The Water Useage Demand Analysis And Waternetwork Design In Cotton Knitted Dyeing And Finishing Enterprise

In China, the cotton printing and dyeing industry has a large consumption of resources and energy, and is one of the industries of emitting large amounts of pollutants. In this study, a typical cotton knitting dyeing factory considered as a case, its cleaner production study, focusing on water conservation and water ues netwok design and optimization, was carried out and the main research results obtained are as follows:First, Through accounting of water balance, dyeing workshop was regarded as the focus of water conservation and waste reduction, here all dyestuffs and auxiliaries are almost used up, which is a major source of various wastewater pollutants, and water consumption account for the total consumption of90%。According to the water balance analysis of water consumption show that per unit of product use128t water, and per unit of product discharge90t CODCrSecondly, on the basis of wate use analysis, in order to minimize the use of fresh water in this factory, water conservation and emission reduction were studied. Based on the pollutant concentration limit value coming from above water quality standards, using electrical conductivity as single restrictive impurity, water pinch analysis was used to calculate smallest volume of fresh water for the factory, during the process that water is modeled as a single impurity water system. Concentration interval diagram (CID) used to determine the system pinch, at the same time, water pinch with the electrical conductivity is3441μS/cm, and the minimum amount of fresh water used is2764.71t/d. Considering the factors of CODCrand Color, considering of waste water treatment plant for more removal of CODcr, which made pinch concentration reduced to60mg/L (when CODCr removal of80%), and then further optimize the water network, the results indicated that the minimum fresh water consumption turn to the1562.24t/d. With the results of water pinch analysis, it was opposed that three types of measures water reuse, including direct reuse of waste water, on-site reuse after a simple treatment, and reuse after end-of-pipe treatment. Finally, comprehensive analysis showed that the largest wastewater reuse rate of this company was65.7%.At last, according to the result of the water pinch analysis,the ruse test of the light pollution wastewater was taken,the result show that the knitting cotton dyeing and finishing wastewater reuse was feasibility.The light polluted wastewater of scouring and bleaching stage can be reused in the scouring and bleaching stage.the light polluted wastewater of the post-processing phase can return used in the dyeing stage. Afftert treat the moderately polluted wastewater with wastewater treatmemt of the corporate, then the continuous microfiltration/ultrafiltration menmbrane process was used, the discharge water mixed with fresh water under a suitable percentage can meet the dyeing process reused water quality requirements well.