The primary role of a drinking water treatment plant is to provide clean, safe drinking water for consumers.

Dissolved organic carbon levels are monitored and disinfectant chemicals are routinely added in order to remove organic matter. Not only are these chemicals a major source of expenditure for the water treatment plant, they also create the need to further measurement of disinfectant biproducts (DBPs), such as Trihalomethanes (THMs) which can be harmful. So, optimising the levels of use of these disinfectants is highly desirable.

The Aqualog provides a simple, robust and reliable method which can be deployed throughout the water treatment process enabling levels of organic carbon levels (and composition) and DBP to be rapidly monitored.

It has already provided huge costs savings at installations throughout The United States.

The task is not trivial though as the levels of organic carbon in a supply can fluctuate greatly, even within a single, twenty-four hour period, depending on rainfall, snowmelt, waste water discharge, etc. To be able to minimise disinfectant dosing levels, scientists need rapid, reliable analyses which can be deployed throughout the water treatment process.

Better Technology

HORIBA Scientific’s Aqualog spectrofluorometer, which measures absorbance spectra and fluorescence Excitation-Emission Matrices simultaneously, gives the plant operators an instantaneous reading of this dissolved organic carbon concentration, and more importantly, its composition.

Aqualog Method v
Conventional Methods


The Aqualog, which incorporates a CCD fluorescence emission detector, has another important advantage. Most water treatment organic laboratories make daily measurements of dissolved organic carbons to keep track of their online monitoring systems, which use generally much simpler types of detectors. These detectors lack the depth of information needed to monitor their system. The Aqualog has a speed advantage in that you can make organic carbon or formation readings in just two or three minutes per sample.

Other systems take 20 to 30 minutes to make these measurements and require a separate absorption measurement to get some idea of the composition. The Aqualog measures both absorption and excitation at the same time.

“The Aqualog is the fastest scanning florescence system available,” says Dr Adam Gilmore , Aqualog Product Manager at HORIBA.

“We have customers who take hundreds of samples a day and they’re always measuring the absorbance and the fluorescence at the same time. The issue is they are primarily limited by their sample preparation. So, the biggest complaint about the Aqualog is that it measures faster than they can generate the samples.”

An accessory “sipper” attachment is available for the Aqualog to take multiple sample measurements more efficiently.

The clear, rapid reporting provided by the Aqualog enables optimised chemical usage.


The Dissolved Organic Carbon (DOC) and enhanced Trihalomethanes (THM) formation predictive features of Aqualog have been documented to save on average 5-10% of the annual chemical budget of a typical drinking water treatment plant. Chemical dosing needs to be applied only when the monitored levels are predicted to rise above pre-determined thresholds to ensure spending remains within the chemical budget for a given water treatment plant.

“You can save up more than a quarter of a million dollars, or $300,000 a year of their $3,000,000 annual chemical budget,” Gilmore said. “It means that the Aqualog typically pays for itself in just a few months.“

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