Textile printing and dyeing wastewater is known for its high color, high concentration of organic matter (COD), and presence of residual dyes and auxiliaries, resulting in significant visual and environmental pollution. The most immediate question facing printing and dyeing companies is: "How can we cost-effectively remove color from wastewater and reduce COD to acceptable levels?"
Textile wastewater treatment requires a combination of physicochemical and biochemical methods. Biochemical treatment alone is limited in its effectiveness in decolorizing many synthetic dyes. Therefore, physicochemical treatment is often used as a core step in pretreatment or advanced treatment. Dissolved air flotation (DAF) plays a key role in this process. By adding appropriate decolorizing agents and flocculants, the microbubbles generated by DAF effectively capture and float dye molecules and colloidal particles bound to water molecules, forming a scum for removal. This is the first step in achieving initial decolorization and COD reduction, with significant and rapid results.
After physicochemical pretreatment, the biodegradability of the wastewater is improved. Subsequent biochemical treatment (such as activated sludge) can further degrade water-soluble organic matter (such as slurry and surfactants). For the solid-liquid separation stage after biochemical treatment, inclined plate sedimentation tanks are chosen for their high efficiency. They ensure effective sedimentation of activated sludge or biofilm, prevent sludge loss, and ensure clear effluent. For small and medium-sized textile mills or in regions with particularly stringent emission standards, investing in a complete integrated treatment system is a common option. Modern integrated treatment equipment integrates and optimizes these processes—physicochemical flocculation and flotation, biochemical reactions, sedimentation, and even advanced treatment units such as ozone decolorization—to achieve fully automated control from inlet to outlet, ensuring stable color and COD removal.
In short, the key to successful textile wastewater treatment lies in the combined process of "physicochemical color reduction + biochemical waste reduction." Dissolved air flotation machines are a powerful tool for efficient decolorization, while inclined plate sedimentation tanks and integrated treatment equipment provide reliable back-end sedimentation and overall solutions, respectively. The process selection should be determined based on the type of dye used and emission standards.
