Assessment of phenolic compound perturbations of a nitrifier microbial association maintained within a continuous-flow multi-stage laboratory model

Abstract

To facilitate rapid examination of the environmental impacts of selected molecules on cycling processes inherent to aquatic ecosystems, a multi-stage model ecosystem was developed. Nitrification was chosen as the criterion for assessing the inhibitory effects of perturbant molecules on a microbial association maintained within the model. Inhibition of nitrification proved to be a sensitive indicator of both phenol and 2,4-dichlorophenol toxicity. Perturbant compound fate was determined by direct analysis and the relationship between residual concentration and nitrifying activity was assessed. Phenol, in concentrations of 20 and 60 mg·l-1, attenuated within the model and it was apparent that low concentrations (<4 mg·l-1) must be reached before nitrification proceeded. 2,4-dichlorophenol in concentrations of 10 and 20 mg·l-1 was found to persist and inhibition of nitrification resulted. Biodegradation data of perturbant compounds were, thus, considered important requisites for assessing potential impacts on aquatic environments. * To whom all correspondence should be addressed.

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