Experimental Study And Modification Practice For The Printing And Dyeing Wastewater Treatment Of Bannner And Tent Factory

The printing and dyeing wastewater is one of organic wastewater with high concentration and difficult to be biodegradable. This thesis aims to the settlement of exixting problems on the wastewater treatment in Shanghai Maofeng Banner & Tent Factory. The original treatment process is improved through on-site investigation and experience from experiment. At the end, the effluent quality can come to the local discharge standard, and part effluent can be reused in the present production process. It will decrease the waste water discharge, economize fresh water resource and reduce the operation cost.According to characteristics of the printing & dyeing wastewater, the new process introduces the "hydrolytic acidification + contact bio-oxidation + coagulation and air-flotation", which is suitable process verified in the experiment. The experiment result shows that the removal rate of COD_cr, BOD₅,SS and chroma is 68.3-78.6%, 68.3-76.1%, 76.0-79.1% and 90%, and theeffluent chroma also comes up to 8-16. Based on the above result, the thesis primarily probes into the degradation mechanism of the v/astewater pollutant indexes, and obtained the corresponding mathematic kinetics model.The modification of the wastewater treatment system does not damage the old constrction units, while is reordering and improving them by choosing the proper treatment process. The old natural sedimentation basin is changed into multi-class hydrolytic acidafication basin and contact oxidation basin, the function of the old coagulation and air-flotation basin is strengthened, and the old electrical oxidation activated carbon tower is improved into the biological activated carbon one. After modification, the treatment cost of wastewater per ton decrease by RMB0.26. The effluent's COD_Cr, BOD₅, SS, NH₃-N and chroma come up to the II-class criteria specified in the Local Wastewater Discharge Standard in Shanghai (DB 31/199-1997). And the principal water quality indexes meet with the Quality Standard of Domestic Water (CJ/T48-1999). Through test of the reused effluent in production, there is no any negative influence on the product quality. The rate of reused effluent comes up to 51.8%, which can save 80 tons fresh water per day. The process improvement achieves favorable profit of environment and economy.