Investigations into using the nematode Caenorhabditis elegans for municipal and industrial wastewater toxicity testing.

This investigative study assesses the ease and usefulness of the nematode Caenorhabditis elegans for identifying contributors to effluent toxicity within an industrial and municipal wastewater treatment plant (WWTP) system. Several different types of industries, including fiberglass manufacturing, paper packaging, and yarn dyeing, discharge effluent into the municipal wastewater treatment plant, which in turn discharges into a local creek. A major objective of this study was to identify primary sources of toxicity throughout the system with a nematode toxicity test. Twenty-four-hour composite water samples were taken periodically over a ten-month period at five strategic points within the system: (1) at the point of discharge at each of the three industries, (2) at the combined industrial influent of the wastewater treatment plant, (3) at the effluent of the WWTP, (4) upstream of the WWTP discharge, and (5) downstream of the WWTP discharge. Samples were analyzed for basic water chemistry, and each sample was tested for whole effluent toxicity using a 72-h nematode test with mortality as the end point. Results suggest that interactions between the wastewaters of certain industries may increase the overall nematode toxicity in the wastewater treatment facility's composite influent and effluent. Nematode mortality trends indicate relatively high toxicity levels in wastewater entering the WWTP from contributing industries. High WWTP influent toxicity may potentially be due to varying flow rate ratios of industrial discharges, release of varying toxic constituents in wastewaters, and toxic interactions between chemical constituents of industrial wastewaters. The evaluation of toxicity within the treatment system may pinpoint locations where pollution prevention strategies may be implemented to reduce overall toxicity at the point of discharge.