Aquaponics system, which combines the concept of both aquaculture and hydroponics, has various sizes growing plants from small indoor units to large commercial units. There are various types of aquaponics such as aeroponics, drip system, deep water culture and nutrient film technique, depending on the water requirement of the plants/ crops. Concerning food insecurity and insufficient farmland in large metropolitan cities like Hong Kong, we tend to provide solutions by extending the farmland on a floating platform in coastal areas using desalinization technology, aeroponics and the applications of Internet of Things (IoT) connecting different sensors to monitor carbon dioxide, water quality and plant growth, as well as control water flow and nutrients leaching rate. The system used the energy which store from solar panels and achieve the target of carbon neutrality.
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Aquaponics Types
Our prototype includes: (i) pre-treatment unit filtering out large suspended solids in seawater, (ii) desalinated unit using Reverse Osmosis turning seawater to freshwater, (iii) storage tank with nutrients leaching, (iv) plant growth unit with aeroponics system with spraying nozzles which keep plants growing with less water required, (vi) solar panels and batteries for power supply and storage. Sensors and timer pumps are installed in the prototype to ensure water flow and quality. The whole system conforms to the concept of sustainable development. Turbidity and salinity in seawater can be lowered in the pre-treatment and desalinated units by 40% and 99% respectively. Mixture of jellyfish and seaweed solution provide sufficient nutrients for plant growth over 2 weeks. Foldable solar panels could achieve solar power by 80%, the energy stored in the battery could provide 7-8 days of power for the whole system.
Aeroponics with desalination application has been adopted in many countries nowadays, particularly freshwater resources become scare under climate change. For example, a closed-loop system using aeroponics and desalinated water in vertical farming units in Israel (Vertical Farming, 2023). Another project in California, US using desalinated water to grow lettuce and herbs irrigated by aeroponic system (WaterFX, 2018). Although some countries have a saltwater aquaponic system, it still exists many limitations that we need to overcome. With the successful demonstration in our lab-scale system, we plan to extend the prototype to large-scale in outdoor environment in future.
References:
WaterFX (June, 2018). California’s first commercial solar desalination plant to being freshwater to the Central Valley. PR Newswire
Vertical Farming – on-site farm: Vertical Field. Vertical Field. (May 3, 2023)
Planting unit (using aeroponics) in the prototype.