A Study To Deep Decoloration Treatment Process Of Spinning Printing And Dyeing Wastewater

China is a great country in spinning printing and dyeing industry. As a major backbone of the economy in China, the printing and dyeing industry drives China economy developing on the one hand, brings about serious pollution to the ecological environment on the other hand. Along with environment protections are increasingly strict and “Ten Laws for Water” are proposed in China, previous sewage discharge standard of spinning printing and dyeing wastewater cannot satisfy the new environmental protection demands. The deep decoloration treatment process to spinning printing and dyeing wastewater is a main problem faced by this industry. Based on this, studies on deep decoloration treatment process to spinning printing and dyeing wastewater standing for improvement of removal efficiencies of color have very important practical significance.This project has carried out a systematic study on deep decoloration treatment process of secondary effluent water in Foshan Xinlong Sewage Treatment Plant of Guangzhou; analyzed the water quality in and out the Xinlong Sewage Treatment Plant based on extensively investigating and analyzing the printing and dyeing wastewater treatment status in China; evaluated the treatment efficiency of secondary treatment process in this sewage treatment plant as well as organic physical and chemical properties in those treated water, which will provide the theoretical basis for determining study routes. The best deep decoloration treatment process is screened out via various mini-tests of deep decoloration treatment process in printing and dyeing wastewater in order to carry out the project design research to the best deep decoloration treatment process and analyze its operating costs.The results showed that COD, BOD and SS and so on indexes of secondary effluent water in Xinlong Sewage Treatment Plant were basically up to standard, but the chromaticity was far more out of limits and the effluent chromaticity was around 80-fold. We can see the major components contain the proteins and humic acid macromolecule organics produced by microbial metabolism during the biological wastewater treatment via analyzing the organic physical and chemical properties in the effluent, of which COD and chromaticity materials are accounted for 46% and 44% respectively in the interval of molecular weight greater than 100 k.Based on the physical and chemical property analysis to the organics of secondary biological treatment effluent, we have proposed a coagulation-orientated deep decoloration treatment process and optimized and screened the flocculant and coagulant aid, and analyzed and evaluated the treatment efficacy of coagulation process. The results suggest that based on PAC as the flocculant(dosage 150mg/L) and PAM as the coagulant(dosage 10mg/L), the effluent chromaticity can be decreased to 50 from 80. In order to further increases of decoloration efficacy, we have studied 6 kinds of treatment processes based on coagulation-centered secondary and three-level chemical-physical groups. The results suggest that ozone pre-oxidation and coagulation combined process not only have significant decoloration efficacy(chromaticity can be reduced to 20), but also decrease the dosage of coagulant and then greatly reduce the operating costs.Project design research is carried out to ozone pre-oxidation-coagulation process and the preliminary design, equipment selection, plane and height layout are implemented to each treatment unit. The operation costs of the deep decoloration treatment process are analyzed and calculated, which will provide the references and basis for designing and building the deep decoloration treatment project in Xinlong Sewage Treatment Plant.