ẢNH HƯỞNG CỦA THỨC ĂN VÀ MẬT ĐỘ NGAO (Meretrix lyrata) TỚI HIỆU SUẤT LÀM SẠCH CÁT TRONG HỆ THỐNG TUẦN HOÀN

This study evaluated the post-harvest sand depuration efficiency of market-sized Meretrix lyrata clams using a recirculating aquaculture system (RAS). A total of three laboratory experiments and 17 pilot-scale trials were conducted. The laboratory trials, each lasting 48 hours, independently examined the effects of three factors: microalgal (Chaetoceros gracilis) concentration (0, 11 × 103, 22 × 103, 33 × 103 cells/ml), feeding frequency (every 3, 6, 9, and 12 hours), and clam stocking density (18, 54, 90, 126 kg/m3). Assessing parameters included survival rate, proportion of clams containing sand, and clearance rate. The optimal microalgae concentration for depuration was determined to be 22 ×103 cells/ml. Feeding every 3 hours resulted in the highest sand removal efficiency; however, a 6-hour interval was adopted in subsequent trials to improve operational feasibility. The best performance in terms of sand removal and clearance rate was observed at a density of 18 kg/m3. Pilot-scale trials conducted under commercial conditions, with densities ranging from 170 to 380 kg/m3, demonstrated that RAS-based depuration was more effective than conventional aerated soaking when the treatment duration exceeded 24 hours. These findings highlight the potential of RAS technology to enhance clam depuration efficiency and provide a foundation for an optimized system aimed at improving meat yield recovery in future applications.