Research On Drain-select System And Reuse Technology Of Dyeing Wastewater

Textile industry has been brought about environmental problems as a traditional industry, especially the issue of printing and dyeing wastewater. Dyeing wastewater recycling can reduce environmental pollution and reduce production costs by water resources reuse. On the basis of the actual situation on the investigation, this paper put forward the concept of wastewater drain-select system and try to reuse wastewater to different production processes according to water quality, and finally develop a viable reuse project.Coagulation and Mineral-catalyzed Fenton-like Treatment Process was used as the primary wastewater treatment of Xiangshan Hengda printing and dyeing factory, but the factory had been using little recycled water due to the lack of detailed water reuse standard and mode. The daily usage of recycled water was only about 246m3, occupied 10.03% of the total water consumption. The system did not run very well because of the aging equipment and the lack of the professional management of the treatment process.The experiment screen out the wastewater of the workshop on the basis of the index of pH, chroma, turbidity and conductivity for practicability and universality. Each drainage of desizing scouring bleaching one bath, scouring, light color soaping, medium color soaping and deep color soaping had been collected and detected. A wastewater recycling screening standard was established according to the daily wastewater treatment capacity and water demand: pH should range from 5 to 10, conductivity should not be larger than 2000 μs/cm, turbidity should not be larger than 100, color should not be larger than 1000.The original wastewater treatment process improvement: the consumption of coagulant PAC is 120 mg/L, and the rate of delivery should be controlled as 3.75 kg/h, and the pH is adjusted range from 7 to 8.The recycled water quality was monitored and water index are as follows: pH approximates 7.5, turbidity approximates 23, chroma approximates 8 to 16, conductivity approximates700 μs/cm, hardness approximates 65 mg/L. The salt accumulation was calculated in the mode of shunt screening, and the salt accumulation limit of this model was 0.579 g/L, which was greatly improved compared with the 6.676 g/L of the conventional mode.The recycled water was used to actual production application such as washing, pretreatment, dyeing of cotton and terylene. The effect was judged by the color of dye liquor, K/S of fabric and capillary, whiteness, fabric strength and crocking fastness. The standard of reused water are as follows: Level 1, pH should range from 7 to 8, conductivity should not be larger than 180 μs/cm, turbidity should not be larger than 8, chroma should not be larger than 4, can be used to light color dyeing; Level 2, pH should range from 7 to 8, conductivity should not be larger than 210 μs/cm, turbidity should not be larger than 12, chroma should not be larger than 8, can be used to the pretreatment of cotton; Level 3, pH should range from 7 to 8, conductivity should not be larger than 677 μs/cm, turbidity should not be larger than 32, chroma should range from 16 to 32, can be used to washing, deep color dyeing of cotton and terylene.A reuse project of cotton wastewater was established for Hengda printing and dyeing factory. The recovery of wastewater reached 29.67% and the usage of recycled water reached 25%.The recycled water was applied to workshop production, contrast with normal production, the DE was 0.61, both crocking fastness and staining fastness were superior to level three.