Toxicity Of Typical Pharmaceutical Wastewater And Receiving Water

Pharmaceutical discharge is one important target in wastewater treatment and disposal in China. The whole life cycle of drug production, results in a large volume of wasterwater, containing soluble raw materials, organic solvent, toxic and hazardous chemicals. The characteristics of pharmaceutical wastewater are complex in componants, recalcitrant to degradation, with high COD. Moreover, the hazoudous ingredients could cause serious harms to the ecosystem. Physicochemical indicators, such as chemical demand of oxygen (COD), biological demand of oxygen (BOD5), and ammonia nitrogen, are employed for discharge regulation of pharmaceutical wastewater in China. However, these parameters can not exactly reflect the potential toxic effects of hazardous substance residues in the wastewater on the ecosystem and human health. Bioassay is an effective method for monitoring water quality and safety. Toxicity test employing aquatic organismis advantageous in reflecting the actual toxic effects of combining exposure to multiple toxic substances in the complex wastewater. In the present study, acute toxicity and gentoxicity effects of the typical pharmaceutical effluents on aquatic organisms were evaluated, as well as the toxicity reduction treated by hydrolytic acidification-aerobic process. Moreover, the genotoxicity and oxidative damage the international standard model organisms Denio rerio and a native species Pseudorasbora parva, were compared, exposed to the pharmaceutical discharges and the receiving water. The aims are to provide theoretical basis for controlling the eco-toxicity and potential hazards to human health caused by pharmaceutical wastewater.The comparision of five different kinds of aquatic organisms at 4 trophic levels in acute toxicity and gentoxicity tests exposed to pharmaceutical effluents were conducted, including bacteria(Photobacterium phosphor eum), phytoplankton(Scenedesmus obliquus), zooplankton (Paramecium caudatums, Daphnia magna) and fish (Denio rerio). The results of the general toxicity tests showed that, the toxic Unit (TU,100/LC50) of the pharmaceutical wastewater ranged in 1.4～2.9 for Denio rerio lethality test,1.0-2.7 in Daphnia magna immobilization test, and 0～1.5 in Paramecium caudatums lethality test. No significant adverse effects were observed on the growth of Scenedesmus obliquus and lumination of Photobacterium phosphoreum. The sensitivity of the test organism in response to the pharmaceutical wastewater followed the order of Denio rerio> Daphnia magna> Paramecium caudatums> Photobacterium phosphor eum and Scenedesmus obliquus, suggesting that the pharmaceutical wastewater may be more toxic to higher organisms. The comet assays with Denio rerio hepatacytes showed that the final effluents still had sginificant DNA damage at the concentration of 2%. After treatment by hydrolytic acidification-aerobic process, the physicochemical indicators of the effluents reached the’Chemical Synthetic Pharmaceutical Industrial Water Pollutant Discharge Standard’, but the effluents still showed acute toxicity on Paramecium caudatums, Daphnia magna and Denio rerio, with TU above 1.0, and caused gentoxicity on Denio rerio.Xi River and Pu River are both the main receiving water body of pharmaceutical effluents in Liao River Basin. The toxicity of surface water samples collected from Xi River, Pu River, and Hun River were assessed, using the international common species, Denio rerio and the native species, Pseudorasbora parva. The water samples caused no lethal effects on both fishes. Compared with control groups, the upstream of Xi River and midstream in Pu River showed no significant genotoxicity to the fishes. But significant genotoxicity and oxidative damage were observed in the downstream of Hun river after the Xi River converges, and in the downstream of Pu River. Comparing with the international common species Denio rerio, the native species Pseudorasbora parva also had the same biological sensitivity and stability in the evaluations of DNA damage and oxidative damage exposed to the samples. Thus, Pseudorasbora parva may be applied as a native species to evaluate the water quality and safety in Liao River Basin.