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Rescue Food. Nourish Our Community
Arlington Visits Deer Island, by Dave Haas
On June 6, six members of Sustainable Arlington and three members of the Arlington DPW took a tour of the Deer Island Treatment Plant. The facility, part of the MWRA system, services 43 communities in the Boston area. The site opened in 1995 following seven years of planning and construction, and treats nearly 400 million gallons of sewage daily, although the capacity of the plant is several times greater.
Sewage from the communities is merged and pumped to the facility through three main pumping stations, where it then undergoes several sequential treatment steps. Primary treatment removes the majority of grit and sludge through gravity separation. Sludge generated during this process is broken down into through anaerobic (oxygen-free) digestion; the resultant material is used as fertilizer. Secondary treatment of the wastewater uses microorganisms in an oxygen-rich environment to break down the majority of the (non-settled) waste material. Finally, the resulting effluent is treated with bleach to remove any remaining pathogens, and then discharged through a 9-mile pipeline into Massachusetts Bay.
What is most remarkable about the Deer Island facility are it’s ongoing sustainability programs. Methane gas generated through sludge digestion (25 times as potent a greenhouse gas CO2) is recycled and used as an on-site process fuel. An array of solar collectors was installed approximately 5 years ago, which now provides the majority of the electric power used on site. Most recently, three wind generators on the southwest side of the island have providing additional power; a fourth system, installed in 2010, is a high-efficiency prototype generator that may be the model for future wind turbines.
For more info on the Deer Island Facility, the link is: www.mwra.state.ma.us/03sewer/html/sewditp.htm