Current Status of Ozone for Municipal Wastewater Treatment in the United States

Abstract

Although ozone technology has been applied for many years to the treatment of drinking water, its application for the treatment of municipal wastewaters is fairly recent. In the United States, pioneering efforts have been made over the past 20 years to develop the technology of wastewater disinfection with ozone. More than 45 sewage treatment plants in the U.S.A. have installed ozone systems, most for disinfection since the early 1970s, although only 25 of these plants use high purity oxygen for feeding the ozone generation equipment rather than air.

The use of ozone for pretreatment of sewage (by oxidation) preparatory to filtration and adsorption of organics by granular activated carbon has been shown to provide significant processing benefits, which include extension of the useful life of the GAC adsorbers before regeneration is required.

A new process for treating primary sewage sludge with ozone and oxygen under pressure, called the “Oxyozosynthesis” process, has operated successfully for ten years, and a second plant has come on-stream. Primary sludge is converted in a batch process to a light, solid material which is odorless and has been approved for land treatment in place of ocean disposal.

The cities of Denver, Colorado and El Paso, Texas have started wastewater reuse programs, in which ozone plays an important role as a polishing and disinfecting agent.