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Water recirculation
Published in Richard W. Soderberg, Aquaculture Technology, 2017
Recirculating Aquaculture Systems (RAS) refer to those facilities where virtually all the water is recycled and the water requirement is only that necessary to replace losses due to evaporation, spillage, and filter backwash. RASs are used within buildings to maintain suitable water temperatures for the species of fish selected for culture. The technology of fish culture in an RAS involves meeting the following environmental requirements of the fish in a self-contained unit: Maintenance of water temperatures for optimum fish growthMaintenance of dissolved oxygen (DO) tensions suitable for efficient respiration and fish healthMaintenance of safe levels of NH3 and other toxic metabolitesMaintenance of water reasonably clear of solid waste
Effects of potassium monopersulfate on nitrification activity and bacterial community structure of sponge biocarrier biofilm in Litopenaeus vannamei aquaculture system
Published in Environmental Technology, 2023
Yazhi Luan, Yang Wang, Chao Liu, Libin Lv, Ailing Xu, Zhiwen Song
Over the last few years, the world-wide production of Litopenaeus vannamei has increased due to the increasing demand for human consumption [1]. The negative impacts of traditional aquaculture are widespread, including environmental hazards from the discharge of farm effluent, waste of water due to the absence of a water recycling system, nutrient pollution and frequent disease outbreaks in aquaculture animals [2]. Recirculating aquaculture systems (RASs) can control environmental conditions and allow for reuse of aquaculture water through filtration and purification, which helps to address some of the impacts of aquaculture systems [3]. Compared to pond aquaculture, RAS seems to provide a long-term growth advantage [4]. However, in closed aquaculture environments, a RAS can increase the risk of pathogen transmission caused by high-density farming [5]. Current disinfection methods for aquaculture water include the use of antibiotics, UV irradiation treatments and ozone to reduce the bacterial load in the water and avoid the proliferation of potentially disease-causing microorganisms [6]. These treatments are effective but have some drawbacks, such as gradual accumulation of antibiotics in water and increased resistance of animals and microorganisms to those antibiotics [7], impacts on the growth and repair mechanism of microorganisms due to UV radiation, causing growth cell death or regenerative cell death and the formation of ozone disinfection byproducts and the toxicity of residual cyclohexanone in shrimp limiting ozone wide application of RASs [6–9].
Membrane aerated biofilm reactor in recirculating aquaculture system for effluent treatment
Published in Environmental Technology, 2022
Juliana Cristina Ribeiro Almeida, João Miguel Merces Bega, Luan de Souza Leite, Jefferson Nascimento de Oliveira, Liliane Lazzari Albertin, Tsunao Matsumoto
Recirculating Aquaculture System (RAS) is a unique indoor fish farming method developed to overcome the shortcomings of traditional outdoor fish farming [8], especially in areas with limited water availability. In many RAS, up to 99% of wastewater is recycled using different purification devices [18,19]. Such a system can be used on both small and large scales due to the quality recovery of effluents through the treatment system [20], and the necessity for a small water volume replacement because of the low evaporation rate and sedimented organic matter discharging in comparison to traditional cultivation systems in excavated tanks [21,22]. Besides, it also offers environmental benefits once it can be used in small areas with high proteins production, contributing to negative anthropogenic impacts reduction on the environment in comparison, for example, to soybean plantation and pasture [19]. Conversely, its main limitations are its capital and operating expenses, which lead to the requirement for careful management [1,18,23].