Toxicity evaluation of pharmaceutical wastewaters using the alga Scenedesmus obliquus and the bacterium Vibrio fischeri

•Pharmaceutical effluents were mainly polluted with organics and phosphorus.•Toxicities of 10 out of 16 effluent samples exceeded the discharge limit value.•V. fischeri was more sensitive than S. obliquus in testing toxicities of effluents.•Toxicities were significantly and positively correlated with COD and NH3-N.•Toxicities along with conventional pollutants could be reduced in most plants.

The toxicity of pharmaceutical wastewaters has recently been the focus of the public in China. This study aimed to evaluate the conventional pollution parameters and toxicities of different raw and treated pharmaceutical wastewaters to algae Scenedesmus obliquus and bacteria Vibrio fischeri. Wastewater samples were collected from 16 pharmaceutical wastewater treatment plants in China. The results of the conventional parameters analysis indicated that the total suspended solids, chemical oxygen demand (COD), ammonia (NH3-N), and total phosphorus (TP) were largely removed after treatment. Pharmaceutical effluents were mainly polluted with organics and phosphorus as indicated by the average COD (388 mg/L) and TP (3.16 mg/L) concentrations. The toxicity test results indicated that the influent samples were toxic to both test species. Although the toxicities could be remarkably reduced after treatment, 10 out of the 16 effluent samples exceeded the acute toxicity discharge limit of the Chinese national standards. Spearman rank correlation coefficients indicated a significantly positive correlation between the toxicity values of S. obliquus and V. fischeri. Compared with S. obliquus, V. fischeri detected more pharmaceutical effluent samples with toxicities. Meanwhile, the toxicity indicators were significantly and positively correlated with the COD and NH3-N concentrations based on a Spearman rank correlation analysis.