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Title: A modeling-based evaluation of the effect of wastewater application practices on groundwater quality
Authors: United States. Army. Corps of Engineers. Philadelphia District.
Reynolds, Charles M. (Charles Michael), 1950-
Iskandar, I. K. (Iskandar Karam), 1938-
Keywords: Groundwater
Wastewater modeling
Nitrogen compounds
Wastewater treatment
Publisher: Cold Regions Research and Engineering Laboratory (U.S.)
Engineer Research and Development Center (U.S.)
Series/Report no.: CRREL report ; 95-2.
Description: CRREL Report
Abstract: The model WASTEN was used to compare several nitrogen input scenarios and to predict the levels of nitrate in groundwater for a proposed wastewater treatment facility at Fort Dix, New Jersey. The primary variables tested were input concentration of NO3-N (nitrate nitrogen) and NH4-N (ammonium nitrogen) and long-term application of wastewater. Two NO3-N loading rates, 4 and 10 mg NO3-N/L, were tested for 168-day simulations. The system’s response was estimated from the NO3-N concentration in water draining below 150 cm. For both input NO3-N concentrations, the predicted NO3-N concentrations in the leachate below 150 cm were less than 2 mg NO3-N/L. The initial NO3-N in the soil profile represented typical background levels for this site. The final NO3-N in the soil profile was affected by both denitrification and leaching. The initial NH4-N in the simulated soil profile was equal to the extractable NH4-N from soil samples taken at the Fort Dix site. Because a portion of the extractable NH4-N exists as exchangeable rather than solution NH4-N, the soil profile values for the solution NH4-N used in the simulation were greater than actual soil solution values would be. Moreover, by adjusting model coefficients, all the initial NH4-N was forced to leach in the model simulations rather than be subjected to nitrification, denitrification, immobilization or plant uptake. Due to the retardation effects on NH4-N mobility caused by soil-ion sorption, the NH4-N leaching was distributed over an extended time rather than moving rapidly below the unsaturated zone. With these assumptions, the WASTEN model predicted that the NO3-N at 150 cm would be less than 1 mg NO3-N/L if the applied NO3-N was 4 mg NO3-N/L, and less than 2 mg NO3-N/L if 10 mg NO3-N/L was applied. The predicted NO4 + concentration in the leachate was very low, even when an initial, uniform saturation of 5.0 mg NH4-N/L in the soil profile was assumed. In field situations there would be little, if any, NO4 + present following tertiary treatment of wastewater. Based on these calculations, the predicted concentration of NH4-N in the applied effluent would remain within regulatory requirements.
Rights: Approved for public release; distribution is unlimited.
Appears in Collections:CRREL Report

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