Progress at Back River

October 21, 1991

Earlier this month, Sen. Barbara Mikulski and Mayor Kurt Schmoke announced a $40-million federal anti-pollution grant to

help finance the on-going work at the Back River sewage plant. The state's largest wastewater-treatment plant, Back River strains up to 180 million gallons a day. Its discharge into the Chesapeake estuarine system has a major impact on the environment that nurtures oysters, clams, crabs and bay fish. Thus, a particular emphasis in Maryland's commitment to the Chesapeake Bay Compact focuses on upgrading the Back River plant.

This grant, to be matched by $32 million in state and local funds, helps speed the expected opening next spring of advanced filtration facilities. These shallow sand filtration beds will provide fine scrubbing of the flow at Back River. Another step, nutrient removal, will be upgraded in three phases at a cost of $124 million. Equipment will strip nitrogen -- a nutrient that harms the bay -- from the waste stream, discharging harmless gas and water. Activated sludge facilities will be upgraded to add new capabilities to the biological processes that now clean Back River's effluent.

The big boost for neighbors comes from the current odor studies. Consultants have found, not to anyone's surprise, that the worst odors come from the earliest stages of wastewater treatment. A mechanical screen building, whose rotating fine-mesh screen strips large particles from the water, also aerates it, churning bacteria that release noxious odors. Authorities sealed that building and have installed an air scrubber, which traps odors. Similar measures have cut the stench from the plant's "head chamber" tank, which feeds other processes. "Weirs," serrated edges of giant settling tanks, also are responsible for smelly releases. The consultants have recommended three remedies: flooding the weirs to minimize the churning of water falling over them; covering the weirs and vacuuming the air above, or covering entire tanks. Tests should determine which is the most cost-effective solution, bringing permanent relief for odor sufferers.

It's never sexy to talk about sewage. But a plant such as Back River, which draws wastewater from Baltimore County and the city, affects the quality of everyone's life in the Chesapeake region, not just those within smelling distance.

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