AWWA WQTC55160

AWWA WQTC55160 Using an On-Line UV Monitor as a Pollution Alarm
Conference Proceeding by American Water Works Association, 01/01/2001

Tan, Seet;Gammie, Leslie

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EPCOR Water downtown water treatment plant in Edmonton, Alberta, Canada, is downstream from 86 storm sewer outfalls. Our concern of possible contaminants coming from the storm sewer outfalls have resulted in a search for a on-line pollution alarm monitor which can do rapid analysis in time to take action on the treatment of the water. The Kontron On-line ultraviolet (UV) monitor with an analysis time of a minute appeared to be capable of acting as a pollution monitor. It measures the standard deviation (SD) of the baseline of 1000 UV scans of the source water from 240 nm to 290 nm. It will compare the standard deviations of any new scan with that of the last scan and generate a value known as the Last Scan Difference (LSD). When the LSD is significantly different from its baseline normal standard deviations, a pollution alarm is triggered. The system was operated between October 98 and April 99 on river water and from Jul 00 to Oct 00 on alum clarified river water. The results gathered from these two periods of operation indicated that the baseline standard deviation was identical regardless of season and differences in the source water. A few "alarm" events occurred, but attempts to identify pollutants during an alarm event by testing for target compounds were unsuccessful. Comparison of the LSD data during alarm events with color, turbidity, pH, volatile organic compounds, UV254 absorbance and ammonia did not show any correlations. There were many set-up challenges with the major problem of supplying enough river water that is low in turbidity and free of bubbles for the instrument to work as per designed. The instrument worked well when alum clarified river water was used and when the Warning and Pollution Alarm was set at Average LSD + 3 SD and Average LSD + 4 SD respectively. However we have discontinued the use of the system in June 2001 because of poor service support in Canada. Includes reference, tables, figures.