Treatment On Printing And Dyeing Wastewater By Combination Of Coagulation-MBR-RO Process

Printing and dyeing wastewater is an important source of pollution in the field of industrial production. This thesis studies the treatment of wastewater containing indigoid dyes produced during the washing process of the denim of Golden Dragon Garment Limited under Shandong Daiyin Group. It put forward the method of using Coagulation–MBR-RO to treat printing and dyeing wastewater and explores various factors affecting the technique. The main content in this paper is as follows:1. In the coagulation experiment, the ferrous ions in ferrous sulfate will affect the chroma removal rate; since the applicable pH range of magnesium chloride is relatively narrow, PAC is therefore selected as the optimal flocculating agent. Orthogonal test is applied to determine the best operating conditions: pH=7, PAC dosage of 900mg/L, sedimentation time of 40min,stirring time of 3.5min. The dosage and pH value determined by the orthogonal test have significant influence on the flocculation effect of PAC, stirring time has but insignificant influence on it and sedimentation time has almost no impact on it.2. In the MBR experiment, the influence of sludge concentration, aeration and HRT operating conditions on the purification effect are investigated. The optimal parameters for MBR reactor are then determined through experiments. Under the premise of ensuring the quality of purified water, HRT should be 8 hours, the aeration should be 1.5m3/h and the sludge concentration should be 6g/L. The removal of pollutants in the MBR reactor is mainly determined by the effect of the reactions of aerobic organism. The film only plays the role of strengthening the biological reactions and ensuring the quality of the treated water.3. In the reverse osmosis experiment, orthogonal test is used to explore the influence of operating pressure, temperature, concentration cycle and flow rate on membrane flux and water purification effect. The conclusion is that pressure and concentration cycle has the most significant impact on the membrane flux, temperature has but not obvious impact, and the changes of flow rate have almost on influence on the membrane flux; concentration cycle and pressure have obvious influence on salt rejection, flow rate has but not obvious impact on salt rejection, and temperature has only little influence on salt rejection; concentration cycle has the biggest impact on the removal rate of COD, then it's the pressure and flow rate. Temperature changes have almost no impact on the removal rate of COD; temperature, pressure and concentration cycle all have little influence on the removal rate of chroma. Flow rate may have influence on the removal rate of chroma, but the influence is not obvious.The optimal technological conditions determined through the experiment is: pressure of 0.60Mpa, concentration cycle of 2, temperature of 20-25℃, and flow rate of 1.2L/min.This paper is a primary exploration of treating printing and dyeing wastewater with Coagulation-MBR-RO group technology. The results of the experiment can, to a certain extent, provide some reference and direction for practical projects.