Legionella Case Study
Summary
A major international airport experienced ongoing water quality issues in the mains cold water tank and associated outlets within its Air Traffic Control (ATC) facility. Supplied by the municipal system, the facility uses water for washrooms, showers, staff kitchens, and utilities. Although potable water is essential, the facility’s water demand is low compared to airport terminals. The self-contained nature of the facility made it an ideal site for a targeted water treatment trial.
Background
WtE projects address multiple critical objectives:
- Environmental Sustainability: Reduces reliance on landfills, minimises methane emissions, and contributes to cleaner air and water.
- Renewable Energy Generation: Converts waste streams into electricity or heat, supporting energy diversification and security.
- Economic Benefits: Generates revenue through energy production, reduces waste disposal costs, and creates local jobs.
- Circular Economy Integration: Encourages resource efficiency and waste valorisation, turning what was once discarded into a valuable asset.
By integrating WtE solutions into your operations or community infrastructure, you can achieve measurable environmental and financial outcomes.
Our Waste-to-Energy Services
The water treatment at the facility involved dosing the mains tank with chlorine dioxide and routine outlet testing. Sampling for Pseudomonas aeruginosa and Legionella was carried out by an accredited third-party laboratory. P. aeruginosa, an opportunistic pathogen, poses a risk primarily to immunocompromised individuals. Total Viable Count (TVC) analysis was used to assess overall microbial levels. Following a positive TVC result, the water system was shut down for two days to shock dose the tank and clean affected areas. Bio load testing in the ATC Tower measured 600 colony-forming units per gramme (cfu/g) despite its regular use of chlorine dioxide. Some zones required repeated treatments (up to 25 times) at an estimated £1,950 per event.
Hypochlorous acid (HOCl)
A fully documented technical trial using Hypochlorous Acid was conducted
HOCl as an alternative water treatment technology to replace the chlorine dioxide. 786 utilises a scalable, proprietary process for producing high-purity, stable HOCl at commercial volumes. Unlike traditional chemicals like chlorine dioxide, which pose health risks and may contribute to microbial resistance, HOCl is a non-toxic, effective, and environmentally safe alternative. Its broad-spectrum antimicrobial action makes it ideal for water treatment across human, animal, agricultural, and industrial applications.
The Trial – HOCl + Dosing Pump
The technical trial integrated HOCl into the ATC tower’s water system via a dosing pump. The trial included an initial shock dose to remove pathogens and biofilm, followed by a controlled maintenance dose to prevent recurrence.
The dosing pump ensured accurate, consistent chemical delivery. Chemical concentration, flow rate, and water quality were closely monitored. Results showed that HOCl, combined with automated dosing, significantly improved treatment efficiency and water quality, while simplifying ongoing maintenance.
Conclusion
The water treatment trial conducted at the ATC tower resulted in a 100% success rate in eliminating all traces of Legionella from the system. The client now plans to use HOCl across the entire airport water network.
From the outset, our team worked closely with the client’s onsite engineers to understand the specific demands of the ATC tower’s water infrastructure and biofilm treatment system. The team conducted a detailed assessment of flow rates, system configuration, and usage patterns to tailor a precise dosing strategy.
By applying deep technical knowledge of shock and maintenance dosing, the team was able to configure the dosing pump and chemical concentrations to match the exact operational needs of the ATC tower site.
Throughout the trial, the team demonstrated agility and responsiveness rapidly adjusting the dosing strategy in response to fluctuations in flow and usage and ensuring uninterrupted treatment performance. The team also handled unexpected challenges with professionalism and confidence, including instances where dosing equipment became accidentally damaged on site when the team responded swiftly with on-site support, equipment replacement, and real-time reconfiguration of the system to maintain treatment continuity.
This trial not only demonstrated the robustness and reliability of HOCl in a live operational environment but also demonstrated an ability to deliver customised, high-performance water treatment solutions in close partnership with clients.
The 786 hypochlorous acid product is highly effective in managing and reducing facility bio loads exceeding 75,000 colony-forming units per gram (cfu/g). This proven effectiveness is based on extensive internal testing, industry standard validation protocols, and the well-documented antimicrobial efficacy of HOCl.
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