Copenhagen’s biowaste may become steaks

As the global population grows, there is increasing demand for sustainable and climate-friendly food products. This applies – not least – to the production of vital proteins. 

A new project based on circular economy examines the possibility of utilizing biowaste from Copenhageners to produce single-cell proteins, which can be used as a protein supplement for humans or be included in animal feed for cattle, pigs, poultry, fish, etc., as a substitute for the climate-damaging alternatives – fish meal and soya beans – used today.

Use of both well-known and newly developed technology 

The project is run by a team of researchers at DTU Environment. “Our idea is to combine existing technology already being used for biogas production with new technology based on the gases and wastewater resulting from biogas production,” says Panagiotis Tsapekos, who is part of the team of researchers.

The project will use biogas produced from organic waste from Copenhagen households, but – in principle – it may equally be biogas produced from wastewater or organic industrial waste. 

The gas methane is separated during the production of biogas. In the project, methane is used as a growth agent for microorganisms known as methylotrophs. These microorganisms have an excellent protein composition and are approved by the EU as a protein supplement for humans as well as for use in animal feed.

In addition to methane, nutrients like nitrogen and phosphorous are also used in the cultivation process for mehtylotrophic bacteria. Both are found in abundant quantities in biogas production wastewater.

“We will use a completely new electrochemical technology to extract the nutrients nitrogen and phosphorus from the wastewater to use them in the protein production process,” says Associate Professor Yifeng Zhang, which is also part of the DTU team.

Both methane and the extracted biogas production nutrients are placed in a reactor in which the methylotrophic bacteria produce single-cell proteins. The proteins can then be harvested from the reactor, freeze-dried, and used as a protein supplement or in animal feed as a substitute for the fish meal or soya beans which currently constitute the protein source. 

“There are great prospects for more climate-friendly future food production if we succeed in using organic waste to extract proteins with the new technologies. Based on our methods, we recycle both the organic material and nutrients from the household waste, which means that nothing is wasted. This results in as little impact on the environment as possible,” says Professor Irina Angelidaki, who is the senior project manager.

A pilot demonstration of the methods will be constructed at the Avedøre Wastewater Treatment Plant in collaboration with Unibio, Envidan, and Biofos. The project is supported by the Ministry of Environment and Food of Denmark and has a duration of 18 months.

(Anne Kirsten Frederiksen)