Effect of Cyanuric Acid on the Inactivation of Cryptosporidium parvum under Hyperchlorination Conditions

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• 作者：Jennifer L. Murphy ; Michael J. Arrowood ; Xin Lu ; Michele C. Hlavsa ; Michael J. Beach ; Vincent R. Hill
• 刊名：Environmental Science & Technology
• 出版年：2015
• 出版时间：June 16, 2015
• 年：2015
• 卷：49
• 期：12
• 页码：7348-7355
• 全文大小：303K
• ISSN：1520-5851

文摘

Cyanuric acid (CYA) is a chlorine stabilizer used in swimming pools to limit UV degradation of chlorine, thus reducing chlorine use and cost. However, CYA has been shown to decrease the efficacy of chlorine disinfection. In the event of a diarrheal incident, CDC recommends implementing 3-log₁₀ inactivation conditions for Cryptosporidium (CT value = 15鈥?00 mg路min/L) to remediate pools. Currently, CYA鈥檚 impact on Cryptosporidium inactivation is not fully determined. We investigated the impact of multiple concentrations of CYA on C. parvum inactivation (at 20 and 40 mg/L free chlorine; average pH 7.6; 25 掳C). At 20 mg/L free chlorine, average estimated 3-log₁₀ CT values were 17鈥?00 and 31鈥?00 mg路min/L with 8 and 16 mg/L CYA, respectively, and the average estimated 1-log₁₀ CT value was 76鈥?00 mg路min/L with 48 mg/L CYA. At 40 mg/L free chlorine, 3-log₁₀ CT values were lower than those at 20 mg/L, but still higher than those of free chlorine-only controls. In the presence of 鈭?00 mg/L CYA, average 0.8- and 1.4-log₁₀ reductions were achieved by 72 h at 20 and 40 mg/L free chlorine, respectively. This study demonstrates CYA significantly delays chlorine inactivation of Cryptosporidium oocysts, emphasizing the need for additional pool remediation options following fecal incidents.