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

Abstract

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 10(4) 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.

Disinfection by-products of chlorine dioxide (chlorite, chlorate, and trihalomethanes): Occurrence in drinking water in Qatar

“…However, each of the common disinfectants can produce disinfection by-products (DBPs) that can pose a threat to human health. ClO 2 has recently been used as an alternative to chlorine as it does not typically lead to the formation of toxic DBPs (Pereira et al, 2008), but it still kills bacteria efficiently and is more powerful than chlorine over a wide pH range (Pereira et al, 2008;Haas, 1990). ClO 2 does not produce significant amounts of halogenated organic DBPs.…”

“…A recent study reported that ClO 2 pre-oxidation reduced THMs and other by-products (Yang et al, 2013). In addition, ClO 2 is a more powerful bactericide than chlorine (Cl 2 ) for water treatment because of its higher oxidation capacity (Pereira et al, 2008).…”

Impacts of water organic load on chlorine dioxide disinfection efficacy

“…Chlorine dioxide has been lately considered as an alternative to chlorine, since its reactions with organic or inorganic species in water do not usually lead to the formation of harmful toxic by-products [4]. In addition, chlorine dioxide (ClO 2 ) is more powerful than chlorine (Cl 2 ) as a bactericide for water treatment due to its higher oxidation capacity [5]. Chlorine dioxide accepts five electrons when reduced to chloride ion.…”

Clues to uncommon and easily overlooked infectious diagnoses affecting the GI tract and distinction from their clinicopathologic mimics

“…105 An intracellular, water-borne parasite, Cryptosporidium is notorious for its resistance to water disinfectant treatment except for ozone. 162,163 Oocysts are swallowed and undergo excystation and release sporozoites, which then attach to and are enveloped by intestinal epithelial cell membranes where they divide inside parasitophorous vacuoles within the microvillous layer, 164 outside of the cell's cytoplasm. They subsequently transform into characteristic round trophozoites.…”