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A wide range of aquaponic systems exist in all continents. Table 6 summarizes several systems and their main characteristics.
Between the years of 2014-2018, the European Union funded COST Action FA1305 'EU Aquaponics Hub', which involved the cooperation of member countries in the research of aquaponic systems as a pertinent technology for the sustainable production of fish and vegetables in the EU. The website of the action is a very good source of information, with links to fact sheets, publications, and training school videos. The same group performed a survey of the use of aquaponics in Europe, underlining that most units are small and related to research (Villarroel et al. 2016). A map of nearly all known aquaponics facilities in Europe was published in Google Maps.
Figure 11: Map of aquaponic facilities
The map includes the location of all the research institutes (blue) and companies (red) currently actively working on aquaponics. It cannot be edited directly, but researchers and companies that want to be added can send their details to [email protected]. As is apparent from the map, industry collaboration is essential for aquaponics to fulfil its promise as a viable system of local food production in the EU. The map currently lists 50 research centres and 45 companies, suggesting a nice balance between research and development.
Table 6: Summary of some aquaponic systems around the world
Country Purpose & type Fish Plants Author(s) Australia Research Backyard system (ebb- and-flow) Murray cod Lettuce Lennard & Leonard 2004 Barbados Research Backyard system (ebb-and-flow) Red Tilapia Basil and okra (growth medium: coconut husk) Connolly & Trebic 2010 United States Virgin Islands Research Commercial system Raft hydroponic Tilapia Basil, okra Rakocy et al. 2003 China Large commercial system (ponds) Environment for natural spawning of native fish Rice, canna flowers Duncan 2014 Germany, Berlin Research, demonstration, education (NFT and NGS* channels) Trout Strawberries, pak choi, mini cucumber, salads Roof Water Farm Hawaii Large commercial system Tilapia Salads Kunia Country Farms Hungary, Kaposvar Social institution (grow beds, NFT) Wels catfish Herbs, lettuce, tomatoes, strawberries Passive Aquaponics Iceland Research Small commercial system (grow beds, raft cultures, NFT channels) Tilapia Tomatoes, beans, lettuce Thorarinsdottir 2015 Iran Research Based on UVI Model Raft, grow beds Common carp, grass carp and silver carp Tomatoes Roosta & Afsharipoor 2012 Slovenia, Naklo Vocational education Based on ‘Waedenswil’ model (grow beds, raft cultures, NFT channels) Carp Salads Podgrajšek et al. 2014 United Arab Emirates Large commercial system Raft hydroponic Tilapia, barramundi Salads Smith 2015 Vietnam Research Backyard system (grow beds) Tilapia Canna flowers, water spinach, salads Trang & Brix 2014
* New growing system: www.ngsystem.com
Iceland: The aquaponic system of Svinna-verkfraedi Ltd consists of three 4 m3 fish tanks, a drumfilter, a biofilter, a sump tank, and NFT channels. The hydroponic part has been used to grow tomatoes, beans, and lettuce. The company is testing different hydroponic systems (grow beds, raft cultures, NFT channels), and has recently added crayfish to the system to make use of the sludge from the fish tanks (Thorarinsdottir 2015).
Hungary: A passive aquaponics house at the ‘Somogy County Association of Disabled Persons’ social enterprise was built by the Hungarian company Passive Aquaponics. The house is heated by gas (70%) combined with a compost heater (30%). Wels catfish (Silurus glanis) is reared in small tanks. Hydroponic units, filled with expanded clay, are used to grow herbs (basil, mint), lettuce, tomatoes, peppers, strawberries, and even banana plants.
Germany: Roof Water Farm in Berlin is a demonstration project for innovative urban water management and food production. The focus is on a hygienically safe use of rainwater, greywater and blackwater combined with decentralised water treatment technologies, for aquaponic and hydroponic food production. Figure 12: Left – Roof Water Farm (Photo: Grit Bürgow). Right – Strickhof agricultural educational centre (Photo: Roger Bolt)
Switzerland: An experimental aquaponic system was built mainly for educational purposes in 2012 at the Strickhof agricultural educational centre in Zürich canton. Constructed at the back of an old greenhouse on an area of approximately 36 m2, it consists of a 3 m3</supfish tank, five NFT channels, and two ebb-and-flow tables.
China: To our knowledge, the largest aquaponic system ever built is on Taihu Lake. The lake has extensive aquaculture industry, which caused eutrophication and thus problems with algal bloom. This situation prompted researchers to search for new solutions. They decided to try a technology called Aqua Biofilter, which is designed to remove the nutrients that cause algal blooms. This resulted in an aquaponic system which covers 1.6 hectares, and is used to cultivate rice in fish ponds (Duncan 2014). Vietnam: Trang and Brix (2014) constructed an aquaponic system in the Mekong Delta, which is one of the most productive aquaculture areas in Vietnam. They built three outdoor pilot-scale closed integrated aquaponic systems (3 x approx. 2 m3), and showed that these can provide significant water savings and enable nutrient recycling compared with traditional fish ponds, and also bring additional profit to the fish farmers.
Iran: An experimental aquaponic system was designed at the Vali-e-Asr University of Rafsanjan based on the UVI model in order to investigate the effects of foliar applications of some micro- and macronutrients on tomato growth and yield in comparison with a hydroponic system. The aquaponic system consists of three separate identical aquaponic units. Each unit has a fish rearing tank, a clarifier, a filter tank, a degassing tank, and a plant growth bed unit (Roosta & Afsharipoor 2012).
United Arab Emirates: In late 2013 one of the world's biggest commercial aquaponic systems was built by Paul Van der Werf from Queensland's Earthan Group. The farm consists of a 4,500 m2 shed which produces around 40 tonnes of tilapia. The facility is also piloting a breeding program for juvenile barramundi. The systems use waste water from a nearby food manufacturer, which would otherwise be dumped in the desert. The only vulnerability of the system is that without evaporative cooling, temperatures in the greenhouse can reach 68°C (Smith 2015).
Barbados has a tropical oceanic climate with little variation in temperatures (approx. 20-32 °C) due to the cooling easterly trade winds from the Atlantic Ocean. An experimental aquaponic system with a volume of approximately 6 m3 was constructed in 2009 with the purpose of obtaining parameters for improving the system, and to make management recommendations with the goal of optimizing fish and plant biomass outputs (Connolly & Trebic 2010). United States Virgin Islands: The University of the Virgin Islands (UVI) commercial scale aquaponic system has become the model for many subsequent systems. The aquaponic system performed well over a sustained period of time, and produced tilapia continuously for 4 years. During that time, two trials were conducted to evaluate the production of basil and okra, which was found to be dramatically higher than in control field production (Rakocy et al. 2003).
Hawaii: Kunia Country Farms began operations in 2010, and is now one of the largest aquaponic farms and producer of leafy greens in the state of Hawaii. Their system is composed of three fish tanks containing tilapia, eighteen grow beds (deep water culture with styrofoam floats), and one sump tank. Each grow bed can hold between 1650 and 3300 plants. The whole system has a water volume of approximately 380 m3. Since the electrical needs of the system are low but still very costly in Hawaii, they plan to build 20 kW photovoltaic system which will generate enough solar power to make the farm electric grid-neutral.
Lennard & Leonard 2004 used Murray cod (Maccullochella peelii peelii) and lettuce (Lactuca sativa) to test differences between two aquaponic flood regimes: (a) reciprocal flow, and (b) constant flow. Their experimental system consisted of 12 separate identical aquaponic units. Each unit had one fish tank, a biofilter, and a hydroponic grow bed. Both systems performed well, but the system with constant flow showed better results in terms of lettuce yield.
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