Zero discharge of electroplating wastewater The characteristics and treatment methods of.
As for electroplating wastewater, you may have heard that it usually comes from equipment cooling water, wastewater plating solution, plating parts cleaning, other wastewater, etc. In fact, the water quality of these electroplating wastewater is complex, basically containing chromium, gold, zinc, silver, cadmium and other heavy metal ions and cyanide. Some even cause cancer, deformity and mutation of highly toxic substances. If discharged directly, it will not only pollute the environment, but also waste precious metals contained in wastewater.
Zero discharge of wastewater, which is also a popular field at present, means that after repeated use, industrial wastewater can be highly concentrated (more than 99%) with high salt content and pollutants, and then recycled, or filtered out insoluble substances with a filter press, and then recycled without any waste liquid discharge. The remaining salt and pollutants in the water will be sent to the waste treatment plant for landfill by means of pressure filtration waste residue or concentration crystallization, or recycled into usable chemical raw materials.
The traditional zero discharge engineering treatment method of electroplating wastewater actually covers a large area, has a large amount of reagent input, high sludge output, high treatment cost, and complex water quality cannot be effectively treated. The traditional process of electroplating wastewater treatment is to add alkali to adjust PH, and then become heavy metal hydroxide, and then add polyaluminum chloride, ferric chloride and other coagulants, and then add acrylamide and other coagulants, to separate the mud in the sedimentation tank, and then conduct membrane filtration.
1. Start to collect acid wastewater, cyanide wastewater, chromium wastewater, pretreatment wastewater, ground wastewater and nickel wastewater by category.
2. The pre-treatment wastewater and acid wastewater need to be collected through pipes and then discharged to the integrated wastewater treatment pool; Then the cyanide containing wastewater is repeatedly broken through the primary and secondary cyanide breaking tanks, and then discharged to the comprehensive wastewater treatment tank after treatment; Chromium containing wastewater is recovered to reduction tank, chromium recovery flocculation tank and chromium recovery sedimentation tank through chromium recovery.
3. The integrated wastewater in the integrated wastewater treatment pool is discharged into the integrated physicochemical reaction unit, which can effectively remove heavy metal ions and solid-liquid separation from the integrated wastewater.
4. The wastewater after solid-liquid separation needs to be filtered by sand filter and discharged into the biochemical reaction unit. The ammonia nitrogen, total nitrogen, total phosphorus and COD in the wastewater can be effectively removed.
5. The wastewater after biochemical treatment needs to enter the softening resin tank in turn through sand filtration to remove calcium. Ultrafiltration can remove macromolecular particles and reverse osmosis desalination. The reverse osmosis water and nickel recovery wastewater are adsorbed by ion exchange, and the concentrated water enters the membrane for concentration and then evaporates and crystallizes.
