Colorimetry for Potability: The Aztec 600

Having immediate access to clean freshwater is often taken for granted. The different stages of treatment that raw water from streams, rivers and lakes experiences to make sure a plentiful supply of safe drinking water is supplied to the taps into the home is seldom considered.

Water utility companies are faced with the task of continually improving processes while keeping prices affordable and meeting a supply that is in ever-growing demand due to population growth and urbanization.

Developments in Continuous Water Analyzers are transforming water process methods of water utilities companies. Whilst conventional methods of sampling and testing have been in long operation across the industry for many years, new opportunities for real-time data are revolutionizing water treatment efficiency.

When it comes to potable water, there are many parameters that demand testing. Here, we specifically consider the ways in which Aluminum, Iron, Manganese and Phosphate levels can have a harmful effect on water quality if left unchecked.

Video showing applications and benefits of ABB's Aztec 600 Water Quality Analyzer

Video Credit: ABB Measurement & Analytics

Aluminum levels in water can be associated with natural presence in soil or as a result of its usage as a flocculant to eliminate impurities throughout the water treatment processes.

While aluminum in drinking water represents a small percentage of an average total daily intake, increased levels of aluminum are believed to be linked to Alzheimer’s disease. Excessive aluminum levels can result in kidney dialysis problems.

Iron in potable water does not pose a health risk. However, when mixed with tea, coffee and some alcoholic drinks, the iron can react with tannins leading to the formation of black sludge.

Iron can stain laundry and other household items, including cutlery and crockery; water fittings such as taps can also be affected by discoloration and iron can obstruct pressure tanks, pipelines, water heaters and water softeners.

Certain geological conditions affect the amount of iron naturally present. Additionally, water flowing through runs of cast iron pipes can be prone to increased levels of iron.

Manganese is a naturally occurring element in many sources of water. While it is believed that it does not present a risk to human health, failure to appropriately control manganese levels will lead to black deposits forming in pipe networks which could lead to potable turning water black when disturbed.

These deposits can soil laundry or stain vegetables when washing or cooking.

Phosphates are typically used by water companies to stop the lead from old pipes disintegrating and moving into the water supply. 

Additionally, phosphates are utilized in agriculture and found in human sewage, animal wastes, industry and detergents. Excessive levels can lead to eutrophication or accelerate the growth of plants and algae on the surface of lakes, rivers, and streams.

These growths cause plants and ecosystems beneath the surface to die by preventing light from penetrating through the water. As dead plants decompose, they consume oxygen in the water, further reducing the oxygen supply for other aquatic life.

Using Colorimetric Measurement to Monitor Potable Water Quality

Colorimetric measurement is utilized throughout water, power and process industries to a significant extent. To describe the process in simple terms, the technique calls for the color-based measurement of a chemical in a solution.

The color is a result of the absorption of specific wavelengths from the visible light spectrum across the range of 400 to 700 nanometers (nm).

Colorimetry for Potability: The Aztec 600

Image Credit: ABB Measurement & Analytics

As several of the measured parameters are colorless, chemical reagents are introduced to produce a reaction that forms a colored compound. Thus, when the reagent, a dilute solution of molecules that absorb light is created.

As a result, the concentration of the parameter being measured can be determined by measuring the absorption/passage of light through the colored sample.

The Benefits of Continuous Online Measurement

Continuous measurement utilizing online analyzers stands in place for the spot testing of samples. Spot testing necessitates the analysis of a single sample at a time, calling into question the accuracy of the process.

By increasing the frequency of sampling, online analyzers offer a better indication of water quality under a range of various conditions. 

Using the principle of colorimetry, ABB’s Aztec 600 series of large case analyzers can measure concentrations of aluminum, iron, manganese and phosphates. With the capacity to evaluate up to six samples an hour, utilizing an LED and detector, the analyzers measure the light passing through a sample.

A single controlled piston pump supplies all the precise sample and reagent fluid handling for measurement, mixing and disposal.

Measurements are acquired prior to the addition of reagents and again after their introduction to compensate for background color and turbidity. These measurements are then contrasted against the calibrated values to work out the value of the sample being measured.

The intrinsic benefits of these analyzers mean that they can be utilized across a wide range of applications, including residual coagulant monitoring. Using an online analyzer facilitates the control of dosing the salts used for coagulation to guarantee the water being treated is up to the required standards.

Cost Saving Benefits

By continually monitoring water quality during the entire water treatment process, using devices such as those in ABB’s Aztec 600 analyzer series provides a variety of cost-saving benefits in contrast to manual sample collection and analysis. 

The leading factor is the ability to optimize plant operation and consistency of output through:

  • Limits failures and maintenance issues caused by underdosing, including increased cleaning of sand filters, plant shutdowns, or overdosing, such as costs of chemical pH correction and discoloration.
  • Reduced operator interruptions due to the capacity of automatic monitoring 
  • Decreased levels of sludge reduce the cost and resources associated with sludge disposal 

Summary

The significance of water as a staple of life, in combination with the increasing need to preserve water supplies, makes it vital to make sure that its quality is consistently safeguarded to reduce the risk of contamination.

By utilizing continuous online measurement, operators can ensure they constantly acquire the appropriate information necessary for the identification of problems and thus optimizing the efficiency of water treatment processes. 

As a manufacturer and supplier of a broad range of continuous water quality analyzers and sensors, ABB facilitates the selection of the appropriate water quality measurement solutions for any given application.

This information has been sourced, reviewed and adapted from materials provided by ABB Measurement & Analytics.

For more information on this source, please visit ABB Measurement & Analytics.

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