St. Petersburg Coastal and Marine Science Center, U.S. Geological Survey, St. Petersburg, Florida, USA.
BCS Laboratories, Inc., Gainesville, Florida, USA.
J Appl Microbiol. 2022 Mar;132(3):2464-2474. doi: 10.1111/jam.15349. Epub 2021 Nov 19.
The study of microbial inactivation rates in aquifer systems has most often been determined in aerobic and oxidized systems. This study examined the inactivation (i.e. loss of infectivity) of MS2, poliovirus type 1 (PV1) and Cryptosporidium parvum in an anaerobic and reduced groundwater system that has been identified as storage zones for aquifer storage and recovery (ASR) facilities.
Anaerobic and reduced (ORP < 250 mV) groundwater from an artesian well was diverted to an above-ground, flow-through mesocosm that contained diffusion chambers filled with MS2, PV1 or Cryptosporidium parvum. The respective infectivity assays were performed on microorganisms recovered from the diffusion chambers during 30- to 58-day experiments. The net reduction in infectivity was 5.73 log over 30 days for MS2, 5.00 log over 58 days for PV1 and 4.07 log over 37 days for C. parvum. The best fit inactivation model for PV1 was the log-linear model and the Weibull model for MS2 and C. parvum, with respective inactivation rates (95% confidence interval) of 0.19 (0.17-0.21) log day , 0.31 (0.19-0.89) log day and 0.20 (0.14-0.37) log day .
The groundwater geochemical conditions in this aquifer enhanced the inactivation of MS2, PV1, and C. parvum at rates approximately 2.0-5.3-fold, 1.2-17.0-fold, and 4.5-5.6-fold greater, respectively, than those from published studies that used diffusion chambers in aerobic-to-anoxic groundwater systems, with positive redox potentials.
Geochemical conditions like those in the aquifer zone in this study can naturally and significantly reduce concentrations of microbial indicators and pathogens of human health concern in injected surface water. Appropriate storage times for injected surface water could complement above-ground engineered processes for microorganism removal and inactivation (e.g. filtration, disinfection) by naturally increasing overall microorganism log-inactivation rates of ASR facilities.
在含水层系统中对微生物失活率的研究通常是在有氧和氧化条件下进行的。本研究检测了在已确定为含水层储存和恢复（ASR）设施的储存区的厌氧和还原地下水系统中，MS2、脊髓灰质炎病毒 1 型（PV1）和微小隐孢子虫的失活（即感染性丧失）。
从自流井中引出厌氧和还原（ORP <250 mV）地下水，输送到一个地上的、流动的中观系统，该系统包含充满 MS2、PV1 或微小隐孢子虫的扩散室。在 30 至 58 天的实验过程中，对从扩散室中回收的微生物进行了相应的感染性检测。在 30 天内，MS2 的净感染性减少了 5.73 个对数，在 58 天内，PV1 的净感染性减少了 5.00 个对数，在 37 天内，微小隐孢子虫的净感染性减少了 4.07 个对数。PV1 的最佳拟合失活模型是对数线性模型，MS2 和微小隐孢子虫的 Weibull 模型，相应的失活率（95%置信区间）分别为 0.19（0.17-0.21）对数天、0.31（0.19-0.89）对数天和 0.20（0.14-0.37）对数天。
该含水层中的地下水地球化学条件增强了 MS2、PV1 和微小隐孢子虫的失活速度，分别约为在有氧-缺氧地下水系统中使用扩散室进行的、具有正氧化还原电位的已发表研究中的失活速度的 2.0-5.3 倍、1.2-17.0 倍和 4.5-5.6 倍。
本研究中的含水层区等地球化学条件可以自然而显著地降低注入地表水对人类健康关注的微生物指标和病原体的浓度。对于注入地表水，适当的储存时间可以通过自然增加 ASR 设施的整体微生物对数失活率来补充地上工程处理（例如过滤、消毒），从而去除和失活微生物。
