Abstract: A system for the treatment of oxidizable contaminants in wastewater includes a contaminant treatment vessel and a hydrogen peroxide supply unit. The hydrogen peroxide supply unit includes a hydrogen peroxide transfer line in fluid communication with the contaminant treatment vessel with an air-gap. A wastewater feed stream may also be in fluid communication with the contaminant treatment vessel. A contaminant treatment vessel effluent stream may also be in fluid communication with the contaminant treatment vessel. A method for the treatment of oxidizable contaminants in wastewater includes supplying wastewater to a contaminant treatment vessel, supplying hydrogen peroxide to the contaminant treatment vessel so that the supply is above the maximum filling level of the vessel in an air-gap, and contacting wastewater in the contaminant treatment vessel with hydrogen peroxide.

Abstract: In a biological wastewater treatment process including secondary clarification, the improvement comprising monitoring the salinity of the wastewater flowing to secondary clarification and adjusting the salinity of the wastewater flowing to secondary clarification by adding water or by adding salt.