WATER TREATMENT PROCESS
Buffalo’s water intake is located in the northeastern region of Lake Erie, just upstream of the Niagara River. This region is known as the Emerald Channel, due to the sparkling clarity of its water. Water rushes into the intake through grates and collects in a circular pool where it drops 60 feet to a 12-foot diameter, mile-long tunnel burrowed under the lakebed. Chlorine may initially be applied in this conduit to control zebra and quagga mussels, it is also used to disinfect the water. The water is gravity fed to an onshore screen house at the Col Ward Pumping Station. There, traveling screens remove large objects such as sticks and other debris that can damage equipment.
Gravity continues to deliver the water through a conduit where chlorine may be fed. Chlorine is added here if feed at the intake is suspended.
Low lift pumps mix and direct the water to a surface conduit. At the pump’s discharge, polyaluminum chloride (PACl) is fed and mixed. PACl is a coagulant designed to cause debris in the water to bind together forming floc. The treated water is directed to an underground basin for flocculation and sedimentation. At the flocculator area, the water is slowly mixed by mechanical paddles to enhance floc formation. This treated water then travels to the settling basins where the heavy floc is allowed to settle out by gravity. The treated water, still containing light floc, is directed over rapid sand anthracite filter beds where filtration occurs, removing the light floc. A filter aid (PACl) is added, when necessary, to enhance filtration, and additional chlorine may also be added if needed. This filtered water enters a 28 million gallon Clearwell, where it is stored until needed in the distribution system.
The rapid sand filters need to be cleaned of trapped debris; this is done by backwashing the filters with potable water stored in washwater tanks. To comply with EPA’s Filter Backwash Recycle Rule the backwash water, containing filter bed debris, is recycled back to the raw water conduit after sludge production in the Thickening Tanks. The Thickening Tanks concentrate the debris into sludge using a polymer and settling tubes. The sludge portion is pumped to an onsite lagoon where further processing takes place before removal to a landfill. The decant portion is directed over a weir at the top of the Thickening Tanks to the Raw water conduit, where the water treatment process begins.
As the potable water leaves the clearwell, a corrosion control additive (a sodium ortho/polyphosphate chemical blend) is used. This serves as a shield against lead leaching into the water from aged residential water pipes and service lines. High lift pumps located at the Ward and Massachusetts Stations deliver the treated water to the community. Our in house laboratory tests the quality and safety of the water at every stage of the treatment process. Additional tests are conducted from samples taken throughout the city, including private homes, businesses and public facilities to ensure our water remains safe.