IDENTIFICATION OF SURFACTANTS AS TOXICANTS IN A PRIMARY EFFLUENT

A partial toxicity identification evaluation (TIE) was conducted with a publicly owned treatment works (POTW) effluent that received no secondary treatment. The effluent was consistently acutely toxic to fathead minnow (Pimephales promelas) and the cladoceran Ceriodaphnia dubia. Initial Phase I toxicity characterization and Phase II identification work with Ceriodaphnia dubia suggested that surfactants were responsible for a significant portion of the toxicity of the effluent. Subsequent experiments concerning the behavior of various mixtures of surfactants in Phase I and Phase II TIE procedures provided additional evidence that these compounds were important determinants of toxicity of the POTW effluent. Finally, measurement of two general classes of surfactants in the test effluent (anionic, nonionic) indicated that there were sufficient concentrations of these compounds to be of toxicological concern. The identification of surfactants as potentially important toxicants in a primary effluent is not particularly surprising in light of their concentrations in untreated or inadequately treated wastewater.