title: Algal toxicity of the alternative disinfectants performic acid (PFA), peracetic acid (PAA), chlorine dioxide (ClO2) and their by-products hydrogen peroxide (H2O2) and chlorite (ClO2-).
abstract: Environmental effect evaluation of disinfection of combined sewer overflow events with alternative chemical disinfectants requires that the environmental toxicity of the disinfectants and the main by-products of their use are known. Many disinfectants degrade quickly in water which should be included in the evaluation of both their toxicity as determined in standardized tests and their possible negative effect in the water environment. Here we evaluated according to the standardized ISO 8692 test the toxicity towards the green microalgae, Pseudokirchneriella subcapitata, of three disinfectants: performic acid (PFA), peracetic acid (PAA) and chlorine dioxide (ClO2) as well as two by-products of their use: hydrogen peroxide (H2O2) and chlorite. All of the five chemicals investigated showed clear toxicity to the algae with well-defined dose response curves. The EC50values ranged from 0.16 to 2.9mg/L based on nominal concentrations leading to the labeling of the chemicals as either toxic or very toxic. The five investigated chemicals decreased in toxicity in the order chlorine dioxide, performic acid, peracetic acid, chlorite and hydrogen peroxide. The stability of the chemicals increased in the same order as the toxicity decrease. This indicates that even though ClO2has the highest environmental hazard potential, it may still be suitable as an alternative disinfectant due to its rapid degradation in water.
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark. Electronic address: rakc@env.dtu.dk.
authors.forename: Ravi Kumar
authors.initials: RK
authors.lastname: Chhetri
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark.
authors.forename: Anders
authors.initials: A
authors.lastname: Baun
authors.affiliation: Department of Environmental Engineering, Technical University of Denmark, Bygningstorvet, Building 115, 2800 Kgs. Lyngby, Denmark.
authors.forename: Henrik Rasmus
authors.initials: HR
authors.lastname: Andersen
mesh_terms: D002712:Chlorides / Q000633:toxicity*; D017606:Chlorine Compounds / Q000633:toxicity*; D000460:Chlorophyta / Q000187:drug effects* / Q000254:growth & development; D004202:Disinfectants / Q000633:toxicity*; D005561:Formates / Q000633:toxicity*; D006861:Hydrogen Peroxide / Q000633:toxicity*; D010087:Oxides / Q000633:toxicity*; D010463:Peracetic Acid / Q000633:toxicity*; D014874:Water Pollutants, Chemical / Q000633:toxicity*
chemical_list: D002712:Chlorides; D017606:Chlorine Compounds; D004202:Disinfectants; D005561:Formates; D010087:Oxides; D014874:Water Pollutants, Chemical; C008817:peroxyformic acid; C025109:chlorine dioxide; D006861:Hydrogen Peroxide; D010463:Peracetic Acid; C001599:chlorite
keywords: Algal toxicity; Chlorine dioxide; Chlorite; Hydrogen peroxide; Peracetic acid; Performic acid; Pseudokirchneriella subcapitata