Sanitation Laboratory, Department of Environmental Engineering, Universidade Federal do Espírito Santo, Ave. Fernando Ferrari, 515, Goiabeiras, 29075051 Vitória, ES, Brazil.
Sanitation Laboratory, Department of Environmental Engineering, Universidade Federal do Espírito Santo, Ave. Fernando Ferrari, 515, Goiabeiras, 29075051 Vitória, ES, Brazil.
Sci Total Environ. 2023 Feb 10;859(Pt 1):160012. doi: 10.1016/j.scitotenv.2022.160012. Epub 2022 Nov 9.
This paper aims to review the main sludge concentration methods used for SARS-CoV-2 detection in sewage sludge samples, discussing the main methods and sample volume related to increased viral load. In addition, we aim to evaluate the countries associated with increased positivity rates for SARS-CoV-2 in sludge samples.
This systematic methodology was registered in PROSPERO and followed the PRISMA guidelines. The search was carried out in the SciELO, PubMed/MEDLINE, Lilacs, and Google Scholar databases in January-March 2022. Quantitative studies with conclusive results were included in this review. Concentration methods (polyethylene glycol (PEG), PEG + NaCl, gravity thickening, skimmed milk flocculation, ultrafiltration, filtration using charged filters, primary sedimentation, and anaerobic digestion), as well as detection methods (RTqPCR and reverse transcription droplet digital PCR assay) were evaluated in this review. The SPSS v23 software program was used for statistical analysis.
PEG (with or without NaCl addition) and gravity thickening were the most used sludge concentration methods to detect SARS-CoV-2. The main method associated with increased viral load (>2,02 × 10^4 copies/mL) was PEG + NaCl (p < 0.05, Mann-Whitney test). The average positivity rate for SARS-CoV-2 in sludge samples was 61 %, and a correlation was found between the sludge volume and the viral load (ro 0.559, p = 0.03, Spearman correlation).
The sludge volume may influence the SARS-CoV-2 load since the virus can adhere to solid particles in these samples. Other factors may be associated with SARS-CoV-2 load, including the methods used; especially PEG + NaCl may result in a high viral load detected in sludge, and may provide a suitable pH for SARS-CoV-2 recovery.
本文旨在综述用于污水污泥样本中 SARS-CoV-2 检测的主要污泥浓缩方法，讨论与病毒载量增加相关的主要方法和样本量。此外，我们旨在评估与污泥样本中 SARS-CoV-2 阳性率增加相关的国家。
本系统方法在 PROSPERO 中进行注册，并遵循 PRISMA 指南。2022 年 1 月至 3 月，在 SciELO、PubMed/MEDLINE、Lilacs 和 Google Scholar 数据库中进行了检索。本综述纳入了具有明确结果的定量研究。在本综述中评估了浓缩方法（聚乙二醇（PEG）、PEG+NaCl、重力浓缩、脱脂乳絮凝、超滤、带电荷的过滤器过滤、初次沉淀和厌氧消化）以及检测方法（RT-qPCR 和逆转录液滴数字 PCR 检测）。使用 SPSS v23 软件程序进行统计分析。
PEG（加或不加 NaCl）和重力浓缩是用于检测 SARS-CoV-2 的最常用的污泥浓缩方法。与病毒载量增加（>2,02×10^4 拷贝/mL）相关的主要方法是 PEG+NaCl（p<0.05，Mann-Whitney 检验）。污泥样本中 SARS-CoV-2 的平均阳性率为 61%，并且发现污泥量与病毒载量之间存在相关性（ro 0.559，p=0.03，Spearman 相关）。
病毒可以附着在这些样本中的固体颗粒上，因此污泥量可能会影响 SARS-CoV-2 的负荷。其他因素可能与 SARS-CoV-2 的负荷相关，包括使用的方法；特别是 PEG+NaCl 可能会导致污泥中检测到高病毒载量，并为 SARS-CoV-2 的恢复提供合适的 pH 值。
