Study On Purifying And Recycling Technologies Of Dyeing And Finishing Effluents

Based on the dyeing and finishing process of the cotton knitting textile, research the recycle techniques of the dyeing and finishing effluents. The study including designing and optimizing the distributary arrangement of the effluents, research on the purifying procedure of the waste water treatment and on the application of treated water for recycle. And economic analysis of the recycle techniques is also involved in the research.In the dyeing and finishing process, the sections, boiling, whitening and dyeing, use a small percentage of water which would be seriously polluted during the producing. But the washing section requires a great more deal of water that would be slightly polluted and have potential for recycle after to be treated. According to the water quality of the effluents, we put forward drainage distributary arrangement for recycle that collect the seriously polluted effluents and feeding them to a public waste water factory for treatment and drainage. Correspondingly, collect the washing effluents to the recycle treatment purifying and recycling.According to the water quality standard for dyeing and finishing industry, combined with washing water quality, we map out an acceptable water quality requirement for recycle. Based on the requirement, design the purifying procedure for treatment that is composed by two-units of biological treatment and deep-seated purifying treatment. After lab-testing, the purifying procedure proved to be feasible for treating the washing water to meet the recycle demand.Consequently, establish a recycle treatment in size of 300m~3/d by reconstructing an old waste water factory. We call it mid-testing treatment. And then, we can research and optimize the design and operation parameter of the recycle treatment. By studying on the mid-testing project, achieve some meaningful project design information. Meanwhile, we also collect a lot of operation data concerning about flux load, pollution load, mixture mode, air-water ratio and water temperature. All those information would be a set of valuable guidelines to design and operate a big scale of reuse project.Results from lab-testing and mid-testing indicate the feasibility of purifying procedure. Next, we would pay attention to the applicability of treated water for recycling to the dyeing and finishing producing. We choose two water quality indexes, pH and salt content, which might have potential negative impact on production quality that can be expressed by indicators color aberration and fastness. By put into force the water purifying, combined with water distributary, other water quality indexes can be control to be invariable that would be helpful for researching the impact of pH and salt content on production quality. We study the impact of pH and salt content respectively. The result is that the production color fastness would drop when pH is higher than 8.5, but the color aberration is acceptable. So we advice the pH of the treated water should be lower than 8.5, and equal to 7 is better. On the other hand, under the accumulation range, salt content have no negative impact on production quality. All these study information could also be the direction to use effluent recycle techniques for dyeing and finishing enterprises. As the basic factor for economic analysis, the recycle project size is determined by recycle techniques and producing characters of the enterprise. According to recycle experiment result, combined with the producing characters and development plan of the enterprise, an acceptable recycle rate,50%,is got. So is the recycle project size. Based on the project size, the cost and the saving could be calculated and a big amount of saving is the result. It is clear that the popularity of the effluents recycle techniques will have a bright future.The research on treatment process and applicability of treated water for recycle, combined with economic analysis, testify the feasibility of the effluents recycle techniques. The whole study would be helpful to popularize the recycle techniques that would create considerable profit for enterprise. Meanwhile, the popularity of recycle techniques would help lessen the pollution caused by dyeing and finishing enterprises that could creates considerable benefit for society and environment.