All water supplied by Jersey Water is treated at one of two water treatment works located at Handois and Augrès. Both treatment works use a two-stage method of water treatment comprising chemically assisted sedimentation and rapid gravity filtration followed by disinfection using chlorine and ammonia (chloramination) and UV.
Jersey Water had previously purchased two Stamolys CA71 chemical photometric analysers from Endress+Hauser to measure the levels of ammonia in the raw water and post filtration.
The measurement checks if the raw water in the reservoir has been contaminated as a result of agriculture or pesticides and also determines the correct dosage of ammonia for the chloramination process.
In order to comply with regulations governing the supply of drinking water, the company needs to detect extremely low concentrations of ammonia – less than 50 parts per billion (ppb).
“We decided on the Stamolys CA71 because it’s the only instrument on the market that has that lower-end range,” confirms Ian Young, Electrical Engineer and Assistant Asset Manager at Jersey Water.
The analysers were connected to the water company’s own sample filtration system consisting of a cloth filter in a plastic housing. But the filters regularly became clogged with organic matter and had to be replaced at a cost of €30 each.
More crucially, the readings from the analyser were inconsistent with the results produced from samples tested in Jersey Water’s laboratory.
Analytical experts from Endress+Hauser were called in to assess the problem.
The CA71 analysers were sent back to the production centre in Germany for testing and it was determined they were working perfectly.
More tests were carried out on the process and it was discovered that algae growth in the filtration system was to blame: the algae were consuming some of the ammonia before it could be detected by the analysers.
The solution was to replace the cloth filtration system with a new sample preparation system from Endress+Hauser, Liquiline System CAT820.
The CAT820 has a ceramic filter that filters samples to 0.1 micron, small enough to allow the dissolved ammonia through but keep other particulates out of the prepared sample. The ceramic filter was fitted inside a custom-built flowcell to make it compatible with the CA71, as the ceramic filter is usually suspended in open tanks to filter samples for analysis by the new Liquiline CA80 colorimetric analysers.
The team at Jersey Water was impressed with the way the problem was speedily resolved.
The new filter has improved reliability at the same time as cutting operating expenditure and maintenance effort.
“Before we had to constantly clean and maintain the cloth filter so it’s saved time and effort and has cut down on instrument downtime. The new system’s not maintenance-free but it’s certainly low maintenance.” Ian Young, Electrical Engineer and Assistant Asset Manager.
By far the biggest benefit is being able to rely on the measurement. As Ian Young says, “We’re getting consistent and accurate results and that’s the most important thing.”
The Liquiline System CAT820 and its ceramic filter unit have been specifically designed for preparing samples for colorimetric measurements in the water and wastewater industries, where sample preparation is absolutely critical to ensure accurate and repeatable measurements for dissolved ammonia and phosphate in particular, as these are regulated measured parameters in both industries.