China attaches great importance to the protection and recycling of water resources. With the promotion of favorable policies such as the new environmental protection law, the sewage treatment market has entered a period of rapid development. Sodium metabisulfite, as a reducing agent, is widely used in sewage treatment.
Taking chromium containing wastewater as an example, the main pollutant component in chromium containing wastewater is Cr6+. Hexavalent chromium poses great environmental hazards and requires the addition of reducing agents to reduce Cr6+to Cr3+and reduce its toxicity. Adjust the pH value to 8-9, and the Cr3+ions in the solution will precipitate to produce Cr (OH) 3. After mud water separation, the sludge will be sent to the disposal center for treatment.
The theoretical mass ratio of sodium metabisulfite to hexavalent chromium is 2.74, which means that if the concentration of Cr6+in chromium containing wastewater is 1ppm, then treating one ton of Cr6+requires the consumption of 2.74g of metabisulfite. The actual usage is magnified by 1.2-1.5 times the theoretical amount, which means that treating one ton of wastewater with a Cr6+concentration of 1ppm requires a consumption of 3.288g-4.11g, usually taken as 1.3 times. Therefore, treating one cubic meter of wastewater with a Cr6+concentration of 1ppm requires a consumption of 3.56g sodium metabisulfite.