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New England
Tries Desalination To Treat Brackish Water
7/24/2006
By
William J. Angelo
Desalination of seawater is becoming a viable
option for parched western and southwestern states. But now one
East Coast state is adopting the technology to create a new drinking
water source. Massachusetts is the site of New England’s first
tidally influenced desalination plant for brackish water, located
on the Taunton River. It will use ultrafiltration membranes with
reverse osmosis to provide 3.2 million gallons per day of drinkable
water to users in Brockton.
Wakefield-based Metcalf & Eddy/ AECOM
designed the plant, located in Dighton and set to finish in 2008.
It will be owned and operated by Aquaria Water LLC, a joint venture
of Inima USA, Brockton, and Bluestone Energy Services Inc., Braintree.
Zoppo Construction, Stoughton, is contractor. “This is our
first project in North America,” says Alfredo Andres, Aquaria
general manager. “Brackish water treatment is cheaper than
seawater and provides us with new market opportunities.” Doug
Gove, M&E project manager says that a 16-mile-long, 20-in.-dia
ductile iron pipeline will connect the plant to the city.
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| Transformation. Wastewater
technology is now going potable. |
The $65-million plant will supplement the
city’s 10.8-mgd surface water system. It will use patented ZeeWeed
immersed, low-pressure ultrafiltration membranes, manufactured by
Zenon Membrane Solutions, Oakville, Ontario, as the primary treatment
process during winter and spring when total dissolved solids are low.
When TDS levels rise, membranes will provide
feed water for a reverse osmosis system to remove salt. Zenon was
acquired by GE Water & Process Technologies Corp, Trevose, Pa.,
in June. “The plant is actually an integrated membrane system,”
says Graham J. Best, Zenon director of drinking water treatment.
“It combines a low-pressure ultrafiltration program with a
high-pressure reverse osmosis system. It’s an emerging market
for membrane technology.”
The ZeeWeed system consists of about 2,500
hollow polymeric membranes, each about 7 ft long, that are suspended
in modules and immersed in 1-million gal process tanks. Sixty-four
modules form a cassette, with three cassettes per train. Taunton will
use three trains. Modules are connected to pumps, which create a slight
vacuum to each fiber that permits water passage but strains out solids,
organic matter and pathogens.
ZeeWeed suction technology was introduced
in the early 1990s, primarily for industrial and municipal wastewater
treatment, Best says. He adds that the approach was used for drinking
water later that decade, with the largest applications now in San
Diego, a 100-mgd system.
“ZeeWeed is a stand-alone system, but
in Taunton we need reverse osmosis because it does not remove dissolved
salt,” adds Best. He says that ultrafiltration capacity must
be 4.3 mgd during reverse osmosis because of lower recovery rates.
Aquaria may eventually boost plant output
to 5 mgd. “Right now we have only one client but if more towns
join we will do the upgrade,” says Andres.
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