Ashland MA Refurbishes Plant for Improved Performance of Ozone System

Ashland and Hopkinton, MA are towns of about 16,000 and 14,000 residents, respectively. They are situated midway between Boston and Worcester in eastern Massachusetts. The Howe Street facility uses clarification, carbon filtration, and ozonation to treat groundwater.

Ashland experiences seasonal increases in manganese in its ground water supply. In Ashland’s water, the manganese is organically bound with an organic molecule such as humic, fulvic or tannic acid. Manganese in such a complex is more difficult to remove because the organic molecule provides a protective shell. Treatment of organically bound manganese leaves increased levels of disinfection byproducts in the finished water.

To address the issue, the Howe Street facility was originally designed to use two ozone generators to oxidize the manganese. Unfortunately, the system was difficult to operate and was taken off line for a couple of years. To bring the ozone generators back on-line, the dielectric modules were cleaned and rebuilt. A number of other improvements were made as well: relocating several valves for easier adjustment and maintenance, installing blow-down valves and drain lines for the degas system, and modifying the degassing and destruct units to vent to the entrained water separator without the need for vacuum pumps. Once the maintenance and upgrades were complete the results were dramatic and the project met the goal of having high quality water.

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