Recovery of raw materials from sewage treatment waste: Power to Protein

Recovering proteins from sewage sludge and using it as animal feed – It sounds futuristic, but it’s getting closer. AEB Amsterdam is working on an advanced process with its partners Waternet, KWR Watercycle Research Institute, AgriNutrition, TKI Watertechnologie and Avecom to make this possible.

According to Sietse Agema, strategist at AEB, “We can use new techniques to recover these proteins from the residues of the fermentation process. For example, bacteria are used to convert the nitrogen into useful proteins. We have already tested this in the laboratory. A pilot plant for the production of this protein will be starting up shortly either at Waternet or AEB in the Amsterdam Harbour area. There will also be a pilot plant established at the Vechtstromen Water Board.”

AEB is fully engaged in innovation to recover more raw materials from waste. Waternet is AEB’s neighbour in the Harbour area and together they have already undertaken several sustainable initiatives. A good example is the fermentation of sewage sludge and the conversion of the biogas released by this process into green gas.


Hydrogen needed
According to Agema, “Bacteria can produce proteins from the ammonia released during the waste water treatment in the wet fraction of the biodigester. All they need to live and grow is ammonia, hydrogen, carbon dioxide and oxygen. These are the ingredients from which they make proteins. The oxygen, ammonia and carbon dioxide are already present in the treatment plant. The hydrogen has to be made, however, for example by the electrolysis of water using sun or wind energy. The quality of proteins produced in this manner is good enough for animal or human consumption. But first, the two pilot projects have to demonstrate that the production is sufficient for scaling up.”


Potential for Power to Protein
If these two pilots succeed, expectations are high. According to Agema, “For Amsterdam, we have calculated that the wet fraction of the sludge fermentation in Waternet’s treatment process can supply sufficient protein to provide 35% of the city’s inhabitants with their primary protein requirement. This is the size of the potential. This enables us to contribute to a sustainable society. The production of proteins in the form of soya as animal feed, for example, requires intensive farming. This uses a lot of water and farmland. We can prevent that by using this technology instead.”