56 SEPTEMBER • WORLD AQUACULTURE • WWW.WAS.ORG AQUACULTURE ENGINEERING SOCIETY CONTRIBUTED ARTICLE: Pilot Bioreactor Performance for the Zero-Emission of Total Suspended Solids Generated in Commercial Atlantic Salmon Land-Based Freshwater Aquaculture Systems Joel Barraza, Carlos Basulto, Macarena Morales, Camilo Merino and German E. Merino Aquaculture effluent treatment systems are diverse, however, they all have the complexity of generating two outputs, on the one hand, treated water with a low level of contamination (according to regulations) and on the other hand, concentrated organic matter such as sludge, where its main characteristic is its high level of humidity, which represents a disposal, cost and management problem in this part of the process (Brooks and Mahnken 2003). One of the conventional alternatives in the solidliquid separation process, to reduce the moisture content in the sludge and with it the volume handled, is the use of chemicals (flocculants and coagulants) that allow generation of a higher sludge concentration in settlers (Figure 1) to subsequently attain final dewatering in a press filter (Figure 2). This conventional process results in sludge with a humidity percentage of around 70%. The most common final management of these compacted solids, with lower percentages of humidity, is their disposal in landfills. Currently, salmonid production systems in fish farming require treatments to reduce sludge generated because of unconsumed feed and feces (Mirzoyan et al. 2010, Cortes et al. 2022). Current solutions for sludge management involve the use of press filters (Figure 2), vacuum filtration (Figure 3), sedimentation beds (Figure 4) and dehydration. However, all these processes only concentrate sludge with different degrees of humidity, and do not solve the problem of solid waste generation and resulting environmental impacts. Innovation for a Sustainable Future The salmon industry in Chile is a cornerstone of the national economy and one of the most dynamic sectors worldwide. However, this sustained growth has brought significant sustainability challenges, particularly regarding wastewater treatment and sludge management in land-based fish farms (Hepp 2014). Increasing regulatory pressure, impacts on ecosystems, and growing consumer demand for products with lower environmental footprints have pushed the industry to seek innovative technological solutions (Rodríguez-Luna et al., 2021). In this context, the Universidad Católica del Norte (UCN), together FIGURE 1. Wastewater sludge treatment concentration by flocculant technology (G. Merino) FIGURE 2. Hydraulic press for sludge dewatering in land-based salmon farms (G. Merino) The salmon industry in Chile is a cornerstone of the national economy and one of the most dynamic sectors worldwide. However, this sustained growth has brought significant sustainability challenges, particularly regarding wastewater treatment and sludge management in land-based fish farms. Increasing regulatory pressure, impacts on ecosystems, and growing consumer demand for products with lower environmental footprints have pushed the industry to seek innovative technological solutions.
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