Experimental Study On The Treatment Of Automobile Coating Wastewater With Hydrolytic Acidification-AGSBR Technology

Controlling pollution from automobile coating wastewater is an important issue in the field of water treatment.Automobile coating wastewater has the characteristics of high concentration of organic matter,low biodegradability index and highly toxic pollutants.As a special biological aggregate,aerobic granular sludge has a good application prospect in wastewater treatment due to its unique structure and characteristics.However,there is no fast and reliable aerobic granular sludge culture mode owing to many factors affecting aerobic granulation at present.One of the reasons limiting the extensive application of aerobic granular sludge is that it takes a long time to cultivate.In order to solve this problem,the rapid cultivation of aerobic granular sludge in SBR reactor was studied.Then,The hydrolytic acidification process was combined with the AGSBR process which inoculated with rapid culture aerobic granular sludge.Through this combination of anaerobic and aerobic process,the degradation experiment of synthetic automobile coating wastewater was carried out,and the change of microbial community structure of aerobic granular sludge in the degradation process was explored.The main contents and research results are as follows:?1?According to the nucleation hypothesis of granular sludge formation,adding inert nuclei to aerobic sludge culture SBR reactor can accelerate the granulation process.Granular activated carbon with effective volume of 0.5%and particle size of about 100mesh was added to SBR reactor to start with.The synthetic water distribution with C:N:P of 100:5:1 was used as the substrate,and the settling time of each week was not as the standard of selective pressure for rapid cultivation of aerobic granular sludge.The results showed that the addition of granular activated carbon could accelerate the formation of aerobic granular sludge.Mature aerobic sludge particles were obtained on the 25th day of operation and the proportion of granular sludge with particle size greater than 0.5mm was more than 50%.SEM showed that granular activated carbon was the induced nucleus in the process of aerobic granular sludge formation,and the growth of sludge microorganisms around it promoted the rapid formation of granular sludge.The experiment showed that adding granular activated carbon in the reactor could realize the rapid cultivation of aerobic granular sludge.?2?Owing to the high concentration of organic matter,poor biodegradability and the presence of toxic pollutants in automobile coating wastewater,the combination process of hydrolytic acidification and AGSBR can be used to degrade the synthetic automobile coating wastewater.After being domesticated,the hydrolytic acidification reactor can remove 41.6%COD on average and improve the biodegradability of wastewater with the BOD₅/COD value can reach about 40%in the effluent.In AGSBR,aerobic granular sludge was cultured rapidly to degrade the effluent of hydrolytic acidification section and the degradation rate of COD reached 91%in this section.Sludge performance analysis showed that the sludge concentration,particle size and sedimentation performance were improved throughout the process.SEM also verified the stable biological structure and abundant biomass of granular sludge.In summary,the average removal rate of COD,NH₄⁺-N,and PO₄^3--P in automobile coating wastewater by the combined process reached 94.6%,93.3%,and 91.7%,respectively.And the degradation efficiency of phenol,the main pollutant in the automobile coating wastewater,was 99.2%.?3?Via Illumina high-throughput sequencing,it was found that the change of microbial community structure was related to the degradation efficiency of pollutants,and the microbial abundance and diversity were significantly improved in the process.Through classification analysis,the dominant bacteria of all sludge samples at the level of phylum,class,order,family and genus was obtained.Among them,Zoogloea,Thauera and Meganema were the dominant bacteria at the level of genus,which were proved to be effective in the removal of organic carbon and nitrogen.Thauera and Zoogloea were the dominant bacteria at the middle and later stage of the experiment which proved that they can remove nitrogen and phosphorus,degrade phenol and promote the growth of aerobic granular sludge.The results showed that the change of microbial community structure of aerobic granular sludge always promoted the more stable operation of the reactor system.Figure[24]Table[4]Reference[108]...