Disinfection By-Product Management - Process Measurement & Analysis

Disinfection By-Product Formation

The use of chlorine disinfection in potable water treatment has the potential to produce various disinfection by-products, which have been classified mainly as halogenated and nonhalogenated by-products. These primary by-products are trihalomethanes (THMs) and haloacetic acids (HAAs). THMs and HAAs are the by-products of chlorination of water that contains natural organic matter (NOM).

THM’s and HAA’s are carcinogenic and are therefore tightly controlled in the water quality regulations of most countries.

The quantity of by-products formed is mainly determined by the amount and type of NOM present in the water at the time of chlorine addition. Secondary variables such as temperature, pH, chlorine dose and contact time also influence the quantity formed.

UV-Vis spectroscopy is a valuable tool that can be used to actively minimise the formation of THMs and HAAs in water treatment.

The s::can UV-Vis spectro::lyser available in the UK from Process Measurement & Analysis can measure the following parameters continuously on-line in any water type:

•NOM Surrogates (e.g. SAC UV254 Absorbance, TOCeq, DOCeq and True Colour)
•NOM Characterisation Parameters (e.g. SUVA, Absorbance Slope Index, Et Band Halfwidth)
•Total THM Formation Potential
•HAA5 Formation Potential
•Chlorine Demand

The s::can UV-Vis spectro::lyser can also run the predictive coagulation control software Com::pass (patent pending).