There are many ways to etch hardware products, including immersion etching, splash etching, and spray etching. After processing, cleaning the products generates a large amount of heavy metal cleaning wastewater, etching wastewater, developing wastewater, and de ink wastewater. The pollutants in this wastewater mainly contain COD SS、 Chromaticity, acidity and alkalinity, etc.

The etching and cleaning wastewater of hardware products can save engineering investment costs and reduce operating costs to the greatest extent possible by first conducting physical and chemical pretreatment of the wastewater, followed by biochemical treatment, to ensure long-term stable and compliant discharge of the wastewater treatment work.

The de ink wastewater flows automatically into the 1 # regulating tank through the collection pipeline, where the water volume is regulated and the water quality is uniform. The tank is equipped with 1 # and 2 # lifting pumps to pump the wastewater into the acid precipitation tank. After acid precipitation, the wastewater flows into the 1 #, 2 #, and 3 # reaction tanks for chemical addition reaction. After the reaction, it flows into the 1 # sedimentation tank for sludge water separation. The precipitated water enters the 2 # regulating tank and is mixed with other wastewater for further treatment.

The cleaning wastewater, etching wastewater, developing wastewater, and pre treated de ink wastewater are mixed in the 2 # regulating tank to adjust the water volume, ensure uniform water quality, and reduce the impact load on the biochemical tank treatment caused by uneven water quality. 3 # and 4 # lifting pumps are installed in the tank to pump wastewater into reaction tanks 4 #, 5 #, and 6 # for dosing reaction. After the reaction, it flows into sedimentation tank 2 # for sludge water separation, and the effluent from sedimentation enters the return tank to regulate water quality.

After the wastewater quality is adjusted, it flows into the biochemical tank, which is divided into anaerobic tank, anoxic tank, first stage aerobic tank, and second stage aerobic tank. The first two stages are anaerobic processes that utilize the acidification and hydrolysis of anaerobic bacteria to convert high molecular weight organic pollutants in the wastewater into small molecule substances through microbial oxidation and decomposition, and can remove most nitrogen and phosphorus pollutants; The last two stages are aerobic processes, which 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 this processHardware cleaning wastewaterThen, the MBR tank is used for sludge water separation. The MBR tank has an efficient solid-liquid separation effect, which is much better than traditional sedimentation tanks. The effluent quality is good and can be directly utilized, achieving complete separation of hydraulic retention time (HRT) and sludge age (SRT). The operation control is flexible and stable.

The MBR tank effluent is pumped into the clean water tank for storage and treatment. The clean water tank effluent is then subjected to deep treatment through a "sand filter+carbon filter+ultrafiltration+reverse osmosis+multi effect pre-treatment" reuse system. After the above treatment, 98.6% is reused, and the rest is concentrated liquid from the evaporator, which must be handed over to qualified units for recycling and treatment.

The etching and cleaning wastewater of hardware products is treated by a wastewater treatment system and a reuse water treatment facility to achieve 96% reuse of process and product water according to the "Industrial Water Quality for Urban Wastewater Recycling" (GB/T 19923-2005). The rest is evaporated and concentrated before being handed over to qualified units for recycling and treatment.