Ecotoxicological impacts associated with fluorescent lamp waste leachates on the marine macroalga Ulva sp

Although regulations require the abandonment of fluorescent lamps (FL), they remain widely used, particularly in developing countries, and generate significant amounts of inappropriately disposed waste. This poses environmental risks due to mercury (Hg) content and socioeconomic challenges, as it also contains critical elements such as rare earth elements (REE). REE recovery from FL often involves acid extraction, yielding concentrated leachates. Some methods, like algal sorbents, are promising, but sorption studies overlook the potential sorption impairment due to leachate toxicity. Moreover, a lack of ecotoxicological studies on FL wastewater impact hinders policymakers' ability to decide on leachate management. Therefore, the present study investigated the ecotoxicological effects induced by real FL waste leachates on the macroalga Ulva sp. The macroalgae were exposed to different dilutions of FL waste leachate for 3 days, and various parameters such as mortality, relative growth rate, chlorophyll content, and biochemical alterations were analysed. The study found positive correlations between Hg, Y, and Eu concentrations in macroalgae and initial element solution levels. All treatments reduced chlorophyll content and growth rates compared to the blank. Fluorescent lamps leachate exposure activated antioxidant and biotransformation enzymes. Nevertheless, lipid damage was observed, while defence mechanisms against FL wastewater-induced stress prevented discoloration and death. The efficiency of REE accumulation did not appear to be compromised.