Innovative electrodes monitor Legionella treatment
Treatment of Legionella in water distribution systems is essential and usually involves copper–silver ionisation, where water is channelled through a device that delivers low-potential electricity to copper and silver electrodes. The positively charged copper and silver ions that are released bond to the bacteria's cell wall, causing it to rupture and the bacteria to die. These ions are also able to penetrate the biofilms of other microorganisms that co-habit with Legionella in water pipes. The SILCO project developed a new analytical monitoring tool based on a mercury-free micro-electrode that could monitor heavy metals at low concentrations in water. At the beginning of the project there was no device available outside the laboratory for monitoring copper and silver concentrations at the part per billion (ppb) level in treated water. As such, the goal was to create a device to continuously measure copper and silver concentrations in Legionella-contaminated water treated with copper–silver ionisation. Heavy metals are highly toxic and dangerous pollutants and therefore monitoring at the trace level is extremely important. Researchers used in the device innovative boron-doped electrodes for longer term monitoring and screen-printed electrodes for shorter term monitoring. The tool was linked to a self-adaptive intelligent controller for managing the dosing of copper and silver. The system also featured a wireless communication interface to allow control over the internet and operation of a central data-recording server. Development of this tool by the SILCO consortium will help reduce the threat of Legionella disease by controlling the bacteria using a novel device that was not previously available. In addition, promising spin-offs are foreseen since the system will also be capable of measuring the range of other trace metals in aqueous environments.