Synergetic inactivation of microorganisms in drinking water by short-term free chlorination and subsequent monochloramination / 生物医学与环境科学（英文）

ABSTRACT

<p><b>OBJECTIVE</b>To introduce synergetic inactivation of microorganisms in drinking water by short-term free chlorination for less than 15 minutes followed by monochloramination.</p><p><b>METHODS</b>Indicator microorganisms such as Escherichia coli, Staphylococcus aureus, Candida albicans, and spores of Bacillus subtilis were used to assess the efficiency of sequential chlorination and free chlorination.</p><p><b>RESULTS</b>The sequential chlorination was more efficient in inactivating these microorganisms than free chlorination, indicating that synergy was provided by free chlorine and monochloramine. Ammonia addition time, temperature and pH had influences on this synergy.</p><p><b>CONCLUSIONS</b>The possible mechanism of this synergy might involve three aspects free chlorine causing sublethal injury to microorganisms and monochloramine further inactivating them; different ability of free chlorine and monochloramine to penetrate and inactivate microorganism congeries; and higher concentration of residual chlorine in sequential chlorination than in free chlorination.</p>