At what frequency should we be testing our wastewater to get actionable data on trends in my community?
The optimal sampling strategy for your community, whether a municipality or a building environment, depends on how you intend to use the data. We generally recommend sampling at least weekly.* If you plan to use wastewater as an early warning system, you may need to sample more often than weekly so that trends based on multiple samples can be quickly evaluated.
Why is a composite sample preferred?
The composite sample provides us with a reliable look into the health of the whole population contributing to the waste stream. If we were to test one sample taken at one instance in time (i.e. a grab sample), that sample would only capture a small subset of the overall population that contributes to the sampling catchment. A composite sample instead combines several subsamples collected at different times across a 24-hour period. Using composite samples allows us to analyze data from a wider population, while grab samples often demonstrate a less representative variability by sampling only a subset of the entire wastewater stream.
How frequently should we pump wastewater during 24-hour composite sampling?
Pumping frequency depends on population size, but in general, we recommend a pumping frequency of every 15 minutes for municipal customers for a total of 96 subsamples over a 24-hour period.
Can Biobot also test samples from effluent or sludge after the primary clarifier?
At this time, we do not test effluent water or sludge as these do not contain useful information for Biobot’s mission of leveraging wastewater for public health. Our lab instead focuses on influent wastewater, including samples collected after the grit removal and bar screen processes. Our methods are best tailored for raw influent samples––the dirtier the better!
Can people catch the virus from handling wastewater?
There is no evidence to date that anyone has become sick with COVID-19 because of exposure from wastewater. Standard practices associated with wastewater treatment plant operations should be sufficient to protect wastewater workers from SARS-CoV-2. These standard practices can include engineering and administrative controls, handwashing, specific safe work practices, and personal protective equipment normally required when handling untreated wastewater. Beyond CDC recommendations for how to protect against COVID-19, no additional COVID-19-specific protections are recommended for workers managing wastewater, including those at wastewater treatment facilities.
*Note: Sampling frequency is dependent on your customer type. Biobot Network participants collect samples on a weekly basis. CDC NWSS program participants sample twice per week.