One of the most common chemical parameters to test in drinking water is the disinfectant used, and two of the most popular disinfectants used are chlorine and chlorine dioxide. Most drinking water is still treated with chlorine to prevent harmful pathogens causing illness. Chlorine may be added as free chlorine or as combined chlorine depending on multiple factors including how quickly the water is to be consumed and the potential for formation of disinfection by-products.

Chlorine dioxide is often used in drinking water treatment, usually towards the end of the distribution network to control specific pathogens, but it is also sometimes used as a pre-treatment for metal removal from the raw water entering a treatment plant.

Typically, the maximum residual disinfectant level (MRDL) for chlorine in drinking water is around 4 milligrams per litre (mg/L) but levels can normally be around 1mg/L in distribution networks.
The discharge limits for chlorine in treated wastewater are usually set by regulatory authorities and may vary, but they are generally low (< 0.1 mg/L) to minimize environmental impact and protect aquatic life.

The maximum allowable concentration for chlorine dioxide in drinking water is typically regulated and in most cases around 0.5 – 0.8 mg/L.

It is important to test chlorine and chlorine dioxide level in drinking water to ensure there is sufficient chlorine for effective disinfection, but also not too high a concentration to cause adverse health effects if consumed. Testing for free, combined, and total chlorine along with chlorine dioxide and other disinfectants is possible using the Lumiso Expert photometer.
Utilising the Lumiso optical set-up, this instrument provides accurate and reliable results which are consistent across our entire range of Lumiso photometers, so disinfectant testing across handheld and benchtop instruments is standardised

Iron and manganese are metals present at high levels in some natural and treated waters due to them being washed from minerals in rocks during weathering processes.

Iron is also sometimes used as part of water treatment processes. However, the presence of high levels of these metals, specifically iron, can affect the taste of water, and high concentrations can discolour drinking water. In general, the recommended limit for iron in drinking water is around 0.3 mg/L (Secondary MCL (Maximum Contaminant Level) under EPA (Environmental Protection Agency).

High concentrations of manganese can cause black discoloration and deposits. The recommended limit for manganese in drinking water is often around 0.05 mg/L according to the DWI and US EPA (Secondary MCL).

Due to the reasons above, iron and manganese are common chemical parameters test for drinking water. Palintest offers two options for iron testing on the Lumiso Expert, more information on the different iron tests available can be found in this article.

Manganese testing is also made quick and simple using the Lumiso Expert.

Aluminium can also be present in water naturally through weathering processes causing it to dissolve from soils or rocks, and this is more common where water is acidic. Also, aluminium sulphate is often using as a coagulant in drinking water treatment to remove suspended solids. Therefore, aluminium testing is required to control aluminium coagulation and filtration processes during drinking water processing.

The Lumiso Expert makes testing simple and easy, especially for tests which are less routine, through the inclusion of on-screen test instructions which demonstrate how to perform the test step-by-step using illustrated instructions. These can be referenced when performing any test, meaning training needs are minimised.

pH is important to monitor and control in drinking water as it can directly affect the performance of the treatment and disinfection process.

The pH of water is a measure of how acidic or alkaline it is. The pH is measured using a scale from 1 – 14, where pH 1 is very acidic, and pH 14 is very alkaline. The acidity of the water is a measure of the number of hydrogen ions present.

The pH of the water will affect the chemistry of the water and how it reacts with chemicals and surroundings, so in most applications maintaining a stable pH is essential.

The WHO state that the pH will vary in different supplies according to the composition of the water and the construction materials used in the distribution system. According to the WHO for effective disinfection with chlorine, the pH should be less than 8.0.

The US EPA consider pH of drinking water a secondary contaminant as it does not have a direct impact on health. According to their secondary standards, pH in drinking water should be between 6.5 – 8.5. A low pH can result in bitter, metallic tasting water and can cause corrosion of pipes. Whereas, a high pH can cause water to have a soda like taste.

The DWI include pH as an indicator parameter. They specify that the pH of drinking water should be between 6.5 and 9.0.

Lumiso Expert utilises a commonly used method called phenol red to determine the pH of water in a reliable, simple way that not only ensures the safety of drinking water but also aids in environmental protection and industrial compliance.

The Chemical Oxygen Demand (COD) of water is a measure of the amount of oxygen that is consumed by reactions with chemicals in the water. Generally, a COD test is used to measure the amount of organic pollutants in a water body as an indicator of water quality.

In a COD test, any organic molecules present in the water will be fully oxidized to CO2 by a strong oxidizing agent under acidic conditions.

COD is used to measure the organic pollution present in wastewater prior to release into the environment. If high COD water gets into the environment this can cause eutrophication and be very damaging to aquatic ecosystems.

Lumiso Expert can be used to monitor COD levels in your wastewater process utilising the Lumiso optical set-up, this instrument provides accurate and reliable results which are consistent across our entire range of Lumiso photometers,

Ammonia is a chemical parameter which is especially important in wastewater processing and treatment. Ammonia concentration can reach extremely high levels in wastewater due to digestion of nitrogen-containing organic waste.

When released into the environment, high levels of ammonia are toxic to aquatic life due to a process known as eutrophication. This is where high concentrations of nitrogen, phosphates and other parameters can lead to high levels of aquatic plant growth and algal blooms which cover the surface of the water, block sunlight and use up all the dissolved oxygen. This means aquatic life can no longer survive.

Therefore, the removal of ammonia has become a legal requirement and part of the process for the treatment of wastewater and sewage. The Lumiso Expert photometer offers multiple different reagents and measuring ranges for ammonia testing to ensure there is a test suitable for all users.

The chemical parameters discussed in this article are just a selection of the chemical testing required for drinking and wastewater treatment. The Lumiso Expert offers multiple tests for these plus many more chemical parameters to cover all of your drinking and wastewater testing needs. A full list of tests available on the Lumiso Expert photometer can be found in our Lumiso Brochure which can be downloaded here.

To find out more about Lumiso Expert or request a quote, contact a member of the team by clicking here.