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Breaking down wastewater articles and terms
The first five articles on the Oak Bluffs special town meeting warrant are for wastewater expansion and improvement projects. They contain some of the highest spending measures on either warrant, and include terms like "primary clarifier" "septage" and "de-watering" - enough to make voters' heads spin. Wastewater facilities manager Joe Alosso explained the various terms, and how passage of the articles will affect the town and it's residents. [Refer also to the glossary of terms and graphic, below.]
Glossary of terms
Wastewater: Water that has been used and thrown away from residential, business or industrial sources. It can contain a variety of waste products including soap, chemicals, or human waste.
Mechanical Bar Screen: Equipment used to remove particles from the incoming wastewater.
Primary Clarifier: A tank that slows the movement of the wastewater entering the plant so any remaining solids (sand, grit, egg shells, coffee grounds, etc.) can settle to the bottom of the tank and be removed. It would also remove oils, fats, and grease, which have caused problems in other parts of the system.
Sequencing Batch Reactor (SBR): High-tech, aerated tubs where microorganisms consume the organic material floating in the water. After a set amount of time, the oxygen that is fed into the tank is turned off. This allows the microorganism, and any solid matter to settle to the bottom of the tank where it can be removed and dewatered. Each batch takes about six hours to complete.
Equalization Tank: After treatment the water is sent here so it can be slowly sent through the sand filters.
Sand Filters: The water passes through a sand filter where any remaining solids that were not captured earlier in the process are removed.
Ultraviolet Disinfection: This is the process of removing pathogenic organisms. A machine shines ultraviolet (UV) light through the water that destroys any viruses or pathogens that could be present. Unlike chemical disinfectants such as chlorine, UV does not leave a residual product.
Viera Park Pump Station: After the water is disinfected it flows down to Veira Park to a pump station that will send it over to Ocean Park.
Ocean Park Sub-Surface Sand Beds: There are 28 beds measuring 50ft X 100ft. The water is sent to these beds where it percolates back into the ground water.
Passage of a third article would begin the design and engineering process for a small regional wastewater plant at the Martha's Vineyard Regional High School. In addition to the high school, the plant would serve Martha's Vineyard Community Services, Woodside Village and the YMCA. Voters are asked to appropriate $350,000 for the project, which would in turn be paid by the users in proportion to their use of the plant.