Toxicity of Organic Chemicals and Their Mixtures to Activated Sludge Microorganisms

Abstract

Toxicity of eightand 10-component mixtures of several organic chemicals to activated sludge (A/S) microorganisms was analyzed. The joint toxic effects of the tested chemicals were found to be simply additive. The quantitative structure activity relationship (QSAR) technique using molecular connectivity indices was used to develop single variable models to fit single chemical toxicity data. A QSAR-based approach is proposed to predict the concentrations of components in equitoxic mixtures that would jointly cause 50% inhibition of the A/S microorganisms. The validity of this predictive approach was demonstrated by comparing the predicted concentrations against those found experimentally.