Measuring Natural Organic Matter by UV Absorbance

Measuring Natural Organic Matter (NOM)- UV Absorbance

There are several areas of the water and waste water treatment industry that require the analysis of the quantity of dissolved organics present in the water. The UVA parameter is an effective measure of the quantity of dissolved organics in water due to the strong UV absorption properties of organic molecules at the UV 254nm wavelength.

With the Real UVT Meter , the UVA parameter can now easily and accurately be measured in the field within minutes. The UVA parameter can be used for many applications, such as UV disinfection, coagulation (GAC) filtration, water and waste water treatment plant efficiency and effectiveness, chlorination and other water and wastewater treatment processes. Below are just a few of the many examples in which measuring dissolved organics are important.

For Monitoring Performance of Coagulants

Coagulants are often used in water and wastewater treatment systems to aid in the removal of dissolved organics in the water by clumping particles together so that they may be easily filtered out.

In order to determine the effectiveness of the coagulants at removing these dissolved organics, the UVT or OVA should be measured before and after the coagulants have been added. This will let the water treatment operator know how well the coagulants are working, As well, the operator can better determine the appropriate does of coagulants to add to the water for their application, which can greatly reduce the cost and improve performance of the water treatment plant.

By monitoring the IVT or UVA of the water supply regularly, it can alert the treatment operators to fluctuations in the amount of dissolved organics that are in the water. It is then possible to make appropriate adjustments to coagulants to ensure continuous and proper treatment of the water supply.

For Monitoring Disinfection By-Product (DBP) Precursors

Chlorine has long been used as a primary disinfection method for many water and waste water treatment applications. However there is growing concern about the harmful DBP;s produced by the use of chlorine,

DBP’s, such as triahalomethanes (THMs), can occur when the natural organic matter (NOM) that is present in the water is combined with chlorine. More specifically, the portion of NOM in the water that is aromatic is the most reactive with chlorine and therefore possessed the most potential for DBP formation. The aromaticity of the organic content in the water in best determined by the UVA parameter.

Therefore, monitoring  the aromaticity of the dissolved organics in a water supply by use of the Real UVT meter can serve as an indicator of the potential formation of DBP’s

As a Surrogate or Supplement to other Water Quality Parameters

There are several common water quality parameters that are used to further understand and characterise NOM for different water and wastewater treatment applications, such as Total Organic Carbon (TOC), Dissolved Organic Carbon (DOC), Specific UV Absorbance (SUVA) and Biological Oxygen Demand (BOD).

Many of these parameters are complicated, time consuming and expensive to test. This makes them practical to use on a regular basis causing an inability to perform routine daily monitoring which is vital to the success of many water and wastewater treatment methods.

However many of these parameters, including the UVA parameter, can be used as supplements or surrogates to one another. Given the affordability, ease of use, accuracy and quick onsite measurement ability of the UVA parameter that the Real UVT meter can provide, the Real UVT meter makes for an invaluable instrument of monitoring NOM.