A study was made of the effect of ultraviolet radiation on the rate and extent of chlorine oxidation of organic material in highly nitrified effluents from biological sewage treatment plants. Ultraviolet radiation will very significantly increase the rate of this reaction. Also, the extent of oxidation which can be achieved by chlorine combined with UV radiation is usually much greater than that which can be achieved by chlorine alone. The rate of the catalytic oxidation is dependent upon pH, and the most rapid rate of oxidation and most efficient use of chlorine are obtained at pH 5. The rate of organic oxidation is not proportional to the chlorine concentration; however, the rate of chlorine consumption is. Large excesses of chlorine do not increase the reaction rate but simply increase the amount of chlorine required to eliminate a given amount of organic matter. The rate and extent of the catalytic organic oxidation at pH 5 are not significantly affected by temperature. However, both the rate and extent of catalytic oxidation are substantially reduced by the presence of ammonia in an effluent. A brief investigation of the scope of the UV-catalyzed chlorine oxidation indicated that phenol, 2,4-dinitrophenol, glycine, formic acid, and o-dinitrobenzene are oxidized rapidly and extensively. On the basis of organic oxidation rate produced per watt of UV output, high-pressure mercury arcs are about 2.7 times more efficient than low-pressure mercury arcs. Process costs of 7.2 cent to 11.1 cent/1000 gal. were estimated, based on several types of commercially available lamps. (Author)

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