Wastewater treatment has been a focus of environmental protection groups for years since the plants are not equipped to treat wastewater containing products of modern life, including toxic chemicals, drugs and cosmetics. It wasn’t until 1972 when the Clean Water Act1 was passed that pollution discharged into U.S. waterways began to be regulated.

The Act is supposed to ensure clean water, but after nearly five decades the waterways are in serious trouble. Sources of pollution range from agricultural runoff and industrial release to worn out pipes and firefighting foam.2

Even the chemicals used during treatment can pollute the waterways. Fish and other wildlife suffer the ramifications of out-of-control water pollution.3,4 Chemical pollution has also reached tap water; in many places tap water has tested positive for heavy metals and disinfection byproducts.5

Sewage sludge masses pulled from raw wastewater can be “treated” and are then called biosolids,6 which are allowed to be sprayed across farm fields on vegetables that end up on your plate. After decades of poor control, the sludge may offer researchers more information about the spread of viruses, including SARS-CoV-2.

Sewage Sludge Offers Epidemiological Insight

The virus that triggers COVID-19 is spread through respiratory droplets. However, researchers have found that the virus can also be detected in human waste. In other words, what’s flushed down the toilet may also contain SARS-CoV-2. In the race to test, some scientists have begun taking samples from sewage sludge.

In a recently published paper by a team from Yale University,7 data were shared after evaluation of sewage sludge from an abatement facility in New Haven, Connecticut. The facility manages waste from 200,000 residents.

Samples were collected from March 19, 2020, to May 1, 2020, and compared to local hospital admission data as well as COVID-19 test results in the community. The researchers wrote:8

“We report a time course of SARS-CoV-2 RNA concentrations in primary sewage sludge during the Spring COVID-19 outbreak in a northeastern U.S. metropolitan area. SARS-CoV-2 RNA was detected in all environmental samples and, when adjusted for the time lag, the virus RNA concentrations were highly correlated with the COVID-19 epidemiological curve (R2=0.99) and local hospital admissions (R2=0.99).

SARS-CoV-2 RNA concentrations were a seven-day leading indicator ahead of compiled COVID-19 testing data and led local hospital admissions data by three days.”

The data showed that testing of sewage sludge could predict, with reasonable accuracy, when there would be a rise in the number who have COVID-19 within the following seven days, and that would lead to a higher number of hospital admissions over the next three days.

One graph from the study was shared on social media.9 It illustrated the lag time between sewage sludge testing and the rise in community-confirmed tests of the virus.

Results from the study were similar to those from one performed by researchers in Massachusetts, published in April. The biotech company Biobot Analytics10 evaluated wastewater from a major urban treatment facility, which they did not identify. Data were collected from March 18, 2020, to March 25, 2020. In a preprint release of the study abstract, the researchers wrote:

“Viral titers observed were significantly higher than expected based on clinically confirmed cases in Massachusetts as of March 25.” The researchers do not know why there is a discrepancy, though.

Differences Between Sewage Sludge and Raw Wastewater

The material that researchers were testing was not pulled directly from raw wastewater. Raw sewage goes through multiple stages of treatment before the solid waste becomes sewage sludge. When wastewater first enters a treatment plant it often contains additional items including wood, rocks and dead animals from time to time.11

This material is filtered to remove large impediments, which are then sent to a landfill. Most of the wastewater system uses gravity, so once the water enters the plant it needs to be pumped into aeration tanks. This is one of the first steps during which wastewater is exposed to air, causing some of the dissolved gases to be released.

Raw waste runs through a series of concrete tanks during which oxygen is bubbled through the water to suspend organic material while other smaller parts are settled out, including things like coffee grounds and sand. In the next tank, the organic part of sewage from your home — the sludge — settles and water is then pumped out of the tanks.

In the process of the sludge settling to the bottom, smaller, lighter material floats to the surface and gets skimmed off. The resulting thick material at the bottom is called sewage sludge. This is the material researchers tested on consecutive days to determine the density of viral material.

To create biosolids,12 the sludge may be treated with lime to eliminate odors. Then, it is processed to control pathogens and other organisms known to trigger infection. Unfortunately, as has been demonstrated in the past, this system is not consistently successful.13 The practice of using biosolids began when it became clear that dumping sludge directly into the waterways was damaging the environment.

The EPA describes the use of biosolids as completing a “natural cycle.”14 If human waste were the only product being returned to the soil on farmlands, it might be the final step in a system of regenerative agriculture. However, industrial waste is also included because the treatment process concentrates toxins, and the waste is then spread as fertilizer.

In an investigation by the Office of Inspector General,15 the agency identified 352 chemical pollutants coming out of wastewater treatment plants and treated biosolids; these included pesticides, pharmaceuticals and solvents. Of these, 61 are listed as hazardous materials with known human health effects.

Sewage Used to Track Other Public health Epidemics

For decades, microbiologists have been studying sewage to evaluate and analyze pathogens. Using the sampling for public health surveillance, however, is relatively new. For example, researchers are using the sludge to detect the polio virus since it can also be shed in human waste.16

Another public health concern that sent researchers to the sewers is the fight against opioid misuse. Biobot Analytics was involved in a competition to measure the concentration of opioids and sewage in order to offer an estimate of local drug use.17

The testing is generalized and doesn’t identify specific homes or individuals, but it does give governments a strong indication of where drug use may be at its highest. The goal was for agencies to be supplied with information that would allow them to proactively address the issue and potentially stem the rise in overdoses and deaths. The mayor of Fort Worth, Texas, who was on the panel of judges, said:18

“It’s a very creative way to use a source of untapped data. Who thinks about measuring wastewater? This is another way to use city assets that we don’t think about to hit a problem like opioids or public health in general.”

The city of Tempe, Arizona, and Arizona State University have partnered up to study the city’s wastewater and use it as a source of public health information.19 Specifically, the city is looking to measure narcotic consumption as they seek a way to reduce the challenges associated with addiction.

Samples are collected over a 24-hour period at the treatment plant and pulled from the sewer line; these can provide a single snapshot of a specific place and time. Researchers have found natural fluctuations from day-to-day information that produce valuable insights on long-term trends.

Arizona State University processes wastewater from more than 300 cities around the world. Tempe is the first to incorporate the data with other tactics to help guide the development of public health policy.

What to Watch for in Your Toilet

Your stool says a lot about your overall health, as its composition is a direct reflection of your gut microbiome. There’s a strong connection between your gut health, mental health and immune system.20

The size, shape and color of your stool give clues as to the state of your overall health and that of your intestinal tract, specifically. It’s normal for the shape and consistency of your stool to fluctuate from day to day, particularly when your diet changes.

In 1997, Dr. Ken Heaton from the University of Bristol developed a chart as a way for his patients to report the form and consistency of their stool.21 The Bristol chart is now widely used and involves a 7-point scale ranging from Type 1, indicating constipation, to Type 7, indicating diarrhea. Types 3 and 4 are considered normal and ideal, while Types 6 and 7 point to inflammation.

stool chart

The shape, color, diameter and texture of your stool are factors you can use to gauge what’s going on. If it’s not ideal, pay attention to the food you eat and how much water you’re drinking. Good options for increasing your fiber intake include organic psyllium, freshly ground organic flaxseed and fruits and vegetables.

I recommend you shoot for 25 to 50 grams of fiber for every 1,000 calories you eat each day. You can also support the health of your intestinal microbiome by adding naturally fermented foods and/or a probiotic supplement. At the same time, you should avoid sugar, health-risks.aspx”>artificial sweeteners and processed foods.

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