Ecotoxicological assessment of waste scrubber water in unicellular algae (Tetraselmis suecica) and Blue Mussel (Mytilus edulis) larvae

Marine scrubbers can be classified into wet and dry scrubbers. Scrubber water (also known as washwater) from both wet scrubber systems has been found to release acidic water containing nutrients and contaminants back to the marine environment, including metals, aromatic hydrocarbons, and soot particles. This is especially true for the open-loop scrubbers that utilize the natural alkalinity of seawater and keep a high flow of process water in order to reduce SO2 in the exhaust and the washwater is discharged to sea, most often without substantial treatment. Little is known about potential impact of the discharged washwater on the marine environment. In ecotoxicological tests, a number of marine organisms have shown negative effects after acute and chronic exposures to varying concentrations of scrubber water, but the main pollutants involved in these responses are not clear yet. The aim of this study was to evaluate the effect of the main pollutants found in open-loop scrubber discharge water for survival, feeding and development of different species at the base of the food web after acute exposures to gas scrubber effluent. Toxicity, mortality, and physiology have been evaluated in marine microalgae, Tetraselmis suecica, and blue mussel (Mytilus edulis) larvae. Direct exposure to scrubber water appears to adversely affect biological and reproductive parameters in invertebrates, raising substantial concerns about ongoing open-loop exhaust gas scrubber system deployment.