AquaTechnica (Apr 2021)
Fitodepuración mixotrófica en sistemas de recirculación acuícola (RAS) para el manejo sustentable de nutrientes contaminantes
Abstract
Industrial aquaculture has grown rapidly due to the increase in world demand for fish and shellfish, which has stimulated the development of aquaculture systems for the cultivation of marine species. The need to maintain high levels of productivity makes them complex unstable systems, prone to disturbances with the potential risk of causing problems of contamination of the natural environment. In intensive aquaculture operations, it is estimated that in the transformation processes for the development and growth of biomass, approximately 75% of the feed is released in the form of nitrogen and phosphorus. During the last decades, efforts have been made to develop processes for the elimination of these nutrients-pollutants, which would otherwise be released into natural water bodies causing eutrophication. The recirculating aquaculture system (RAS) is the conventional culture system; it includes a nutrient removal stage with biofilters of aerobic bacteria that favor the nitrification process, although the biofilter technology has operational difficulties such as the decrease in oxygen concentration, accumulation of organic matter and difficulty of back-rinsing, among others. Thus, options have emerged based on the activity of photoautotrophic organisms, taking advantage of the ability of aquatic plants, macro and microalgae, to effectively eliminate nutrients-pollutants (phytodepuration), consuming in addition to carbon and nitrogen, also phosphorus, the latter without the ability to be removed with nitrifying biofilters. However, this treatment strategy has not been used in intensive aquaculture due to the high availability of the area in demand, which exceeds that required by compact equipment for nitrifying biofiltration. Mixotrophic phytodepuration, which corresponds to the integration of two tertiary wastewater treatment technologies (biofiltration-autotrophic and phytodepuration), could be an efficient response for the treatment of aquaculture wastewater, given the interaction between the organisms involved. For this reason, this review focuses on the potential use of mixotrophic cultivation for the control of nutrients-pollutants in "RAS" or aquaculture wastewater, in addition to contributing to the development of circular economy.
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