| The organic matter of the painted wastewater is complex and difficult to handle and direct discharge poses a great threat to the water environment and human health.This test is aimed at the low biodegradability of automotive coating wastewater and the direct use of aerobic biological treatment is not effective.It is proposed to treat it with a hydrolytic acidification process with a circulation system to change or destroy the structure and properties of pollutants in wastewater.Improve its biodegradability and reduce part of the load for later biological treatment.In this paper,the effects of different factors on the hydrolysis and acidification of automotive coating wastewater were studied and the optimal operating parameters of the reactor were determined.Then,the reactor is operated under the optimal operating parameters to analyze the treatment effect of the automobile coating wastewater.The subsequent application of the SBR process for aerobic biological treatment of automobile coating wastewater further illustrates the effect of the hydrolysis acidification process.The effect of the filler on the treatment of automotive coating wastewater by the hydrolysis acidification process was also tested.Finally,the granular sludge was used to hydrolyze and acidify the automobile coating wastewater and observe its treatment effect.The specific test content and conclusions are as follows:(1)The hydrolysis and acidification sludge is cultured and acclimated in the early stage to complete the start of the reactor.Then the effects of reaction time,circulation flow rate and volumetric load on the hydrolysis and acidification of automotive coating wastewater were tested,and the optimal operating parameters of the reactor were determined.It was found that the COD removal rate and acidification rate increased with the increase of reaction time to some extent.The longer the reaction time,the higher the COD removal rate and acidification rate.When the reaction time was 24 h,the COD removal efficiency of the hydrolyzed and acidified automobile coating wastewater was the acidification rate is the best.Overall,the increase in circulating flow rate also increases with the COD removal rate.When the circulating flow rate is increased to 180-240L/h,the sludge and automobile coating wastewater are almost completely mixed,and the COD removal rate reaches a maximum of about 24%.Considering the reaction time and the influence of circulating flow on the reactor,it is determined that the reaction time is 22-24 h,and the circulating flow rate is 180L/h,which is the best operating condition of the reactor.(2)Under the optimal operating parameters,the test of hydrolysis and acidification of automotive coating wastewater was carried out.During the stable operation,it was found that the COD removal rate of the automobile coating wastewater was basically stabilized at about 21% after the hydrolysis acid treatment.The effluent volatile fatty acid increased compared with the influent water,the acidification rate was about 10%;the effluent BOD5/COD was greater than the influent water,BOD5/COD increased by 19.4%.The ammonia nitrogen removal rate is between-171.6% and 86.9%,and the average removal rate of total nitrogen is around 33%.It shows that after the hydrolysis and acidification of automobile coating wastewater,the acid production and biodegradability are improved,and the complex organic pollutants in the wastewater are degraded into simple substances.(3)When the effect of the filler on the hydrolysis and acidification of automotive coating wastewater was investigated,it was found that the COD removal rate of the hydrolysis acidification reactor was basically stabilized at about 21%,and the acidification rate was about 10%.Under the same operating conditions,the average removal rate of COD in the hydrolysis acidification reactor without filler was 14.2%,and the acidification rate was about 7.0%.Combined with the removal effect of COD and the change of volatile fatty acids,the filler can strengthen the hydrolysis acidification process to treat automotive coating wastewater.(4)The automotive coating wastewater that has not been subjected to the hydrolysis acidification process is directly subjected to aerobic biological treatment and subjected to a hydrolysis acidification process in a comparative test for aerobic biological treatment.It was found that compared with the direct aerobic biological treatment of automobile coating wastewater,the autoclave wastewater was hydrolyzed and acidified and then subjected to aerobic biological treatment to remove pollutants.(5)In the experiment of hydrolyzing and acidifying automotive coating wastewater with aerobic granular sludge,it was found that the COD removal rate was between 10% and 15.2%;the effluent VFA concentration was between 54.2 and 117.2 mg/L,and the acidification rate was between 7.7%-10.3%;the average removal rate of total nitrogen is about 12%;and the removal rate of ammonia nitrogen is between-46.7% and 6.6%.It shows that the granular sludge hydrolysis and acidification of automobile coating wastewater is effective.The pollutants in the wastewater are removed in a small amount,and the volatile fatty acids in the effluent are improved.Compared with the flocculated sludge hydrolysis and acidification of automotive coating wastewater,it is shorter.The response time is not very different.During the test,the granular sludge disintegrated.Through the recovery of the disintegrated sludge,particles were formed in a short time,and the MLSS and SV of the sludge recovered to the original level and the sedimentation performance became better. |
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