Printing and dyeing wastewater contains dyes, slurries, additives and other substances that are difficult to biodegrade or even biotoxic, which is a typical refractory wastewater. The treatment methods of printing and dyeing wastewater include adsorption method, membrane treatment method, coagulation method, advanced oxidation method and its combination process. The printing and dyeing enterprise park requires that the wastewater discharged by the printing and dyeing enterprise must be preliminarily treated before it can be included in the centralized sewage plant for treatment, therefore, most of the wastewater collected by the centralized sewage plant is a pollutant that is difficult to be treated by conventional technology, which puts forward high requirements for the treatment process. Printing and dyeing wastewater treatment Powdered activated carbon-activated sludge technology (PACT) is to add powdered activated carbon to the activated sludge system to remove pollutants through adsorption. At the same time, activated carbon strengthens the carrier function and increases the contact opportunity between microorganisms and organic matter, thereby improving the treatment efficiency. In this study, on the basis of the original ordinary activated sludge method, the experimental study of PACT technology for the treatment of printing and dyeing wastewater was carried out, the composition of organic matter in the inlet and outlet water of the system was investigated, the structure and functional genes of the microbial community of the system were analyzed, the microbial flora affecting the treatment effect and the composition of pollutants in the wastewater were explored, and finally the essential information such as the composition change of organic matter and the functional flora of the biological system in the printing and dyeing wastewater was obtained, in order to provide new ideas for the development of the treatment process of refractory printing and dyeing wastewater. Five Principles of Sludge Drying Process: Activated Carbon Adsorption and Regeneration Process Design.
1. Test methods and analysis methods.
On the basis of the traditional activated sludge method, PACT technology is adopted, and the wastewater to be treated after pretreatment by the conditioning tank and the primary sedimentation tank is continuously injected into the biological pool test device of the traditional activated sludge method, and the continuous aeration in the device maintains the mass concentration of dissolved oxygen, and the concentration of activated sludge is within the relative range. The screened powdered activated carbon was put into the biological pool, and the COD concentration, organic matter composition and microbial community structure in the activated sludge were investigated after stable operation.
2. Test results and discussion.
1.The removal effect of PACT on COD.
After the PACT technology was adopted, the COD concentration of the effluent in the biological treatment section was continuously reduced when the COD concentration in the influent water increased, the COD removal rate was stable at more than 90%, and the treatment capacity of the biological treatment section was significantly improved. Since the sewage received by the centralized sewage plant is full of pollutants that are difficult to remove by ordinary biological treatment, the COD removal rate is still stable at more than 90% in this case, indicating that this technology has a good treatment effect on printing and dyeing wastewater.
There is such a difference between COD and BOD, and it is a long knowledge! Determination of Chemical Oxygen Demand (COD) 2Analysis results of organic matter composition in effluent from biological pool.
After the test, it was found that 20 organic substances were detected in the influent water, most of which were long-chain and benzene ring structure, as well as organic compounds containing chlorine, sulfur and other toxic components, and 10 substances were detected in the effluent treated by PACT technology, indicating that the organic matter in the wastewater was effectively removed.
3.LC-OCD analysis results of biopool inlet and outlet water.
The printing and dyeing wastewater is preliminarily precipitated to exclude the influence of large suspended solids or sediments. From the test results, it can be seen that the dissolved organic carbon in the COD of the influent water only accounts for 163%, but the proportion in the effluent increased to 476%, indicating that most of the insoluble organic carbon was removed, and the proportion of dissolved organic carbon in the remaining COD increased significantly. At the same time, the hydrophilic organic carbon in both the inlet and outlet water accounts for more than 70% of the dissolved organic carbon. The removal rate of macromolecular substances in the effluent was 87%, indicating that most of the macromolecular organic compounds were removed or converted into small molecules after treatment.
III. Conclusion. PACT technology is an effective printing and dyeing wastewater treatment technology, which realizes the effective removal of refractory organic matter and COD in printing and dyeing wastewater through the synergistic effect of activated carbon adsorption and activated sludge biodegradation.