Comparison of First And Second Generation Enhanced Photo-Oxidation For the Destruction of Water Born Organic Contaminants (1992)

Abstract Two areas of environmental concern effecting the petroleum industry are:Decontaminating process waterRemediating contaminated ground water at various sites. In recent years the ultra violet enhanced oxidation process (EOP) has become an accepted method of dealing with both these concerns. In the 1970's the first generation of this technology was used. As with any promising technology it was applied in situations beyond its capabilities. This gave rise to a second generation EOP that over came the short comings of the first generation technology. This paper will compare the first and second generation features:UV light sources, spectrum and intensity.Single verses dual path destruction.Light tube clarity.Use of new chemical accelerators. This comparison shows the EOP has advanced to the point it will effectively destroy virtually any organic compound in an aqueous solution. Introduction Over the past few years, the use of ultraviolet enhanced oxidation process (EOP) to treat ground and process water contaminated with petroleum products has become more widely accepted by both the regulatory community and those seeking a cost effective solution to their remediauon requirements. EOP is a destruction technology, as such there are no secondary disposals/liability issues surrounding its use compared to the more traditional treatment options such as air stripping or carbon adsorption. ALL of these essentially transfer contaminants from one medium to another. In some cases of biological treatment the sludge can be a secondary liability. EOP technology has evolved from a first generation developed in the 1970's to a second generation which was developed m the 1980' s. As in most technological development the rust manifestations are pushed beyond their capabilities. This gives rise to second generation technologies which are developed to overcome the problems encountered by the first generation when pushed beyond its capabilities. This holds true with EOP. The first generation EOP relied almost exclusively on hydroxyl radical driven destruction. This resulted in the inability to destroy certain compounds. Also, it suffered from a problem of lamp fouling in numerous applications. The now well proven second generation EOP, ie, RAYOX ®(2) technology has significantly improved the application versatility, the economics, and performance capability of this inherently attractive treatment alternative. This paper outlines the reasons for, the nature of, and the benefits derived from second generation EOP treatment. Specific examples drawn from actual systems have been chosen to highlight the rationale behind the significant advantages of the second generation. FIRST GENERATION EOP The first generation units uses either low pressure or high pressure mercury vapour lamps. These have a very narrow band of UV light, primarily 254 nm (see Figure 1). This technology relies primarily on the production of hydroxyl radicals. This is accomplished by the subjugation of hydrogen peroxide or ozone to ultra-violet light. There are several methods of generating the hydroxyl radical (OH °) from ozone and/or hydrogen peroxide exposed to ultraviolet light.