Toxicity Of Pharmaceutical Wastewater And Chemical Mixtures On Aquatic Organisms

Toxicity of pharmaceutical wastewater was checked with chemical analysis and a battery of acute toxicity tests. The correlations between the wastewater toxicity and physicochemical parameters and metal speciation concentrations were investigated to gain insight into the toxicity source of pharmaceutical wastewater. Besides, the toxic effects of cadmium (Cd) and sodium dodecyl benzene sulfonate (SDBS) on Daphnia magna and Danio rerio were investigated. Independent Action (IA) and Concentration Addition (CA) models were applied to predict the joint toxicity of Cd and SDBS based on the individual component toxicity.Firstly, the toxicity of pharmaceutical wastewater on lux bacteria (Photobacterium phosphoreum), alga (Scenedesmus obliquus), crustacean (Daphnia magna) and fish (Danio rerio) was studied. The results showed that, the pharmaceutical wastewater had acute toxicity on the four organisms and after "hydrolysis & acidification+ aerobic biological" process, the wastewater had no toxicity on P. phosphoreum, D. magna and D. rerio, but had toxicity on S. obliquus. Pearson's correlation analysis illustrated that the wastewater toxicity on P. phosphoreum had a strong linear correlation with COD, NH3-N, Labile-Cu and dissolved-Cu (p<0.01), linear correlation with pH (p<0.05), the toxicity on S. obliquus had a strong linear correlation with NH3-N, pH and conductivity (p<0.01), linear correlation with Labile-Cu and dissolved-Cu (p<0.05).Secondly, the toxicity of Cd and SDBS, two chemicals with high concerns in Chinese waters, on the immobilization of D. magna and the swimming behavior of D. rerio was investigated. Combination index (CI) illustrated that Cd and SDBS expressed a synergistic effect on the immobilization of D. magna; and an antagonistic effect on the swimming speed D. rerio, but a synergistic effect on its vertical position in the water column. Based on the observed data, the IA model was more appropriate than the CA model in the prediction of their joint toxicity.The study revealed that, certain correlations exited between the toxicity of pharmaceutical wastewater and physicochemical parameters and metal speciation concentrations. The joint toxicity of Cd and SDBS on aquatic organisms was not simply additive effect. These results gained insight into the toxicity source of pharmaceutical wastewater, gave an example of the joint toxicity investigation and aided to understand the integrated toxicity and aquatic ecological risk of chemicals and wastewaters.