Researchers turn treated wastewater into electricity and pollutant removal

By AI, Created 5:56 AM UTC, May 28, 2026, /AGP/ – Lanzhou Jiaotong University researchers developed a droplet-based generator that harvests energy from treated municipal wastewater while helping remove pollutants. The system powered LEDs, charged capacitors and supported electrochemical treatment, pointing to a potential low-carbon upgrade for wastewater plants.

Why it matters: - Municipal wastewater plants discharge large volumes of treated water every day, and much of the residual mechanical and electrostatic energy is normally lost. - The new droplet-based electricity generator system turns that wastewater stream into a source of usable power while also supporting pollutant removal. - The approach could help treatment facilities offset some operating energy use and lower carbon emissions.

What happened: - A research team led by Dr. Beidou Xi at Lanzhou Jiaotong University and the State Key Laboratory of Environmental Criteria and Risk Assessment developed a droplet-based electricity generator (DEG) system for treated municipal wastewater. - The study was made available online on May 10, 2025, and published in Volume 161 of the Journal of Environmental Sciences on March 1, 2026. - The work builds on triboelectric nanogenerator, or TENG, technology, which captures low-frequency and low-power energy.

The details: - Researchers fabricated DEG devices with commercially available hydrophobic films, including perfluoroethylenepropylene copolymer, polytetrafluoroethylene and polypropylene. - Falling wastewater droplets produced electricity through triboelectrification and electrostatic induction at the film surface. - FEP-based devices performed best among the tested materials. - A single DEG device reached 22.47 V, 2.11 μA and 15.18 μW when operated with secondary wastewater effluents. - One droplet impact was enough to light 15 LEDs. - A six-device DEG system, connected in parallel and rectified, generated stronger output and charged capacitors efficiently. - The six-device system powered an LED continuously without external electricity. - Wastewater quality affected performance, with lower dissolved solids and lower ion concentrations improving electron transfer. - Once secondary effluents met China’s Grade I-A discharge standard, wastewater treatment method differences had little impact on generator performance. - The DEG system also powered stainless steel electrodes submerged in municipal wastewater for electrochemical pollutant removal. - That setup removed about 12% of ammonium nitrogen and more than 40% of chemical oxygen demand, or COD. - Tiny bubbles created during electrolysis helped pollutants attach and separate through electro-flotation. - Alternating current from the DEG system reduced electrode passivation and helped maintain electrochemical activity. - Continuous polarity reversal helped prevent mineral buildup on electrode surfaces. - In dye tests using methyl orange, a six-device system powered electrocatalytic degradation for 54 hours without an external power supply. - The system achieved 91.31% COD removal and 96.08% decolorization in the dye experiment.

Between the lines: - The study suggests wastewater treatment plants may be able to harvest energy from the same streams they are already processing, instead of treating effluent only as a disposal problem. - The mixed energy-and-treatment function is the key advance. It could make TENG-based systems more practical than energy harvesting alone. - The results also show that treated wastewater quality matters, so real-world deployment would likely depend on how consistently plants meet discharge standards.

What’s next: - The researchers say the system points to broader use of TENG technology in sustainable environmental engineering. - Future work will likely focus on scaling the DEG design, testing durability and assessing how it performs in full wastewater facilities. - The team frames the platform as a possible route for wastewater resource recovery, carbon reduction and more self-powered treatment operations.

The bottom line: - The Lanzhou Jiaotong University system shows that treated wastewater can do more than leave a plant — it can help power the process and clean the water further.