The Research In Reusing Treatment Of Cotton Printing And Dyeing Wastewater

The research object of this paper is the reusing treatment of CPDW.Based on the investigation and analysis of CPDW treatment all over our country,advise the reusing treatment method of hydrolytic acidification-aerobic biochemical process-aerating biological filterdynamic ceramic membrane filter for the project.In this research,to offer the theorizations for the advanced CPDW treatment,the biodegradability under the aerobic condition of three series dyes including of reactive dyes,vat dyes and disperse dyes have been studied systematically and vat dyes has also been studies under the facultative condition.The quality request of reuse water from CPDW has been advised and studied,salt concentration and pH value influence in dyeing process have been analyzed through experiments.Shandong one knitting printing and dyeing mill has been chosen as the testing base for the pilot research,to validate useful of the treatment method of hydrolytic acidification-aerobic biochemical process-aerating biological filterdynamic ceramic membrane filter.At last,base on the size of this project,the cost and the saving could be calculated and a big amount of saving is the result.It is clear that the popularity of the effluents recycle techniques will have a bright future.The results after comprehensive analyses are as following:1.The major treatment method of CPDW in our country is biochemical treatment,especially, the mass of the treatment method is aerobic biology treatment,and some are combined with chemical treatment.And the surface aeration and catalytic oxidation are the major treatment method of aerobic biology treatment.Due to this result,in this research,biochemical treatment-physical chemical treatment was chosen as the pre-treatment before the advanced CPDW treatment.By the secondary hydrolytic acidification and A/B/C thrice catalytic oxidation, adding to physical chemical deposition and biologic filter,COD removal ratio was predicted to 90%,color removal ratio was predicted to 88%.And then the dynamic ceramic membrane was used to remove color,suspended solid and COD ulteriorly to ensure the effluent water meet the need of printing and dyeing process.2.Decolor of dyes is always the difficult problem in the PDW treatment.The study on the biodegradability of dyes to solve the decolor problem is one of the keys in PDW reusing treatment.3 series of dyes,namely 35 dyes,reactive dyes,vat dyes and disperse dyes were mensurated the aerobic biodegradability by BOD₅/COD.The results showed that reactive dyes and disperse dyes were main of poorly biodegradable,and vat dyes were almost the hardly biodegradable organics.By the results of the aerobic biodegradability,vat dyes which were the most hardly to biodegrade were chosen to test the facultative condition by active sludge treatment. The results showed that under condition of facultative,the biodegradability of vat dyes was improved.7 dyes which belonged to hardly biodegradable have changed to poorly biodegradable with the obvious decolor.So when the facultative aerobe treatment combined with the aerobic treatment,the dyes in PDW would be removed effectively.3.In this research the reusing water quality of CPDW has been discussed.Compared to the water quality of printing and dyeing,conductance and hypermanganate index were added in the reusing water quality and mensuration of color was changed also.Because the water quality of printing and dyeing was used to assess the water from surface water or ground water,colorimetry of platinum and cobalt was suit to them,but the color of reusing water of CPDW from different dyes,the dilute multiple was more suitable for assessing reusing water of CPDW.By the dyeing experiments,the results showed that the salt concentration in dyeing water would influence the dyeing effect.As to the dye of reactive violet X-2R which was used in these experiments,when the concentration of sodium sulfate was above 4.0g/L,the staining in fastness to soaping of the dyeing textile was low than 2 class,the dyeing textile couldn't reach the requite.So it is necessary to pay attention to the salt concentration in the reusing water. 4.One typical of cotton knitting printing and dyeing enterprise was chosen as the base of pilot research.The scale of treatment was 5t/d of rinsing CPDW.The treatment technics was secondary hydrolytic acidification and thrice aerobic biochemical process which made the load of sludge was turned from heavy to light and aerating biological filter and dynamic ceramic membrane filter.The effluent was reused to practical dyeing process.The results showed that the quality of effluent was steady,invest and running cost was cheap,soaping fastness of dyeing textile was 4 class.It also showed that distributing CPDW to light and heavy by water quality could reduce the running cost and prevent the Cumulation of salt in reusing water effective.5.As the basic factor for economic analysis,the recycle project size is determined by recycle techniques and producing characters of the enterprise.According to recycle experiment result, combined with the producing characters and development plan of the enterprise,we limit the recycle rate at 45%and the recycle project size is determined.Based on the project size,the cost and the saving could be calculated and a big amount of saving is the result.It is clear that the popularity of the effluents recycle techniques will have a bright future.The above proved that pretreatment by biological and physics chemistry and advanced treatment by dynamic ceramic membrane would be a applied and effective technics for CPDW treatment to reuse.