The HBOD test: a new method for determining biochemical oxygen demand

Abstract

ABSTRACT: The conventional biochemical oxygen demand (BOD) test requires a series of sample dilutions and can be very time‐consuming to perform. Although newer oxygen utilization tests based on pressure changes in sealed devices do not require dilutions, they are too expensive to use routinely for wastewater samples. A rapid and inexpensive test is proposed for determining oxygen demand. This procedure, called the headspace biochemical oxygen demand (HBOD) test, uses non‐diluted wastewater samples, because additional oxygen from the container headspace is available to the microorganisms. The total oxygen demand is calculated from oxygen depleted from both the liquid and the air phases in the sealed container. Using samples from 3 wastewater treatment plants, it is shown that the HBOD test, if conducted over a 5‐day period, provides similar results to the BOD test. The three main advantages of the HBOD test are that the test can be performed more easily than the BOD test because no sample dilutions are necessary, the oxygen demand determined within a shorter period of time (24–36 h) can provide an accurate prediction of the 5‐day value, and the experimental conditions used in the HBOD test more accurately reproduce the hydrodynamic and culture conditions typical of wastewater treatment bioreactors. These advantages make the HBOD test more useful for treatment plant process evaluation and control.