BASHAAR Y. AMMARY
Abstract
A new graphical method for the determination of the BOD first order model coefficients (k and L) with lag periods is introduced. The new method is based on a dimensionless analysis of the first order equation. Curves for the theoretical dimensionless first order model with different lag periods and for different k values are drawn using MATLAB software. The experimental BOD values are made dimensionless by dividing them by the experimental BOD3 or BOD4 (or even BOD5) depending on the length of BOD measurement. These values are then compared with the theoretical curves having different lag periods and the theoretical curve closest to the experimental data is used to evaluate k, L and the lag period. In the new method it is easier to observe the closeness of the experimental data to the first order model and lag periods can easily be detected. In addition, the length of BOD measurements can be reduced to 4 or even 3 days instead of the usual 5 or 6 days.