NITROGEN DYNAMICS IN A MATURATION WASTE STABILIZATION POND SYSTEM RECEIVING INDUSTRIAL WASTEWATER IN MABIBO AREA DAR ES SALAAM, TANZANIA
A mathematical model describing the dynamics of Nitrogen transformation and removal in a maturation Waste Stabilization Pond (MWSP) system receiving industrial wastewater was developed. Simulation of the processes was done using STELLA 8_1®, based on the principle of conservation of mass. Besides, measurement of different parameters input to the model was made. Model simulation and mass balance analysis results show that nitrification was responsible for the majority of nitrogen transformation at 36.9% (38.1 mgl-1d-1), followed by plant uptake at 31.6% (32.55 mgl-1d-1); mineralization at 21.05% (21.65 mgl-1d-1); sedimentation/accretion at 9.3% (9.1 mgl-1d-1) transformation. Regression analysis indicates a good agreement between simulation results and actual measurements with R2 of 0.749 for NO3-N, 0.709 for NH3-N, 0.985 for Org-N, and 0.973 for Soil/Sediment-N. These results suggest that the developed model is capable of simulating the dynamics of nitrogen transformation and removal in a Maturation Waste Stabilization Pond system receiving industrial wastewater, and can be utilized as a tool in assessing nitrogen levels at various pollution scenarios to aid decision making as regard to protecting water bodies receiving effluent from these systems.