An improved solution of first order kinetics for biochemical oxygen demand

Abstract

This paper evaluated selected Biochemical Oxygen Demand first order kinetics methods. Domesticinstitutional wastewaters were collected twice in a month for three months from the Obafemi Awolowo University, Ile-Ife waste stabilization ponds. Biochemical Oxygen Demand concentrations at different days were determined using standard method. The Biochemical Oxygen Demand concentrations were used in the first order kinetics parameters (ultimate Biochemical Oxygen Demand and Biochemical Oxygen Demand reaction rate constant) determination using various methods. Accuracies of these methods were evaluated using relative error, Akaike Information Criterion (AIC), Analysis of Variance and model of selection criterion (MSC). The study revealed that ultimate Biochemical Oxygen Demand were in the range of 822 to 1813 mg/L and Biochemical Oxygen Demand removal rate was between -0.442 and -0.134/d. The average of the relative errors (%) ranged between 0.62 and 39.53, while MSC values ranged between -0.91 and 7.59 for the various methods. The results revealed that Microsoft Excel Solver provided an improved description of Biochemical Oxygen Demand removal patterns based on relative error, MSC and AIC. The study concluded that Microsoft Excel Solver, non-linear regression, least squares and Thomas' methods were valuable methods at higher confidence levels based on lower values of AIC and relative errors and high values of MSC. Microsoft Excel Solver method was the best for solving first order kinetics of Biochemical Oxygen Demand.

Keywords: Wastewater, Environmental Engineering, Biochemical Oxygen Demand Kinetic Parameters, Statistical Evaluation