Freshwater fish farming plays an important role in aquaculture production. This work combines three main components, aquatic recirculation system, solar water treatment, and photovoltaic plan system, which shape an integrated system that supports the sustainability of Camarones River, a desert climate location in the northern region of Chile.
Fish is an essential source of food for 3 billion people globally, constituting at least 50% of the animal proteins and essential minerals consumed by 400 million people in the poorest countries.
In this context, according to the UN Food and Agriculture Organization (FAO), in 2018 the global aquaculture production of food fish was 80 million tons, and sales corresponded to USD $231.6 billion, providing 10.8 kg of fish per capita in 2016.
It should be noted that Freshwater fish farming plays an important role in aquaculture production, 47.5 million tons of fish were reached in 2016.
Considering that sustainable development cannot be achieved without resilient livelihoods, we chose, as an example of resilience, Camarones, a village in the Arica and Parinacota Region in the northern part of Chile.
This town as an interior desert climate, is over 1,000 m above sea level, without coastal oceanic influence. In addition, the Camarones Valley is characterized by being arid, with a null annual rainfall, and with average temperatures of 18 ºC.
Moreover, the days are mostly filled with clear skies, and drier than the coastal desert climate, with an average relative humidity of 50%.
A pilot-scale system driven with solar energy for river shrimp (Cryphiops caementarius) farming, using solar water treatment technology, was implemented, to reduce the arsenic content in the natural waters of the Camarones River.
Considering all different parts of the problem, to implement the solution, a circular economy concept is considered to ensure sustainability.
The greatest potential of the Camarones area is an average solar radiation of 2,957 kWh m2 year2, which represents an opportunity to use solar energy for different applications, such as photovoltaic, thermos solar technologies, and solar water treatments among others.
“Compared to land-based crops and animal production, fish are quite sensitive to water contaminants; therefore, aquaculture production is vulnerable to deterioration in water quality.”
Currently, recurrent diseases in aquaculture and climatic effects have brought attention to the aquaculture industry, to implement land-based aquaculture recirculation systems as an alternative to traditional open pond and cage culture systems.
In the aquaculture recirculation system, fish feed is virtually the only source of carbon and nitrogen solids, which are the main sources of pollution. It is estimated that, by weight, the amount of solids produced in an aquaculture recirculation system represents approximately 30–60% of the applied fish feed.
“Fish feed contains 25–65% protein, as does shrimp feed, corresponding to 4.1–10.7% organic nitrogen. Only about 20–30% of the nitrogen in the applied feed is retained by the fish, while the rest is excreted in the water.”
Therefore, it is estimated that approximately 75% of the protein nitrogen from fish is released into the water, with a significant portion composed of total ammonia nitrogen. Ammonia is toxic to many fish, even at low concentrations.
Rainbow Trout (Oncorhynchus mykiss) is a resistant, fast-growing fish, easy to spawn, tolerant to a wide range of environments and manipulations, of soft meat, and highly versatile. The quality of water for rainbow trout farming is given by the set of physical, chemical, and biological properties, as seen in Table 1.
It is worth it to mention that the monitoring of water quality parameters of the trout production was optimized in a previous work of the Fondo de Innovación para la Competitividad Regional (FIC-R).
Another parameter to consider is the feeding, which must be palatable and contain all of the necessary elements to ensure optimal quality of the meat of the specimens, being the proteins (which must contain at least 10 essential amino acids) and the essential fatty acids indispensable for the construction of tissues and energy for the fish.
The river shrimp live in rocky bottom sectors, remaining, during the day, hidden among the coastal vegetation, submerged or under rocks at the bottom of the river, and their activity is preferably nocturnal.
The highest concentration of larvae is found in the river mouths, this is due to a positive affinity to salinity; later they go higher upstream of the river. It is worth it to mention that the quality of the water for the production of river shrimp is also important.
Table 2 shows the main physical and chemical properties that a body of water must comply with.
The Integrated Aquaculture Recirculation System (IARS)
IARS was designed, built, and implemented in a period of 3 years, from January 2018 to September 2020, including the co-construction stage, which was of great relevance to incorporate aspects, such as the shrimp–fish relationship.
Moreover, the land conditioning, planimetry, civil works, and the installation of three main components were carried out, as detailed below:
Component 1: Solar Water Treatment Plant
The Camarones is characterized by its natural waters (surface and underground) with high levels of arsenic. According to the above, the solar water treatment plant was designed and implemented considering the characteristics of the sector related to water quality, solar radiation, among others.
Through this plant and with the support of solar radiation, it is possible to reach arsenic concentrations within 0.03 and 0.05 mg L-1, removing 95% of the arsenic present in the natural waters of the Camarones River.
Component 2: Aquaculture Recirculation System
It is a terrestrial aquaculture recirculation system, where the water is partially reused and the simultaneous farming of shrimp and trout is achieved, providing a stable farming medium, which must be managed in an integral way.
“Among all of the advantages offered by this type of system, the principal is the reduced water consumption, and for this initiative, a system renewal was considered, between 5 and 10% of the entire farming volume per day.”
On the other hand, these systems allow better opportunities in waste management, nutrient recycling, hygienic disease management, and greater control of biological contamination. In addition, with these systems, it is possible to opt for a greater variety of farming of hydro biological species, considering the production of fry until their fattening.
Component 3: Photovoltaic Plant
For an aquaculture recirculation system and solar water treatment plant operating, a photovoltaic plant was installed that supplies the electrical energy necessary for the operation and functioning of the different equipment in an integrated aquaculture recirculation system. In addition, a generator set was considered as backup in emergency situations.
In the circular economy, system resources, energy, and materials are reused several times, considering minimal processing for each subsequent use, through a closed circuit.
Figure 1 shows the implemented system, which, through the three main components (solar water treatment plant, aquatic recirculation system and photovoltaic), considering the principles of the circular economy, can aspire to sustainability.
To aspire to sustainable development through a circular economic model, it must be considered that operating the integrated aquatic recirculation system plant will generate a liquid waste of salts in aqueous solution and sludge through the solar water treatment and the aquatic recirculation system.
This waste will be disposed in desiccating pools for liquid waste, whereby decantation the supernatant liquid will be used to irrigate the green areas in integrated aquatic recirculation system plant, halophyte species resistant to saline waste.
On another hand, the sludge resulting from aquaculture systems produced by feces and food remains have higher carbon (C), nitrogen (N), and phosphorus (P) contents than natural sediments, nutrients that will be used as plant fertilizer.
“The plant species to be farmed are typical from the area, such as carrot, onion, garlic, alfalfa, among others. The simultaneous production of agricultural and aquaculture products is not a novelty. There are several initiatives and studies in this regard.”
However, achieving this diversification of products from solar-treated water is very relevant. In this sense, this study considers a circular economy approach, to manage the waste generated by the integrated aquatic recirculation system, whose waste can be valorized through agricultural products and savings in water consumption.
In addition, through the installation and implementation of the integrated aquatic recirculation system, it contributes, reducing over-exploitation of the aquaculture on land and promoting a more sustainable use of aquatic resources, since it generates a sustainable management of the river shrimp resource, by restoring the species taken from the river.
Discussion and Conclusions
This work combines three main components, aquatic recirculation system, solar water treatment, and photovoltaic plan system, which shape an integrated system that supports the sustainability of Camarones.
This initiative encourages the mitigation of environmental impacts, considering: the reduction of greenhouse gases, the reuse of liquid waste, and sludge for irrigation and as fertilizers, respectively.
Moreover, it is possible to consider the adoption of the principles of the circular economy in the integrated aquaculture recirculation system plant. Furthermore, the simultaneous obtaining of halophytic plants and ornamental forage species that would support the preservation of the natural ecosystem of the sector is allowed.
“In addition, to obtain nutrients through the aquaculture recirculation system, a source of nitrogen and phosphorus, for agricultural crops, represents an alternative for the final disposal of these residues.”
The important thing, when reusing, is to promote a zero liquid discharge, and by adding value to the
waste, this initiative becomes sustainable and friendly to the environment, fitting all of the principles and strategies of the circular economy.
For this reason, it is necessary to change the way in which society produces and consumes.
This is a summarized version developed by the editorial team of Aquaculture Magazine based on the review article titled “INTEGRATED AQUACULTURE RECIRCULATION SYSTEM (IARS) SUPPORTED BY SOLAR ENERGY AS A CIRCULAR ECONOMY ALTERNATIVE FOR RESILIENT COMMUNITIES IN ARID/SEMI-ARID ZONES IN SOUTHERN SOUTH AMERICA:A CASE STUDY IN THE CAMARONES TOWN” developed by: LORENA CORNEJO-PONCE, Universidad de Tarapacá, Arica, Chile, PATRICIA VILCA SALINAS, Universidad de Tarapacá, Arica, Chile, HUGO LIENQUEO-ABURTO, Universidad de Tarapacá, Arica, Chile, MARÍA J. ARENAS, Universidad de Tarapacá, Arica, Chile, RENZO PEPE-VICTORIANO, Universidad Arturo Prat, Arica, Chile, EDWARD CARPIO, Universidad Nacional de Ingeniería, AND JUAN RODRÍGUEZ, Universidad Nacional de Ingeniería.
The original article was published on DECEMBER 2020, through WATER under the use of a creative commons open access license.
The full version can be accessed freely online through this link: doi:10.3390/w12123469