Using bacteria to convert wastewater into valuable resources

Environment and sustainability 31. mar 2022 2 min Full professor, Section Leader Mark van Loosdrecht Written by Morten Busch

Today, only about two thirds of the world’s population are guaranteed clean drinking-water. Fortunately, this percentage is rising. However, global challenges such as pollution from chemicals, climate change with droughts and floods, increasing urbanisation and lack of investment in infrastructure, including wastewater treatment, are threatening this trend. The demand for water has never been greater, and water has therefore never been higher on the political agenda.

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For decades, the focus in wastewater treatment has primarily been on developing even better physical and chemical methods, but Dutch microbiologist Mark van Loosdrecht has taken a different perspective and focused on the biological aspects – with great success.

Throughout the last 25 years, Mark van Loosdrecht and his team have developed a series of new wastewater treatment processes, taking advantage of nature’s own principles in wastewater treatment and resource recovery. The purpose of his work is to create healthier natural water ecosystems, a more sustainable circular economy and better balance in nature for the benefit of millions of people all over the world.

“I try to understand the bacteria and their interactions and, with their help, try to recover all the valuable nutrients from the wastewater. Wastewater treatment can therefore actually become good business rather than an increasing expense for countries globally,” explains Mark van Loosdrecht, Professor in Environmental Biotechnology at Delft University of Technology, the Netherlands.

For his outstanding contributions, Mark van Loosdrecht was awarded the 2022 Novozymes Prize.

The Prize is awarded to recognise outstanding research or technology contributions that benefit the development of biotechnological science for innovative solutions. The Prize is accompanied by DKK 5 million and is awarded by the Novo Nordisk Foundation.

Bernard Henrissat, Chair of the Committee on the Novozymes Prize, says: “Professor Mark van Loosdrecht’s achievements have had an enormous impact in environmental biotechnology. He has developed biological processes that could efficiently remove environmental pollutants, and full-scale reactors based on Mark’s research and design are in operation or under construction on almost all continents. His innovations and inventions have revolutionised wastewater treatment and resource recovery, and he is a very deserving recipient of the 2022 Novozymes Prize.”

Mark van Loosdrecht says: “I am grateful and honoured to be receiving the Novozymes Prize and thereby follow in the footsteps of the great scientists to receive the Prize before me. I would like to thank my team and colleagues without whom I wouldn’t have been able to be where I am today.”

25 years of new wastewater treatment processes

Mark van Loosdrecht started developing water and wastewater treatment processes at Delft University of Technology in 1988. The discharge of phosphates into surface water leads to eutrophication and blooming of algae, which was a huge problem at the time. In 1998, the BCFS® process and became the first of a series of new wastewater treatment processes developed by van Loosdrecht and his team. This was followed by the development of the SHARON process which combined with the ANAMMOX® process helps convert nitrogen-containing compounds and avoid the emission of nitrous oxide, an extremely potent greenhouse gas.

In the following years, while SHARON and ANAMMOX® plants were implemented worldwide, Mark van Loosdrecht took wastewater treatment to the next level by studying other natural microbial processes in sludge.

“When bacteria grow together, they can make very fluffy structures, as in conventional wastewater treatment, or compact structures that much more easily separate from the cleaned water. Coincidentally, the phosphate-removing bacteria are such bacteria. We thereby converted the activated sludge into small granules that contain various layers of these bacteria trained to perform a specific function,” says Mark van Loosdrecht.

The big advantage here was time. The smoother and denser bacterial granules settled at 1 metre in less than 5 minutes compared with 1 metre per hour for conventionally sludge. The researchers dubbed the technology Nereda® – derived from the Nereids, mythical Greek water nymphs.

Although the vision of Mark van Loosdrecht and his colleagues in Delft of turning sludge into economically profitable resources has not yet been achieved, they are now closer to realising their long-standing dream. By analysing the Nereda® granules, they have discovered several substances with a possible market potential such as Kaumera Nereda® Gum, a sustainable biopolymer.

“There is already a market for this biopolymer, which in combination with clay has proven to be comparable to some of the existing fibre-reinforced plastics – and with even better fire-retardant and heat-resistant properties. The material is actually so attractive that a colleague has started making jewellery from Kaumera Nereda® Gum. Its beautiful pearly lustre can remind us of things that can be made from what we flush down the toilet,” concludes Mark van Loosdrecht.

The 2022 Novozymes Prize was awarded to Mark van Loosdrecht, Professor in Environmental Biotechnology at Delft University of Technology, Netherlands.

Mark van Loosdrecht is chair professor in Environmental Biotechnology at the Delft University of Technology. I am fascinated by Microbial Ecology and...

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