Evaluation of Daphnia magna as an indicator of Toxicity and Treatment efficacy of Municipal Sewage Treatment Plant

Abstract

Performance evaluation of wastewater treatment plants (WWTPs) with special reference to toxicity reduction using Daphnia magna straus as test organism is very important to study the likely adverse effects of thetreated wastewater on the aquatic ecosystem of receiving waters and to detect common environmentally realistic concentrations of pollutants at different concentration levels and toxicity discriminatory ability to distinguish different degree of toxicity and toxic specificity of the compounds on target organisms. This test can be considered asuseful analytical tool for screening of chemical analysis and early warning system to monitor the different operational units of wastewater treatment plants. Interrelationship between COD, SS with respect to Daphnia toxicity (Gd) suggests that improvement of the toxicological quality of wastewater could be linked to the removal of both COD and suspended solids. Both the parameters (COD & SS) can serve as a regulatory tool in lieu of an explicit toxicological standard. An important feature of this work was to emphasize the significance of toxicity tests. It could help to reduceinfluent toxicity and thereby avoid impacting microorganisms’ population in activated sludge systems. This study shows the difference between using physico-chemical and biological criteria to define the quality or toxicity ofwastewater, making it clear that both methods are indispensable and complimentary and support the earlier view that Daphnia magna can serve as a valuable model for bio- monitoring of water pollution and for evaluation of the toxicity of an effluent and risk assessment in an aquatic body, as it is highly sensitive to pollutants.