As many of the parameters to be measured are colourless, chemical reagents are used to create a reaction that forms a coloured compound. Adding the reagent creates a dilute solution of molecules that absorb light. By measuring the absorption/ passage of light through the coloured sample, the concentration of the parameter being measured can be ascertained.
The benefits of continuous online measurement
Continuous measurement using online analyzers replaces spot testing of samples. Spot testing relies on analysis of one sample at a given time and the accuracy is therefore questionable. By increasing the frequency of sampling, online analyzers provide a true indication of water quality under a variety of conditions.
ABB’s Aztec 600 series of large case analyzers use the principle of colorimetry to measure concentrations of aluminium, iron, manganese and phosphates. Able to measure up to six samples an hour, the analyzers use an LED and detector to measure the passage of light through a sample. A single precisely controlled piston pump provides all the sample and reagent fluid handling for measurement, mixing and disposal. Measurements are taken before and after the addition of reagents to compensate for background color and turbidity. These measurements are compared against the calibrated values to calculate the value of the sample being measured.
The inherent benefits of these analyzers enable them to be used in a variety of applications, including residual coagulant monitoring. Using an online analyzer can help to regulate the dosing of the salts used for coagulation to ensure the treated water meets the required standards.
Cost saving benefits
As a means of continually monitoring water quality throughout the water treatment process, using devices such as those in ABB’s Aztec 600 analyzer series offers a range of cost saving benefits compared to manual sample collection and analysis.
Foremost amongst these is the ability to optimize plant operation and output consistency through:
· Reduced failures and maintenance issues caused by underdosing, such as plant shutdowns or increased cleaning of sand filters, or overdosing, such as discoloration or costs of chemical pH correction
· Reduced operator intervention through the ability to carry out automatic monitoring
· Decreased levels of sludge, leading to a reduction in the cost and resources connected with sludge disposal
The importance of water as a staple of life, coupled with the growing need to conserve water supplies, makes it critical to ensure that its quality is always safeguarded to minimize the risk of contamination. By using continuous online measurement, operators can ensure they are always in possession of the information they need to pinpoint problems and optimize water treatment efficiency.
As a manufacturer and supplier of a wide range of continuous water quality analyzers and sensors, ABB can help you to choose the right water quality measurement solutions for your application.