Scientists at Nanyang Technological University, Singapore (NTU Singapore) have developed a groundbreaking way to turn sewage sludge—a waste product from wastewater treatment—into green hydrogen for clean energy and protein for animal feed.
Their solar-powered method could help solve two major problems: waste management and the need for sustainable resources.
As cities grow, so does the amount of sewage sludge produced.
The United Nations estimates that by 2050, 2.5 billion more people will live in cities, leading to even more wastewater and sludge.
Over 100 million tons of sewage sludge are generated globally every year, and traditional ways of getting rid of it—like burning or dumping in landfills—are expensive, inefficient, and harmful to the environment.
NTU scientists have now developed a cleaner, more efficient solution that turns this waste into valuable resources while cutting down pollution.
The new method combines mechanical, chemical, and biological steps to transform sewage sludge.
- Breaking Down the Sludge: The sludge is first broken down mechanically. A chemical treatment then separates harmful heavy metals from useful organic materials like proteins and carbohydrates.
- Solar-Powered Conversion: A special electrochemical process powered by sunlight transforms the organic materials into acetic acid (used in food and medicine) and hydrogen gas, a clean energy source.
- Producing Protein for Animal Feed: The remaining nutrients are fed to light-activated bacteria, which convert them into single-cell protein, a nutritious ingredient for animal feed.
Compared to traditional methods like anaerobic digestion, which can only recover 50% of organic material, the NTU process recovers 91.4%. It also converts 63% of the organic carbon into single-cell protein, while eliminating toxic heavy metals.
This solar-powered process is also highly energy-efficient, producing up to 13 liters of hydrogen per hour with an efficiency rate 10% higher than conventional hydrogen generation methods. Most importantly, it reduces carbon emissions by 99.5% and energy use by 99.3%, making it an environmentally friendly alternative.
Lead researcher Associate Professor Li Hong from NTU’s School of Mechanical and Aerospace Engineering said, “Our method turns waste into valuable resources, reducing environmental damage while creating clean energy and sustainable food.”
Co-lead researcher Professor Zhou Yan added, “By combining mechanical, chemical, and biological techniques, we’ve created a solution that tackles both pollution and resource shortages.”
The research, published in Nature Water, shows that sewage sludge doesn’t have to be just waste—it can become an important part of a sustainable, circular economy.
While this method is promising, more studies are needed to scale it up for use in large wastewater treatment plants. The biggest challenge is reducing the cost of the electrochemical process and designing a system that can be easily installed in existing facilities.
First author Dr. Zhao Hu hopes this research will change how we see sewage sludge—not as waste, but as a valuable resource that can support clean energy and sustainable food production.
If scaled up, this technology could revolutionize wastewater treatment, providing a green solution for managing waste while producing clean energy and food for the future.
Source: KSR.
