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Simulation of Nitrogen Transport in Soil Under Municipal Wastewater Application Using LEACHN 1
Author(s) -
Kunjikutty Sobhalatha P.,
Prasher Shiv O.,
Patel Ramanbhai M.,
Barrington Suzelle F.,
Kim SeungHyun
Publication year - 2007
Publication title -
jawra journal of the american water resources association
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.957
H-Index - 105
eISSN - 1752-1688
pISSN - 1093-474X
DOI - 10.1111/j.1752-1688.2007.00086.x
Subject(s) - leachate , wastewater , lysimeter , environmental science , leaching (pedology) , nitrate , denitrification , environmental engineering , groundwater , pollution , nitrogen , environmental chemistry , soil water , chemistry , soil science , ecology , geology , geotechnical engineering , organic chemistry , biology
To reduce the risk of surface and ground water pollution from nitrate, and in so doing improve the quality of receiving waters, better management options for land application of wastewater must be explored. In order to determine proper and environmentally safe wastewater land application methods, different application scenarios were simulated in this study to determine the fate and transport of nitrogen in sand‐filled field lysimeters. The Leaching Estimation and CHemistry Model for Nutrients (LEACHN) model was used to assess alternative wastewater land application scenarios: applications of low‐, medium‐, or high‐N concentration wastewaters, at different rates (0.06, 0.19, 0.31, or 0.6 m 3 /m 2 /day), under continuous or intermittent application. In the simulations, the NO 3 − ‐N levels decreased in the leachate with an increase in wastewater application rates, due to enhanced denitrification in the upper anoxic zone of the soil generated under high flow rates. With low‐N concentrated wastewater, under all tested flow rates, the NO 3 − ‐N levels in the leachate were below the permissible limit. When medium‐N wastewater was applied, the NO 3 − ‐N level in leachate from the highest flow rate was below the permissible limit. Therefore, wastewater with low‐N concentrations, about 10 and 0.5 mg/l NO 3 − ‐N and NH 4 + ‐N, may be continuously applied to soil at all tested flow rates, with minimal nitrate pollution problems. Medium and high‐N concentrated wastewaters increased nitrate levels in the leachate, as compared to their levels in the low‐N concentrated wastewater. It appears that while low‐N wastewater can be safely applied to land without much nitrate leaching problems, the application of medium and high‐N wastewater could pose nitrate pollution problems. The simulation with intermittent application of low‐, medium‐, and high‐N concentrated wastewater at different rates showed a 51‐89% greater reduction in NO 3 − ‐N levels in the leachate, than for continuous application under all tested wastewater N‐levels and flow rates. Also, the levels of NO 3 − ‐N in their leachates were below the permissible limit. Therefore, wastewater with high levels of nitrogenous compounds (up to 54 NO 3 ‐N mg/l) could be treated through an intermittent application to land.