A study published in Environmental Science and Ecotechnology reports a self-powered system that integrates electrically assisted forward osmosis (eFO) with a microbial desalination cell (MDC) to recover water and fertilizer from livestock wastewater without external electricity. The closed-loop platform uses bioelectricity generated by wastewater-fed microbes to drive nutrient and water recovery, addressing growing water scarcity, energy constraints, and fertilizer demand.
Conventional wastewater treatment focuses on pollutant removal, but the field is shifting toward resource recovery. Forward osmosis can draw water across a membrane with low pressure, and bioelectrochemical systems like MDCs convert organic matter into electricity while moving salts. However, these technologies are often run separately, and electrically assisted FO typically requires external power. The new system overcomes these limitations by linking the two processes so that microbial electricity powers the eFO module.
Researchers from Temple University and New Jersey Institute of Technology (DOI: 10.1016/j.ese.2026.100730) tested the system with synthetic livestock wastewater. In the eFO module, an osmotic gradient pulls water from wastewater toward a magnesium sulfate draw solution. A mild electric field drives magnesium ions back toward the wastewater side, where they react with ammonium and phosphate to form struvite, a slow-release fertilizer. In the MDC, electroactive microorganisms oxidize organic matter, generate electrons, and support desalination. The microbial electricity is harvested, stored in a supercapacitor, regulated, and fed back to the eFO unit.
At bench scale, the MDC generated over 7.0 milliwatts while the eFO module consumed less than 1.0 milliwatt. Compared with a control, water flux increased by 57%, struvite recovery rose 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 to predict performance across different conditions.
The study shows how wastewater treatment can be redesigned as a connected resource-recovery loop. The internal feedback—using microbial electricity to control ion movement and fertilizer formation—makes the approach practical for nutrient-rich streams like livestock wastewater, where water recovery, salinity control, and phosphorus recovery create value. The work points to applications in decentralized treatment, agricultural waste management, and future resource-recovery facilities.
Scale-up will require engineering optimization, including hydraulic retention times, module sizing, struvite harvesting, membrane scaling, and electrode durability. 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 supported by the U.S. Bureau of Reclamation and the NSF/BSF project.
