A-frame systems
A-frame systems consist of a stepped arrangement of hydroponic channels (Sánchez-Del-Castillo et al. 2014), or angled panels of geotextile for aeroponic cultivation (Hayden 2006). Fruit bearing crops growing in the lower sections of an A-frame system may experience partial shading, and consequently produce a high number of small and malformed fruit, experience increased fruit rot, and exhibit problems with fruit colouration. This can be avoided by using systems with grow beds that slowly rotate around the A-frame to ensure that the plants obtain uniform sunlight, irrigation and nutrients as they pass through different points in the structure. For example, the A-Go-Gro (AGG) system developed by Sky Greens in Singapore (Figure 14) consists of tall aluminium and steel A-frames that can be as high as 9 metres tall, with 38 tiers of growing troughs that can contain either soil or hydroponic solution. Each frame has a footprint of only 5.6 m2, and the system is capable of producing 1000 tons of vegetables per hectare/year. The frames are housed in translucent greenhouses and the rotation of the troughs at a rate of 1 mm/s means that each trough rotates around the frame three times a day, which ensures uniform distribution of sunlight and good air flow, and reduces or even eliminates the need for artificial lighting in some areas of the greenhouse. Rotation is powered by a patented low carbon hydraulic system that makes efficient use of gravity and therefore consumes little energy; only 60 W is required to power one frame. Rainwater collected in an overhead reservoir passes down through the water pulley system, and is then redirected back up to the reservoir by a pump powered by a generator (Al-Kodmany 2018).
Figure 14: A-frame system at Sky Greens, Singapore http://www.skygreens.com/wp-content/uploads/2014/05/Skygreens-Vertical-Farm1.jpg
THORILEX Ltd has developed a patent pending aquaponic system where the plants are grown on stainless steel A-frames ranging from 3 up to 8 metres high (Figure 15). Planting baskets designed to optimise root growth and maximise nutrient uptake are placed in double rows in stainless steel channels. The trays of plants then rotate around the frame so that they receive an equal amount of light from the LEDs positioned above each frame. The self-cleaning, stainless steel fish tanks come in two sizes, for juvenile and market-sized fish. The system is therefore adjustable and scalable for commercial-scale growing (Figure 16). Currently the system can only be found in the THORILEX 2 hectare showcase farm in the Czech Republic, but the intention is to bring this innovative system to markets across the world. That is why THORILEX designs products using the ‘IKEA-model’: being highly modular, they can be easily packed, shipped and delivered with minimal costs.
Figure 15: The THORILEX system http://thorilex.com/
Figure 16: The THORILEX commercial aquaponics farm http://thorilex.com/
The A-frame hydroponic system developed by the Chinese Jiangsu Skyplant Greenhouse Technology Company (Figure 17) could also be used for aquaponics. The structure has a footprint of 5 m2, and each of the food-grade PVC-U channels contain 25 holes, resulting in 250 plants per structure, or 50 plants/m2.
Figure 17: The Jiangsu Skyplant Greenhouse Technology Company system http://thorilex.com/
Copyright © Partners of the Aqu@teach Project. Aqu@teach is an Erasmus+ Strategic Partnership in Higher Education (2017-2020) led by the University of Greenwich, in collaboration with the Zurich University of Applied Sciences (Switzerland), the Technical University of Madrid (Spain), the University of Ljubljana and the Biotechnical Centre Naklo (Slovenia).