ABSTRACT
In wastewater irrigation, the primary concern with respect to nitrogen is the possibility of nitrate contamination of domestic water supplies and the attendant risk of methemoglobinemia in human infants. Aside from the possible risk of groundwater contamination, it is desirable to recycle nitrogen wherever feasible, since it is an essential nutrient required for the production of food and fiber. Its reuse represents energy conservation. Wastewaters typically contain three forms of nitrogen: organic, ammonium, and nitrate; low concentrations of nitrite may be present. Like other cations in wastewater, ammonium ions can be absorbed by the negatively charged clay and organic colloids in soil. A mechanism of temporary ammonium retention involves assimilation by soil microorganisms. In spite of the great differences between soils and their capacities to retain Phosphorus, the nature of retention reactions is remarkably uniform, and their extent can be estimated from relatively simple relationships.
