Sodium metabisulfite is utilized in water treatment primarily for its effectiveness in two main areas:

1. Dechlorination: Sodium metabisulfite is commonly employed to remove chlorine and chloramines from water. Chlorine and chloramines are often added to municipal water supplies as disinfectants to kill harmful bacteria and pathogens. However, residual chlorine can be undesirable in certain industrial processes, aquariums, or for drinking water quality. Sodium metabisulfite reacts with chlorine and chloramines, converting them into harmless chloride ions and sulfur dioxide:

2Na2​S2​O5​+2Cl2​→2NaCl+2SO2​+O2​

Na2​S2​O5​+3Cl2​+H2​O→2NaCl+2HCl+SO42−​

2. Oxygen Scavenging: Sodium metabisulfite is effective as an oxygen scavenger in boiler feedwater and other industrial water systems. Oxygen in water can cause corrosion of metal pipes and equipment. Sodium metabisulfite reacts with dissolved oxygen to form sulfate ions, thereby reducing the oxygen concentration in the water:

2Na2​S2​O5​+O2​+2H2​O→2NaHSO4​+2NaOH

What Is The Use Of Sodium Metabisulfite In Water Treatment

Other uses of sodium metabisulfite in water treatment include:

Reduction of Heavy Metals: It can act as a reducing agent to precipitate and remove certain heavy metals, such as chromium and arsenic, from wastewater.

PH Adjustment: In some cases, sodium metabisulfite is used to adjust the pH of water by adding an acidic component, which is useful in certain industrial processes.

Microbial Control: It helps control microbial growth in water systems, such as cooling towers and process water tanks, by limiting the availability of oxygen and ensuring water quality.

Overall, sodium metabisulfite plays a crucial role in ensuring water quality by removing harmful chlorine compounds, scavenging oxygen to prevent corrosion, and aiding in the treatment of wastewater containing heavy metals. Its effectiveness, safety, and ease of application make it a valuable tool in various water treatment applications across industries.