Assessment of virus concentration methods for detecting SARS-CoV-2 IN wastewater.

Wastewater-based epidemiology has been described as a valuable tool for monitoring the spread of severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) in a community. However, there is no consensus on the best concentration method to allow reliable detection of SARS-CoV-2 in this matrix, considering different laboratory facilities. This study compares two viral concentration methods, ultracentrifugation (ULT) and skimmed-milk flocculation (SMF), for detecting SARS-CoV-2 in wastewater samples. The analytical sensitivity (limits of detection and quantification [LoD/LoQ]) of both methods was evaluated using a bovine respiratory syncytial virus (BRSV) as a surrogate. Three different approaches were conducted to establish LoD of each method based on the assays on the standard curve (ALoDsc), on the dilution of internal control (ALoDiC), and the processing steps (PLoD). For PLoD, ULT method had the lowest value (1.86 × 103 genome copy/microliter [GC/µL]) when compared to the SMF method (1.26 × 107 GC/µL). The LoQ determination showed a mean value of 1.55 × 105 GC/µL and 3.56 × 108 GC/µL to ULT and SMF, respectively. The detection of SARSCoV-2 in naturally contaminated wastewater revealed 100% (12/12) and 25% (3/12) of detection using ULT and SMF with quantification ranging from 5.2 to 7.2 log10 genome copy/liter (GC/L) and 5.06 to 5.46 log10 GC/L, respectively. The detection success rate of BRSV used as an internal control process was 100% (12/12) for ULT and 67% (8/12) for SMF, with an efficiency recovery rate ranging from 12 to 38% and 0.1 to 5%, respectively. Our data consolidates the importance of assessing the methods used; however, further analysis should be carried out to improve low-cost concentration methodologies, essential for use in low-income and developing countries.

Assessment of combined treatment of landfill urban solid waste leachate and sewage using Danio rerio and Daphnia similis.

The co-treatment from Morro do Céu landfill leachate with domestic sewage in the Icaraí STP was monitored with regard to the behavior of toxicity of its inflows and outflow. Leachate not exceeded 1.5% in volume in the plant. The acute ecotoxicological tests showed that, although leachate is far more harmful to D. rerio (LC50 approximately = 4) and D. similis (LC50 approximately = 5) than sewage (LC50 approximately = 62; LC50 approximately = 22), statistically the mixture of leachate with sewage did not result in a more toxic inflow (LC50 approximately = 57; LC50 approximately = 12) for treatment than raw sewage. After treatment, the outflow toxicity (LC50 approximately = 76; LC50 approximately = 16) complied with the environmental laws.