Study On The Application Of Chemical-Biological Combined Process In Treatment Of Printing And Dyeing Wastewater

China's textile industry has the advantage of one of the traditional pillar ndustries, with the rapid development of the national economy and entering WTO, China has become the world's largest textile producer. Our existing textile enterprises are using the processing technology with water as the medium. In fabric processing, printing and dyeing and other processes have to consume large amounts of clean water. Dyehouse manufacting each 100m of fabric products, will produce 3.5 to 5.5T wastewater. According to incomplete statistics, China printing and dyeing waste water emissions makes up about 40% of industrial wastewater, up to 4×106～5×106m3/ d, more than 950 million tons of waste water each year. Printing and dyeing wastewater are characterized by extensive distribution. Printing and dyeing wastewater is a kind of intractable industrial wastewater, its characteristic are high concentrations of pollutants and great variation, bleaching difficulties, poor biodegradability. In recent years, with the new techniques, new materials, new dyestuff and auxiliaries development and application make printing and dyeing wastewater treatment difficulty continuously increased, developing highly efficient and stable printing and dyeing wastewater treatment technology, enhance the operating parameters control technology become the focus of printing and dyeing wastewater treatment resrarch.In this paper, studying on an textile enterprises integrated discharged waste water as treatment object, and the synthetic wastewater quality are:COD concentration is 1600～1750 mg·L-1, BOD5 concentration is 300～400 mg·L-1, SS 350～450 mg·L-1, Color 550 to 700 times, pH value is 10 to 13. On the basis of in-depth study the treatment principle of printing and dyeing wastewater, determined the plant renovation project of the printing and dyeing wastewater treatment process as "First flotation+Hydrolysis+Two-stage biological contact oxidation+Secondary coagulation, "and according to the technology route to update and modified the original treatment structure to meet the requirements of wastewater treatment effluent quality. Through laboratory test discussed the performance of different types of coagulants purificating dyeing wastewater, screened and determined the coagulant with best coagulation efficiency and it's applicating optimum conditions. Study the modified biological treatment system organic matter and color removal efficiency during the biofilm culturing. Explore the main parameters which impact biological treatment unit system operation and control. Analysis the modified wastewater treatment system operation effectiveness and the feasibility of the design technology. The results show that PAS is he best coagulant, flotation devices running better and reduced the amount of consumption of sulfuric acid to adjust the pH value. During the mixed phase the optimum adding PAS condition is the pH 9, adding 100 mg·L-1 PAS, 250r/min stir lmin. the average of values of flotation effluent's COD, SS, and color were 1006 mg·L-1,138 mg·L-1 and 352 times and the removal rate reached 40.3%, 65.5% and 42.1%.Hydrolysis acidification pool and biological contact oxidation pond were separated running when the biological treatment unit processing operating. Sludge was inoculated, and after one week by intermittent water for nausea exposure, the biological reaction pool was hanged membrane successfully with tan mucosa membrane on the surface filler. Microorganisms were cultivated and acclimated after hanged membrane. COD,BOD5 and coloring removal rate were 82%,76% and 75%. COD of effluent was 130 mg·L-1,45 mg·L-1 and chromaticity was low of 90 times. B/C of the hydrolysis pool was increase from 0.25～0.3 to 0.3～0.4.System under load operation, by the results of running under different operating conditions, we can get:hydrolysis acidification unit and biological contact oxidation pond removal rate of pollutants with the increase of HRT performed increased at first, then slowly decreased. Dissolved oxygen has little impact on the biological contact oxidation pond effluent water quality, with the dissolved oxygen concentration increased, the organic matter removal rate of contact oxidation pond has experienced a gradual increase, but decreased after the procedure. When the hydrolysis tank HRT was 8h, biological contact oxidation pond HRT was 1 Oh, DO concentrations at about 4 mg·L-1, performed the best effect, color removal and B/C value in hydrolysis tank reached 54.3% and 0.386, organic average removal rate in contact oxidation pond reached 86%, contact oxidation tank volumetric loading reached 2.2 kg COD·(m3·d)-1, the system is stable.The secondary coagulation tank added after the biological treatment unit stabled wastewater treatment process effluent quality, the average of COD, BOD5, Color. SS. stabled at 70.8 mg·L-1,18.6 mg·L-1,26.9 times and 44.1 mg·L-1, reached the GB4287-1992 "textile industry water pollutants discharge standards" first class standard.The total removal of reform process (First flotation+Hydrolysis+Two-stage biological contact oxidation+Secondary coagulation) COD, BOD5 and SS, respectively,1116.9 t·a-1,277.4 t·a-1 and 292 t·a-1, have significant environmental benefits. Have a wide range of applications in the medium and Small dyeing enterprises in the printing and dyeing wastewater treatment, and satisfy the requirements of the state's high-polluting industrial wastewater treatment; after modified each processing unit works good and stable; the overall level of wastewater treatment technology and control technology have improved.