Bacteria in Wastewater Could Generate Power and Fertilizer - If Engineers Can Scale It Up

Every year, humanity flushes away 359 billion cubic meters of wastewater. Contained within that flow are organic compounds carrying chemical energy, nitrogen and phosphorus that crops need, and water that billions of people lack access to. The waste treatment infrastructure built to handle this volume consumes enormous amounts of electricity. Researchers have long pursued the question of whether the organic matter in wastewater could generate energy rather than consume it.

Microbial electrochemical technologies, or METs, are the most developed answer. In a new lead article published in Frontiers in Science, four researchers - Prof. Uwe Schroeder, Prof. Falk Harnisch, Dr. Elizabeth Heidrich, and Dr. Deepak Pant - survey what METs have achieved, where they have been deployed, and what obstacles must be cleared before they can operate at scale.

How Bacteria Do the Work

The core principle is electrochemically active bacteria that naturally transfer electrons outside their cells during metabolism. In a microbial fuel cell, those electrons flow through an external circuit, generating electrical current. Variations on the design allow the same microbial activity to produce hydrogen gas, extract nutrients like nitrogen and phosphorus for fertilizer use, or drive electrolysis that purifies water.

METs are not a single technology but a family of related systems, each optimized for a different output. A treatment plant might use one configuration to offset its own energy costs while another recovers nutrients for agricultural use.

From Festival Grounds to Sub-Saharan Farms

Pilot installations have operated in circumstances as varied as the UK's Glastonbury Festival - where waste is abundant and time-limited - and field trials in Uganda, Kenya, and South Africa, where reliable grid electricity is scarce and agricultural nutrient access constrains food security. These pilots test performance under real conditions: variable inputs, untrained operators, inconsistent temperatures, and remote maintenance requirements.

The Scaling Problem

The central challenge is economic. METs can produce electricity, fuels, and fertilizers from waste streams, but so far at costs that are difficult to justify against conventional alternatives. Scaling up microbial fuel cells tends to reduce power density in ways engineers have not yet fully resolved. Regulatory pathways for using MET outputs vary enormously by country and often lack frameworks for these novel production routes. Material costs for electrodes and membranes remain high.

On 7 May 2026, from 16:00 to 17:30 CEST, the four authors will present findings and discuss the path from pilot projects to deployment in a Frontiers in Science Deep Dive session: "Waste to value: microbial electrochemical technologies for sustainable water, material, and energy cycles." The research connects to UN SDGs on clean water (SDG 6), affordable clean energy (SDG 7), and sustainable agriculture (SDG 2). Whether that potential translates into deployed infrastructure depends on the engineering, economic, and regulatory barriers the authors identify.