Intro:
The deer island water treatment facility is located on deer island on Boston harbor. The facility is a 3.8 billion dollar project to protect Boston harbor and the local wildlife from sewage pollution. The facility services the sewage in fluent from 43 communities around the greater Boston area.
The Process
The facility pumps in water thru four large tunnel the tunnels are equipped with ten 3500 hp pumps in addition to six 600hp pumps, and is equipped to handle 910 mgd per day.
After pumping the first part of the removal process begins. The influent is pumped thru a grit removal system which removes sand, gravel, and any other large debris which is shipped to a landfill.
Primary Treatment then occurs to clarify (50-60%) of the solid suspended particulate which are found in the influent, as well as 50% of the pathogens and toxins. This is done by gravity using 48, 186 ft tall 41 ft wide by 24 ft deep clarifiers.
Secondary Treatment occurs thru a series of mixers reactors clarifiers. This system removes non-settle able materials by a biological and other gravity processes. The processes use aerobic bacteria which naturally remove certain pathogens and other unwanted material . This process boosts removal to up to 85%
The next step in the process is sludge treatment which takes place on sludge which is built up from the first two processes in treatment. This process occurs in a process much like the stomach where natural bacteria eat the sludge. This process occurs in the 14, 130 ft tall 90 ft wide egg shaped digesters which are the most prominent feature of the island. The process produces methane and solid matter, the methane is used in boilers which burn to heat the facility as well as provide heat for the processes which occur throughout the facility. The remaining solid is moved off the island to a facility which is turns it into fertilizer which can be used for a variety of things.
Once the processes are complete the treated effluent is pumped out 9.5 miles thru a 24 ft wide pipe into massachussetts bay.
Conclusion
The deer island water treatment facility is a state of the art facility which protects the fragile water of boston harbor from the pollution of the large population which lives around its waters. The facility performs an essential task for the commonwealth and is a great example of a facility which other metropolitan areas could employ.