Maintaining Water Quality Standards – the role of Turbidimeters
Jul 09 2019
In the UK and throughout Europe, all drinking water must be safe and have the trust of consumers. Improved water quality is being demanded and utilities face an increasingly challenging climate. The challenge is to continue to improve drinking water without the cost being passed onto consumers. As well as meeting parametric standards, water suppliers must ensure tap water is ‘wholesome’, i.e. it looks good, tastes good and doesn’t cause any harm.
Accurate and rigorous assessments of quality have a huge role to play in meeting this challenge and one of the key measures of water quality is turbidity. If water looks turbid, it may not only look unpalatable but may also contain other harmful material. Low turbidity following pre-treatment is a pre-requisite to effective disinfection and essential to maintain consumer confidence.
Turbidity has traditionally been measured using contact turbidimeters, nephelometry-based instruments which measure how light is scattered by the particles at an angle of 90° to the incident beam.
The reliability of some instruments has proven problematic, with contamination a repeated issue, increasing maintenance costs and downtime. Typically, the optical windows need cleaning, the light sources replacing, and the instruments recalibrating at regular intervals.
Significantly, the light source is a light emitting diode (LED) with a lifetime of approximately 100,000 operating hours, rather than a more short-lived bulb, meaning replacement is unnecessary and recalibration negated.
Several features underpin the instrument’s reliability, including the unique sample chamber design which prevents measurement errors due to reflected light, whilst a photodiode monitors the intensity of the emitted beam. The drain ensures the measurement chamber is cleared of settled particles, whilst the flow monitoring system, accessible remotely, makes sure the flow is always maintained.
In short, Swan’s AMI Turbiwell is a non-contact turbidimeter for the automatic and continuous measurement of turbidity in drinking water, as well as surface and wastewater, meeting the requirements of ISO 7027.
The AMI Turbiwell is easy to install, comprising of a complete, panel mounted system; tested, calibrated and ready for operation, minimising downtime and disruption during installation.
It is also extremely durable, as at no point are the optics in direct contact with the water, so the likelihood of contamination is significantly lower. Condensation is prevented due to the naturally heated optics, reducing maintenance and negating the need for drying agents.
AMI Turbiwell includes very robust electronics, incorporating long-lasting components, like the LED, with a lifetime of over 100,000 operating hours and a photodiode that monitors the LED’s performance, the need for replacement is unnecessary and recalibration is negated.
In addition, this instrument needs far less maintenance than other turbidity measurement devices. The unique non-contact design and components that endure, mean maintenance costs, downtime and disruption are vastly reduced, operations run more smoothly, and operation costs are kept to a minimum.
South West Water’s Head of Water Quality, Chris Rockey advised “following extensive trials we determined the Turbiwell best suited our needs and we have recently extended its use into other low level applications such as monitoring trunk main conditioning schemes. The provision of a pre-assembled, pre-tested instrument and the approach to instrument quality control are two examples of how we have benefitted from our collaboration with Swan. Quality control is increasingly important as we now rely heavily on these measurements to ensure our consumers can trust their tap water.
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