In closed-loop water systems—such as Recirculating Aquaculture Systems (RAS), cooling towers, hot water circulation, industrial cooling loops, aquariums, swimming pools, or laboratory/pharmaceutical ultrapure water recirculation—water is continuously cycled rather than frequently discharged or replenished. This conserves resources but increases risks: accumulation of organics (e.g., feed, waste, nutrients) leads to eutrophication (excess nitrogen/phosphorus), stagnation, warmth, and light exposure in some setups, promoting proliferation of pathogens (e.g., Legionella, Pseudomonas aeruginosa, viruses) and algae. UV recirculating water purification integrates UVC LED water disinfection modules directly into the recirculation loop for continuous, chemical-free treatment.
