ABSTRACT
The objective of this study was to develop a MATLAB based simulation modeling using SIMULINK tools that produced dissolved oxygen sag curve, and applied it to Bindare stream in Zaria, Kaduna State-Nigeria, in order to assess the stream dissolved oxygen level and its self-purification capacity as a mitigation measure in stream pollution control.. Laboratory test of selected water quality parameters which includes Dissolved Oxygen (DO), Biochemical Oxygen Demand (BOD), pH, Total Dissolved Oxygen (TDS), alkalinity, Electrical Conductivity (EC) and temperature was carried out in four sections of the stream as stipulated by "Standard Method" along the 6 kilometer stream stretch. Results generated by the model simulation included critical dissolved oxygen deficit Dc, critical time tc of travel by the stream to attain Dc. The stream mean dissolved oxygen DO of 6.4mg/L was obtained which was within the range Stipulated by APHA, AWWA, and WEF 1995. .Determination Coefficient R2 (found to be 0.86) was applied to check correlation between simulated and theoretical calculated results using Streeter-Phelps dissolved oxygen sag formula. It was therefore concluded that the Dissolved Oxygen Sag generated using MATLAB Simulink is a time saving calculation tool for DO studies, user friendly and can be applied to any stream/river of known required input parameters.