Evaluation of the combination of linear alkylbenzene sulfonate (LAS) with emerging pollutants

Abstract

The presence of surfactants and other emerging pollutants in water bodies has become a major environmental concern in several places around the world, since these pollutants cause adverse problems in aquatic ecosystems and compromise public health regarding the supply of good quality water. These pollutants often originate from various sources, including industrial activities, pharmaceuticals, and personal care products. A critical aspect of this issue is that many of these pollutants and their mixtures are difficult to degrade in biological treatment processes, requiring auxiliary treatments. Electron beam technology has been applied in various environmental matrices to degrade these pollutants, helping not only to increase degradability, but also to reduce the toxicity of these compounds. The present work aimed to evaluate the single and combined effects of the LAS surfactant with emerging pollutants (caffeine and the antibiotic ciprofloxacin) on the aquatic organism Daphnia similis. The electron beam (EB) treatment for reducing the toxicity of isolated compounds was also evaluated. The organisms were exposed to samples (non-irradiated and irradiated LAS and mixtures) for 48 hours, and the observed effect was immobility. Toxicity was evaluated through EC50 (median effective concentration) calculations. The EC50 values showed a high toxicity level for the LAS surfactant, with EC50s below 9%. Caffeine and ciprofloxacin EC50 data were higher than 20%. The EC50% values of the mixtures were close to the values of the isolated compounds. After EB treatment (5 kGy), about 70% acute toxicity reduction was obtained for the LAS surfactant. The combined presence of surfactants and emerging pollutants in aquatic matrices requires a comprehensive approach to monitoring and mitigating their impacts in order to protect aquatic ecosystems and human health.