The traditional flow-through or outdoor static-water aquaculture systems require frequent and substantial water exchange. In contrast, the Indoor Recirculating Aquaculture System (RAS) controls water quality by treating and reusing water through circulation, enabling smooth biological production. However, the establishment cost of RAS is relatively high, and energy consumption for water treatment exceeds that of traditional aquaculture ponds. Developing cost-effective and highly efficient RAS systems can significantly reduce the investment and operational costs of water treatment equipment, creating an economically viable recirculating aquaculture model.
We have established a novel, energy-efficient recirculating aquaculture system capable of supporting a stocking density of 20-30 kg per ton of water, over 10 times higher than the traditional outdoor pond stocking density of approximately 2-3 kg per ton of water. The system comprises three main components: the aquaculture zone, the physical filtration zone, and the nitrification and oxygenation zone. Organic particles discharged from the aquaculture tank first flow by gravity into the physical filter. A motor then pumps the filtered water into the biological nitrification tank. This filtration unit offers low construction costs, low energy consumption, and reduced maintenance requirements. The biological filter tank, approximately 1.6 meters tall, is filled with K1 plastic media with a specific surface area of 150 m²/m³. Intensive aeration enhances oxygen levels and maintains the media in motion, facilitating nitrification. Compared to conventional fixed-bed filters, this setup improves treatment efficiency by 8-10 times. Finally, the treated water flows back into the aquaculture tank by gravity, completing the cycle. The system’s network monitoring unit, controlled by a microchip, integrates functions such as error detection, data upload, and interface display. In the event of abnormalities, the system triggers an alarm to alert management personnel for immediate resolution.