Reuse of Water and Nutrients in Soilless Plant Culture

Maha Ezziddine of the Faculty of Engineering and Science has submitted her thesis entitled "Reuse of Water and Nutrients in Soilless Plant Culture" and will defend the thesis for the PhD-degree on Friday 21 April 2023. 

Ezziddine has attended the PhD programme in Engineering and Science, in the discipline Civil and Structural Engineering. 

Summary of the thesis by Maha Ezziddine:

New Research Promotes Sustainability in Soilless Agriculture

Recent study introduces methods to prolong nutrient solution use and utilize aquacultural waste in soilless plant growth systems In response to the growing challenges faced by traditional soil-based agriculture, such as soil degradation, water scarcity, and climate change, a recent study has been conducted to explore sustainable solutions for soilless plant culture systems. These solutions offer the potential for more efficient resource use and a reduced environmental impact.

The study proposes two novel approaches to decrease soilless agriculture's reliance on scarce and non-renewable mineral fertilizers. The first approach focuses on extending the lifetime of nutrient solutions used in recirculating hydroponic systems, while the second approach presents a comprehensive method for treating and reusing aquacultural sludge as a nutrient source for soilless growth systems.

The research findings indicate that the nutrient solutions in hydroponic systems can be reused for up to six weeks without affecting the quality or yield of the produce, such as lettuce. This significantly extends the typical one-week interval at which many growers discard the nutrient solution, resulting in reduced waste and more efficient resource use.

Additionally, the study shows that aerobic digestion is a practical method for extracting nutrients from aquacultural waste, making them suitable for soilless growth systems. The biopolymer chitosan was successfully employed as a safe and efficient flocculant for solid removal from aerobically digested aquacultural waste. By utilizing the recovered nutrient solution from aquaculture waste, lettuce was grown in a closed hydroponic system, achieving comparable yields and quality to conventionally grown lettuce.

These encouraging results emphasize the possibility of substituting synthetic fertilizers with nutrient solutions derived from aquaculture waste, offering a more sustainable and eco-friendly fertilization strategy for soilless culture systems. As global challenges in food production and resource management continue to escalate, this research provides a promising path towards more sustainable and efficient agricultural practices.

What to do as an online audience member:

The disputation is open to the public, but to follow the trial lecture and the public defence online, transmitted via the Zoom conferencing app, you have to register as an audience member on this Zoom link.

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We ask online audience members to join the virtual trial lecture at 10:05 at the earliest and the public defense at 12:20 at the earliest. After these times, you can leave and rejoin the meeting at any time. Further, we ask online audience members to turn off their microphone and camera and keep them turned off throughout the event. You do this at the bottom left of the image when in Zoom. We recommend you use ‘Speaker view’. You select that at the top right corner of the video window when in Zoom.

Opponent ex auditorio:

The chair invites members of the public to pose questions ex auditorio in the introduction to the public defense. Deadline is during the break between the two opponents. The person asking questions should have read the thesis. For online audience the Contact Persons e-mail are available in the chat function during the Public Defense, and questions ex auditorio can be submitted to Emma Elisabeth Horneman on e-mail emma.e.horneman@uia.no.