Qiacube connect system

The preanalytical methods used in this study were summarized in Table S1.
Method 1 was the benchmark for PEG-precipitation method. Specifically, the wastewater samples were briefly centrifuged at 2000 × g for 2 min to remove large particles. After separating the supernatant (40 mL), 4 g PEG (10%, w/v) and 0.8 g NaCl (2%, w/v) were added for flocculation. The mixture was shaken in an orbital shaker at 25 ℃ for 2 h with the speed of 180 rpm for incubation. After that, a second centrifugation was performed at 4750 × g for 30 min to obtain approximately 1∼2 mL of precipitate for transferring into a new 2 mL microcentrifuge tube. The third centrifugation at 20,000 × g was conducted for 2 min, and the supernatant was discarded carefully without disturbing the pellet at the bottom using a pipette. Next, the pellet was used for RNA extraction using the QIAamp Viral RNA Kit (Qiagen, referred to as “QIAamp Viral” in the following description, Catalog number: 52904) in the QIAcube Connect System (Qiagen). The elution volume was 50 μL.