Recovery Act Impact: Clean and Drinking Water State Revolving Funds
The project involves taking salted water from the Palmer River at low tide when salinity levels are low, treating it for drinking water and discharging at high tide.The significance of the desalinization plant is vital to this town which has experienced chronic water shortages with demand often outstripping supply, especially during the summer.
The plant's funding - the total cost of the project is $18 million - is receiving $1.15 million under the stimulus-funded state revolving fund program through the Massachusetts Department of Environmental Protection.
According to Robert Marquis, superintendent of the Swansea Water District, cold water desalination is not usually implemented in the Northeast because the reverse-osmosis membranes - which are what removes the salt from the water - don't function in very cold weather.
To enable the process to work, the plant site was located two miles away from the river, allowing the water's temperature to increase in the pipeline.
The desalination plant withdraws 4 million gallons of water from the river during two daily cycles at 5,400 gallons a minute. The raw water is pretreated with membrane filtration, followed by reverse osmosis, producing 1.2 million gallons of drinking water and returning 2.8 million gallons of reject water back to the river at 3,700 gallons a minute.
Marquis added that the desalination process is combined with a separate process for treatment of a groundwater source at the plant site, for a combined total daily production of 2.2 million gallons, a capacity that can serve 20,000 people. Eventually, he said, the plant will have the capacity to be regional, helping towns like nearby Rehoboth, which doesn't have a water treatment facility.
"Membrane filtration is the wave of the future," he said.