Virtues of acclimated microbial cultures in wastewater characterization and treatment

Abstract

Biochemical Oxygen Demand (BOD) is one of the parameters used to characterise wastewater. It is used to gauge the pollution strength of wastewater and it is an imperative test in stream pollution control activities. However, BOD measure alone can be misleading. This paper evaluates how acclimation of BOD seed microbial cultures influences the characterisation of wastewater, mainly based on BOD results. BOD tests on refinery wastewater confirmed that the use of acclimated cultures results in higher BOD levels than the ones from tests done using standard laboratory seed cultures. For example, for the same sample of wastewater, tests done with standard seed cultures gave an ultimate BOD (BODu) value of 122 mg/L whereas a test carried out using acclimated seed cultures gave a BODu value of 533 mg/L. Generally, tests mediated with acclimated seed cultures had higher reaction rates and larger BODu values. The recalcitrance of refinery wastewater was indicated by its COD/BOD ratio of up to 16:1 as opposed to a ratio of 1:5.1 - 3.0:1 for easily biodegradable wastes. The main take-home message from this paper is two-pronged: 1) BOD tests on recalcitrant wastewater must be done using acclimated seed cultures, and 2) the assessment of the strength of recalcitrant or toxic wastewater must be based on both BOD and COD tests.

Journal of Building and Land Development Vol. 13 (1) 2006: pp. 32-38