aquaponics

Aquaponics is a recircu-lation system in which plants are used as nitro-gen filters for dischar-

ges from aquaculture activities, thus obtaining a twofold bene-fit: filtering water used for fish and obtaining a by-product that increases the company’s profitabili-ty. Furthermore, products obtained from this system are very healthy

since they do not contain chemical fertilizers or pesticides.

Countries such as Australia, Canada, the United States, Holland, Korea, and Mexico have reported successes in this regard. Technology improves and is adapted to the different conditions of each of them, such as: climate, cultivation species, regulations, production costs, among others.

Aquaponics tests, experimen-tal systems, and commercial farms have been tried out in Mexico for the last 7 years.

CICESEa In 2008, an experiment in which effluents of an aquaculture system for farming Nile tilapia (Oreochromis niloticus) was conducted at the Department of Aquaculture of the

Aquaponics is Growing in Mexico

Bofish farm has tunnel-type greenhouses for farming Nile tilapia and zenith-type greenhouses for cultivating lettuce and basil.

By: Carlos León Ramos*

Due to the problems of water shortage and limitation, aquaponics is growing day by day. Despite the fact that it is in the experimental stages, more countries are increasingly adding themselves to the implementation of this system.

Center of Scientific Research and Higher Education (CICESE). The initial farming density amounted to 30.9 kg/m3 and the final one, of 50.7 kg/m3, together with the cul-tivation of strawberries (Fragaria ananassa, camarosa variety), to study the dynamics of three macro-nutrients in the integral system. The system was designed so that the water coming from the recirculation system could flow through the aqua-ponics system at a 6 liter per minute rate. 28-10.16 cm. (4”) diameter and 6 m long pipes, amounting as a whole, to 168 linear meters, were used. The recirculation system’s ave-rage temperature is 25.9oC, and in the aquaponics system, 20oC; the average pH for both systems is 7.0.

400 strawberry plantules were grown using the nutrient flow tech-nique using perlite as substrate. The experiment lasted 92 days and a growth rate of 3.7 grams a day, with a feed conversion rate of 2.0 (that is, 2 kilograms of feed to pro-duce 1 kilogram of fish) and a feed efficiency rate of 0.5 was obtained for tilapia.

The nitrogen-containg com-pound and total phosphorous removal efficiency in the recircu-lation system biofilter, as well as in the aquaponics nutrient film sys-tem, were determined during the experiment.

Certain nutritional deficiencies were determined in the strawbe-rries being grown and therefore, it was necessary to add potassium, calcium, and iron. The following assessments intend to characterize the mass flow in order to delimit and dimension the size of a straw-berry cultivation (F. ananassa) based on the cultivation of tilapia (O. niloticus).

Acuicultura del desiertob

In the coastal area of Baja California, Mexico, about 30% of the popula-tion is involved in agro-industrial activities. The shortage of water has caused a large uncertainty as regards the economic development of their activity, since the region’s annual rainfall does not exceed 400 mm. Currently, it is considered a desert area and the salinization of the aquifers has been a severe pro-blem. The area used for agricultural purposes has decreased 20% in the last five years and consequently, a strong and severe decrease in jobs

Lettuces 14 days after transplant.

has occurred in rural areas. Due to these problems,

Acuicultura del Desierto S. de P. R. de R.L., an association of rural production was organized in 2004. Since then, it produces commer-cially aquaculture species such as tilapia and rainbow trout, besides organic vegetables and herbs and is dedicated to the technological development of agro-industrial sys-tem, the latter being the area of greater focus.

The aquaponics system is loca-ted inside a one thousand squa-re meter greenhouse, formed by seven, three meter diameter geo-membrane tanks. These cultivation units are connected to a biofilter in which nitrification takes place and thereafter, a 35 PVC pipe system, on a nutrient film (NFT) is used; as well as four 27 meter long x 1 meter wide ponds for a floating root system on polystyrene sheets for growing basil.

Approximately three tons of tilapia per cycle and a weekly production of 300 to 350 grams of basil per square meter are obtained with this system. Tilapia is stocked in the system at 50 grams and harvested at 400 grams. Crops are

rotated weekly in order to obtain a constant vegetable production.

UAGc

Since 2001, as part of the acade-mic supplement in Aquaculture Engineering which is taught at the Marine Sciences Laboratory of the Autonomous University of Guadalajara located in Barra de Navidad, Jalisco, trials are conduc-ted with aquaponics systems for the purpose of contributing to the knowledge of this technique of aquaculture production.

During the first trial, 30 tila-pias with an average weight of 95 grams were stocked in a 600 liter fiber glass tank (at a work volume of 450 liters). The fish were measu-red and weighed at the beginning of the experiment and every 15 days, in order to adjust their daily feed ration to 3% of the total bio-mass. This rank was placed on a wooden base to cause a 5o slope in its bottom to allow cleaning it. A wooden support was placed in the tank’s upper portion, to which a 1/3 HP capacity continual use hydraulic pump was attached to send the water of the tilapia tank to the hydroponic beds. 24 plastic

faucets with rubber hoses were inserted into the pipes coming from the pump in order to distribu-te drip water on the plants’ roots.

Then, 16–10 cm. long cucumber plantules were planted for each hydroponic bed (n=2), which con-sisted in 0.6 m3 capacity fiber glass chutes. Each chute was filled in the following order: from the bottom upward, 0.18 m3 of gravel (> 2 cm. in diameter) and fine gravel (0.5 cm. in diameter), and 0.12 m3 of sand (< 0.2 cm in diameter), all of which were previously washed, disinfected, and dried in the sum prior to being introduced into the beds. A mesh was placed between each gravel and sand layer in order to prevent them from mixing. Just like in the case of the fish tank, the hydroponic beds were placed on wooden bases with a 10º slope in order for the filtered water to fall once again, by gravity, into the tilapia container. Additionally, nitrifying bacteria were placed in the beds 15 days after having intro-duced the fish into the tank and 15 days prior to planting the plants. The planting of the plants marked the beginning of the trial. Nitrogen, ammonia, nitrite and nitrate con-centration was recorded weekly at the tilapia tank’s inflow and outflow to verify the operation of the nitrification process by bacteria in the hydroponic beds. During the entire trial, nitrogen levels in their different forms were acceptable for growing tilapia.

The cucumber harvest began on the eighth week after they were planted. It was possible to harvest almost 2.6 Kg of vegetables in a two and a half month cultivation period (142 g on average per cucumber), whereas the final ave-rage weight of the fish was 125 g (0.4 g gain/day). In comparison to other works, the yields obtained can be considered low, since there were technical problems during the trial that prevented a larger efficiency of the system’s biological components. One of these pro-blems was that at the end of the experiment, 20% of the fish were females; therefore energy was used for reproductive functions, instead of for growth. On the other hand, and despite that the plants had abundant florescence toward the

This system is made of 28-10.16 cm. (4”) diameter and 6 m long pipes, amounting as a whole, to 168 linear meters.

seventh week of cultivation, fer-tilization was very poor due to the lack of care against pests and diseases in the greenhouse.

Similar aquaponic experiments were conducted in latter years, using 3 fiber glass chutes to grow beefsteak tomatoes, obtaining simi-lar results.

Thereafter, a new design was prepared in Guadalajara, Jalisco, in which a fiber glass tank with Mozambique tilapia (Oreochromis mossambicus) was used and gra-vity filtration components were installed: cylindrical-conical settler, mineralization tank with anaero-bic bacteria and two lettuce chu-tes using a floating root system. Simultaneously Australian red claw crayfish (Cherax quadricarinatus) were being produced in four ear-

then ponds covered with 600 gage polyethylene. Water with suspen-ded and dissolved solids was suc-ked into the aquaponics system to take advantage of the nutrients. Water containing solids larger than 100 microns that may settle was sucked and sent to irrigate flowers growing around the area of the experiment.

BOFISHd Bofish has 4,000 square meters, 2,000 of which are used for pro-duction in recirculation and aqua-ponics systems.

The farm has tunnel-type green-houses for farming Nile tilapia and zenith-type greenhouses for cul-tivating lettuce and basil. Water temperature required in fish green-houses amounts to 28°C, whe-

aquaponics

reas in the plant greenhouses, air temperatures of around 22°C are required. Water with fish nutrients goes from one section to the other and is recirculated once again to the fish tanks, with just one new water inflow which amounts to 1.5% of the total volume.

The aquaculture component currently consists in 19 fiber glass tanks and plastic membranes, in which monthly splitting takes place in accordance with the size of fish. Tanks are placed in different sec-tions, depending on their size and fish growth stage, the larger ones being used for the first 12 weeks (from 1 to 100 grams) and the following ones, for the remaining 24 weeks, in which fish from 500 grams to 1 kilogram are expected in 30 to 42 weeks, respectively.

In order to optimize the use of nutrients and increase the operation’s profitability, there is a filtration area in which mechani-cal and biological filters are used, through which water flows by gravity, that is, without requiring any additional pumping that may increase the cost of production or that could have an impact on the environment.

The filtration system comprises two cylindrical-conical clarifiers in which particles larger than 100 microns and that can cause pipe-line obstruction and/or the for-mation of gases and anoxic (oxy-gen-free) areas, settle. Thereafter, water circulates to 4 mineralization tanks in which the presence of heterotrophic bacteria mineralize nutrients, so plants may dispose of a larger amount thereof. After this process, there is a degasifying tank where gases such as carbon dioxide, methane, and hydrogen sulphides, produced by fish and bacteria, are released. An experi-ment to capture these gases and channel them toward the plant greenhouse, thus taking advantage of the carbon dioxide to accelerate plant growth, took place during one stage.

Last but not least, water with nutrients (or waste) travels to hydroponic chutes, where romai-ne, butterhead, and Italian lettuce, escarole, and basil are grown in a deep bed or floating root system.

Countries such as Australia, Canada, the United States, Holland, Korea, and Mexico have reported successes in this regard.

In this component, the plant is grown at densities between 30 to 20 plants per square meter, depen-ding on the variety (butterhead let-tuce, at 30 plants/m2; romaine and Italian lettuce and escarole, at 25 plants/m2; basil, at 20 plants/m2). Planting and harvesting is schedu-led weekly in order to have a uni-form removal of nutrients from the system and a constant distribution in marketing channels. Lettuce, as well as basil, has a 4 to 5 week growth period; therefore, about 1,000 and 600 plants, respectively, can be harvested per week.

In the case of tilapia, scheduling is done with a 6 week difference, to homogenize the contribution of

nutrients and to supply the conti-nuous market demand of live fish in the area. Depending on the sys-tem in which they are farmed, fish densities range from 15 to 69 kg/m3; therefore, scheduled harvests amount to 2 tonnes a month.

The farm also has experimen-tal nutrient film systems where strawberries are grown; fertigation systems where cherry and Roma tomatoes are grown, as well as beets, Swiss chard, spinach, bro-ccoli, cucumbers, squash, anthu-rium, green onion and cilantro on substrates such as coconut fiber, moss or peat, perlite and volcanic rock.

An Alternative Worth the While ConsideringAquaponic systems are a profitable and sustainable alternative for the agriculture, as well as aquaculture sector, since they are a production system in which water is taken advantage to the most; waste is taken advantage of as nutrients; space is small due to the densities handled; and energy is minimized by gravity. Hence, it is a recircu-lation system, sustainable for the environment, through which high value products are obtained in the market because these are grown with organic nutrients, free of che-micals or pesticides.

Aquaponics is a recirculation system in which plants are used as nitrogen filters for discharges from aquaculture activities.

a By: Dr. Manuel Segovia Quinterob By: Ocean. Enrique Strassburger Madrigal

c By: Doc. Manuel García Ulloa-Gómezd By: IBAC. Carlos León Ramos *carlos@acuaponia.com

Australian red claw crayfish (Cherax quadricarinatus) tanks with pipes as hidden places.

Nile tilapia (Oreochromis niloticus) culture; the initial farming density amounted to 30.9 kg/m3 and the final one, of 50.7 kg/m3

aquaponics