The Study Of The Treatment Method Of Alkali-minimization Printing And Dyeing Wastewater

In our counrty,printing and dyeing industry are emplying alkali-minimization technics to deal with crude terylene from 80'.Now that technics has emplied more,so bings the new type wastewater: alkali-minimization wastewater.In this paper,the resource and the water qulity and the quantity of alkali-minimization from shengze townjiangsu province were investigated. Compared with the treatment methods of alkali-minimization printing and dyeing industrial wastewater,a treatment method was brought.The first step was the resouce called TA(terephthalic acid) could be reclaimd by acidation.Then the wastewater contained TA from acidatiqn and printing-dyeing wastewater were mixed to be further treated by anaerobic-biological contact oxidation method.The result of investigation shows alkali-minimization wastewater of printing- dyeing industry was so little,which had much higher organic concentration and basicity and contaminated badly. The water quality and COD of alkali-minimization wastewater account for 5-10% and 50% above respectively in the whole printing-dyeing wastewater,whose COD is 20000~ 100000 mg/L and pH is 12 upword.Alkali-minimization wastewater is hard treated directly by bio-degraded or phsical degraded,if which mixed with printing-dyeing wastewater will aggravate the environment and will be treated more difficultly.When adding acid to alkali-minimization by pH3~4,ninty pecent at least of TA will separate out the water.The crude TA reclaimd could be the raw material of cable and polyester and so on.Per ten kilogram crude dry TA could gain 3 yuan.So the wastewater can turn into treasure,and after acidation the COD of the wastewater descended greatly to 8000mg/L lower if the reclaim of TA is only 70%.When the alkali-minimization wastewater of acidation-pretreatment blended with printing and dyeing wastewater,the system of hydrolysis-acidification and aerobic biological contact oxidatioin with influent COD790~850mg/K BOD5400~450, TA260-290mg/K colour400(dilution ratio) and pH9~10.5,had a removal efficiency of COD, BOD5, TA, colour 93.5%, 96%, 96% and 92.5% respectively,, In the end,the effluent quality meets the requirement of discharge standard for wastewater. Simultaneously,the excess activated sludge that drained from the sediment pool returned thehydrolysis-acidification pool could be degraded and has no effect on the wastewate treatmental system,so the treatment cost of sludge could also be lower.Results showed, the characteristic pollutant TA could be bio-degraded.TA can hard be degraded by hydrolysis-acidification treatment,and easily be degraded by aerobic bio-treatment if the solution has enough oxigen.The result about the study of kinetics is that the parameters are KTA 1.87% KCOD 1.08% Y0.1413 and ts, min13.73 and KdO.0798 repectively.By studying the kinetics parameters can direct the art design and management of the wastewater treatment,and make for improving the efficiency of wastewater treatment.