Optimizing the best wastewater decolorization method

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Select the best wastewater decolorization method. From the perspective of currently applied wastewater treatment technology, methods that can effectively remove the color of wastewater include adsorption, coagulation, biological, membrane separation, chemical oxidation, and electroflocculation. 1. Adsorption and decolorization Adsorption and decolorization technology relies on the adsorption of adsorbents to remove color. Commonly used adsorbents include regenerable adsorbents such as activated carbon, ion exchange fibers, etc. and non-renewable adsorbents such as various natural minerals (bentonite, diatomaceous earth), industrial waste (coal slag, fly ash) and natural waste (charcoal, sawdust), etc. The adsorbents currently used for adsorption and decolorization mainly rely on physical adsorption, but ion exchange fibers, modified bentonite, etc. also have chemical adsorption. 2. Flocculation and decolorization Coagulation and decolorization uses flocculants to flocculate the color-forming substances in the wastewater to precipitate and decolorize. Flocculation decolorization technology has low investment costs, small equipment footprint, and large processing capacity. It is a commonly used decolorization technology. 2.1 Inorganic coagulants include metal salts and inorganic polymer flocculants. Widely used metal salts include aluminum salts and iron salts ； Inorganic polymer flocculants are a new type of water treatment agent developed on the basis of traditional metal salt flocculants. They have strong adaptability, non-toxicity, can double the efficiency and are relatively cheap. They have been rapidly developed and widely used. 2.2 Organic polymer flocculant, polyacrylamide (PAM) is the most widely used, and it has three types: nonionic, cationic and anionic. 3. Oxidation method decolorization Chemical oxidation method decolorization refers to using the oxidizing properties of chlorine, ClO2, O3, H2O2, HClO4 and hypochlorite to break the chromophore groups in wastewater or change its chemical structure under certain conditions, thereby achieving the purpose of decolorizing wastewater. Oxidation methods include chemical oxidation, photocatalytic oxidation and ultrasonic oxidation. Although the specific processes are different, the decolorization mechanism is the same. Chemical oxidation is a relatively mature method currently studied. Oxidants generally use Fenton's reagent (Fe2+-H2O2), ozone, chlorine, sodium hypochlorite, etc. 4. Biological decolorization Biological decolorization uses microbial enzymes to oxidize or reduce colored molecules and destroy their unsaturated bonds and chromogenic groups to achieve the purpose of decolorization. 5. Electrochemical decolorization: The electrochemical method purifies wastewater through electrode reactions. According to the electrode reaction mode, electrochemical methods can be subdivided into internal electrolysis, electroflocculation and electroflotation, and electrooxidation. The most famous internal electrolysis method is the iron filings method. 6. Membrane separation method for decolorization In the field of wastewater treatment, membrane separation method is a technology that uses synthetic or natural polymer membranes, using external energy or chemical potential differences as the driving force, to selectively separate pollutants in water, thereby purifying wastewater. Process Selection After years of practice, on-site inspections and process modifications of various enterprises' sewage treatment stations have basically determined a set of high-efficiency, low-cost basic operation modes (on this basis, it can be increased or decreased according to the actual situation of the enterprise), so that the effluent can ensure that the discharge reaches the standard. Wastewater generally uses: “A combined process of “physical and chemical precipitation (or flotation) + anaerobic (or facultative) + aerobic + physical and chemical precipitation”. In the above process, the first step of physical and chemical precipitation uses a flocculating decolorizing agent combined with PAM to assist coagulation, which not only effectively removes more than 40% of COD and other substances such as suspended solids, ammonia nitrogen, etc. through flocculation, but also, with its unique decolorization effect, the wastewater can be made colorless or light-colored in the first step! The cost is only a few tenths of a yuan, laying the foundation for low-cost operation. After the biochemical water is released, for many companies, all other indicators can meet the standards, except for the color, which is usually light yellow or brown. for example: Coking wastewater, printing and dyeing wastewater. Papermaking wastewater, etc. Capable units can use activated carbon filtration and adsorption or ClO2, O3 oxidative decolorization or even membrane separation decolorization. However, everyone knows that these require large investments and relatively high operating costs! Through comparative practice, we have selected a special biochemical water decolorizing agent from many agents. According to the color of different effluents, the cost of adding the amount is controlled to the lowest, so that the color of the effluent can fully meet the standard. To sum up, when many companies are suffering from chromaticity problems, they might as well experiment more with decolorizing agents to solve the chromaticity problem under the premise of low-cost operation and avoid high investment!