Recycled Water Corrosivity Control: The Additional Advantage of Disinfection with Sodium Hypochlorite

Recycled water corrosivity control is an important consideration in the design and operation of wastewater treatment plants and recycled water distribution systems. Even mild corrosivity can have significant long-term impacts on equipment and pipelines. Corrosivity control involves adjustments to water chemistry (pH, alkalinity, hardness, etc.), but how adjustments are implemented can vary based on existing treatment processes. For the Michelson Water Recycling Plant, corrosivity control was achieved by modifying an existing process rather than adding a new one. This paper discusses the investigation and evaluation of several treatment alternatives for corrosivity control. The study resulted in replacing chlorine gas disinfection with sodium hypochlorite disinfection, which offered the additional advantage of addressing operational, regulatory, and safety concerns associated with the use and storage of gaseous chlorine. The study highlights the connection between disinfection and corrosivity, an important consideration for other agencies starting water recycling programs to meet increasing water demand.