AWWA WQTC60557

The spectral ultraviolet (UV) absorbance of the chemical additives used during UV validation to adjust theUVT is an important consideration when validating medium pressure UV systems. The spectralUV absorbance should mimic that of the water that will be treated by the UV system at the watertreatment plant. Current UV absorbers used are coffee and lignin sulphonic acid. For a given UVtransmittance at 254 nm, the UV absorbance at higher wavelengths tends to be greater than thatof water treatment plant waters. This impacts both dose delivery and monitoring by the UVreactor. For a given flow, UVT 254, and lamp output, dose delivery during reactor validationwill be lower than at the WTP. For a given flow, UVT 254, and UV sensor reading, dosedelivery indicated by the UV reactor's monitoring system during validation will be higher duringvalidation than at the WTP if the UV sensor is located relatively close to the lamps and lower ifthe UV sensor is located relatively far from the lamps. With the latter case, the US Environmental Protection Agency UVDGMrecommends application of a safety factor to account for the underestimation of dose by themonitoring system. All of these outcomes impact the capital and O&M costs of medium pressuresystems. In this study, concentrates from reverse osmosis (RO), nanofiltration (NF), and ionexchange (IX), an agricultural growth-enhancement product, and lignin sulphonic acid werecompared as UV absorbers for validating MP UV systems. Includes 5 references, tables, figures.

Product Details

Edition:

Vol. - No.

Published:

11/15/2004

Number of Pages:

13

File Size:

1 file