Comparing the Efficacy of Chlorine, Chlorine Dioxide, and Ozone in the Inactivation of Cryptosporidium parvum in Water from Parana State, Southern Brazil

• Published in: Applied biochemistry and biotechnology 2008-12, Vol.151 (2-3), p.464-473
• Main Authors: Pereira, Juliana Tracz, Costa, Adriana Oliveira, Oliveira Silva, Márcia Benedita de, Schuchard, Wagner, Osaki, Silvia Cristina, Castro, Edilene Alcântara de, Paulino, Rosangela Clara, Soccol, Vanete Thomaz
• Format: Article
• Language: English
• Subjects: Animals; Biochemistry; Biotechnology; Brazil; calves; Chemistry; Chemistry and Materials Science; Chlorine; Chlorine - pharmacology; Chlorine Compounds - pharmacology; chlorine dioxide; Cryptosporidium; Cryptosporidium parvum; Cryptosporidium parvum - drug effects; Disinfectants; Disinfection - methods; Drinking water; feces; Hypochlorous Acid - pharmacology; in vitro studies; Inactivation; Oocysts; Oocysts - drug effects; Oxides - pharmacology; Ozone; Ozone - pharmacology; public water supply; Public waters; Water Purification - methods; Water supply; Water treatment; Waterborne diseases
• ISSN: 0273-2289; 1559-0291
• DOI: 10.1007/s12010-008-8214-3

In the present work, assays were performed to compare the efficacy of hypochlorous acid, chlorine dioxide, and ozone in the inactivation of Cryptosporidium oocyst in public water supply from Brazilian South conditions. Experiments were carried out in samples containing 2 x 10⁴ oocysts/ml of C. parvum purified from feces of experimentally contaminated calves. An in vitro excystation method was used to evaluate oocysts' viability and to determine the inactivation rates of hypochlorous acid at 2 ppm, chlorine dioxide at 1, 2, and 5 ppm, and ozone at the doses of 0.18, 0.24, 0.36, 0.48, and 1.44 mg/l. By using hypochlorous acid, the maximum inactivation rate obtained was 49.04% after 120 min. Chlorine dioxide at 5 ppm inactivated 90.56% of oocysts after 90 min of contact. Ozone was the most effective product, rendering an inactivation of 100% with the concentration of 24 mg/l. Resistance of Cryptosporidium to the usual disinfectants and the need for more effective water treatments to prevent waterborne diseases in Brazil are discussed in this manuscript.