Washing And Dyeing Wastewater Treatment Process And Mechanism

Washing and dyeing industries, which with small scale and great numbers were scattered, have prospered in recent years, the wastewater from these factories have been polluting the enviorment seriously. Because the wastewater was hardly concentrated, it is necessary to develop a kind of new treatment technology with the feature of simplicity, little investment and being suitable for this industry's characteristics.According to the characteristics of the washing and dyeing wastewater, a kind of physical- chemistry treatment technology was developed. The wastewater from Zhuzhou was found to be the charaters: pH 2~6,CODcr 250~4000mg/L, colourity 250-1000 times,turbidity 320~1200 degree.The effects of different factors such as pH, flocculating agent amount, stirring time and settling agent were investigated. The optimal reaction conditions in the physical- chemistry process: pH 9~10; inorganic compound flocculating agent 0.4 ~ 0.6kg/m3; polyacrylamide 3~4 g/m3; activated flyash 2~3kg/m3 and keeping stirring five minutes. After coagulating settling, the effect could achieve the remival efficiency of 80% CODcr, 98% colourity and 96% turbidity; water quality could meet the second integrated wastewater discharge standard. At the same time, function mechanism of flocculating agent and flyash were initially discussed.For the disadvantages of slow sedimentation rate and large volume in the physical- chemistry treatment, the coagulating electrical floatation was studied in the article. The result showed that in the electrical floatation process, cathode is graphite, anode is Fe ,electric pressure is 8~llvolt, consumption of energy is about 0.08 degree/m3; CODcr remival efficiency could reach 87%. And the mechanism of elctronical floatation process was initially discussed.At last, the commercial tests were studied; two process schemes were adopted in the tests. For the simple flocculating settling physical-chemistry process, yielding water quality: CODcr<150mg/L, BOD5< 30mg/L, colourity <10 times, turbidity30; This process possessed the characteristics of less investment, simple process, and small floor area,and was fit for dealing with the wastewater of common sportswears. For the combined process of coagulating-biochemical process , coagulating settling was primary treatment and activated sludge process was secondary treatment; this process possessed the characteristics of little more investment and operating cost and better effect , and was fit for dealing with the seriously polluted wastewater of jeans; the wastewater being treated: CODcr<50mg/L,BOD5<20mg/L, colourity 10 times , turbidity 25, and could be recycled.