Abstract Pathogen inactivation due to temperature exposure was studied in full-scale covered aerated static piles (CASP) treating municipal biosolids. The objectives of the study were to assess the impact of the temperature contact time on pathogen inactivation and to analyze whether the gradual increase in temperature, as occurs in compost piles, trigger a viable-but-non-culturable (VBNC) state. Twenty-two temperature probes imitating random particle behavior were seeded with Escherichia coli and Salmonella and introduced into the CASP. It was found that 92% of the compost pile experienced temperatures ≥55 °C for at least three consecutive days during the first stage of composting (36 days). This number rose to 93% after the pile was turned and composted for a further 20 days. At the end of active composting, the fecal coliforms level in the compost matrix, determined by culturing methods, was <103 MPN·g−1 total solids, while Salmonella was below its detection limit of <3 MPN·4 g−1 total solids. The molecular method indicated that there were live cells which had apparently entered a VBNC state. Nonetheless, it was concluded further study is needed to assess overall risk, since other factors such as pH, toxic compounds, and microbial competition and antagonism were excluded from this particular study. In future, as the techniques presented herein are refined, they may be useful for validating different types of composting technologies for sanitation effectiveness.

中文翻译：

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生物固体堆肥设施的卫生保证：评估温度-接触时间标准的效率

摘要 在处理城市生物固体的全尺寸覆盖加气静力桩 (CASP) 中研究了由于温度暴露引起的病原体灭活。该研究的目的是评估温度接触时间对病原体灭活的影响，并分析温度的逐渐升高（如堆肥）是否会触发可行但不可培养 (VBNC) 状态。将 22 个模拟随机粒子行为的温度探针接种大肠杆菌和沙门氏菌，并引入 CASP。结果表明，在堆肥的第一阶段（36 天）中，92% 的堆肥堆至少连续三天经历了≥55°C 的温度。在堆肥堆再堆肥 20 天后，这个数字上升到 93%。在主动堆肥结束时，通过培养方法测定的堆肥基质中的粪便大肠菌水平<103 MPN·g-1 总固体，而沙门氏菌低于其<3 MPN·4 g-1 总固体的检测限。分子方法表明存在明显进入VBNC状态的活细胞。尽管如此，由于其他因素如 pH 值、有毒化合物以及微生物竞争和拮抗作用被排除在这项特定研究之外，因此得出的结论是需要进一步研究来评估总体风险。将来，随着这里介绍的技术得到改进，它们可能有助于验证不同类型的堆肥技术的卫生有效性。分子方法表明存在明显进入VBNC状态的活细胞。尽管如此，由于其他因素如 pH 值、有毒化合物以及微生物竞争和拮抗作用被排除在这项特定研究之外，因此得出的结论是需要进一步研究来评估总体风险。将来，随着这里介绍的技术得到改进，它们可能有助于验证不同类型的堆肥技术的卫生有效性。分子方法表明存在明显进入VBNC状态的活细胞。尽管如此，由于其他因素如 pH 值、有毒化合物以及微生物竞争和拮抗作用被排除在这项特定研究之外，因此得出的结论是需要进一步研究来评估总体风险。将来，随着这里介绍的技术得到改进，它们可能有助于验证不同类型的堆肥技术的卫生有效性。