Research For The Treatment Of Knitting Dyeing Wastewater By BH1 Coagulation Decolorant

Dyeing is an important part of the textile industry,and also is a major source of textile industry wastewater. Printing and dyeing wastewater ,which is discharged in the pretreatment, dyeing, printing and finishing process of cotton, wool,chemical fiber and the other textile products, is widely recognized as intractable industrial wastewater. Its composition of pollutants is extremely complex, including dyes, textile auxiliaries, chemical synthesis slurry, surfactants, other chemical agents (such as bleach) and so on,which are used in process of the fabric fibers.Coagulation is one of the main methods of dyeing wastewater treatment. In this paper, BH1 coagulation decolorant was used on the knitting dyeing wastewater (dyeing water of a dyeing factory in Qingdao) treatment, research for the decolorization and COD removal effects of dyeing wastewater knitting by this coagulation decolorant, and initially optimize the reaction conditions including the optimal pH and dosageof the coagulation, investigate the mechanism of coagulation, experimental techniques and data processing commonly using curve optimization. Finally ferric and aluminum salts which belonged to conventional coagulant were used in comparion experiments so as to confirm the feasibility and competitiveness of this coagulant in practical application.The results show that, for dyeing wastewater(knitted cotton) of a printing and dyeing factory in Qingdao, the optimal pH of BH1 coagulation decolorant was 8, while the optimal dosage was 1.2ml/L, in this case,the rmoval rate of COD and chroma was 64%,89%, Compared with conventional coagulant such as aluminum sulfate, ferrous sulphate, the removal rate of COD and chroma were significantly increased, the COD of treated water was less than 200mg/L,which can meet Grade II of "Integrated Wastewater Discharge Standard" (GB8978-1996) Table 4, while the chroma was less than 40 times,which can meet Grade I of GB8978-1996.Comparing with conventional coagulant, BH1 coagulation decolorant not only had the advantages of high chroma rmoval rate and high COD removal rate, but also had the features of low cost, simple operating and good Settlement, Therefore, this coagulant had highly competitive whether in economic or in treatment effect.Dosage prediction model of GM (0, N) was built by Gray theory , the optimal dosage of BH1 coagulation decolorant was 1.09ml/L, which was predicted by GM (0, N) model, and compared to the experimental optimal dosage 1.2ml/L,the relative error is 9.17%. But the maximum relative error of this prediction model was 20.50% ,while the minimum error was 3.61%, and the average value of relative error was 9.83%. Overall, the error could be controlled within an acceptable range, to have a better processing and simulation for the nonlinear relationship among many factors. therefore, in practical application, it is feasible to achieve automatic control of dosing system for BH1 coagulation decolorant by dosage prediction model of GM (0, N).