Incorporation of black soldier fly larvae (BSFL) in fecal sludge management shows promise as a resource recovery strategy. BSFL efficiently convert organic waste into valuable lipids and protein, which can be further processed into commercial products. Ensuring the microbial safety of waste-derived products is critical to the success of resource-oriented sanitation and requires the development of effective sludge treatment. This study evaluates the microbial treatment efficacy of the viscous heater (VH) for fecal sludge management and potential application of the VH in BSFL production. The VH is a heat-based fecal sludge treatment technology that harnesses the viscosity of fecal sludge to achieve pasteurization temperatures. Inactivation of in situ Escherichia coli, total coliform, heterotrophic bacteria, and somatic coliphage was evaluated in fecal sludge that was treated for 1–6 min at VH temperature set-points of 60°C and 80°C. The VH inactivated in situ E. coli, total coliform, and somatic coliphage in fecal sludge to below the limits of detection (1- to 5-log₁₀ inactivation) when operated at the 80°C set-point with a 1-min residence time. Both temperature set-points achieved 1- to 3-log₁₀ inactivation of in situ heterotrophic bacteria. The VH was also evaluated as a potential pretreatment step in BSFL production. BSFL grown in untreated and VH-treated fecal sludge demonstrated similar results, indicating little impact on the BSFL growth potential by VH-treatment. However, BSFL bioconversion rates were low for both substrates (1.6% ± 0.6% for untreated sludge and 2.1 ± 0.4 VH-treated fecal sludge).

中文翻译：

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评估热处理粪便污泥在南非黑士兵蝇幼虫生产中的微生物安全性

在粪便污泥管理中加入黑士兵蝇幼虫（BSFL）显示出有望作为一种资源回收策略。BSFL有效地将有机废物转化为有价值的脂质和蛋白质，然后可以进一步加工成商业产品。确保废物衍生产品的微生物安全性对于成功实现资源导向型卫生至关重要，并且需要开发有效的污泥处理方法。这项研究评估了粘性加热器（VH）在粪便污泥管理方面的微生物处理功效以及VH在BSFL生产中的潜在应用。VH是一种基于热的粪便污泥处理技术，可利用粪便污泥的粘度达到巴氏灭菌温度。原位大肠杆菌的灭活在粪便污泥中评估总大肠菌群，异养细菌和体细胞噬菌体，这些粪便污泥在60°C和80°C的VH温度设定点处理了1-6分钟。当在80°C设定值下以1分钟的停留时间运行时，VH使粪便污泥中的原位大肠杆菌，总大肠菌群和体细胞噬菌体灭活至检测限以下（1-5灭₁₀灭活）时间。两个温度设定点均实现了原位失活（1-3 log _10）异养细菌。VH还被评估为BSFL生产中潜在的预处理步骤。在未经处理和经VH处理的粪便污泥中生长的BSFL表现出相似的结果，表明通过VH处理对BSFL的生长潜力几乎没有影响。但是，两种底物的BSFL生物转化率均较低（未经处理的污泥为1.6％±0.6％，经VH处理的粪便污泥为2.1±0.4）。