Original article by Tor Bagger, AAU (Aalborg University) Communikation and Public Affairs

According to the paper, the research is now so advanced that it is ready for industrial production and use in practice.

Sustainable alternative

“The perspective is enormous, because you’re taking something that is currently waste and making high-value products from it,“

says Professor Per Halkjær Nielsen, Department of Chemistry and Bioscience at Aalborg University in Denmark, about the results of a research project that utilizes surplus biomass in wastewater treatment plants in new ways. The focal point is biopolymers that can be described as long chains of molecules that are bound to each other and that are produced by living organisms, including bacteria. Today, synthetic polymers produced in the petrochemical industry from crude oil are used in many contexts including plastics, textile fibers, adhesives and paints. But with future production of biopolymers at wastewater treatment plants, it will be possible to extract a sustainable alternative to oil-based polymers through a waste product.

Research project REThiNk

Biopolymers can be used as a binding agent in paper and in building materials, and they can be used as a material for flocculation where small particles clump together and settle as part of the water purification of harbour sludge, lakes and wastewater treatment plants. An additional bonus is that biopolymers from wastewater treatment plants appear to be fire-retardant. Thus, there is a potentially large market for biopolymers if they can be produced commercially in a sustainably way. According to the research project “Recovery of extracellular polymers from wastewater treatment residuals as a new circular biopolymer” (REThiNk) there is potential for this.

The goal of REThiNk is to create the foundation for industrial scale-up in the short term so that in the long term there will be a real revolution in recycling biomass from wastewater treatment plants all over the world and not just in Denmark. It also requires mapping bacteria at wastewater treatment plants around the world so that it is possible to predict how each of them can play a role in biopolymer production, phosphorus extraction, etc.

How the extraction of biopolymers from wastewater works

In a wastewater treatment plant, there are several hundred different species of bacteria that produce many types of biopolymers with different properties. These bacteria use the biopolymers as an adhesive to form colonies and adhere to surfaces so they are not just flushed out of the treatment plant. Biopolymers can be extracted by changing the pH and temperature of the water to produce cellulose and gelatinous biopolymers. These can be used for a variety of industrial products.

The expectation is that it will be possible to create factories that produce biopolymers from Danish wastewater treatment plants. And the potential is great, since hundreds of thousands of tons of bacteria are produced annually in Denmark alone. As an added benefit, minerals and other valuable components can be harvested from the wastewater that arrives at the treatment plants. Among them is phosphorus, which is on the EU’s list of critical raw materials that may be difficult to obtain in the future.

Study

In the REThiNk project, Aalborg University is collaborating with Delft University in the Netherlands and Aarhus University (Denmark). The researchers have just published their results in the scientific journal Current Opinion in Biotechnology.