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Efficiency of Nitrogen Removal in a Simulated Overland Flow Waste Water Treatment System
Author(s) -
Chen R. L.,
Patrick W. H.
Publication year - 1981
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq1981.00472425001000010022x
Subject(s) - denitrification , nitrate , surface runoff , nitrification , chemistry , environmental chemistry , nitrogen , soil water , nitrite , redox , surface water , environmental engineering , environmental science , soil science , inorganic chemistry , ecology , biology , organic chemistry
In a simulated overland flow waste water treatment system, vertical measurements of redox potential indicated the presence of both oxidized and reduced zones that provided favorable conditions for simultaneous nitrification‐denitrification reactions. Addition of C sources substantially reduced the redox potential and enhanced the rate of nitrate reduction. Nitrogen transformation rates were examined by the use of labeled 15 N under controlled laboratory conditions. Adsorption and retention of NH 4 + ‐N in soil matrix accounted for approximately 70–90% of the NH 4 + ‐N applied in simulated waste water. Nitrification occurred in surface oxidized soil layers, resulting in conversion of waste water N to nitrate and nitrite. The downward movement of nitrate to the reduced soil layers in the overland flow model during subsequent application of waste water lead to denitrification and assimilatory nitrate reduction. Estimation of N balance in this study indicated that the overland flow system was capable of removing 80–90% of the added NH 4 + ‐N within the N concentration range commonly found in municipal waste waters. However, labeled 15 N data showed that an average of 11–21% of the N was taken up by vegetation and approximately 5–10% was immobilized and incorporated into soil organic N. Thus, the net loss of N is much less than would be predicted by nonlabeled N mass balance calculations. Overall, only 66–80% of the added labeled N was removed from the simulated overland flow model under laboratory conditions.