Exploring the potential of duckweed (Lemnaceae) as a circular protein crop on agri-food industry wastewaters

Increasing human populations, global warming, and dwindling natural resources are putting significant strain on food production systems. Current livestock systems are inherently inefficient and require large inputs of plant proteins (e.g., soybeans), the cultivation of which is unsustainable. Policies such as the European Union ‘Green Deal’ and the ‘Protein Strategy’ aim to increase sustainability by reducing negative environmental impacts and providing alternative sources of protein. Duckweeds are small floating aquatic plants known for their rapid growth and high dry weight protein content. Duckweed cultivation on agri-food wastewaters offers a potential solution for their valorisation through simultaneous phytoremediation and the production of a protein-rich biomass. In this thesis, through several laboratory-scale trials (100 mL – 7.5 L), it was explored whether two readily available agri-food wastewaters, dairy soiled water and meat processing wastewater, could support duckweed growth. Dairy soiled water was found to support sustained duckweed growth with regular pH adjustment, while providing a protein-rich biomass with an amino acid profile comparable to that of soybean meal. Meat processing wastewater supported duckweed growth and the rapid uptake of nutrients, providing effective phytoremediation albeit with the generation of a low protein biomass. When dairy soiled water and meat processing wastewaters were blended, duckweed-based valorisation was greatly improved through increased phytoremediation and valuable plant biomass production. These findings highlight the potential for duckweed-based valorisation of agri-food wastewaters under the principles of the circular economy, whereby agri-food wastewaters act as nutrient inputs to produce a protein-rich crop.

Grantor dc:publisher

University College Cork

Year dc:date.issued

2025

Author dc:creator

• Redmond, Cian

Advisors dc:contributor.advisor

• Jansen, Marcel A. K.
• Coughlan, Neil

• Duckweed
• Phytoremediation
• Circular economy
• Agriculture
• Wastewater
• Food industry
• Plant protein
• Alternative protein

Statement dc:rights

• © 2025, Cian Redmond.

Licence dc:rights.uri

• https://creativecommons.org/licenses/by-nc-nd/4.0/

Language dc:language.iso

en

Handle dc:identifier.uri

https://hdl.handle.net/10468/18896

OAI identifier oai:identifier

oai:cora.ucc.ie:10468/18896