Tag Archives: sewer

How your sewage reflects how wealthy you are

There’s a lot you can learn from a person’s sewage sludge. In the past, researchers have employed wastewater epidemiology to study trends in drug consumption based on a community’s urine and poop that drains in the sewer. One such study, for instance, found that London has the highest concentration of cocaine in its sewage out of 50 large European cities. Now, a new study used similar methods to gauge the socioeconomic status of different urban communities.

Credit Pixabay.

Researchers in Australia analyzed samples from 22 water treatment plants in six of the country’s states in 2016. The chemicals they found were correlated with 40 different socioeconomic factors for each area, like education, rent price, etc.

Inverse reports that the researchers eventually learned that the wastewater from wealthier communities (where rent was over $470/week) showed higher levels of vitamins, citrus, and fiber, while poorer communities showed higher levels of prescription pain relievers and antidepressant medications.

Some of the prescription drugs that were more present in poorer communities included tramadol, desvenlafaxine, mirtazapine, pregabalin, atenolol. Meanwhile, sewage from wealthier households contained higher levels of proline betaine, a component of citrus flesh, as well as enterodiol and enterolactone, which are plant by-products. These signatures suggest that these households consume more fresh fruits and vegetables than lower-income communities.

The sewage of high-income households also had higher levels of vitamins B3, E, and B6 than lower-income communities.

“Our study shows that chemicals in wastewater reflect the social, demographic, and economic properties of the respective populations and highlights the potential value of wastewater in studying the sociodemographic determinants of population health,” the authors wrote in the journal Proceedings of the National Academy of Sciences.

Waste-water epidemiology is still in its infancy, but studies such as these show just how powerful this method can be to tease out all sorts of trends — so powerful that some have criticized it for infringing on people’s privacy, not unlike mass surveillance.

Other scientists are looking at the untapped potential of sewage in different ways. One group has found a cost-effective and environmentally-friendly method that can produce energy from sewage using purple bacteria. Sewer sludge may also be a literally golden opportunity. One study estimated that a city with 1 million inhabitats has as much as $13 million worth of valuable metals, including gold and silver, in its sewage sludge.

glow in the dark tampon

How glowing tampons help detect sewer leaks in your freshwater drain

Ironically enough, one male researcher from England used tampons to detect grey water contamination, or laundry system run off, that might be present in waterways. The tampons absorbed key signature chemicals that glow in the dark, making them easy to use and cheap. Moreover, it’s more reliable than consecrated and expensive methods.

Typically, each town or city has two separate sewage system. There’s one for all the waste you flush down the drain, toilet, washing machine or dishwasher, and another for rainwater that gets collected from places like  roofs, paved roads, parking lots etc. This latter kind of sewer, called a storm sewer, is important to keep clean and clear of the sanitary sewer since it’s directly drained into streams or rivers. Sometimes the two mix, however, for various reasons. Someone might have had the bright idea to make his own home plumbing and make a mess of it. Some might intentionally contaminate the storm water.

Whatever’s the case, it’s important to locate waste in waterways as soon as possible to minimize damage. Generally, environmental agencies around the world have a couple of techniques at their disposal. These are cumbersome however, to say the least. For instance, spectrometers are widely used to analyze for contaminants, but these are expensive and require highly trained personnel to use. A newer grey water detection method involves inserting fibre optic cables but these cost 13USD per meter.

Inspired by the Environmental Protection Agency in the US who used cotton pads to monitor pollution, two Yorkshire researchers decided to test the method locally using a much more handy and readily available solution: tampons. But since when are tampons fitted with spectrometers? This requires a bit of background. Ever wonder how detergents make your clothes “whither than white” and get rid of yellow stains? Well, it all involves a clever trick; hint: the yellow doesn’t really go away.  To make clothes appear whiter, detergent manufacturers put an additive called an ‘optical brightener‘ that absorbs into the fabric and remains absorbed after the laundry is finished. There are many such molecules that act like OBs (read optical brighter, not the tampon brand…), but they all seem to do the same thing – they fluoresce. When exposed to UV light, the chemicals emit blue light that helps cancel out the yellow tinge and tricks the eye into thinking the clothes are more white than they really are. Clever indeed, but oh so tricky.

Anyway, the OBs can be used as indicators for gray water pollution. If these are found in a storm sewer, then it means water from washing machines is leaking through somewhere. Once you detect the leak, it’s all a matter of tracing the plumbing to the source.  Professor David Lerner, a professor of environmental engineering at the University of Sheffield and colleagues placed tampons, tied to bamboo poles, in 16 surface water sewers and left them in place for three days. They then took the samples and put them under a black light. Contaminated samples glow bright in the dark because of the OBs. They found that even in small concentrations, the contaminated tampons glowed.

“You do get people looking at you strangely, but the tampon is not that obvious,” said Professor David Lerner, a professor of environmental engineering at the University of Sheffield.

“It’s cheap, it’s easy and it does the detective work,” he added.

The method works so well that the biggest problem the researchers faced were well-intentioned neighbors who misidentified the tampons for garbage and threw them in the bin. Because anyone can use a tampon, the researchers propose a sort of citizen science project where community members are invited to sample their local sewers and test for results themselves. If done right, in conjunction with an online app for instance, a nice networked map of storm water mishaps could be made – all at the fraction it currently costs to make.

“More than a million homes have their waste water incorrectly connected into the surface water network, which means their sewage is being discharged into a river, rather than going to a treatment plant.

“It’s very difficult to detect where this is happening, as the discharge is intermittent, can’t always be seen with the naked eye and existing tests are complex and expensive.

“The main difficulty with detecting sewage pollution by searching for optical brighteners is finding cotton that does not already contain these chemicals. That’s why tampons, being explicitly untreated, provide such a neat solution. Our new method may be unconventional – but it’s cheap and it works.”

Of course, more investigations are required to determine whether the method is reliable as it sounds. The results published in the Water and Environment Journal definitely promising though.