteria on the treatment of high chlorine organic wastewater in sequencing batch activated sludge reactor(SBR)and sequencing batch biofilm reactor(SBBR)were studied,respectively.Then,the influence of salinity on the treatment performance of the reactor was analyzed from the aspects of treatment performance and microbial metabolic activity.At the same time,the best process was selected.Finally,the salt-tolerant bacteria biointensive treatment of actual wastewater was carried out with anearobic treatment effluent of VC wastewater,which obtianed a good treatment effect.The main conclusions were as follows:1)Two strains of salt-tolerant bacteria were isolated: Mangrovibacter yixingensis(T3)and Thauera selenatis(T4).Both of them were weakly salt-tolerant bacteria.The optimal parameters of the isolated salt-tolerant bacteria: salinity 2%,pH7 and the inoculation ratio 1.25:1 of T3/T4.Under these conditions,the salt-tolerant bacteria had the highest COD removal efficiency of 80.26%±0.12%.2)SBR reactor was used to treat the simulated wastewater.The SBR2 reactor strengthened by salt-tolerant bacteria had better adaptability to salinity.When the salinity was less than 3.0%,the COD removal efficiency of SBR2 reactor was more than 90%.When the salinity reached 4.0% and 5.0%,the COD removal rates of SBR2 were 76% and51%,respectively,higher than those of the control group.In the high salt environment,T3 was the dominant bacteria,showing a certain biological enhancement effect in the process of COD removal.3)SBBR reactor was used to treat simulated high salt wastewater.When the salinity was not higher than 3%,SBBR1(white breathing ring packing),SBBR2(biological rope packing)and SBBR3(polyurethane sponge suspended sphere packing)all had good treatment effect on COD,and the COD removal rate reached more than 90%.Among them,SBBR1 has the highest COD removal performance,and the microbial community diversity is richer.4)Two kinds of reactors,SBR and SBBR(with white breathing ring packing)were used to treat the anaerobic treatment effluent of VC wastewater.The removal performances of COD in SBR#1 and SBBR#1 reactors,which were strengthened by salt-tolerant bacteria were significantly higher than that of the control group(SBR#2SBBR#2).When the hydraulic retention time was 24 h,both of the COD removal rates in SBR#1 and SBBR#1 reactor with salt-tolerant bacteria were about 83.3%.When the hydraulic retention time was 36 h,the COD removal rate could be reached more than 90%.In the effluent of SBR#1 and SBBR#1,both of the concentrations of COD could be meet the discharge standard of “Discharge Standard for Water Pollutants of Fermentation Pharmaceutical Industry”(GB 21903-2008).