Wastewater
Treatment Plant
Raw water entering the Plant normally consists of 99.9% water and
0.1% dissolved and suspended solids. The water enters the Plant through
a 12” sewer line from Heaton St. and a 15” sewer from Grape Street. Raw
water passes through the bar screen.
Bar Screens
The bar screens are designed to remove large solids such as sticks,
rags, paper, etc. Once through the bar screens the water enters the grit
chambers.
Grit Chambers
The grit chambers remove sand, small rock, etc. from the grit chambers.
The water is then directed into three primary clarifiers which hold a
total of 121,200.00 gallons.
Primary Clarifiers
The primary clarifiers are where most of the settleable solids and some
suspended solids are removed. Most of the solids in the primary
clarifiers settle to the bottom and are pumped to the anaerobic
digester.
Anaerobic Digester
Decomposition of organic material in the digester is a continuous two
step process. Two different kinds of bacteria are involved. In the first
step, the organic material is converted into organic acids by
acid-forming bacteria. The organic acids are used as food in the second
step by strictly anaerobic methane-forming bacteria, which convert the
acids into methane and carbon dioxide gases. During the last step,
complete digestion takes place. At this point the sludge is completely
stabilized and ready for dewatering. It is then hauled away and
applied to agricultural land.
Trickling Filters
The clear water off the top of the primary clarifiers is pumped to the
trickling filters. The tickling filter process consists of spraying the
wastewater over a bed of media of crushed rocks to form a biological
slime layer. This slime, or zoogleal film, is composed primarily of
bacteria, protozoa, and fungi. As wastewater trickles downward through
the voids of the media, organic matter and dissolved oxygen are absorbed
into the film and at the same time, the metabolic end products such as
carbon dioxide, water, nitrates and sulfates are released. From here,
the water flows to the final clarifiers.
Final Clarifiers
These clarifiers are sedimentation and flotation units. Settleable
solids during the detention period settle down to the bottom of the
clarifiers. These settled solids are scraped by the sludge collectors to
the sludge wells and pumped to the digester.
Disinfection
Chlorine is injected to kill bacteria once contact time is achieved for
disinfection. Sodium bisulphite is then injected for dechlorination of
the finished water before release into Rock Creek.
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