The project

In 2013, non-chemical water treatment Advance Oxygenation Technology (AOT) Wallenius, was trialled as an alternative to traditional chemically dosed fill and test water on the incoming mains of four large closed water systems at a construction project in the Midlands.

Filling and pressure testing closed systems with treated water is widely adopted during construction. The process involves proportional dosing of a biocide into the fill and test water at source, which has several drawbacks, including untrained and unprotected operatives coming into contact with diluted biocides. Alternatively, initial pipework testing is often completed using air, which also comes with health and safety risks.

The efficacy of the process is also compromised as only low levels of biocide can be dosed and biocides do not kill bacteria instantly, leading to further dilution where parts of a system are opened to sections previously tested.

Download the full case study here: AOT for construction case study

The solution

By using AOT Wallenius non-chemical water treatment instead of chemical dosing, bacteria is instantly killed, eliminating the need for air-testing and reducing health and safety risks, improving sustainability by reducing chemical usage.

To install AOT Wallenius, the mains water supply was initially disinfected using chlorine dioxide at fill points, temporary flushing connections and hoses to eliminate an existing biofilms immediately downstream of the 110 v AOT unit. All fill and test water, plus subsequent flushing water was then pre-treated before introduction into the systems.

The outcome

Following installation, the system was tested throughout the water treatment process and post completion, with UKAS accredited laboratory analysis providing excellent results which showed bacterial levels to be virtually non-existent. The use of AOT Wallenius on the incoming mains supply provided a safe, environmentally and cost effective alternative to traditional chemical dosing.

AOT installed throughout

AOT installed throughout

AOT removed early October

AOT removed early October

NB: AOT does not replace any of the closed system cleaning processes as it will not eliminate bacteria and biofilm already present in closed system. Biocide washing is still highly recommended and final biocide dosing on completion is essential. AOT Wallenius is designed to produce the best possible conditions for a successful cleaning programme.

About AOT Wallenius

Originally developed and patented by Wallenius in Sweden to disinfect ship ballast water before being discharged, AOT has been adapted to provide a chemical free treatment process on cooling towers, incoming water supplies and domestic hot water systems.

Guardian Water Treatment have further developed the process to eliminate bacteria during construction of closed systems, not only at the fill and test stage, but also to treat the water used for flushing during the water treatment programme.

AOT involves a low power light source reacting with a patented catalytic coating to produce highly reactive particles which rip hydrogen atoms from bacteria giving a 99.9% kill rate on all bacteria.

Download the full case study here: AOT for construction case study