The core of the device lies in its utilization of modified wood, treated to selectively permit the flow of specific ions while blocking others, thereby creating an electrochemical gradient. This gradient drives the movement of ions through the wood’s porous structure, generating an electric current without the need for external fuel or complex machinery. The principle harnesses the inherent ionic charge disparities in TDS, such as sodium, chloride, and other charged species common in wastewater streams.

What makes this development particularly remarkable is the continuous nature of electricity generation. Traditional systems that attempt to harvest energy from wastewater often face limitations due to ion depletion or require intermittent regeneration cycles. By contrast, this wood-based generator capitalizes on the constant influx of dissolved ions in untreated wastewater, sustaining electrical output over extended periods.

The implications for environmental sustainability and energy recovery are profound. Wastewater treatment facilities, typically energy-intensive, could incorporate these power generators to reduce operational energy demands or even achieve energy neutrality. Moreover, the use of wood—a renewable, biodegradable material—as the primary structural medium underscores the project’s commitment to eco-friendly design principles.

Technically, the research team engineered the wood’s microstructure to enhance ion selectivity, employing chemical modifications to introduce functional groups that attract and transport targeted ions. This customization ensures optimal efficiency, converting the ion concentration gradient directly into usable electricity with minimal losses. The natural alignment of wood fibers facilitates rapid ion transport, improving current density and overall power output.

Experimental results demonstrate stable voltage and current generation from real wastewater samples, confirming the generator’s practical applicability. The system’s robustness against variable wastewater compositions and flow rates highlights its potential for widespread deployment. Additionally, the low cost and scalability of wood modification processes make this technology economically viable for large-scale implementation.

Future prospects include integrating these generators into existing water treatment infrastructures, urban runoff systems, or remote water sources lacking grid connectivity. Beyond electricity production, the device may serve dual functions by aiding in ion removal and water purification, addressing multiple challenges simultaneously.

This breakthrough exemplifies how interdisciplinary biomaterials research and environmental engineering can converge to produce transformative sustainable technologies. By tapping into the latent electrical potential of everyday wastewater, the wood-based ion-selective generator paves the way for a new class of clean energy harvesters that are both practical and environmentally harmonious.

Subject of Research: Energy generation from total dissolved solids in wastewater using wood-based ion-selective materials

Article Title: Continuous electricity from charged total dissolved solids in wastewater using a wood-based ion-selective power generator

Article References: Yan, W., Sun, J., Han, M. et al. Continuous electricity from charged total dissolved solids in wastewater using a wood-based ion-selective power generator. Nat Commun (2026). https://doi.org/10.1038/s41467-026-75514-7

Image Credits: AI Generated

The innovative method capitalizes on the triboelectric nanogenerator (TENG) principle, a technology that harvests mechanical and electrostatic energy through contact electrification and electrostatic induction. While TENGs have been explored in various contexts, their application in municipal wastewater energy recovery has remained largely untapped. By focusing on the energy potential contained within secondary effluents—wastewater after primary treatment—the research team led by Dr. Beidou Xi has demonstrated an effective solution that harvests energy often lost during effluent discharge.

At the heart of the DEG system is a contact layer fabricated from hydrophobic films such as perfluoroethylenepropylene copolymer (FEP), polytetrafluoroethylene (PTFE), and polypropylene. When wastewater droplets impact these films, the interaction generates a charge differential attributed to triboelectrification. Of the materials tested, FEP exhibited superior performance, facilitating a maximum output voltage of 22.47 volts and a current of 2.11 microamperes for a single device. This electrical output translates to a peak power delivery of approximately 15.18 microwatts, a magnitude sufficient to power 15 light-emitting diodes (LEDs) with just one droplet.

Scaling up the technology, the researchers assembled a multi-device DEG system, connecting six individual units in parallel. Post-rectification, the collective system exhibited enhanced electrical output capable of continuously illuminating LEDs without any external power input. This significant advancement underscores the system’s potential to be integrated into existing municipal wastewater treatment plants as a self-sustaining energy harvesting module that could simultaneously offset energy consumption and lower operational carbon footprints.

Critical to the system’s efficiency is the quality of the wastewater itself. The team observed that effluents with reduced dissolved solids and lower ion concentrations improved electron transfer efficiency between droplets and the hydrophobic film. This finding reveals a notable dependency of triboelectric performance on wastewater chemistry. However, once effluent standards comply with China’s rigorous Grade I-A discharge criteria, different treatment modalities exert minimal impact on generator performance, suggesting the system’s adaptability to various treated wastewater qualities.

Beyond energy harvesting, the DEG system demonstrated remarkable functionality in active pollutant removal. The harvested electrical energy was redirected to stainless steel electrodes submerged within the municipal wastewater. The resulting electrochemical reactions effected a reduction in ammonium nitrogen levels by approximately 12% and chemical oxygen demand (COD) by over 40%. The generation of microscopic gas bubbles during electrolysis facilitated electro-flotation, a process where contaminants attach to the bubbles and are thus separated from the water more effectively. This mechanistic synergy enhances treatment efficacy without the need for external power sources.

Interestingly, the utilization of alternating current generated by the DEG system delivered an ancillary benefit: mitigating electrode passivation. The reversible polarity of the current prevented the accumulation of mineral layers on electrode surfaces, which often hampers electrochemical efficiency. This dynamic maintenance of electrode activity ensures sustained treatment performance, a crucial factor for long-term deployment in wastewater treatment contexts.

The electrocatalytic prowess of the DEG system extended to the degradation of dyes, a persistent class of wastewater pollutants. Using methyl orange as a test contaminant, the six-device configuration powered electrocatalytic degradation over a continuous 54-hour period without auxiliary energy inputs. The systematic decline in ultraviolet-visible absorption peaks associated with methyl orange signified the effective breakdown of its chemical bonds, achieving a COD removal efficiency exceeding 91% and a decolorization rate over 96%. Such results emphasize the system’s capability to treat complex organic pollutants through sustainably harvested electricity.

This research epitomizes the broader implications of TENG technology in sustainable environmental engineering. By unlocking energy embedded in secondary effluents, facilities traditionally dependent on external power can evolve into resource recovery hubs, leveraging wastewater not as a liability but as a renewable energy asset. This paradigm shift has the potential to revolutionize water treatment infrastructure, integrating green energy generation directly into wastewater management while enhancing pollutant removal.

Dr. Beidou Xi emphasizes the dual benefits of this approach: “Our study not only demonstrates a novel method for secondary effluent energy harvesting using TENG technology but also introduces a sustainable framework for wastewater resource recovery and carbon reduction.” Such integrative strategies, combining material science, electrochemistry, and environmental engineering, may well set the stage for next-generation municipal wastewater facilities that align with global carbon neutrality targets.

The study’s successful demonstration opens doors for future exploration—integrating larger-scale TENG systems, optimizing film materials for increased electron transfer, and coupling with advanced treatment technologies to tackle diverse pollutants. Moreover, the DEG system’s ability to function independently of external power underscores its potential utility in decentralized water treatment, especially in energy-constrained or remote regions.

In light of mounting environmental pressures and urbanization, this pioneering work offers a tangible pathway for sustainable wastewater management. By transforming treated effluent into a self-powered cleaning mechanism, the droplet-based electricity generator system showcases a visionary approach to mitigating water-energy nexus challenges while advancing the global agenda for clean water and sustainable development.

Subject of Research: Not applicable

Article Title: A droplet-based electricity generators (DEGs) system for harvesting secondary effluent energy

News Publication Date: 1-Mar-2026

References: DOI: 10.1016/j.jes.2025.05.020

Image Credits: Credit: Thomas Hawk from Openverse

Keywords

Power industry, Industrial sectors, Energy infrastructure, Energy resources, Energy, Physics, Conservation of energy, Energy transfer, Free energy, Technology, Applied sciences and engineering, Nanotechnology, Electricity, Electrical power, Electrical engineering, Electrical power generation, Energy harvesting, Power systems, Electrometry, Experimental physics