Dilutions of Glucose and Glutamic Acid Analyzed as Multi-Order BOD Reactions

Abstract

The Biochemical Oxygen Demand (BOD) of a mixture of glucose and glutamic acid is a standard test solution which provides a reasonably repeatable value of the 5-day BOD. The objective of this study was to evaluate the reaction order from respirometer data of BOD of glucose and glutamic acid mixtures. The mixtures ranged in increments of 10% from 10% strength (90% dilution) to 100% strength (no dilution). There were 10 replications of each strength of sample, so that the BOD of 100 samples measured at daily intervals for 5 days were available. The data were tested for goodness-of-fit to three BOD reaction models: a first-order model, a half-order model, and an order-n model. The root mean squared error measured the goodness-of-fit. Twenty-six percent of the samples fit the first-order model best, 63% fit the half-order model best, and 11% fit the order-n model best.