The sewage that enters the plant will undergo a series of treatment processes in order to meet our National Pollutant Discharge Elimination System permit which is set by the Ohio Environmental Protection Agency.

Preliminary treatment is the first process and is a physical treatment that is used to remove all the inorganic materials from the incoming waste water.  The waste water first flows to an automatic bar screen used for removing any rags, trash, and all other debris larger than 3/8 inch in size.  After leaving the screening room, the flow enters two aerated grit chambers.  These grit chambers are designed to keep the organic waste in suspension while removing heavier grit (sand, gravel, etc.) that made it past the bar screen.  Grit settles at the bottom of the tank and is physically removed at a later date.  The waste water then flows by gravity to four primary treatment tanks that are designed to create detention time to allow for physical settling of raw sludge.   This raw sludge is then pumped twice daily to the digester for further treatment at the solids handling facility.

Next step ... Secondary Treatment.

After preliminary treatment, the waste water flows by gravity to the next process known as Secondary Treatment.  Secondary treatment is a biological treatment process designed to remove nitrogen, phosphorus, organics, and other different types of bacteria contained in living systems.  Our secondary treatment process consists of four aeration tanks and five blowers (only two run at any one time, providing oxygen to the aeration tanks), and three secondary clarifiers for settling.  A large portion of the settled sludge is recirculated to the head of the aeration tanks.  This recirculated sludge is known as Return Active Sludge, or 'RAS'.  A smaller portion recirculated sludge is wasted to the head of the plant which allows us to control our mixed liquor suspended solids (MLSS) concentration, and is known as Waste Activated Sludge, or 'WAS'.

Next step ... Tertiary Treatment

Following Secondary Treatment, the waste water receives Tertiary Treatment.  After the flow leaves the secondary clarifiers it is lifted by two screw pumps and a lag pump (only one runs during normal flow periods) to the disk filter room where it flows by gravity through three disk filters.   The disk filters remove almost all of the remaining suspended solids and allow us to meet permit limits monthly.  The disk filters run at different intervals according to the amount of flow entering them.

Next step ... Disinfection.

The next treatment step is known as Disinfection.  After the flow leaves the Tertiary Treatment, it enters the Ultra Violet Disinfection Channel.  From May 1st through October 31st every year, UV Disinfection is used to control our fecal coliform levels in accordance with our NPDES permit.  Our UV System consists of two separate units, each equipped with thirty bulbs.  These units rotate automatically on a weekly basis, except in times of high flow where both units are needed simultaneously.

Next step ... Post Aeration.

The Post Aeration system is designed to provide additional dissolved oxygen to the final effluent to assure that we meet our NPDES permit limits.  The Post Aeration system consists of a channel with two mounted mixers in tandem.  These are used to agitate the water and provide additional dissolved oxygen.  Following the channel aerators, the water flows by gravity through an aqueduct to the cascade aerator for additional agitation.  The cascade aerator is a set of stairs down which the water flows before falling into the discharge channel.  Between the discharge channel and the receiving stream is where we sample our final effluent continuously to assure a quality effluent which is well within all of our NPDES limit requirements.

The raw sludge that settles in the primary clarifiers is pumped twice daily by two raw sludge pumps to the Anerobic Digesters.  The Anerobic Digestion system consists of two digester tanks that are both mixed and heated to between 96 and 100 degrees Fahrenheit by boilers that are fueled by the methane gas produced during the digestion process, or supplemented by natural gas if needed, and a sludge holding tank for storage and de-watering.  After the sludge is pumped to each tank, it is ready to be fed through a gravity line to the Belt Filter Press feed pumps.  The digested sludge is mixed with polymers for thickening prior to hitting the Belt Filter Press for de-watering.  The pressed sludge is then hauled to the drying beds by plant operators for additional drying time.  The dried sludge will then be hauled away and land applied at a later date.

Equalization basins are used during high flow conditions to store and provide primary treatment to any influent flows exceeding 6.02 million gallons per day.  When the plant exceeds its ability to treat any more waste water, the excess is diverted to these equalization basins, each with a capacity of 1.4 million gallons.  This water is stored in the basins until it can be re-introduced at the had of the plant for processing once influent flows have returned to normal levels.