A study published in Environmental Science and Ecotechnology presents a self-powered system that treats wastewater while recovering clean water and fertilizer, using only the energy generated by microbes in the waste stream. The research, conducted by scientists at Temple University and New Jersey Institute of Technology, combines electrically assisted forward osmosis (eFO) with a microbial desalination cell (MDC) to create a closed-loop process that turns one treatment challenge into a power source for another.
The integrated eFO-MDC system addresses a growing need for wastewater treatment that goes beyond pollutant removal. With water scarcity, energy constraints, and fertilizer demand on the rise, the field is moving toward resource recovery. Conventional forward osmosis can draw water across a membrane with low hydraulic pressure, while bioelectrochemical systems like MDCs convert organic matter into electricity and help move salts. However, these technologies are often run separately, and electrically assisted FO usually requires continuous external power. The new design solves this by using bioelectricity generated in the MDC to drive the eFO process.
In the eFO module, an osmotic gradient pulls water from the wastewater side toward a magnesium sulfate draw solution. When a mild electric field is applied, magnesium ions migrate back toward the wastewater side, where they react with ammonium and phosphate to precipitate struvite, a slow-release fertilizer. The MDC houses electroactive microorganisms that oxidize organic matter, generating electrons that support desalination. The researchers harvested this microbial electricity, stored it in a 400-farad supercapacitor, regulated the voltage, and fed it back to the eFO unit.
At bench scale, the MDC generated more than 7.0 milliwatts, while the eFO module consumed less than 1.0 milliwatt. Compared with the control, water flux rose by 57%, struvite recovery increased from 0.25 to 0.71 grams at 1.8 volts, and total desalination efficiency improved by 45%. At higher voltage, struvite recovery reached 1.03 grams at 3.8 volts. The team also developed a hybrid model combining mechanistic transport equations with a support vector machine (SVM) to predict struvite recovery, chemical oxygen demand, conductivity, and power output across different operating conditions.
The authors said the study shows how wastewater treatment can be redesigned as a connected resource-recovery loop rather than a set of separate unit operations. The important step lay in allowing the electricity generated by microorganisms to directly control ion movement and fertilizer formation. This internal feedback makes the approach more practical for nutrient-rich streams such as livestock wastewater, where water recovery, salinity control, and phosphorus recovery can all create value.
The results point to applications in decentralized wastewater treatment, agricultural waste management, and future resource-recovery facilities. However, scale-up will require engineering work: the MDC produced enough power for the eFO module, but hydraulic retention times, module sizing, struvite harvesting, membrane scaling, and electrode durability still need optimization. A techno-economic assessment estimated a bench-scale net treatment cost of $10.2 per cubic meter, falling to $3.3 per cubic meter in an engineering scale-up scenario.
The study was partially supported by the U.S. Bureau of Reclamation (Award# 13761566 and R22AC00433) and the NSF/BSF project (Award# 2215387). Publication of this article was funded in part by the Temple University Libraries Open Access Publishing Fund. The full study is available at https://doi.org/10.1016/j.ese.2026.100730.
