Upcycling Nitrogen to Convert Sewage Sludge to Animal Feed

Nitrogen exists in many forms in the environment and can enter aquatic systems from fertilizer run-off and wastewater discharges. Treated domestic sewage sludge will have varying levels of nitrogen, depending on the method of treatment used. Most treatment plants decrease the level of total nitrogen in sewage sludge via cell synthesis and solids removal. However, unless there is a specific treatment provision for nitrification, most of the ammonia nitrogen passes through.

An overabundance of nitrogen can lead to harmful algal blooms in bodies of water which cause major environmental challenges in many parts of the world. In Canada, it has been a worsening problem for Lake Erie since the 2000s. Algal blooms cause water bodies to turn green and can produce toxins that are dangerous to humans and animals, contaminate drinking water supplies, and cause low oxygen ‘dead zones’ resulting in fish kills. It has severe negative impacts on human health, aquatic ecosystems and the local economy.

One solution is being explored by Dutch researchers. Project to Protein aims to determine the potential of upcycling nitrogen from ammonia found in sewage water and convert it into a high value single cell protein for use in animal feed. This concept was based on the process of microbial biosynthesis of hydrogen, CO2, and nitrogen in a reactor system using lithrotropic bacteria than can break down these substrates into simpler inorganic molecules. Great care must be taken in this process because hydrogen, the energy source of the system, is extremely flammable. The hydrogen is mixed with other elements such as oxygen from water hydrolysis, carbon dioxide, and ammonium from the wastewater.

They used a sewage water treatment plant at Enschede in the Netherlands to test the concept. The test was led by Emeritus Professor Willy Verstraete of the Department of Biochemical and Microbial Technology, University of Ghent. Nijhuis Water Technology, a Dutch company, processed the ammonia sulphate from the treatment plant’s reject water, which is rich in ammonium concentrations, and air stripped it at high temperatures.

An animal nutrition ingredient supplier, Barentz, was brought in to analyze the quality of the protein produced by the system. The goal is to produce 0.5 to 1 kg of single cell protein per day using the pilot reactor system.

Bioproducts specialist Avecom then studied the output of the system to determine the viability of the output for use in feeds and determined that “The sequence of amino acids found in the protein generated from that reactor was compatible to that of fishmeal or soymeal.”

At the moment, the program is still in its early stages and is still far from attaining commercialization. They are now seeking investors who are willing to put a significant investment to scale up the concept.

If you are a municipality in Ontario and in need of a biosolids management solution, please feel free to contact us at 1 (877) 479-1388.


Upcycling Nitrogen to Convert Sewage Sludge to Animal Feed
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