Recovering resources from wastewater streams supports the circular economy


As major global trends require many industries to find innovative ways to be sustainable and more energy efficient, A recent paper prepared by a KAUST PhD student and his collaboratorsPublished in Nature Communications, it provides a fresh perspective.

The research details a process in which the ammonium present in wastewater can be removed directly in one step with energy recovery in the form of electric current or energy rich hydrogen gas.

Through the process of removing ammonium from wastewater before it is discharged, the energy can be harnessed and used for various applications. Image credit: KAUST

Dario Rangel ShawPhD student from The Water Desalination and Reuse Center at King Abdullah University of Science and Technology (WDRC), studying under Professor Pascal PsychaliHe got prestigious Discovery Prize For the best scientific paper from International Society of Microbial Electrochemistry and Technology (ISMET). Shaw’s work in the anaerobic oxidation of ammonium based on electron transport (electric anamox) was recognized as the best scientific publication and major innovation in 2020.

“These results have an important impact in the context of energy-saving treatment of nitrogen-rich wastewater,” said Xu.

Towards a positive energy system

The breakthrough underpinning the research demonstrates how anamoxic bacteria can oxidize ammonium along with respiration based on extracellular electron transport. This process represents a more energy-efficient wastewater treatment method because it harnesses the ability of the sudden anamox bacteria to “breathe” the solid state.

The anamox process involves the oxidation of anaerobic ammonia. This method is used for sustainable wastewater treatment because it facilitates lower energy consumption compared to conventional wastewater treatment methods. The goal is to remove ammonium, a contaminant, in wastewater before discharging it.

In addition to treating water, our goal is to reuse treated water in specific applications while recovering energy at the same time, ”said Pascal Sikali, associate professor of environmental science and engineering at KAUST. Basically, we want to convert wastewater. Wastewater treatment plants from energy intensive systems to energy neutral or possibly energy positive systems.

By harnessing the microorganisms in nature, the KAUST team is using environmental biotechnology to build bioreactors that select the right organisms capable of achieving these energy-saving goals. Instead of adding energy, the goal is to make the process neutral, at least, or optimally generate more energy than is required to treat the wastewater. This recovered energy can then be used for various purposes.

Anammox bacteria grow on the surface of the electrode and convert ammonium into nitrogen gas. The electrons emitted from this process flow through the electrode in the form of an electric current that can be used to generate energy-rich hydrogen gas. This is a step forward towards energy neutral or positive wastewater treatment. Image credit: KAUST

Possible applications

There are currently two pioneering technologies being explored to apply this research. The team has built reactors on a trial scale next to the KAUST wastewater treatment plant. Using the wastewater of the KAUST community, these systems are combined with PV panels to treat wastewater. Reclaimed solar-powered water can be used, for example, to irrigate a campus golf course.

Different techniques may be used depending on the type of organism. In the course of Shaw’s work on electrolytic anamox, wastewater not only contains ammonia, but also organic matter. Therefore, another way to combine technology to generate electricity is to harness the potential energy of organic compounds for wastewater.

Hence, the two units use different methods. The first unit removes organic matter and generates electricity or hydrogen, and the second unit converts ammonia into energy-rich hydrogen.

You can process both and generate hydrogen at the same time. Both processes can be combined with solar energy because you don’t need a lot of energy to drive the process, ”explains Sikali.“ We’re very excited about the work. ”


Water scarcity is an important issue that must be addressed at the regional and global levels. The KAUST team process can help meet this major challenge while achieving energy efficiency goals. Hydrogen gas is known as an energy-rich gas that can also be used as a fuel, so this is an excellent environmentally friendly step forward for sustainable wastewater treatment.

This interdisciplinary approach, which includes chemistry, process engineering, microbiology, next-generation sequencing technologies and bioinformatics, provides value-added prospects for advancing the circular economy and Vision 2030.

For example, a large project in NEOM involves converting renewable energy (solar and wind energy) into hydrogen. With the Haber-Bosch process, hydrogen can be converted into ammonia and then transported to different markets. The challenge is to convert ammonia back into hydrogen in an energy-efficient way, to eventually be used as fuel. Conventional methods require expensive metal catalysts and require high pressure and temperature conditions above 500 degrees.

Shaw’s anammox process uses microorganisms to convert ammonia to hydrogen again at room temperature.

“In our case with electrophoresis, the growth of environmental strains of anamox bacteria at room temperature represents a significant advantage in relation to these other stimuli,” said Shaw.

Source: KAUST

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