Assessing the ecological risk of representative wastewater based on a growth inhibition method with freshwater algae (Raphidocelis subcapitata)

Wastewater contains a vast number of pollutants that potentially threaten the ecosystem after being discharged into the environment. The present study aimed to develop a rapid and sensitive toxicity detection method for assessing the ecological risk of wastewater. Raphidocelis subcapitata was used as the test organism in the algal growth inhibition test, and the anti-interference capacity of R. subcapitata itself and three biomass measuring methods (spectrophotometer, electron particle counter and chlorophyll fluorescence) on sample color and sample particulate matter were examined. The results revealed that chlorophyll fluorometry was more suitable for determining biomass in the growth inhibition test. Furthermore, chlorophyll fluorometry was selected to evaluate the combined toxic effects and sensitivity of R. subcapitata to wastewater from different industries. Microalgae respond differently to the toxicity of wastewater from various sources. The LID values for chemical wastewater 2, urban sewage 1, pharmaceutical wastewater 1, electroplating effluent and pharmaceutical wastewater 2 were 4.0, 3.0, 2.7, 2.4 and 2.0, respectively. The present study investigated the toxicity response of R. subcapitata to wastewater from various industries by growth inhibition experiments to comprehend the possible ecological concerns of wastewater from diverse businesses. This study will provide a significant basis for the design of detection methods and a comprehensive evaluation of toxicity in surface water environments.