How Bioelectrochemical Systems are Revolutionizing Wastewater Treatment
Imagine a wastewater treatment plant that not only cleans water but also generates electricity, recovers valuable metals, and produces clean hydrogen fuel. This isn't science fiction—it's the promise of bioelectrochemical systems (BES), a groundbreaking technology that harnesses the natural metabolism of bacteria to solve multiple environmental challenges simultaneously.
Recovery rate of high-purity lithium from spent lithium-ion batteries using microbial electrochemical technology 1
Projected global market for BES by 2035, growing from $1.5 billion in 2025 3
At the University of Surrey, scientists recently developed a microbial electrochemical technology that can recover 90%–95% of high-purity lithium from spent lithium-ion batteries, offering a more sustainable alternative to conventional recovery methods 1 . This innovation exemplifies the potential of BES to transform how we manage resources and waste.
As we face mounting pressures from resource scarcity and climate change, bioelectrochemical systems represent a compelling example of how we can work with nature rather than against it.
Bioelectrochemical systems operate on a fascinating principle: certain microorganisms, known as exoelectrogens, can naturally transfer electrons outside their cells during metabolic processes 6 . These "electric microbes" effectively serve as living catalysts that can convert chemical energy stored in organic matter directly into electrical energy.
Exoelectrogens oxidize organic matter at the anode
Electrons are released and travel through external circuit
Electrons combine with protons at cathode to form water or other products
In a typical BES, bacteria on the anode electrode break down organic pollutants in wastewater, releasing electrons and protons in the process. The electrons travel through an external circuit to the cathode, generating an electrical current, while the protons migrate through a membrane to the cathode chamber. At the cathode, these components combine with oxygen to form water or with other elements to create valuable products like hydrogen gas 6 .
Every bioelectrochemical system consists of several essential components:
The electrode where exoelectrogens form a biofilm and oxidize organic matter, releasing electrons. It typically consists of carbon-based materials like carbon felt, carbon mesh, or graphite brushes 6 .
The electrode that receives the electrons and facilitates reduction reactions. Depending on the system, these reactions can produce electricity, hydrogen, or other valuable chemicals 6 .
A semipermeable barrier that separates the anode and cathode chambers while allowing positive ions (cations) to pass through, maintaining the system's electrical neutrality 6 .
The "workhorses" of the system, including well-studied species like Geobacter sulfurreducens and Shewanella oneidensis, which possess unique capabilities for extracellular electron transfer 6 .
Bioelectrochemical technology encompasses several system types, each optimized for different applications:
| System Type | Primary Function | Key Applications | Products Generated |
|---|---|---|---|
| Microbial Fuel Cells (MFCs) | Electricity generation | Wastewater treatment, biosensing | Electricity, treated water |
| Microbial Electrolysis Cells (MECs) | Chemical production | Resource recovery, hydrogen production | Hydrogen, methane, other chemicals |
| Microbial Desalination Cells (MDCs) | Salt removal | Water desalination | Desalinated water, electricity |
MFCs represent the most mature form of BES technology, accounting for 65.8% of the bioelectrochemical systems market 3 . These systems focus primarily on generating electricity from organic matter while simultaneously treating wastewater. Their appeal lies in their ability to address two challenges—waste management and energy production—simultaneously, making them particularly attractive for energy-intensive wastewater treatment plants.
MECs require a small input of electrical voltage to drive chemical reactions that would otherwise be thermodynamically unfavorable. Unlike MFCs, which generate electricity, MECs consume modest amounts of electricity to produce valuable products like hydrogen gas, methane, or other chemicals from waste organic matter 6 . This approach can be more efficient than conventional water electrolysis for hydrogen production.
MDCs represent a three-chamber system that leverages exoelectrogenic bacteria to drive salt removal from water. Located between the anode and cathode chambers, the central desalination chamber uses the electrical potential generated by bacteria to migrate salt ions out of the water 6 . This innovative approach offers the promise of low-energy desalination, which could be transformative for water-scarce regions.
One of the persistent challenges in bioelectrochemical sensing has been detecting minute quantities of environmental contaminants. Traditional sensors often struggle with weak signals and background interference, limiting their practical applications for monitoring pollutants in complex environments like wastewater.
In early 2025, an interdisciplinary team at Rice University unveiled a breakthrough method that dramatically enhances the sensitivity of bioelectrochemical sensors 4 . Their innovative approach integrated organic electrochemical transistors (OECTs) with biological fuel cells to amplify signals by an unprecedented three orders of magnitude (1,000 to 7,000 times stronger than previous methods).
The team coupled OECTs with two types of biofuel cells: enzymatic fuel cells using glucose dehydrogenase and microbial fuel cells employing electroactive bacteria. The key innovation was keeping the OECT and fuel cell separate, which maintained optimal chemical environments for both components while still achieving powerful signal amplification 4 .
To demonstrate real-world applicability, the researchers engineered E. coli bacteria with an arsenite-responsive extracellular electron transfer pathway. This enabled detection of arsenite—a toxic water contaminant—at concentrations as low as 0.1 micromoles per liter, far surpassing conventional detection methods 4 .
The system also successfully demonstrated lactate sensing in sweat, highlighting its potential for wearable health monitoring that could benefit athletes, medical patients, and military personnel through real-time metabolic monitoring without complex, high-power electronics 4 .
The industrial wastewater segment represents the largest application area for BES, accounting for 42.5% of market demand in 2025 3 . Industries are increasingly gravitating toward these systems for their ability to handle high-strength wastewater while recovering energy, maximizing both treatment efficiency and cost effectiveness.
A compelling example comes from Chinese researchers who developed an electrocatalytic-bioelectrochemical coupled system for treating penicillin wastewater . This innovative approach achieved a total penicillin removal rate of 98%, while the BES's maximum power density increased by 473% compared to treating raw penicillin wastewater.
Perhaps one of the most exciting developments in BES technology is its application for recovering valuable resources from waste streams. The University of Surrey's BELIEVE project has demonstrated remarkable efficiency in recovering 90%-95% of high-purity lithium from spent lithium-ion batteries 1 .
"Our goal was to develop a bioelectrochemical system that uses microbial electrochemical technology to extract high-purity lithium from used batteries—which is currently very difficult to do"
Similarly, researchers have demonstrated that BES can facilitate ammonium recovery from waste streams 5 . The process involves transporting ammonium ions across a cation exchange membrane from the anode to the cathode chamber, where the high pH converts them to ammonia gas that can be stripped and captured in acid solution as a valuable nutrient product.
The signal amplification breakthrough at Rice University highlights the growing importance of BES in environmental monitoring 4 . These systems can be engineered to detect specific contaminants at incredibly low concentrations, providing early warning systems for water quality assessment.
Bioelectrochemical sensors offer advantages of sensitivity, specificity, and low power requirements, making them suitable for deployment in remote locations where continuous monitoring is essential but power sources may be limited.
Despite their significant promise, bioelectrochemical systems face challenges in scaling up from laboratory prototypes to full-scale industrial applications. Technical hurdles include high production and operating costs, limited system stability, and occasional low energy efficiency 6 7 .
Ongoing research is addressing these limitations through advances in materials science, particularly the development of more affordable electrode materials and membranes, as well as innovations in system architecture that improve performance while reducing costs.
The global market for bioelectrochemical systems in wastewater treatment is experiencing robust growth, with significant regional variations:
| Country | Projected CAGR | Key Growth Drivers |
|---|---|---|
| China | 16.1% | Rapid industrialization, stringent environmental regulations |
| India | 14.9% | Expanding manufacturing sector, government sustainability initiatives |
| Germany | 13.7% | Engineering excellence, environmental technology innovation |
| United States | 10.1% | Advanced environmental regulations, technology innovation |
China's leadership in market growth is driven by "rapid industrial development and increasingly stringent environmental regulations," along with government support for environmental technology development 3 . Similarly, India's strong growth is supported by "rapid industrialization, growing environmental awareness, and increasing government focus on sustainable water treatment" 3 .
Research and implementation of bioelectrochemical systems rely on a range of specialized materials and reagents:
Carbon felt, graphite brushes - Serve as the foundation for microbial colonization and electron transfer, prized for their conductivity, high surface area, and biocompatibility 6 .
Nafion™, CMI-7000 - Enable selective ion transport between chambers while maintaining system electroneutrality 6 .
Geobacter sulfurreducens, Shewanella oneidensis - Function as natural catalysts that drive the core bioelectrochemical processes through extracellular electron transfer 6 .
Acetate, glucose, ammonium chloride - Provide essential nutrients and electron donors for microbial growth and metabolism in laboratory systems 5 .
Flavins, neutral red - Facilitate electron transfer between bacteria and electrodes in some system configurations, though self-mediated transfer is increasingly common 7 .
Potentiostats, reference electrodes - Enable precise control and monitoring of electrochemical parameters during system operation and optimization 5 .
Bioelectrochemical systems represent a paradigm shift in how we approach environmental management, transforming waste from a disposal problem into a resource opportunity. From recovering high-purity lithium from batteries to generating electricity while treating wastewater, these systems exemplify the principles of a circular economy where waste streams become valuable resources.
"Our next steps will focus on proposals to expand the technology to recover and separate all valuable metals from batteries, including high-value cobalt, nickel and manganese. While challenging, this is a crucial step toward establishing a truly circular battery economy."
In the coming decades, as the global population continues to grow and resources become increasingly scarce, technologies that can extract maximum value from waste streams will become essential rather than optional. Bioelectrochemical systems, with their elegant integration of microbial metabolism and electrochemistry, offer a promising path forward—proving that sometimes the most powerful technologies are those that harness the wisdom of nature itself.