Chemical Treatment of Metal Finishing Industrial Wastes and Wastewaters in the Presence of Chelating Substances

ABSTRACT: Regulated heavy metals are typically removed from industrial wastewater through a metal hydroxide precipitation and sedimentation process. Complicating the treatment of these waste streams is the presence of commingled chemicals such as detergents, surfactants and other chelating substances associated with the metal finishing and electroplating processes. During wastewater treatment, these chelating substances form highly stable complexes with heavy metals thus inhibiting them from being removed. Oxidation of chelating substances using a variety of strong chemical oxidants is a financially expensive and potentially hazardous approach used to overcome the negative effects of heavy metal complex formation. Development and implementation of innovative redox chemistry offers numerous advantages over chemical oxidation in treating industrial wastewater impacted by chelating substances. By completely eliminating the need to remove the chelating substances, the new redox chemistry method reduces both the chemical treatment costs as well as the capital costs associated with installation of unit operations required to support chemical oxidation. Moreover, with the reduction in chemical use, implementation of the new redox chemistry method significantly reduces the facility"s operations and maintenance costs as well as increasing the protection of worker health and safety from hazardous chemical exposure. BENEFIT: The anticipated benefits in developing and implementing cutting edge redox chemistry for the treatment of industrial wastewaters impacted by chelating substances include the following: The ability to consistently and reliably achieve legally enforceable wastewater discharge standards for heavy metal pollutants in the presence of strong chelating agents. Reduction in wastewater treatment operation and maintenance costs needed to support chemical oxidation of chelating substances. Reduction in wastewater treatment capital costs associated with installation of new physical unit operations and flow separation. Increase in the protection of worker health and safety associated with hazardous chemical exposure. Technology is completely compatible with current facility wastewater treatment operations and associated infrastructure.