In the race to make aquaculture more sustainable, recirculating aquaculture systems (RAS) are emerging as a critical technology—but they’re hitting some hard limits. A new review by Ziang Kong of Tongji University’s State Key Laboratory for Water Pollution Control and Green Resource Recycling takes a hard look at where RAS excels and where it stumbles, especially when it comes to energy use and pollutant removal. The findings aren’t just academic; they point to real commercial opportunities—and challenges—for industries tied to water, energy, and food.
One of the biggest hurdles in RAS is nitrogen removal. Traditional nitrification-denitrification processes are reliable but energy-intensive. Kong and colleagues highlight emerging alternatives like the Feammox pathway, an autotrophic nitrogen removal process that could cut energy use by up to 44.7% compared to conventional methods. “These pathways are promising,” Kong notes, “but they’re still largely confined to the lab. We need better reactor stability and process control before they can scale up in real aquaculture settings.” For an industry under pressure to reduce its carbon footprint, that kind of efficiency gain could be a game-changer—if the engineering catches up.
Another bottleneck lies in biofilm management. Thick biofilms can clog systems and disrupt water flow, forcing operators to pump more energy into circulation. Kong’s team suggests that modifying filter media and controlling fluid shear stress could help maintain steady-state microbial communities—essentially fine-tuning the system to run smoother and longer. That’s not just about uptime; it’s about reducing the energy load on pumps and aerators, which can account for a significant share of RAS operating costs.
Pathogen control is another pressure point. Traditional chemical disinfectants and antibiotics are blunt instruments—they kill pathogens but also disrupt the system’s ecology, fueling antimicrobial resistance. The review points to alternatives like performic acid as more targeted options, though they come with their own cost and handling considerations. More precise technologies, such as quorum quenching and gene silencing, are theoretically elegant but remain years away from practical deployment in large-scale systems. “We’re trading precision for scalability right now,” Kong explains. “The engineering challenges are real, especially when it comes to maintaining activity and keeping costs down.”
Perhaps the most immediate commercial impact comes from advances in multiphase separation and advanced oxidation processes (AOPs). Mechanical micro-screens often miss fine particles, leading to organic buildup and higher oxygen demand downstream. Microbubble-driven dissolved air flotation offers a more efficient way to capture those particles, reducing the load on biofilters and cutting energy use in the process. Meanwhile, AOPs like ozone and photoelectrocatalysis can break down stubborn pollutants—but they come with a catch. “Too much oxidation can trigger unintended consequences, like the spread of antibiotic resistance genes,” Kong warns. Balancing treatment intensity is key, and that’s where digital tools could play a crucial role.
Looking ahead, the future of RAS may lie in integration—both technological and systemic. Kong’s team envisions hydrodynamic optimization using computational fluid dynamics to reduce hydraulic energy waste, AI-driven predictive water quality control to move from reactive to proactive management, and renewable energy integration to power oxygenation and temperature control. “The goal isn’t just to treat water better,” Kong says. “It’s to build systems that are self-regulating, energy-efficient, and resilient.” Digital twin technologies, which combine real-time sensor data with mechanistic models, could serve as the backbone of this next-generation RAS, enabling early warning systems and continuous optimization.
For the energy sector, these developments are more than a niche opportunity—they’re a glimpse into a future where water treatment and energy management are tightly coupled. As aquaculture intensifies to meet global protein demand, RAS will need to become not just sustainable, but energy-smart. The research published in *Energy and Environmental Protection* (能源环境保护) doesn’t just diagnose the problems—it charts a path forward, one where innovation in water treatment could ripple across energy grids and supply chains. The question now is how quickly industry can turn these insights into action.