Domestic dye wastewater treatment technologies

Dye wastewater has always been a type of wastewater that is difficult to treat. In recent years, some projects seem to have adopted new processes using MBR membrane bioreactor systems for its treatment; the water treated in this way can be reused. However, it is said that the membranes tend to get contaminated easily

Reply to 2# hff98791: I heard that there are also catalytic oxidation and adsorption methods – are these already mature?

Reply 1# AITsong: I personally prefer the biochemical method – it represents a cost-effective process route. Below are the relevant details I found. However, the specific process still needs to be customized and optimized based on actual conditions. After entering the 1990s, industrial technology advanced rapidly. Adjustments in the industrial and product structures led to changes in the quality and volume of dye wastewater. As a result, many new methods for treating dye wastewater were developed based on existing technologies. These include physical methods (such as adsorption, membrane separation, and extraction), chemical methods (including coagulation sedimentation, chemical oxidation, photocatalytic oxidation, and electrochemical treatment), and biochemical methods (such as aerobic biological treatment, anaerobic biological treatment, and combined aerobic-anaerobic biological treatment). Each of these methods has its advantages, but they also have shortcomings. For example, coagulation sedimentation is costly to operate, generates large amounts of sludge, and is difficult to dewater ； Chemical oxidation methods are costly and highly toxic; the microorganisms used in biochemical methods have specific requirements regarding nutrients, pH level, temperature, etc., resulting in relatively strict treatment conditions. Therefore, studying practical methods for treating dye wastewater holds great practical and theoretical significance. Currently, there are numerous methods for decolorizing dye wastewater reported in both domestic and international research, but their decolorization mechanisms can be classified into two categories: one involves the enrichment of organic dyes using a mediator, followed by separation and removal ； The second is to disrupt the structure of dye molecules in order to achieve degradation and decolorization.

Reply to 4# wwzing: Could you please explain in detail the mechanism of decolorization? Thanks a lot. . . . . . . . . . . . . . . . . . . . .

The question posed by the original poster is too general; there are great differences among various types of dye wastewater and their water qualities, and the synthesis processes also vary greatly. A lot of the water has high acidity, high COD, and high color intensity – basically the so-called \"three highs\" – and there aren’t many good solutions for this. Biochemicals must be neutralized on the spot, and the cost is not low. Let’s not talk about the cost of catalytic oxidation. High-efficiency decolorants do work, but they are extremely expensive. Adsorption seems like an attractive option, but the materials recovered generally have low value, making it uneconomical; moreover, the investment and operational costs are not necessarily low either. The complexation extraction seems to work well; experiments have been conducted, but there is also an issue of extractant loss. Consider all factors comprehensively; the key is to look at water quality and quantity before determining the appropriate process. Empty talk is useless; practical action is what saves the country.