148 Biological control unit: a real alternative to disinfectants for a more sustainable aquaculture A.P. Gallemí DTU AQUA, Technical University of Denmark BACKGROUND AND INTRODUCTION Aquaculture is one of the fastest growing sectors within the food industry. Nevertheless, one of the most common problems encountered in fish farms are algae blooms, and especially, harmful algae blooms (HABs). Farmers use different types of disinfectants to eliminate these toxic microorganisms. However, some disinfectants are ineffective against some of the most common toxic algae species (cyst-forming species). Given the increasing trend of the aquaculture industry, chemical usage and discharge can only increase, unless an alternative method to eliminate algae blooms is found. This project has focused on exploring the usage of zooplankton, natural predators of the algae, to eliminate them from aquaculture systems. The specific aims of this work were to check if using zooplankton was both biologically and technically feasible – it should be an efficient removal method and easy to implement –, as well as to realistically evaluate and compare it with current removal methods. M ETHODS 1) Biological part: 3 different highly-toxic algae species – all responsible for losses in the aquaculture industry – and 2 zooplankton species were used. To make experiments realistic, “bloom-like” concentration of algae was used. 2) Technical part: a small-scale bioreactor was used to determine the feasibility (in terms of flow and velocities) of using zooplankton in recirculating aquaculture systems. This information is key to understand how to implement this new alternative in real systems. 3) Evaluation: both methods, biological control and peracetic acid (PAA), were evaluated under 6 different scenarios. Criteria were based on the industry’s preferences. Figure 1. Biological Control Unit Results and Conclusions The study showed: 1) Biological control is feasible both from biological and technical perspective. 2) Biological control in the tested conditions is as efficient as commonly-used concentrations of PAA. 3) Biological control is more effective than PAA in treating blooms of cyst-forming species. 4) Biological control outscored PAA in most of the studied scenarios. 801 ENVIRONMENTAL PROBLEMS & SOLUTIONS POSTER IDEA MASTER THESIS
Grøn Dyst 2016
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