How advanced sensing is raising the bar
MEASUREMENT & MONITORING CHLORINE FILTRATION IN DIALYSIS
BURKERT
How advanced sensing is raising the bar
In 2022, more than 30,000 people in the UK were undergoing kidney dialysis. For every one of those patients, water quality is not a background consideration but a frontline safety issue. Dialysis machines rely on large volumes of treated water, and any trace contaminants that remain can pass directly into the bloodstream. Among the most critical of these contaminants is chlorine.
Chlorine is essential for the disinfection of drinking water, protecting public health by controlling microbial growth. However, what is beneficial at the municipal supply level becomes dangerous once water is used for haemodialysis. Even trace levels of free chlorine or chloramines can damage red blood cells, cause haemolysis and lead to serious patient harm. As a result, dialysis water treatment systems must reliably remove chlorine and continuously verify that removal is effective.
The role of carbon filters in dialysis water treatment
Granular activated carbon( GAC) filters are the established solution for removing chlorine in dialysis plants. Installed upstream of reverse osmosis( RO) membranes and dialysis machines, these filters adsorb chlorine and in most cases chloramines too, protecting both patients and sensitive downstream equipment, helping to ensure a continuous supply of purified water.
However, GAC filters are consumable assets. Their performance degrades over time depending on inlet chlorine concentration, water flow rates and total throughput. If a filter becomes
Periodic maintenance is simple with plug-and-play design.
saturated with chlorine without detection, chlorine breakthrough can occur suddenly. For dialysis centres and hospitals, this makes effective monitoring essential.
Best practice requires chlorine to be measured both before and after the carbon filters. At the inlet, operators need to understand the incoming chlorine load and track trends over time. At the outlet, they must confirm“ zero chlorine” conditions continuously. Any delay in detection increases the risk of exposure, which is why response time and measurement reliability are so critical.
Limitations of traditional chlorine monitoring
Historically, chlorine measurement has relied on either amperometric sensors with electrolyte buffers or colourimetric analysers. While both technologies are well established, neither is ideally suited to highcriticality healthcare applications.
Traditional amperometric probes typically have T90 response times of two to three minutes and require frequent maintenance. Electrolytes must be replenished, membranes cleaned and electrodes manually serviced to remove scaling. Measurement accuracy is also sensitive to pH drift, often necessitating offline verification.
Colourimetric analysers offer good accuracy but at the cost of speed and complexity. Reagents must be handled and replaced, and while full reaction times can be completed in 2-3 minutes, sampling frequency is often reduced to once every 15 minutes to an hour, to save on costly reagent consumption. For dialysis water systems, where rapid response to chlorine breakthrough is essential, these delays can compromise safety margins.
86 PECM Issue 80