Comparative Study of Two Bioassays for Applications in Influent Wastewater Toxicity Monitoring

Bioluminescent bacteria-based assays can be used for influent wastewater toxicity monitoring for biological wastewater treatment systems. The most thoroughly studied bioluminescent bacteria-based test is the Microtox® assay. However, the response to toxicants of Photobacterium phosphoreum, the marine bacterial strain used in this assay, is different from that of the activated sludge microorganisms. We developed a continuous influent wastewater monitoring system based on the bioluminescent bacterium Shk1, a genetically modified Pseudomonad isolated from the activated sludge in an industrial wastewater treatment plant. The Shk1 toxicity data were correlated with the Microtox® toxicity data for 79 organic compounds and the two toxicity assays were compared. The Shk1 assay is less sensitive than the Microtox® assay and could therefore be more suitable for influent wastewater toxicity monitoring.