Wastewater contains untapped resources that, if reclaimed, could power agriculture, global sanitation and its own treatment to help the world meet UN SDG goals, according to a review published in Frontiers in Science.
Every year, the world produce about 359 billion cubic meters of wastewater. Half of this is discarded, with the rest expensively and inefficiently treated for reuse. Emerging microbially powered tech could reclaim these resources from the drain, save money, and reduce environmental harms.
The review demonstrates how microbial electrochemical technologies (METs) as a more efficient way to treat wastewater, using microbes known as electrogenic bacteria. These bacteria transfer electrons to their surroundings, creating an electrical current when they are connected to electrodes in a fuel cell. In laboratory settings, they can convert up to 35% of wastewater’s chemical energy into electricity. The authors say, in principle, the power generated could even help run the water sector itself, which currently accounts for around 4% of global energy use.
The microbes can also help to extract nutrients from wastewater, cleaning it for further use. These critical fertilizer ingredients are typically produced in energy-intensive or unsustainable processes. Removing these compounds from wastewater would have the double benefit of reclaiming valuable resources and reducing pollution.
Despite their potential, these technologies face challenges to widespread adoption. Tight regulatory frameworks are often not suited for circular economies that repurpose waste. For example, in many countries, urine-derived fertilizer cannot be used for growing food or animal feed. There are also engineering obstacles in ensuring that the MET materials maintain high performance when running continuously.
In pilot trials, METs have proved efficient. For example, a urine-powered MET called Pee Power was trialed at the Glastonbury Festival in 2015, one of the world’s largest outdoor music festivals. It has since proved successful in longer-term field trials in Uganda, Kenya, and South Africa. The system converts wastewater to electricity, powering lighting around the toilets to reduce safety risks in areas without an electricity supply.
“The journey of METs over the last 20 years has moved us from understanding the 'microbial black box' to building modular, scalable systems capable of real-world impact,” said Deepak Pant from the Flemish Institute for Technological Research (Belgium). “We are now at a stage where these technologies are technically feasible. The next step is ensuring they are economically competitive with traditional treatment methods. By strategically integrating METs into our existing infrastructure, we can transform global wastewater management into a self-sustaining engine for resource recovery.”
Data from Frontiers