A Chemox Treatment For Urea- And Ammonium-Contaminated Groundwater

In a pilot project performed at a fertilizer manufacturing facility, a one-step chemical oxidation technique successfully treated urea- and ammonium-contaminated groundwater. The oxidation reaction occurred in an 1,100-gallon batch reactor. The contaminated inflow was buffered by the metered addition of sodium bicarbonate solution and subsequently treated with sodium hypochlorite in an 8:1 weight ratio of Cl-2:N. In an instantaneous reaction, the urea and ammo-nium-N were completely oxidized to nitrogen gas that was vented to the atmosphere during mixing. The pH of the reactor discharge was similar to 6.5. Sodium sulfite was used to reduce residual hypochlorite in the reactor effluent to chloride to provide process water with characteristics suitable for discharge. Oxidation rates were similar with different strengths of hypochlorite; however, a 5 to 6 percent sodium hypochlorite (as Cl-2) solution was the most stable. (C) 2005 Wiley Periodicals, Inc.