Acute toxicity of disinfection by-products from chlorination of algal organic matter to the cladocerans Ceriodaphnia silvestrii and Daphnia similis: influence of bromide and quenching agent

Author(s)

Leite, Luan de Souza ; Ogura, Allan Pretti ; dos Santos, Danilo Vitorino ; Gaeta Espindola, Evaldo Luiz ; Daniel, Luiz Antonio

• Document type: Journal article
• Source: Environmental Science and Pollution Research; v. 29, n. 24, p. 11-pg., 2022-01-21.

Abstract

Algal organic matter (AOM) in water reservoirs is a worldwide concern for drinking water treatment; once it is one of the main precursors for disinfection by-products formation (DBPs). In this context, this study investigated the ecotoxicity of DBPs from chlorination of AOM to Ceriodaphnia silvestrii and Daphnia similis (Crustacea, Cladocera). The bioassays evaluated three scenarios, including the AOM extracted from Chlorella sorokiniana, the quenching condition used in the tests, and the DBPs formed after the chlorination of the two test waters with AOM (with and without bromide presence). The results showed that AOM has no toxic effects for the tested species under typical environmental concentration (5 mg.L-1). However, since AOM is a potential precursor of DBPs, the toxicity of two test waters (TW-1 and TW-2) after the chlorination process (25 mg Cl-2.L-1, for 7 days, at 20 degrees C) was tested. The sample with higher toxicity to the tested species was TW-1, in which chloroform and chloral hydrate were quantified (615 and 267 mu g.L-1, respectively). However, TW-2 showed lower concentration of chloroform and chloral hydrate (260 and 157 mu g.L-1, respectively), although bromodichloromethane, dibromochloromethane, and bromoform were also detected (464, 366, and 141 mu g.L-1, respectively). Although free chlorine is highly toxic to the tested species, the quenching conditions also affected the organisms' survival due to the use of ascorbic acid and the presence of reaction intermediates. Nonetheless, both species were more affected by TW-1 and TW-2 than the quenching condition. These results endorse the importance of removing the AOM before the disinfection process to avoid the formation of DBPs. In addition, ecotoxicological analyses could provide a more comprehensive assessment of water quality, especially considering the challenges of quantifying DBPs and other emerging contaminants. Highlights Algal organic matter (AOM) is a precursor of DBPs in chlorinated water. Environmental concentrations of AOM did not show toxicity to the two species. The quenching condition of free chlorine using ascorbic acid was toxic. Chlorination of AOM formed DBPs concentrations toxic to the cladocerans. Among the five detected DBPs, chlorinated species were more toxic than brominated. (AU)

• FAPESP's process: 19/05759-1 - Study of Algal Organic Matter (AOM) removal by coagulation-flocculation and use of pre-treatments
• Grantee: Luan de Souza Leite
• Support Opportunities: Scholarships in Brazil - Doctorate