United States Environmental Protection Agency, Office of Research and Development, Research Triangle Park, NC, USA.
Jacobs Technology, Inc, Research Triangle Park, NC, USA.
J Environ Manage. 2021 Feb 15;280:111684. doi: 10.1016/j.jenvman.2020.111684. Epub 2020 Dec 7.
In the event of a large, aerosol release of Bacillus anthracis spores in a major metropolitan area, soils and other outdoor materials may become contaminated with the biological agent. A study was conducted to assess the in-situ remediation of soil using a dry thermal treatment approach to inactivate a B. anthracis spore surrogate inoculated into soil samples. The study was conducted in two phases, using loam, clay and sand-based soils, as well as biological indicators and spore-inoculated stainless-steel coupons. Initial experiments were performed in an environmental test chamber with temperatures controlled between 80 and 110 °C, with and without added humidity, and with contact times ranging from 4 h to 7 weeks. Tests were then scaled up to assess the thermal inactivation of spores in small soil columns, in which a heating plate set to 141 °C was applied to the soil surface. These column tests were conducted to assess time requirements to inactivate spores as a function of soil depth and soil type. Results from the initial phase of testing showed that increasing the temperature and relative humidity reduced the time requirements to achieve samples in which no surrogate spores were detected. For the test at 80 °C with no added humidity, 49 days were required to achieve soil samples with no spores detected in clay and loam. At 110 °C, 24 h were required to achieve samples in which no spores were detected. In the column tests, no spores were detected at the 2.5 cm depth at four days and at the 5.1 cm depth at 21 days, for two of the three soils. The experiments described in the study demonstrate the feasibility of using dry thermal techniques to decontaminate soils that have been surficially contaminated with B. anthracis spores.
在大都市地区发生大规模、气溶胶形式的炭疽杆菌孢子释放事件时，土壤和其他室外材料可能会受到生物剂的污染。本研究旨在评估使用干热处理方法原位修复土壤的效果，该方法用于使接种到土壤样本中的炭疽杆菌孢子替代物失活。该研究分两个阶段进行，使用壤土、粘土和沙质土壤，以及生物指示剂和接种孢子的不锈钢试片。初始实验在环境测试室中进行，温度控制在 80 至 110°C 之间，有或没有额外的湿度，接触时间从 4 小时到 7 周不等。然后进行了扩大规模的测试，以评估小土壤柱中孢子的热失活动力学，其中将加热板设定在 141°C 以加热土壤表面。这些柱测试用于评估灭活孢子所需的时间与土壤深度和土壤类型的关系。测试的初始阶段结果表明，增加温度和相对湿度可以减少达到无替代孢子检测样本所需的时间。在 80°C 且无额外湿度的情况下，在粘土和壤土中需要 49 天才能达到未检测到孢子的样本。在 110°C 下，需要 24 小时才能达到未检测到孢子的样本。在柱测试中，对于三种土壤中的两种，在四天时在 2.5 厘米深度处和在 21 天时在 5.1 厘米深度处均未检测到孢子。本研究中描述的实验证明了使用干热技术对表面受到炭疽杆菌孢子污染的土壤进行去污的可行性。
