A Modeling-Based Evaluation of the Effect of Wastewater Application Practices on Groundwater Quality,

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. jg