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Kinetics of tap water dechlorination and aquatic health impacts of selected dechlorination chemicals

Posted on:2009-12-09Degree:M.A.ScType:Thesis
University:Carleton University (Canada)Candidate:Weerasinghe, Bhagya NFull Text:PDF
GTID:2441390002997025Subject:Engineering
Abstract/Summary:
The kinetics of seven dechlorination agents (DA) was studied to identify the efficacy of dechlorination under variable dosage, mixing (periodic/continuous), and pH conditions (6.5--8.6 and/or >9). Dechlorination reactions at 1x stoichiometric dosage (mg DA/mg Cl2) of the DAs are rapid in most cases, but not instantaneous and in some cases needed more than stoichiometric dosage to ensure a near zero residual level (0.02 mg/L total residual chlorine, as required by CEPA (1999)). Dechlorination kinetic analysis revealed reactions were either pseudo-first or zero order with respect to total chlorine concentration in solution at the 10x stoichiometric dosage and second order overall at 2--4x stoichiometric dosages. 48-hour aquatic toxicity tests were conducted using Daphnia magna to identify the acute (short-term) toxicity affects of the dechlorination chemicals over a range of concentrations (0--200 mg/L). Sodium sulfite and thiosulfate were found to have the least aquatic mortality effects while hydrogen peroxide and calcium thiosulfate had the most deleterious effects.;Keywords. dechlorination kinetics, dechlorination, aquatic toxicity, sulfur salts, thiosulfates...
Keywords/Search Tags:Dechlorination, Kinetics, Aquatic, Dosage
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