In the future, wastewater treatment plants will have the change to be sustainable biorefineries, according to the Resource Recovery at the University of Borås, Sweden.

Wastewater treatment plants in the world are producing a huge amount of sludge that is normally anaerobically digested (AD) to produce biogas and to reduce sludge volume. Food wastes are also a challenge in the world, where landfilling, composting and AD are the current treatments. While biogas production has economic challenges, such plants have to buy and add external carbon source such as ethanol or methanol into their denitrification process for removing nitrogen and phosphorous from wastewater. In the future,  wastewater treatment plants can have a broader function by being converted into biorefineries for the production of everything from biogas to different new materials, according to new research out of the University of Borås, Sweden.

Mohammad Taherzadeh, the lead of the project said, “But with our technology, we can develop a platform so that the treatment plants can be transformed into refineries where different chemical substances can be extracted and used to produce different types of materials. Fatty acids are a kind of intermediate product.”

The functions of fatty acids are similar to that of sugar in various petrochemical and biological processes, namely, as sustenance for the microbes used in the processes. By successfully producing and extracting fatty acids, these substances can be further processed to other products such as bioplastics or butanol. The remaining sewage sludge in the process can be used as a substrate in a biorefinery.

"Another feature of the method is that carbon contained in the sludge can be extracted, and therefore there can be a circular process in which the carbon is used to remove nitrogen and phosphorus from the wastewater, and which we do not want to get into our waterways, as it leads to eutrophication. Today, treatment plants purchase large quantities of carbon for this process."

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