Skid-mounted painting wastewater treatment equipment addresses the treatment of high concentrations of organic matter by employing a multi-stage synergistic process to achieve efficient degradation and compliant discharge. Due to the complex composition of painting wastewater, containing recalcitrant organic matter such as resins, pigments, and solvents, its chemical oxygen demand (COD) and biochemical oxygen demand (BOD) are typically high, and its biodegradability is poor, making traditional single-stage processes insufficient to meet treatment requirements. Therefore, skid-mounted equipment often employs a combined process of "pretreatment + advanced oxidation + biological treatment + deep purification" to form a multi-layered pollution interception system.
The pretreatment stage is crucial for reducing the load on subsequent treatment processes. Skid-mounted equipment typically integrates bar screen interception and equalization tank homogenization functions. Coarse and fine bar screens remove large suspended solids such as paint residue and fibers, preventing pipe blockage; the equalization tank uses a stirring device to balance water quality and quantity, avoiding the impact of wastewater concentration fluctuations on treatment stability. Some equipment also adds coagulants at this stage, utilizing the synergistic effect of polyaluminum chloride (PAC) and polyacrylamide (PAM) to destabilize and coagulate colloidal particles. Suspended solids and some organic matter are further removed through sedimentation or flotation, creating favorable conditions for subsequent treatment.
Advanced oxidation processes are the core means of tackling recalcitrant organic matter. Skid-mounted equipment often employs Fenton oxidation, ozone oxidation, or photocatalytic oxidation technologies. These technologies generate highly oxidizing hydroxyl radicals (·OH) to oxidize large organic molecules into smaller fragments, or even directly mineralize them into carbon dioxide and water. For example, Fenton oxidation uses ferrous ions (Fe²⁺) to catalyze the generation of hydroxyl radicals from hydrogen peroxide (H₂O₂), exhibiting highly efficient degradation capabilities for benzene compounds, esters, and other organic matter. Ozone oxidation, through the direct oxidation of ozone molecules and a free radical chain reaction, simultaneously removes color and odor substances. These processes significantly improve the biodegradability of wastewater, providing a foundation for subsequent biological treatment.
The biological treatment stage achieves deep degradation of organic matter through microbial metabolism. Skid-mounted equipment typically employs a combined "hydrolysis acidification + aerobic biological" process. The hydrolysis acidification tank utilizes facultative bacteria to decompose large organic molecules into small volatile fatty acids (VFAs), improving the biodegradability of wastewater. The aerobic biological tank uses activated sludge or biofilm processes, employing aerobic microorganisms to convert organic matter into carbon dioxide and water. Some equipment also incorporates a membrane bioreactor (MBR), using ultrafiltration membranes to retain microorganisms, achieving sludge-water separation and extending sludge age, further improving treatment efficiency and effluent quality.
Deep purification processes are the last line of defense to ensure compliance with discharge standards. Skid-mounted equipment usually integrates sand filtration, activated carbon adsorption, and membrane separation technologies. Sand filtration uses quartz sand layers to retain residual suspended solids, while activated carbon adsorption utilizes its high specific surface area to remove dissolved organic matter and color. Membrane separation technologies such as ultrafiltration (UF) and reverse osmosis (RO) can intercept fine particles, bacteria, and dissolved salts, ensuring the effluent meets reuse standards. For example, reverse osmosis membranes can remove over 95% of dissolved organic matter, and the produced water can be reused in the water curtain circulation system of paint spraying workshops, achieving water resource recycling.
The modular design of skid-mounted equipment is another advantage for its efficient treatment of high-concentration organic matter. By integrating pretreatment, advanced oxidation, biochemical treatment, and deep purification units into a standardized skid, the equipment can be quickly installed and flexibly moved to adapt to different site requirements. Simultaneously, the automated control system can monitor water quality parameters in real time and automatically adjust the dosage of chemicals and aeration intensity to ensure stable and reliable treatment results.
The skid-mounted equipment can also be customized to adjust process combinations according to the characteristics of wastewater from different industries. For example, paint spraying wastewater from automobile manufacturing companies contains heavy metal ions, requiring the addition of a chemical precipitation unit in the pretreatment stage; wastewater from furniture factories has high color, allowing for enhanced ozone oxidation and activated carbon adsorption processes. This flexibility enables the skid-mounted equipment to be widely used in paint spraying wastewater treatment scenarios in industries such as automotive, electronics, and furniture.
Skid-mounted painting wastewater treatment equipment achieves efficient degradation and resource utilization of high-concentration organic matter through the synergistic effect of multi-stage processes. Its modular design, automated control, and customization capabilities not only improve processing efficiency and stability but also reduce operation and maintenance costs and floor space, providing an integrated solution for industrial wastewater treatment.
