Hardware acid pickling and phosphating cleaning wastewater refers to the treatment of various appearance parts of zinc, aluminum, die-casting and stamping hardware, as well as the spraying of powder and oil on the surfaces of cabinets and chassis, hardware and electrical appliances, hardware equipment, medical equipment, and hardware lighting fixtures. During processing and production, the main pollutants are degreasing wastewater, spray painting wastewater, phosphating and passivation wastewater. These types of wastewater contain petroleum, phosphate ions, metal ions, low molecular weight, organic compounds, pigments, surfactants, COD, SS, pH and other pollutants. The concentration is high and the composition of the wastewater is complex, resulting in poor biodegradability and relatively high treatment difficulty.

The wastewater from the hardware acid pickling and phosphating cleaning industry is discharged in compliance with Class A effluent standards through the use of coagulation sedimentation, anaerobic, aerobic, sedimentation, MBR membrane and other process technologies.

The wastewater from hardware acid pickling and phosphating cleaning flows into the original regulating tank, where the wastewater is regulated to ensure uniform water quality and reduce the impact load on the air flotation tank treatment caused by uneven water quality. The original regulating tank was equipped with a lift pump to lift the sewage into the air flotation unit for oil removal pretreatment, then into the reaction tank for flocculation reaction, and finally into the sedimentation tank for mud water separation, removing some COD from the water BOD、 Chromaticity, acidity, alkalinity, and SS, etc.

The sedimentation effluent enters the callback tank to regulate the water quality and then enters the anaerobic tank. Through the acidification and hydrolysis of anaerobic bacteria, the high molecular weight organic pollutants in the wastewater are converted into small molecule substances through the oxidation and decomposition of microorganisms, and then enter the aerobic tank. The oxygen is supplied through fan aeration, and under the action of aerobic microorganisms, the organic pollutants in the wastewater are degraded. The effluent from the aerobic tank flows into the secondary sedimentation tank. The main function of anaerobic tank is to further degrade large molecular organic matter, making the removal efficiency of aerobic tank higher. The packing material in the anaerobic tank increases the biomass in the tank, allowing microorganisms to come into contact with pollutants more thoroughly, resulting in more complete degradation of pollutants, especially with strong adaptability to high concentration wastewater. The function of an aerobic tank is to thoroughly degrade pollutants, further degrade small molecule organic matter, fully utilize pollutants in sewage, absorb, transform, store, and utilize pollutants, and degrade pollutants to an acceptable risk level in the water body, thereby achieving high-quality water quality.

After biochemical treatment, the effluent contains flocculants and requires solid-liquid separation treatment. MBR membrane has efficient solid-liquid separation effect, which is much better than traditional sedimentation tanks. The effluent quality is good, with suspended solids and turbidity close to zero, and can be directly utilized. It achieves complete separation of hydraulic retention time (HRT) and sludge age (SRT), and the operation control is flexible and stable. Finally, the MBR effluent is further filtered through sand and charcoal filtration, ultrafiltration, and reverse osmosis to ensure that the effluent meets the standard and is stable.

　　hardwareThe wastewater from acid pickling and phosphating cleaning can meet the first level standard of Guangdong Province's local standard "Water Pollutant Discharge Limits" (DB44/26-2001) after being treated using the above sewage treatment process and combination process design.