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(registered) 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(registered) toxicity data for 79 organic compounds and the two toxicity assays were compared. The Shk1 assay is less sensitive than the Microtox(registered) assay and could therefore be more suitable for influent wastewater toxicity monitoring.