集中空调冷却塔运行管理中军团菌繁殖的主要影响因素初探

Influencing factors of Legionella reproduction in cooling tower operation and management

目的分析集中空调冷却塔结构、设置、管理、消毒等环节中影响军团菌繁殖的因素,为有效控制冷却塔军团菌污染提供科学依据。方法于2013年5—9月,采集北京市16家大、中型公共建筑集中空调冷却塔的192件冷却水样品进行军团菌检测,现场勘查冷却塔设置环境、塔体及部件现况、管理及消毒措施、相关设施设备运行维护等情况,以军团菌检测结果为因变量进行非条件logistic回归分析。结果单因素logistic回归显示,冷却水管是否存在死水区、消毒剂投加地点、消毒剂投加频率、冷却塔运行时长及冷却水样品采集时间均对冷却水军团菌检出有影响,阳性率较高(P<0.05);进一步采用多因素logistic回归显示,冷却水管存在死水区(OR=12.987)、消毒剂投加在系统(OR=3.019)、投加消毒剂时间间隔≥2 d(OR=3.390)、采样时间为夏季(OR=4.406)是冷却水嗜肺军团菌污染的危险因素,均有统计学意义(P<0.05)。结论采样季节和消毒措施对冷却塔军团菌污染有影响,可据此制定更为有效的冷却塔军团菌污染控制措施。

Objective To explore the potential influencing factors for Legionella reproduction in the cooling tower operation and management and to provide scientific evidence for Legionella contamination control. Methods A total of 192 water samples were collected from the cooling towers in 16 large-scale public buildings in Beijing from May to September in 2013, and the Legionella contamination was investigaetd. The information about the settings of cooling tower, the tower body and units,management and sterilizing measures and other related factors were collected by the questionnaires. The data were analyzed by unconditional logistic regression model. Results A significant relationship was observed between the positive rate of Legionella measuring in cooling water and each influencing factors such as stagnant water, sanitizer dosing point, sanitizer dosing frequency, operating period, and the month of sampling by using univariate non-conditional logistic regression. The multiple logistic regression analysis revealed that the risk factors of Legionella reproduction were stagnant water（OR=12.987,P〈0.05）,sanitizer dosing at the cycling-system（OR=3.019,P〈0.05）, overlong interval of sanitizer dosing（OR=3.390,P〈0.05） and summer（OR =4.406,P〈0.05）. Conclusion The main influencing factors for the Legionella reproduction are season and sterilizing measures, which provide scientific evidence for prevention and control of Legionnaires disease caused by cooling tower contamination.