Utilities Division The City of Wooster utilities division extends a commitment to excellence in public service through the proper treatment, protection, and preservation of the cities water resources.
Primary Treatment
Sewage plants are usually built at the lowest point of the collection system, and the City of Wooster is no exception. This allows the sewage to flow to the plant by gravity, except for areas serviced by lift stations.
The comminutor is the first step in the sewage treatment process. It screens out large materials, and chops up the remaining debris into pieces that are small enough so that they are not able to clog pipes (in theory). Because our comminutor is located prior to grit removal, the blades wear rapidly and soon become ineffective.
The sewage is then pumped up into the detritor, which removes grit and floatable solids. As the sewage enters the tank, the flow decreases, allowing grit to settle. It is then moved by a mechanical scrapper to an automatic rake, which pushes it into a dumpster, which is then hauled away. After the detritor was constructed, it was discovered that it gets cold in Ohio in the winter, and that in order to keep the rake from freezing, it had to be enclosed and heated.
Very few sewage plants have a vacuator. Its job is to remove grease. Sewage is drawn up into the tank by a vacuum. Air is then pumped into the sewage, causing the grease to separate and float to the top, where it is removed. Additional grit also settles and is removed.
The purpose of the three primary clarifiers is to allow the sludge in the sewage to settle out. The sludge is scraped off of the bottom by an automatic scraper and sent to the digesters. Many small sewage plants have only primary treatment, and discharge the settled sewage to the receiving waters at this point. We are an advanced secondary treatment plant, which means that additional processing is done. From here, the settled sewage is sent to the aeration tanks.
