Printing and Dyeing Wastewater Treatment Method

The printing and dyeing industry is a typical high water consumption industry, which consumes nearly 100 million tons of softened water for process use every year. The source and pollutant composition of printing and dyeing wastewater are very complex, characterized by large changes in water quality, high organic content, and high chroma (mainly colored dyes). of waste. As the country and society pay more and more attention to environmental protection requirements and requirements for sustainable development, traditional printing and dyeing wastewater treatment methods have become more and more difficult to meet production and environmental protection requirements.

Printing and dyeing wastewater refers to the wastewater discharged from the pretreatment, dyeing, printing and finishing of cotton, wool, linen, silk, chemical fiber or blended products. Printing and dyeing wastewater has the characteristics of large water volume, high content of organic pollutants, deep chroma, large alkalinity, and large changes in water quality, and is a difficult industrial wastewater to treat.

There are four main treatment methods for printing and dyeing wastewater, physical treatment, chemical treatment, biological treatment, and alkali reduction treatment. Printing and dyeing wastewater has poor biodegradability and is difficult to decolorize. The decolorization effect of printing and dyeing wastewater is one of the key indicators to evaluate the effectiveness of wastewater treatment methods. The commonly used treatment methods are flocculation and re-flocculation, a passive treatment method of biochemical regeneration. The project covers a large area, the process is long, the infrastructure and operation costs are high, and the treatment effect is unstable. Some dyes are easily soluble in water, and due to the large molecular weight of dyes, most dyes can form hydrophilic colloids in water, which makes the conventional decolorization of printing and dyeing wastewater very difficult. Therefore, more economical and effective decolorization methods and Printing and dyeing wastewater treatment technology for the removal of refractory biodegradable organic matter.

The conventional treatment methods of printing and dyeing wastewater are generally divided into two types of treatment processes: biochemical + physicochemical and physicochemical + biochemical. However, due to the lack of hydrolysis and acidification unit, there is a problem that the reaction of aerobic biochemical unit is not thorough enough in actual operation, resulting in high costs for subsequent physicochemical treatment. . The "hydrolysis + aerobic" series process of hydrolysis and acidification treatment is added in front of the traditional aerobic biological treatment device, which can hydrolyze the difficult-to-degrade organic substances in the printing and dyeing wastewater to generate more easily biodegradable substances, and improve the biodegradability of the wastewater. degradability, thereby improving the COD removal rate of the traditional process.

At present, many newly built printing and dyeing wastewater treatment plants in China (including domestic sewage and centralized treatment of printing and dyeing wastewater) all adopt the "hydrolysis-aerobic" biological treatment process developed by this process, which has achieved obvious environmental and economic benefits. Membrane separation technology is a new type of efficient and environmentally friendly separation technology. In recent years, with the continuous development and progress of membrane separation technology in China, modern high-tech membrane separation technology (mainly ultrafiltration, nanofiltration and reverse osmosis technology) ) has been widely and successfully applied in the treatment of printing and dyeing wastewater, and has produced good economic and social benefits, bringing new opportunities for technological innovation in the printing and dyeing industry.

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