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The Duck Island Clean Water Facility is a 32 million-gallons-per-day activated sludge treatment plant. The facility accepts wastewater from the City of Lowell and the towns of Chelmsford, Dracut, Tewksbury, and Tyngsborough.
LOWELL REGIONAL WATER AUTHORITY
Duck Island Clean Water Facility
Duck Island Process Flow
Select each image to learn more about the process it represents:
Primary clarification (aka “settling”) allows for further settlement of large suspended solids, grease, and other floatables. Our primary clarifiers have an average total suspended solids removal of 65%. The solids produced by the primary clarification process are then sent on to the gravity thickeners.How You Can Help: Please dispose of fats, oils, and grease in a trashcan and never flush baby wipes (even the ones that say they’re “flushable”).EndFragment
The solids collected from the bottom of the settling process are sent to the gravity thickeners. Gravity thickeners allow for further settling of solids using gravity.
Biological treatment uses naturally occurring bacteria to digest and breakdown pollutants present in wastewater. Our aeration basins are divided into aerated and unaerated zones that support the health of desired bacteria and help to kill dangerous bacteria.
The polishing process uses additional clarifiers to allow for the settlement of fine solids and active bacteria. A portion of the solids collected from the bottom of the secondary clarifiers is recycled into the biological treatment process.
The solids collected from the polishing process that are not recycled to biological treatment are pumped to the rotary drum thickeners for thickening. Rotary drum thickeners consist of rotating cylindrical drums that separate water from the solids.
The centrifuge accepts thickened sludge from the rotary drum thickeners and gravity thickeners for further dewatering. The liquid that is removed from the sludge is sent to the influent structure at the beginning of the Duck Island facility.
The disinfection process involves adding chlorine to the processed water to kill remaining pathogens and bacteria. Next, we remove the chlorine to protect aquatic life and maintain the water quality of the Merrimack River.
Treated water discharged from the Duck Island Clean Water Facility always meets the rigorous standards outlined in the Clean Water Act (CWA). We work hard 24/7 to serve our customers and minimize human impact on water quality and aquatic life in the Merrimack River.
The dewatered cake that is created by the centrifuge is loaded onto hauling trucks using a series of conveyors for off-site disposal.
The raw wastewater then passes through two bar screens to remove large debris. A significant amount of the solids removed by the bar screen is trash that ended up in the collection system.
How You Can Help: Please dispose of all litter in trash cans so it does not end up in the sewers.