Toxicity assessment of water at different stages of treatment using Microtox assay

Abstract

Abstract. Number of potentially toxic hydrophobic organic contaminants e.g. polycyclic aromatic hydrocarbons, pesticides, polychlorinated biphenyls and dioxins having entered aquatic environment, including potential sources of drinking water. Unfortunately, not all micropollutants can be removed during water treatment processes. What is more, disinfectants can react with some organic compounds already present in the water, and form disinfection by-products which also can be toxic. The aim of this study was to assess toxicity of water at different stages of water treatment and to verify usefulness semipermeable membrane devices in monitoring of drinking water. For this purpose, semipermeable membrane devices (SPMDs) were deployed in a surface water treatment plant. To determine the effect of water treatment on the presence of toxic micropollutants, study was conducted for a period of 5 months. Three sampling places were chosen: raw water input, stream of water just before disinfection and treated water output. After sampling dialysis in organic solvent was carried out and extracts were then analyzed with the Microtox acute toxicity test. The study has indicated the utility as well as some limitations of combining SPMDs with bioluminescence assay in the monitoring of biological effects of bioavailable hydrophobic pollutants in drinking water.

Ecotoxicity assessment of camphor oxime using Microtox assay – preliminary research

“…Luminescent bacteria emit light when they are in optimal environmental conditions. The presence of toxic substance causes a change in the cellular state, rapidly reflected in a decrease of light emission [17]. The Microtox 81.9% Basic Test with 14 double dilutions was chosen to provide a wider range of tested concentrations due to the fact that the ecotoxicity of camphor oxime was completely unknown.…”

“…exposure time. For the calculations of percent inhibition of light emission, the following equations were used [13,17]:…”

“…Γt is the ratio of light lost at time t to light remaining at time t, which can be convert to % effect. The final expression of the toxic response of the samples is presented as EC50 which is the Effective Concentration of the samples reducing light emission by 50%, and estimated from the linear regression of the log of each concentration level of the contaminant versus percent inhibition (% effect), as described in [17].…”

“…DMSO is used in cytotoxicity assays as well [16]. Because the solvents possess some toxicity themselves, the analysis is based on the comparison of the ecotoxicity effect of the solvent, and solvent with dissolved substance [17].…”

Comparative Performance of Catalytic Fenton Oxidation with Zero-Valent Iron (Fe(0)) in Comparison with Ferrous Sulphate for the Removal of Micropollutants

“…In most cases, organic pollutants could partially be mineralised but the formation of oxidation products is commonly observed, which could possess more toxicity than their parents' pollutants and thus, the toxicity assessment before and after water treatment is necessary [30,31]. The Microtox protocol is a straightforward approach for the assessment of toxicity and provides the information on samples' potential to inhibit/promote bioluminescence, which is influenced by the tested compound's toxic profile [32].…”