Current time-temperature relationships for thermal inactivation of Ascaris eggs at mesophilic temperatures are too conservative and may hamper development of simple, but effective sanitation
Current time-temperature relationships for thermal inactivation of Ascaris eggs at mesophilic temperatures are too conservative and may hamper development of simple, but effective sanitation
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DOI：
10.1016/j.wroa.2019.100036
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发表时间：
2019-12-01
期刊：
影响因子：
7.5
通讯作者：
Angenent, Largus T.
中科院分区：
文献类型：
--
作者：
Harroff, Lauren A.;Liotta, Janice L.;Angenent, Largus T.
蛔虫卵由于其高抗性脂膜和在环境中长时间存活的能力，通常被用作粪便污泥和废水处理过程中病原体灭活的指示物。目前的指导方针表明，单独的热处理不能在低于45摄氏度的温度下使蛔虫卵死亡，尽管文献中的一些证据表明这是不正确的。在这里，我们进行了对照实验，以测试中温温度对蛔虫灭活的影响。我们将猪蛔虫卵暴露于34摄氏度和45摄氏度之间的温度梯度，在厌氧和有氧条件下，观察所需的暴露时间为3个对数减少。事实上，我们发现低于45摄氏度的温度确实会使这些鸡蛋腐烂，并且所需的暴露时间比目前的指导方针建议的时间短两个数量级。厌氧暴露的结果被用来开发一个时间-温度关系，是适合蛔虫灭活在中温温度。来自文献的数据表明，我们的关系是保守的，当蛔虫卵悬浮在粪便污泥或粪便中时，在环境条件下发生更快的灭活。一个特定的好氧关系没有开发，但我们证明，好氧条件下导致更快的失活比厌氧条件。因此，厌氧关系为这两种情况提供了保守的指导。我们证明，相对较低的温度可以大大影响蛔虫的生存能力，并建议中温温度可以用于废物处理过程中的病原体。开发安全、低投入、中温处理工艺对于确保普遍获得安全卫生设施和排泄物管理特别有价值。(C)2019年，任作者。由爱思唯尔有限公司发布
Ascaris eggs are commonly used as indicators for pathogen inactivation during the treatment of fecal sludge and wastewater due to their highly resistant lipid membrane and ability to survive in the environment for long periods of time. Current guidelines suggest that thermal treatment alone cannot inactivate Ascaris eggs at temperatures below 45 degrees C, although some evidence in the literature suggests this to be incorrect. Here, we performed a controlled experiment to test the effect of mesophilic temperatures on Ascaris inactivation. We exposed Ascaris suum eggs to a temperature gradient between 34 degrees C and 45 degrees C under anaerobic and aerobic conditions to observe the required exposure times for a 3-log reduction. Indeed, we found that temperatures lower than 45 degrees C did inactivate these eggs, and the required exposure times were up to two orders of magnitude shorter than suggested by current guidelines. Results from the anaerobic exposures were used to develop a time-temperature relationship that is appropriate for Ascaris inactivation at mesophilic temperatures. Data from the literature demonstrated that our relationship is conservative, with faster inactivation occurring under environmental conditions when Ascaris eggs were suspended in fecal sludge or manure. A specific aerobic relationship was not developed, but we demonstrated that aerobic conditions cause faster inactivation than anaerobic conditions. Therefore, the anaerobic relationship provides a conservative guideline for both conditions. We demonstrate that relatively low temperatures can considerably impact Ascaris viability and suggest that mesophilic temperatures can be used in waste treatment processes to inactivate pathogens. The development of safe, low-input, mesophilic treatment processes is particularly valuable for ensuring universal access to safe sanitation and excreta management. (C) 2019 The Author(s). Published by Elsevier Ltd.