Modern technology has made it easy to minimize how much we think about poop. Most of the time, our poop literally flushes out of sight, out of mind, and far away from our noses. But our poop can actually have an exciting life after it leaves us.
Poop is rich with energy, so much so that it can be used as a source of electrical power. For a program I hosted about the fascinating world of feces, we visited a farm in Ontario where a third-generation farmer, who originally trained as an engineer, set up a biogas operation on his family’s dairy farm. Every day, waste from the cows – along with human waste from the farm’s toilets and other organic waste – is pumped into an anaerobic digester. The digester is filled with microbes that feed on the poop and produce methane and other gases. These power a generator, which in turn produces enough electricity to power five farms. The resulting solid waste is a fluffy material called digestate, which is rich in compounds like ammonium and phosphorus, and can be used as fertilizer.
We also visited another engineer looking to put poop to a surprising new use. In Washington State, Janicki Bioenergy’s Omni Processor machine is able to take raw sewage and turn it into fresh, clean, and safe drinking water. By boiling the sewage and turning the resulting steam back into liquid water, the machine removes impurities. The solid waste that’s left is burned as fuel for the machine, making the entire system a self-contained, two-in-one sewage treatment and drinking water plant – an incredible technology with obvious applications in settings where both sewage and access to water are critical public health issues.
Poop can do much more than provide us with energy and water. It can also provide insight into not just our own microbiome, but our collective microbiome. In my work in public health, my colleagues and I have long thought about how we could use DNA sequencing on the sewage produced by a city’s inhabitants to look for trends in diseases and perhaps spot outbreaks earlier than with our usual methods.
The Underworlds team at the Sensible City Lab at MIT is doing just that, and they didn’t just stick to diseases. They also look at what the waste in our sewers can tell us about what a neighbourhood is eating, which drugs – over-the-counter, prescription, or otherwise – its residents are taking, and even how much stress hormone they’re producing. Just as uBiome helps you understand your own health, projects like Underworlds help researchers like me understand an entire population’s health.
One of the most surprising things I discovered in talking to the Underworlds team was how this technology is being used to track opioid use in real-time. North America is currently dealing with an epidemic of opioid overdoses, and this sort of information can help to direct emergency response and public health efforts to the neighbourhoods where they’re needed the most. Thanks to this amazing, targeted technology, perhaps my wish for a tool to track trends in diseases – and even manage an epidemic by getting ahead of a pathogen before the situation gets out of control – may come true.
Jennifer Gardy PhD, is an assistant professor at The University of British Columbia, where she is the Canada Research Chair in Public Health Genomics, and a Senior Scientist at the BC Center for Disease Control. She regularly hosts episodes of CBC Television’s long running weekly science documentary, The Nature of Things. Her hour long program, Myth or Science: the Power of Poo, premiered in April and was nominated for several Jackson Hole Science Media Awards.