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Study On Treatment Of Leather Coating Wastewater By Coagulation Precipitation- Hydrolysis Acidification- Contact Oxidation

Posted on:2016-03-23Degree:MasterType:Thesis
Country:ChinaCandidate:Z R WangFull Text:PDF
GTID:2191330461490862Subject:Municipal engineering
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The leather industry has brought great economic benefits, but also brought great pressure on the environment. There is a great difference between the quality and quantity of wastewater which produced by each link involved in the manufacturing process. Leather coating wastewater is a kind of industrial wastewater produced in the manufacturing of leather. It has some characteristics: poor biodegradability, complicated, high organic content, low biodegradability, harmful. The discharge of unteated leather coating wastewater will bring serious pollution to the environment. This study was aimed at the in-depth study on the leather coating wastewater.Firstly, the research object was the wastewater which produced in the workshop. According to the existing technique of similar industrial wastewater and the characteristics of leather coating wastewater, the study decided to adopt the coagulation sedimentation-hydrolysis acidification-contact oxidation process. Then the simulation reactor was designed and assembled.Secondly, the optimal coagulant and coagulation conditions were determined by experiments. The coagulant and the best dosing quantity were determined by single factor experiment. Three factors including mixing intensity, reaction time, settling time, and their respective levels were screened out by further tests. Then a scheme of orthogonal test, which includes 3 factors and 3 levels, was designed. The purpose of the experiment was to obtain the optimal process combination of coagulation. According to the effect of treatment under different p H value and economic factors, the p H value didn’t need to be adjusted.Thirdly, the treatment effect, process parameters and influence factors were discussed by the test. The sludge inoculation was used for the start-up of hydrolysis acidification and contact oxidation reactor. The hydraulic retention time(HRT) was controlled to be 16 h, 14 h, 12 h, 10 h, 8 h, 6 h, 4 h, 2 h during the operation. Then the optimal HRT was selected. The optimal dissolved oxygen concentration of hydrolysis acidification was determined by the operation effect. The DO of contact oxidation reactor was from 1 to 2 milligram per litter, from 2 to 3 milligram per litter, from 3 to 4 milligram per litter, from 4 to 5 milligram per litter, respectively. Then the optimal DO was determined. The impact of influent loading on the operation was analysed by comparing the change of effluent quality. The impact of temperature on the operation was analysed by comparing the change of quality. The minimum operating temperature was determined by economical, seasonal and other factors.Fourthly, the project was running on the basis of simulation test. the research object was the leather coating wastewater which produced by one leather enterprise of Baoding. Then the wastewater treatment engineering was constructed and debugged. The hydrolysis acidification and contact oxidation reactor were started in the winter. The process had considered the data of simulation test. The sand filtration and activated carbon adsorption equipment were added after the biological treatment unit to meet the requirements of water quality. The engineering was debugged with the data of simulation test during the operation.The result shows that the leather coating wastewater could be effectively treated by the coagulation sedimentation-hydrolysis acidification-contact oxidation process. The process has high stability and high capacity to resistant the shock loading. The effluent quality could meet the standard of reuse when the process was added sand filtration and activated carbon adsorption equipment. The project has achieved social, economical and environmental benefits.
Keywords/Search Tags:leather coating wastewater, coagulation and sedimentation, hydrolytic acidification, contact oxidation
PDF Full Text Request
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