Experimental Study On Treatment Of Textile Dyeing Wastewater By Aerobic Granular Sludge

Textile dyeing wastewater has always been a difficult problem in industrial wastewater treatment,which has the characteristics of large discharge,complex water component,high chroma and difficult to handle.At present,the treatment method of textile dyeing wastewater is usually a combination of biological method and physicochemical method.The traditional treatment method has the problems of long process flow,high pretreatment agent cost and large amount of sludge generated,which makes the efficient treatment of textile dyeing wastewater extremely urgent.Because the features of aerobic granular sludge,such as the ability to remove various pollutants of wastewater in a biological pool,the high biomass,the small excess sludge,and the strong tolerance to toxic and hazardous substances and high-load wastewater,therefore,it enabled aerobic granular sludge a potentially efficient wastewater biological treatment technology.In order to study the feasibility of aerobic granular sludge treatment of textile dyeing wastewater,the aerobic granular sludge method was used to treat simulated wastewater and actual textile dyeing wastewater,and 16 S rDNA sequencing method was used to analyze the microbial flora in the system.Provide reference for the treatment of textile dyeing wastewater.The main results of this study are as follows:(1)Aerobic granular sludge was domesticated successfully in simulated textile dyeing wastewater at 49 d.The black particles of 2~5mm were formed in sequencing batch reactor with high organic load(OLR 3kg·(m3·d)-1)and the ratio of height to diameter is 3.9.The granular sludge cultured under high load was loose,and the SVIvalue was 83.36mL/g.The system is in a dynamic equilibrium process of particle formation,disintegration and repair.(2)The average removal rates of COD,ammonia nitrogen,TP,and chromaticity of simulated textile dyeing wastewater by aerobic granular sludge were 92.33%,56.65%,95.12%,and 69.03%,respectively.The average removal rates of COD,ammonia nitrogen and TP in raw textile dyeing wastewater by aerobic granular sludge are 70.96%,28.63% and 83.41%,respectively.In addition,the ammonia nitrogen and TP effluent of actual wastewater reach the standard of direct discharge,while the COD effluent fails to meet the direct discharge standard.So COD is the key point in the treatment of textile dyeing wastewater,and it requires subsequent advanced treatment.(3)Under the condition of glucose as the co-substrate,when the glucose concentration is 500mg/L and the concentration ratio of glucose concentration to textile dyeing wastewater is 1:1,the treatment effect is best.The average removal rates of COD,ammonia nitrogen and TP in raw textile dyeing wastewater by aerobic granular sludge are 85.26%,70.23%,88.68%,respectively,which results is higher than that in the raw water without co-substrate,indicating that the addition of glucose promoted the removal of pollutants from the system.(4)There were significant differences in microbial community structure at different stages of aerobic granular sludge operation.Proteobacteria was the dominant strain in the system,followed by Bacteroidetes.After the system transitioned from simulated textile dyeing wastewater to actual wastewater,the abundance of Proteobacteria decreased,while the abundance of Bacteroides increased,indicating that Bacteroidetes could better adapt to the actual wastewater quality.(5)At the subordinate classification level,the dominant genus in the simulated textile dyeing wastewater has obvious effects.The Magnotospirillum genus of Rhodospirillaceae in the ?-proteobacteria family is the absolute dominant genus of the system,which plays an important role in degrading dyes and COD removal.When the aerobic granular sludge is operated in complex actual wastewater,the original dominant species,Magnetospirillum,disappears in the system,while the new populations appear,and the removal of pollutants in textile dyeing wastewater is the result of a combination of various flora.The tracer Thiothrix in the actual wastewater accounts for a relativelyhigh proportion(11.12%)in the system.This strain will expand the sludge and is not conducive to the stable operation of the system.Therefore,it is necessary to control the growth of such microorganisms.Thauera is a functional bacteria in the system that mainly degrades aromatic contaminants such as dyes.