Aquaponics

 

A small, portable aquaponics system

Aquaponics portmanteau of the terms aquaculture and hydroponic.

Aquaponic systems vary in size from small indoor or outdoor units to large commercial units, using the same technology. The systems usually contain fresh water, but salt water systems are plausible depending on the type of aquatic animal and which plants.[citation needed] Aquaponic science may still be considered to be at an early stage, relative to other sciences.

Contents

[edit] Function

Aquaponics consists of two main parts, with the aquaculture part for raising aquatic animals and the hydroponics part for growing plants.[1] Typical components include:

  • Rearing tank: the tanks for raising and feeding the fish;
  • biofilms, and for settling out fine particulates;
  • Biofilter: a place where the nitrification bacteria can grow and convert ammonia into nitrates, which are usable by the plants;[1]
  • Hydroponics subsystem: the portion of the system where plants are grown by absorbing excess nutrients from the water;
  • Sump: the lowest point in the system where the water flows to and from which it is pumped back to the rearing tanks.

Depending on the sophistication and cost of the aquaponics system, the units for solids removal, biofiltration, and/or the hydroponics subsystem may be combined into one unit or subsystem,[1] which prevents the water from flowing directly from the aquaculture part of the system to the hydroponics part.

[edit] Nitrification

Nitrification, the aerobic conversion of ammonia into nitrates, is one of the most important functions in an aquaponics system as it reduces the toxicity of the water for fish, and allows the resulting nitrate compounds to be removed by the plants for nourishment.[1] Ammonia is steadily released into the water through the excreta and gills of fish as a product of their metabolism, but must be filtered out of the water since higher concentrations of ammonia (commonly between 0.5 and 1 ppm)[citation needed] can kill fish. Although plants can absorb ammonia from the water to some degree, nitrates are assimilated more easily,[2] thereby efficiently reducing the toxicity of the water for fish.[1] Ammonia can be converted into other nitrogenous compounds through healthy populations of:

In an aquaponics system, the bacteria responsible for this process form a biofilm on all solid surfaces throughout the system that are in constant contact with the water. The submerged roots of the vegetables combined have a large surface area, so that many bacteria can accumulate there. Together with the saliency of ammonia and nitrites in the water, the surface area determines the speed with which nitrification takes place. Care for these bacterial colonies is important as to regulate the full assimilation of ammonia and nitrite. This is why most aquaponics systems include a biofiltering unit, which helps facilitate growth of these microorganisms. Typically, after a system has stabilized ammonia levels range from 0.25 to 2.0 ppm; nitrite levels range from 0.25 to 1 ppm, and nitrate levels range from 2 to 150 ppm.[citation needed] During system startup, spikes may occur in the levels of ammonia (up to 6.0 ppm) and nitrite (up to 15 ppm), with nitrate levels peaking later in the startup phase.[citation needed] Since the nitrification process acidifies the water, non-sodium bases such as potassium hydroxide or calcium hydroxide can be added for neutralizing the water’s pH[1] if insufficient quantities are naturally present in the water to provide a buffer against acidification. In addition, selected minerals or nutrients such as iron can be added in addition to the fish waste that serves as the main source of nutrients to plants.[1]

A good way to deal with solids buildup in aquaponics is the use of worms, which liquefy the solid organic matter so that it can be utilized by the plants and/or animals.

[edit] Hydroponics subsystem

Plants are grown as in hydroponics systems, with their roots immersed in the nutrient-rich effluent water. This enables them to filter out the ammonia that is toxic to the aquatic animals, or its metabolites. After the water has passed through the hydroponic subsystem, it is cleaned and oxygenated, and can return to the aquaculture vessels. This cycle is continuous. Common aquaponic applications of hydroponic systems include:

  • Deep-water raft aquaponics: styrofoam rafts floating in a relatively deep aquaculture basin in troughs.
  • Recirculating aquaponics: solid media such as clay beads, held in a container that is flooded with water from the aquaculture. This type of aquaponics is also known as closed-loop aquaponics.
  • Reciprocating aquaponics: solid media in a container that is alternately flooded and drained utilizing different types of siphon drains. This type of aquaponics is also known as flood-and-drain aquaponics or ebb-and-flow aquaponics.
  • Other systems use towers that are trickle-fed from the top, nutrient film technique channels, horizontal PVC pipes with holes for the pots, plastic barrels cut in half with gravel or rafts in them. Each approach has its own benefits.[3]

Most green leaf vegetables grow well in the hydroponic subsystem, although most profitable are varieties of chinese cabbage, lettuce, basil, roses, tomatoes, okra, cantaloupe and bell peppers.[2] Other species of vegetables that grow well in an aquaponic system include beans, peas, kohlrabi, watercress, taro, radishes, strawberries, melons, onions, turnips, parsnips, sweet potato and herbs.[citation needed] Since plants at different growth stages require different amounts of minerals and nutrients, plant harvesting is staggered with seedings growing at the same time as mature plants. This ensures stable nutrient content in the water because of continuous symbiotic cleansing of toxins from the water.[4]

[edit] Aquaculture subsystem

Freshwater fish are the most common aquatic animal raised using aquaponics, although freshwater crayfish and prawns may also be used.[9] may also be used, if the fish in the system need not be edible.

[6]

[edit] Normal operations

Aquaponic systems do not typically discharge or exchange water under normal operation, but instead recirculate and reuse water very effectively. The system relies on the relationship between the animals and the plants to maintain a stable aquatic environment that experience a minimum of fluctuation in ambient nutrient and oxygen levels. Water is only added to replace water loss from absorption and transpiration by plants, evaporation into the air from surface water, overflow from the system from rainfall, and removal of biomass such as settled solid wastes from the system. As a result, aquaponics uses approximately 2% of the water that a conventionally irrigated farm requires for the same vegetable production.[citation needed] This allows for aquaponic production of both crops and fish in areas where water or fertile land is scarce. Aquaponic systems can also be used to replicate controlled wetland conditions that are useful for water treatment by reclaiming potable water from typical household sewage.[citation needed] The nutrient-filled overflow water can be accumulated in catchment tanks, and reused to accelerate growth of crops planted in soil, or it may be pumped back into the aquaponic system to top up the water level..

The three main inputs to the system are water, Spawn or fry may be added to replace grown fish that are taken out from the system to retain a stable system. In terms of outputs, an aquaponics system may continually yield plants such as vegetables grown in hydroponics, and edible aquatic species raised in an aquaculture.

[edit] History

[edit] Ancient

Aquaponics has ancient roots, although there is some debate on its first occurrence:

[edit] Regions

[edit] North America

[edit] United States

While the development of aquaponics is often attributed to the various works of the New Alchemy Institute and the works of Dr. Mark McMurtry et al. at the North Carolina State University, many papers of initial development of aquaponics concepts pre-date both institutions by nearly a decade.

Tom and Paula Speraneo, owners of a small greenhouse operation near West Plains, Missouri, modified the North Carolina State method and raised tilapia in above-ground tanks inside a solar greenhouse. The effluent from the tanks was used to fertigate gravel-cultured vegetables in raised benches.

In addition, the Speraneos manipulated the watering cycle, and this methodology of the Speranos forms the basis for the style of “flood & drain” media grow bed aquaponics systems that have been widely adopted in Australia based on models promoted by Joel Malcolm and Murray Hullam, and are now gaining increasing popularity in the United States.

Inspired by the successes of the New Alchemy Institute and the North Carolina State University with aquaponics, other institutes followed suit. Besides the reciprocating aquaponics based on the techniques developed by Dr. Mark McMurtry et al. at the North Carolina State University, Dr. James Rakocy and his colleagues at the University of the Virgin Islands researched and developed the “Deep Water” or “Raft Culture” aquaponics[18] The system combines tilapia with various vegetables.

In 1997 Rebecca L. Nelson and John S. Pade began publishing the Aquaponics Journal, a quarterly scientific journal that brings together research and various applications of aquaponics from around the globe.

Recent years have seen a shift towards community integration of aquaponics, such as the nonprofit foundation [20] In addition, aquaponic gardeners from all around the world have gathered in online community sites and forums to openly share their experiences and promote the development of this form of gardening.

[edit] Canada

The first aquaponics research in Canada was a small system added onto existing aquaculture research at a research station in Lethbridge.[citation needed] Canada saw a rise in aquaponics setups throughout the ’90s, predominantly as commercial installations, that for example combine trout with floating lettuce production,[21] or to water fruiting vegetable crops that warm up the water too much to be recirculated back into the fish ponds. Eels are also known to be raised.[citation needed] A setup based on the deep water system developed at the University of Virgin Islands was built in a greenhouse at Brooks, Alberta where Dr. Nick Savidov and colleagues researched aquaponics from a background of plant science. The team made findings on rapid root growth in aquaponics systems, on closing the solid waste loop, and that because of certain advantages in the system over traditional aquaculture, the system can run well at a low pH level, which is favoured by plants but not fish. The Edmonton Aquaponics Society in Northern Alberta is adapting Dr. Savidov’s commercially sized system to a smaller scale prototype that can be operated by families, small groups, or restaurants. They intend to further develop the closed solid waste loop.

[edit] South America

[edit] Barbados

[22]

[edit] Asia

[edit] Bangladesh

 

Vegetable production part of the low-cost Backyard Aquaponics System developed at Bangladesh Agricultural University

Bangladesh is the world’s most densely populated country. Most of its farmers use/misuse agrochemicals to enhance food production/storage life. However, the country is yet to establish a good monitoring system to ensure chemical-residue free safe food in the market,[24] capable city dwellers are looking for a better way to grow their own safe foods for domestic consumption. To help support mainly this client group and people living in adverse climatic conditions such as salinity-prone southern part and flood-prone haor area in the eastern region, a low-cost model of backyard aqaponics system[25] has been developed by Professor Dr. M.A. Salam at the Department of Aquaculture of Bangladesh Agricultural University, Mymensingh.[26] The initial model has been developed in 2011, and demonstrated and reported to the press in January 2012.[27] Further research may be necessary to develop appropriate models for different situations among client groups.

[edit] Taiwan

Taiwan is a densely populated island that is faced with freshwater scarcity. Dispensation of water is government-controlled. The closed-loop system of aquaponics is used by agricultural farmers to save water by also rearing fish, while fish farmers grow plants that filter the water from the fish tanks. Taiwan Aquaponics Association is the not-for profit federation to promote Aquaponics at Taiwan. [27]

[edit] Japan

Japan is another highly densely populated country that has a long history of agricultural innovation and technological improvement. Aquaponics however, has only recently been introduced to this country, and there have been some projects to integrate aquaponics into communities in 2011 Tōhoku earthquake and tsunami. Japan Aquaponics, founded by Aragon St-Charles, is a leading social enterprise that is pioneering the use of aquaponics in this country.

[edit] Australia

Due to a ban on tilapia in all states, native freshwater fish including Silver Perch, Jade Perch, Sleepy Cod, Murray Cod and Barramundi are popular in aquaponics and aquaculture systems,[2] along with non-native rainbow trout, brown trout and Crayfish such as common yabby and Redclaw.

The law changed in WA June 2012, banning tilapia.

[edit] Pros and cons

The unique advantages of aquaponic systems are:

  • Conservation through constant water reuse and recycling.
  • Organic fertilization of plants with natural fish emulsion.
  • The elimination of solid waste disposal from intensive aquaculture.
  • The reduction of needed cropland to produce crops.
  • The overall reduction of the environmental footprint of crop production.
  • Building small efficient commercial installations near markets reduces food miles.
  • Reduction of pathogens that often plague aquaculture production systems.
  • Reduction of erosion by eliminating the need to plough the soil.

Some conceivable disadvantages with aquaponics are:

  • Initial expenses for housing, tank, plumbing, pumps, and grow beds.
  • The infinite number of ways in which a system can be configured lends itself to equally varying results, conflicting research, and successes or failures.
  • Some aquaponic installations rely heavily on man-made energy, technological solutions, and environmental control to achieve recirculation and water/ambient temperatures. However, if a system is designed with energy conservation in mind, using alternative energy and a reduced number of pumps by letting the water flow downwards as much as possible, it can be highly energy efficient.
  • While careful design can minimize the risk, aquaponics systems can have multiple ‘single points of failure’ where problems such as an electrical failure or a pipe blockage can lead to a complete loss of fish stock.
  • Like all aquaculture based systems, stock feed usually consists of fish meal derived from lower value species. Ongoing depletion of wild fish stocks makes this practice unsustainable. Organic fish feeds may prove to be a viable alternative that negates this concern. Other alternatives include growing [30]

[edit] Gallery

[edit] See also

[edit] References

  1. ^ http://www.aces.edu/dept/fisheries/aquaculture/documents/309884-SRAC454.pdf
  2. ^ http://www.backyardaquaponics.com/Travis/aquaponic.pdf
  3. ^ Lennard, Wilson A.; Leonard, Brian V. (2006), “A comparison of three different hydroponic sub-systems (gravel bed, floating and nutrient film technique) in an Aquaponic test system”, Aquacult Int (14): 539–550
  4. ^ Rakocy, James E.; Shultz, R. Charlie; Bailey, Donald S.; Thoman, Eric S. (2004), M.A. Nichols, ed., “Aquaponic production of tilapia and basil: Comparing a batch and staggered cropping system”, Acta Hort (ISHS) (648)
  5. ^ Backyard Aquaponics. “Fish Page: Other Species”. http://backyardaquaponics.com/information/45-fish.html. Retrieved December 2011.
  6. ^ http://aquaponicscommunity.com/group/bluegillorbreamgrowers. Retrieved December 2011.
  7. ^ Aquaponics Community. “Catfish Growers”. http://aquaponicscommunity.com/group/catfishgrowers. Retrieved December 2011.
  8. ^ Aquaponics Community. “Koi Growers”. http://aquaponicscommunity.com/group/koigrowers. Retrieved December 2011.
  9. ^ Aquaponics Community. “Goldfish Growers”. http://aquaponicscommunity.com/group/goldfishgrowers. Retrieved December 2011.
  10. ^ Boutwell, J. (2007, December 16). Aztecs’ aquaponics revamped. Napa Valley Register.
  11. ^ Rogosa, E. (2010). Aquaponics: How does aquaponics work? Retrieved November 26, 2010.
  12. ^ Crossley, Phil L. (2004), “Sub-irrigation in wetland agriculture”, Agriculture and Human Values (21): 191–205
  13. ^ BOUTWELL, JUANITA (december 15, 2007), “Aztecs’ aquaponics revamped”, Napa Valley Register
  14. ^ “Space agriculture for habitation on mars and sustainable civilization on earth”, Recent Advances in Space Technologies, 2009. RAST ’09: 68–69, 2009
  15. ^ [1]
  16. ^ McMurtry, M. R., Nelson, P.V., & Sanders, D.C. (1988). Aqua-vegeculture systems. International Ag-Sieve, 1(3), article 7.
  17. ^ Bocek, A. (2010). Water harvesting and aquaculture for rural development. Retrieved December 24, 2010.
  18. ^ University of the Virgin Islands, Agricultural Experiment Station [AES] (2010). Aquaculture – Aquaponic Systems. Retrieved November 27, 2010.
  19. ^ Harris, L. Kasimu. “http://www.louisianaweekly.com/aquaponics-being-taught-in-vietnamese-community/”. Louisiana Weekly. http://www.louisianaweekly.com/aquaponics-being-taught-in-vietnamese-community/. Retrieved 13 February 2012.
  20. ^ Staff (29 April 2012) Fish farming in a high-rise world BBC News US and Canada, retrieved 30 April 2012
  21. ^ Nelson, R. L. (2007). 10 systems around the world. Aquaponics Journal, 46(3), 8.
  22. ^ c Bishop, M., Bourke, S., Connolly, K., & Trebic, T. (2009). Baird’s Village aquaponics project: AGRI 519/CIVE 519 Sustainable Development Plans. Holetown, Barbados: McGill University.
  23. ^ Závodská, A., & Dolly, D. (2009). A comparison of small scale farming in Barbados, Dominica, and Trinidad and Tobago. San Juan: Association for International Agricultural and Extension Education (AIAEE).
  24. ^ Some important talks on pest management (বালাই দমন সংক্রান্ত জরুরি কিছু কথা). In Bengali. The Daily Sangbad, 29 January 2011
  25. ^ ‘Backyard Aquaponics System’ An outstanding research by BAU teacher. The Independent, January 26, 2012
  26. ^ Fish & vegetable culture through aqaponics technology (এ্যাকোয়াপনিক্স প্রযুক্তিতে মাছ-সবজি চাষ). In Bengali. The Daily Janakantha, January 28, 2011
  27. ^ Innovation of a BAU researcher: “Aquaponics technology” three times production without any cost (বাকৃবি গবেষকের উদ্ভাবন ‘একোয়াপনিক্স প্রযুক্তি’ খরচ ছাড়াই উৎপাদন তিন গুণ). In Bengali. The Daily Kalerkantho, January 25, 2011
  28. ^ Rogosa, E. (2010). Organic aquaponics. Retrieved November 27, 2010.
  29. ^ Amadori, Michael (2012). “Fish, Lettuce and Food Waste Put New Spin on Aquaponics”. http://www.newswise.com/articles/view/578382/?sc=rssn&utm_source=feedburner&utm_medium=feed&utm_campaign=Feed%3A+NewswiseScinews+%28Newswise%3A+SciNews%29 Environmental Science and Forestry (ESF)
  30. ^ Royte, Elizabeth (July 5, 2009). “Street Farmer”. The New York Times Company. http://www.nytimes.com/2009/07/05/magazine/05allen-t.html?sq=aquaponics&st=cse&adxnnl=1&scp=10&pagewanted=2&adxnnlx=1299564045-NgXx2LMa3/ee2z6MNr9YdA. Retrieved 8 March 2011.

[edit] External links

This article uses material from the Wikipedia article Aquaponics, which is released under the Creative Commons Attribution-Share-Alike License 3.0.


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