The overall purpose of this study was to evaluate the ability of sulfur dioxide (SO2) to remove nitrate-nigrogen (i.e., reduction to a gaseous form) from the secondary wastewater effluent. To accomplish th above task, a jar test procedure was established and the concentration of NO3-N along with the concentration of NH3-N present in the secondary wastewater, treated with SO2, were measured initially and after 10 min, 20 min, 30 min, 40 min, and 24 hr. Then, the percent NO3-N removal was calculated, comparing the NO3-H concentrations measured in each treatment with the initial values. The above procedures were conducted for 36 different runs resulting from variation of the parameters which were believed to effect the kinetics of the reaction (i.e., SO2 concentration, presence of catalysts, temperature, and NO3-N concentration). Three levels of SO2 (500, 1000, 2000 mg/1), two levels of NO3-N(25-30 and 40-45 mg/1), two temperatures (20 degrees and 35 degrees Celsius), and two different catalysts (Fe+3 1 mg/1 and Feo 1 g/1) were used in this study. Prior to the jar tests, it was necessary to develop techniques to eliminate the SO2 interferences with analysis of NO2-N, and NH3-N. Two approahces were made to accomplish this task. First by air stripping of the SO2 treated secondary wastewater sample; secondly by diluting the SO2 treated secondary water to decrease the SO2 concentration to a level of less than 80 mg/1 as SO2. Satisfactory results were obtained applying both stripping and dilution methods.
Ghorashian, Javid; Adams, V. Dean; and George, Dennis B., "Removal of Nitrogen From Secondary Wastewater Effluent Through No 3-N Reduction Using Sulfur Dioxide (SO2)" (1982). Reports. Paper 465.