Algal/bacterial uptake kinetics of dissolved organic nitrogen in municipal wastewater treatment facilities effluents.

The simulation and analysis of the degradation process of organic nitrogen contaminants in wastewater treatment facility effluent is important to the estimation of its actual contribution to eutrophication, and it is crucial to the developing of watershed protection plan. In this study, algal and algal/bacterial based bioassay was conducted to study the bioavailability of dissolved organic nitrogen contaminants in wastewater treatment plants effluents, and 4 kinetic models were used to describe the mineralization process. The traditional 1-pool model that was commonly used in water quality models showed poor correlation (r = 0.613 ± 0.261), while the other three models performed much better (r > 0.950). The model coefficient and simplicity were studied using Akaike information criterion and Bayesian information criterion, and Gamma model was indicated to be the best model since it presented the most parsimonious fit to the data with the fewest terms. This study exhibited that the bioavailability and degradation rate of organic nitrogen in wastewater effluent varied greatly, and this variation should be considered in water quality models. Besides, Gamma model could be used to modify the current Total Maximum Daily Load models to provide a scientific basis for making watershed protection plans and controlling eutrophication.