Flow from Providence, North Providence, Johnston, and portions of Lincoln and Cranston
61 miles of NBC-owned pipes
The state’s largest and one of the country’s oldest wastewater treatment facilities
Capacity: 200 million gallons per day preliminary and primary treatment
65 MGD secondary treatment
Wastewater treatment is a 24 hour a day, 7-day a week process to clean used water. As the incoming flow enters the facility, bar racks catch large pieces of debris such as branches and trash before they interfere with the treatment process. Smaller debris like gravel and coffee grounds are also separated from the flow using aerated grit tanks. This material is washed and trucked along with the bar rack screenings to the Central Landfill for proper disposal. This procedure is called preliminary treatment. The next step in the treatment process is primary treatment and involves the separation of settleable solids from the wastewater using settling tanks and floatable solids using skimming devices. Up to sixty (60) percent of the solid material is removed at this point. Secondary treatment removes up to 85% of the solid material from the flow. It is a two-step process involving aeration and clarification.
Oxygen is supplied to the wastewater to stimulate the growth of helpful bacteria and other microorganisms which break down and consume or eat the remaining organic waste products and impurities. Once in the final clarifying tanks, the mass of organisms (activated sludge) is separated from the wastewater. Some activated sludge is used to reseed the treatment process and the rest is removed. The flow is then channeled into the chlorine tank to kill harmful bacteria
(disinfection). To prevent the chlorine from harming aquatic life, a dechlorination facility removes chlorine residuals before releasing the flow into the receiving waters. The treated flow exiting the facility is called effluent. The solid material removed from the treatment process is called sludge or
biosolids. At the Field’s Point facility, the biosolids removed from the primary and final clarifiers are pumped to gravity thickeners to be concentrated.
The biosolids are then moved off-site to a facility that produces an
environmentally-friendly compost-like material.
Flow from Pawtucket, Central Falls, Cumberland, Lincoln, the northern portion of East Providence and a small section of Smithfield
28 miles of NBC-owned pipes
116 MGD preliminary and primary
46 MGD secondary treatment
The treatment process is similar at the Bucklin Point facility to Field’s Point; however,
disinfection occurs via ultraviolet light, and nitrogen is also removed from
the effluent.
Thanks to a $70 million upgrade to the Bucklin Point facility completed in
June 2006, the plant now features hydraulic and process improvements as well as updates to the instrumentation and controls at the plant to ensure reliable and continuous process control. These improvements
have increased the capacity of the facility to treat more dry and wet weather wastewater flows.
Throughout the treatment processes at both facilities, samples of the wastewater are taken and analyzed in the NBC’s state-of-the-art laboratory to ensure that both facilities are in compliance with state and federal regulations.
