Abstract

Energy and Environmental Engineering, Inc., East Cambridge Massachusetts, developed a photochemical treatment process that oxidizes organic compounds in wastewater. The process features an Excimer laser, which produces energy sufficient to fragment the bonds of the organic contaminants without altering the water molecules. The developer envisions the process as a final treatment step and claims applicability to groundwater and industrial wastewater containing organics, such as halogenated aliphatics, substitued aromatics, and organic acids. Contaminated wastewater is pumped through a filter unit to remove suspended particles. The filtrate is mixed with stoichiometric quantities of hydrogen peroxide. This mixture is fed to the photochemical reactor and irradiated. Energy from the laser is absorbed by the organic compound(s) and the oxidant, making both species reactive. The reactor effluent is directed to a vented storage tank, where the carbon dioxide product is vented. Base may be added to the storage tank to neutralize any acids formed. Reaction products are carbon dioxide, water, and the appropriate halogen acid. Reaction kinetics depend on contaminant concentration, peroxide concentration, irradiation dose, and irradiation frequency. Studies of the process used the existing bench-scale system, which treats solutions containing up to approximately 100 ppm of total organic carbon at a rate of 1 gallon per minute. Destruction efficiencies between 88% and 99% have been obtained for benzene, benzidine, chlorobenzene, chlorophenol, phenol, and dichloroethene. Preliminary cost evaluation shows that the process is competitive compared to other UV oxidation processes and carbon adsorption.

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Posted February 16, 2000

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