Membrane Technology For The Printing And Dyeing Wastewater Treatment And Reuse Technology Research

In China, the textile printing and dyeing industry not only consumes a large quantity of clean water but also discharges a vast amount of wastewater. These pollutants are not only featured as large quantity but also are difficult to treat with. With the rapid development of textile material and technology, large amounts of hard biodegradation organic pollutants such as PVA material and new auxiliaries are discharged into dyeing wastewater, leading to serious shortage and pollution of water resources. Therefore, it is meaningful for water conservation and environment protection to treat dyeing wastewater effectively.Membrane technology is one of the most promising wastewater treatment technologies in21st century. Recently advanced treatment and reuse of the dyeing wastewater has become one of the hotspots for its feature such as easy operation, significant treatment effect, energy consumption, low maintenance cost, convenient operation and management. In this research, secondary sedimentation tank effluent from one textile printing and dyeing company in Shandong was sampled and analyzed. Deep treatment was operated by making use of microfiltration-nanofiltration (MF-NF) integrated membrane system which is among membrane separation technology. The microfiltration was conduct as pretreatment process in order to avoid blocking nanofiltration membrane, for the turbidity value of the wastewater was beyond nanofiltration water limits.In this work, a MF-NF integrated membrane system and experimental device was designed. Turbidity of the printing and dyeing wastewater was removed by MF. The variation of permeate flux and CODcr removal ratio by MF with operating pressure was investigated. Then the influence of permeate flux and CODcr removal ratio by NF with operating pressure, pH, temperature, concentration scale and desalination rate was studied. The effluent quality was also analyzed for the scheme of pilot test. The results were as follows:(1) The turbidity removal efficiency was up to93.34%～96.82%, which meet water quality standard of NF. CODcr removal ratio was about50%by MF treating. Operating pressure had no great influence on CODcr value of the water treated by MF. Based on an overall consideration of experimental data, operating pressure was chose at0.05MPa.(2) Experiments showed that the optimum operating conditions of NF were as follows:pH valu was4, operating pressure was1.2MPa, temperature was30℃. CODcr value of permeate water was less than50mg·L-1when concentration scale was up to8, which was still meet the discharge standard.(3)The leachate dealed with the MF-NF integrated membrane system up to the standard of The urban sewage recycling industrial water quality GB/T19923-2005which can be used as the industrial water.(4) A pilot-plant which has the wastewater treatment capacity of33000m3per year was built. Among the dyeing wastewater30000m3will be recycled for industrial uses. The results showed that the MF and NF membrane areas which is needed are45m2and33m2, respectively. The results estimated the gross investment is about500thousand yuan. It will coat1.1yuan per cubic meter for33000m3printing and dyeing wastewater advanced treatment by making use of MF-NF integrated membrane system.