Table 1.
Summary of detection and quantification of SARS-CoV-2 in wastewater and sludge in WWTPs.
| Location | Period of examination | Sample condition (type, volume, temperature) | Method of RNA extraction, detection and quantification | RNA concentration of influent (copies/L or samples positive) | Wastewater treatment technologies | RNA concentration of effluent (copies/L or samples positive) | Reference |
|---|---|---|---|---|---|---|---|
| Spain, Region of Murcia | March 12 to April 14, 2020 | Municipal WW;Grab sampling 200 mL; 4 °C | NucleoSpin RNA virus Kit; TaqMan real-time RT-PCR; gc | 5.1 ± 0.3, 5.5 ± 0.2, and 5.5 ± 0.3 log10 gc/L of N1, N2 and N3 primer/probe mixes | CAS, Coagulation, Flocculation, SF, Disinfection, UV, NaClO | Secondary effluent: 5.4 log10 gc/L of N2 primer/probe mixes; Tertiary effluent: No detection | [33] |
| India, Ahmedabad | May 8 and 27, 2020 | Hospital treating WW; 4 °C | NucleoSpin® RNA virus Kit; TaqPathTM Covid-19 RT-PCR Kit; Ct value | 8 May: 100% of positive rate (5.6 × 10(copies/L)); 27 May:100% of positive rate (3.5 × 102(copies/L)) | UASB | 8 May: 0% of positive rate 27 May: 0% of positive rate | [41] |
| Itlay, Milano and Monza e Brianza | April 14 and 22, 2020 | Municipal WW; Grab sampling Separate stainless steel buckets | QIAMP Viral RNA mini Kit; 2019-nCoV real-time RT-PCR kit panel; Ct values | April 14: 75% of positive rate(3/4); April 22: 25% of positive rate(1/4) | CAS + peracetic acid or high intensity UV | No detection | [35] |
| India, Jaipur | May 4 to June 14,2020 | Municipal WW and Hospital WW; Sterile bottles | Allplex™ 2019- nCoV Assay Kit; TaqPath™ COVID-19 Combo Kit; Ct values | Positive | MBBR/SBR + Cl/UV | Negative | [36] |
| Chile, Santiago | May 20 to June 16,2020 | Sewage; 24 h composite sample; Sterile propylene bottles | QIAamp® Viral RNA Mini Kit; TaqMan 2019-nCoV Assay Kit v1; Ct values | 20 May: 354–628(copies/L); 16 June: 2304–4805(copies/L) | n.a. | 20 May: 10–20(copies/L); 16 June: 0–167(copies/L) | [44] |
| France, Paris | March 5 to April7, 2020 | Municipal WW; 11 mL | PowerFecal Pro kit on a QIAsymphony extractor,QIAGEN; PCR Inhibitor removal resin; Ct values | 100% of positive rate (over 106(copies/L)) | n.a. | 75% of positive rate (6/8); (near 105(copies/L)) | [25] |
| China, Wuchang | February 5 to March 10, 2020 | Municipal WW; Grab sampling; 2.0 L; 4 °C | EZ1 virus Mini Kit; AgPath-ID™ One-Step RT-PCR Kit; Ct values | Non-detected (After primary disinfection tank before septic tank) | Preliminary disinfection tank + Septic tank | (7.5 ± 2.8) × 103 to (14.7 ± 2.2) × 103 copies/L in the effluents of septic tanks | [71] |
| Spain, Ourense | April 6 to April 21,2020 | Municipal WW; 250 mL; 24 h composite samples; 4 °C | STARMag 96 × 4 Universal Cartridge Kit; RT-qPCR Allplex system™ 2019-nCoV; Ct values | 100% of positive rate (5/5); | Grit and sand separator, primary settler, SBR, Microfiltration | Secondary effluent: 25% of positive rate (1/4); Finally effluent: No detection | [34] |
| Japan, Kofu | March 17 and May 7, 2020 | Municipal WW; Grab sampling; 1.0 L; | RNeasy PowerWater Kit; High-Capacity cDNA Reverse Transcription Kit; Ct values | 4.0 × 103 to 8.2 × 104 copies/L | CAS: primary sedimentation, aeration, final sedimentation, chlorination | Secondary effluent: 1.4 × 102 to 2.5 × 103 copies/L | [39] |
| USA, Louisiana | January to April 2020 | Municipal WW; 24 h composite samples; −80 °C | ZR Viral RNA Kit; High Capacity cDNA Reverse Transcription Kit; Ct values | 13% of positive rate(2/15) | n.a. | None of the secondary treated and final effluent samples | [40] |
| Spain, Ourense | April 6 to April 21, 2020 | Sludge; 250 mL; 4 °C | STARMag 96 × 4 Universal Cartridge Kit; RT-qPCR Allplex system™ 2019-nCoV; Ct values | 41% of positive rate(14/34) in primary sludge, biologic sludge, and thickened sludge | Gravity thickening and centrifuge, thermal hydrolysis, anaerobic digestion | 0% of positive rate(0/5) in digested sludge | [34] |
| USA, New Haven | March 19 to May 1, 2020 | Sludge; −80 °C | RNeasey PowerSoil Total RNA Kit; Bio-Rad iTaq Universal Probes One-Step Kit; Ct values | 100% of positive rate; 1.7 × 103 to 4.6 × 105 copies/mL | Settler | n.a. | [27] |
| Turkey, Istanbul | May 7, 2020 | Sludge; Grab sample | Roche MagNA pure LC total nucleic acid isolation Kit; Ct values | 100% of positive rate in primary sludge, 1.25 × 104 to 2.33 × 104 copies/L | CAS | 100% of positive rate in waste activated sludge, 1.17 × 104 to 4.02 × 104 copies/L | [26] |
Note: n.a.: not available.
CAS: conventional activated sludge; SF: Sand filtration; UASB: upflow anaerobic sludge blanket reactor; MBBR: moving bed biofilm reactor; SBR: sequencing batch reactor.