Specific ultraviolet absorbance (SUVA) provides a general characterization of the nature of natural organic matter (NOM) in a water sample and is typically performed for the purpose of determining disinfection by-product (DBP) formation potential.
SUVA is calculated by dividing the UV absorbance at 254 nm (cm-1) by the DOC, dissolved organic carbon, (mg/L) of a water sample, expressed in units of L/mg-m.
This allows the aromatic biased UV254 measurement to be normalized over the overall organic load in the water. A characterization of the aromaticity of the water independent from the general level of organics in the water can then be obtained.
A high SUVA indicates a large portion of humic matter present in the water and that NOM will control coagulant dose. Since aromatic organics have a greater tendency to react with disinfectants to create DBPs, a high SUVA indicates there is a greater potential for the formation of DBP’s.
For further details about measuring SUVA click here to link to EPA Method 415.3 – Measurement of Total Organic Carbon, Dissolved Organic Carbon and Specific UV Absorbance at 254 nm in Source Water and Drinking Water.