Nitrogen Transformations in Land Treatment

The storage lagoon of a land treatment system functions as a dynamic biological reactor in which algae and bacteria can transform input nitrogen. A quantitative estimate of these nitrogen transformations is needed for proper design of the spray irrigation component of land treatment. In this study, a simulation model was developed to predict the concentrations of inorganic and organic nitrogen and algae in the lagoon throughout the winter storage and irrigation months; pilot plant data were used for verification. Both the predicted and observed results indicated a large reduction in inorganic nitrogen caused by algal uptake during most of the irrigation period. The model was then applied to achieve a better balance between nitrogen supplied by the lagoon and crop demand throughout the growing season.