Each city in the world inevitably produces purification sludgethe dense organic residue generated by the treatment of waste water. This mass accumulates at a dizzying pace, with beyond 100 million tons of dry sludge produced every year globally. Their disposal is expensive and complicated: sludge can contain organic substances, nutrients such as nitrogen and phosphorusbut also heavy metals and toxic compounds. Currently, the most common solutions are combustion, which releases harmful substances, or composting, which however requires very long times.
Now, however, a new discovery could radically change the management of these waste. A team of scientists from the Nanyang Technological University of Singapore has developed a revolutionary system that transforms purification sludge into two precious resources: unicellular proteins, usable as animal feed, and green hydrogen, a clean fuel. The research, published in the magazine Nature Wateropens the way to a more sustainable model of urban waste management.
How the new method of conversion of purification sludge works
The process developed by the researchers is divided into Three fundamental phasesusing advanced technologies e renewable solar energy.
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Mechanical-chemical decomposition: Muds are subjected to an intensive grinding with the addition of an alkaline catalyst (such as potassium hydroxide). This treatment breaks the molecular structure of the material and allows you to separate the useful components, while trapping heavy metals in a solid and safe form to dispose of.
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Electrolysis and green hydrogen production: the dissolved organic part is treated through a system of Electrolsis powered by solar energy. Here the key transformation takes place: instead of simply degrade, the organic material undergoes an electrochemical oxidation that leads to the formation of volatile fatty acidsin particular acetic acidan essential element for the production of microbial biomass. At the same time, al cathode of the system, the water is broken down to generate green hydrogena clean fuel with enormous potential for the industrial and transport sector.
- Protein production through phototrophic bacteria: Acetic acid and other generated compounds are then used as nourishment for Viola phototrophic bacteria bacteriacapable of converting organic matter into Unicellular proteins. These proteins can be used as animal feedoffering a sustainable solution for the zootechnical industry.
A revolutionary environmental impact
The idea of reusing purification sludge is not new, but the results obtained with this system are extraordinary. 91% of the organic carbon present in the sludge is recovered and converted into useful productswhile the 63% of total carbon It turns into proteins.
The most surprising aspect, however, concerns CO₂ emissionswhich are demolished of the 99.5% Compared to traditional treatment methods, such as anaerobic digestion.
The main question is now: can this technology be applied on a large scale? According to Dr. Zhao Hu, the main author of the study, the answer is yes. The system was designed to be modular and adaptableintegrated in existing treatment plants without the need for expensive infrastructure changes. This means that it could be implemented both in large metropolises and in smaller urban centers, offering an ecological alternative to waste management.
With the continuous growth of the population and the acceleration of urbanization, the problem of mud disposal becomes increasingly urgent. This innovative method could represent an epochal turning point, transforming an environmental problem into a precious resource.
If adopted on a global scale, it could redefine the very concept of refusal, transforming the superfluous into value and significantly reducing the ecological impact of the cities. The future of sustainability could start from the purification sludge.
