Breakthroughs in Recirculating Aquaculture: Zero-Discharge Systems and Emerging Tech Reshape Global Industry

Zero-Discharge IMTA-RAS Sets New Benchmark in Vietnam

Vietnamese researchers have pioneered an integrated multi-trophic recirculating aquaculture system (IMTA-RAS) for whiteleg shrimp, achieving zero water exchange over 124 days. The system combines shrimp, Nile tilapia, and algae (Cladophora glomerata and Gracilaria tenuistipitata), leveraging trophic synergy to recycle nutrients. Results show remarkable efficiency:  

● 45.9% nitrogen and 27.6% phosphorus utilization  

● Shrimp yield of 6.9 kg/m² with 62.2% survival  

● Tilapia mucus and algal compounds suppressed pathogenic Vibrio, reducing antibiotic use by 90%.  

● This innovation addresses Mekong Delta’s pollution crisis, where traditional farms discharge 49.6g nitrogen per kg of shrimp produced.

Cutting-Edge Decontamination Technologies Emerge  

German scientists propose cold atmospheric plasma (CAP) and pulsed electric fields (PEF) as alternatives to UV/ozone in RAS. Key findings:  

● CAP achieves log10 reduction factor (RF) of 2.1 against Gram-negative bacteria (e.g., Vibrio) in RAS water.  

● PEF demonstrates RF up to 5.5, rivaling UV efficacy.  

● Though CAP consumes 4× more energy than UV, its synergy with existing systems offers promise for pathogen control in turbid water.

Market Surge: RAS to Hit $14.7B by 2032  

Global RAS market valuation will grow at 8.32% CAGR (2025–2032), driven by sustainable seafood demand and urbanization. Key trends:  

● Vertical systems dominate (60% revenue share) for space/water efficiency.  

● Finfish lead species adoption (salmon, trout), followed by crustaceans like shrimp.  

● Major players (Skretting, AKVA Group, AquaMaof) focus on AI-driven automation and hybrid designs to curb energy costs.

EU Project Converts Waste into Resources  

The EU-funded AQUAPHOENIX initiative launched in 2025 to tackle aquaculture sludge in Norway’s Hardanger Fjord, where salmon farms generate 70,000+ tons of sludge annually. The project:  

● Deploys sludge-collection tech (Ragn-Sells, Framo) to prevent eutrophication.  

● Converts waste into renewable energy and phosphorus-rich fertilizers, reducing reliance on imports.

RAS as a Bioplastic Degradation Accelerator

Japanese researchers discovered RAS environments rapidly break down polybutylene succinate-co-adipate (PBSA) bioplastics:  

● PBSA film fully degrades within 144 hours in Nile tilapia tanks.  

● Pseudomonas bacteria dominate early degradation (24h), confirmed via SEM and 16S rRNA sequencing.  

● This positions RAS as a testing ground for eco-friendly materials, potentially curbing ocean plastic pollution.

Energy Debate: Feed, Not Power, is Top Environmental Burden  

Contrary to assumptions, a Swedish lifecycle assessment reveals aquafeed production—not energy—drives 60%+ of RAS emissions. Components like poultry byproducts and soy contribute to eutrophication. However, renewable energy adoption (e.g., hydropower in Scandinavia) mitigates this impact, highlighting region-specific sustainability strategies.  

The Path Forward  

As RAS transitions from niche to mainstream, innovations in nutrient recycling, energy-efficient tech, and waste valorization are critical. With projects like IMTA-RAS and AQUAPHOENIX proving circularity’s viability, the industry moves closer to achieving "blue growth" without compromising ecological resilience.