A mechanistic model for assessing biodegradability of complex wastewaters

This study proposes a two-stage biodegradation process linked by a bio-transformation process as a mechanism involved in the biodegradation of complex industrial wastewaters; and developed a mechanistic oxygen uptake model based on the proposed mechanism. The reliability of the new mechanistic model was eveluated using various representative organic mixtures including glucose/glutamic acid solutions, three types of wastewaters, ozone treated secondary effluents, and various fragments derived from these effluents. The results revealed that (1) through proper calibration, the new mechanistic model can satisfactorily predict the oxygen uptake by various complex wastewaters over the long term; (2) the new model can be used reliably to assess and effectively to compare the biodegradability of complex wastewaters; (3) the new model, considering both stoichiometry and kinetics of biochemical reactions, is also simple but sensitive, and is a practical measure for evaluating the mechanistic-kinetic constants involved in the biodegradation processes. The reliability of the new model has also been verified by using the data from another independent study. The results from this study also suggested that the new model provides a uniform means of assessing the alteration of biodegradability induced by various physical and chemical treatment processes.