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Learn How Akron Treats Wastewater

Process Flow Diagram Process Flow Diagram
Influent Screen Influent Screen

PRELIMINARY TREATMENT


INFLUENT SCREENING
There are 4 continuously cleaned screens which are rotated in and out of service to distribute wear evenly among the units. These influent screens remove material such as rags, leaves, sticks, etc., that would clog pumps and pipelines. This material is disposed of by land filling.

GRIT REMOVAL
The grit removal tanks remove sand, stones and other grit-like materials that would cause wear to pumps and clog pipelines. Four quick settling tanks are designed to remove the grit, but not the light organic solids. The grit is disposed of by land filling.

STORM RETENTION
The function of the Storm Retention Tanks is to provide flow equalization through temporary storage of wastewater during periods of high flow. When high flows subside, wastewater is pumped back into the plant for treatment.


PRIMARY TREATMENT


SEDIMENTATION AND FLOATATION
Primary treatment removes organic solids by sedimentation and flotation. The solids that settle to the bottom of the 24 Primary settling tanks are collected and pumped to the Gravity Thickener Tanks. The treated primary effluent goes on to the Activated Sludge Process for further treatment. Grease and other floating matter are removed from the surface of the tanks and dewatered prior to disposal.

Primary Tank Primary Tank

SECONDARY TREATMENT


SECONDARY AERATION (Activated Sludge)
The Activated Sludge Process is an aerobic, suspended growth, biological treatment method. It uses the metabolic reactions of microorganisms to produce a high quality effluent by converting and removing substances that have an oxygen demand. To sustain the aerobic bacteria, approximately 40 million cubic feet per day of air (oxygen) is required.

SECONDARY CLARIFIERS
After a period of approximately 8 hours in the aeration tanks, the wastewater flows into Secondary Clarifiers. The solids are separated from the treated wastewater by gravity settling. The treated wastewater leaves the clarifiers and then flows to the Chlorine Contact Tanks. The solids (microorganisms) that settle to the bottom of the clarifiers are mostly returned to the Aeration Tanks to feed on the incoming organic waste. The solids that are not returned are sent to the Gravity Belt Thickeners for volume reduction prior to further treatment.

EFFLUENT DISINFECTION
Before the water is released to the Cuyahoga River, it is disinfected with Sodium Hypochlorite (a strong bleach) to kill pathogenic organisms. Approximately 30 minutes of contact time is allotted for the disinfecting process to take place. To reduce the chlorine residual of the treated effluent, Sodium Bisulfite is fed just prior to the plant discharge point.

EFFLUENT OXYGEN
An Oxygen Enhancement System is utilized at the CCT area. Its purpose is to ensure that the Dissolved Oxygen of the plant effluent is no less than 5.0 mg/L which is mandated by the OhioEPA. Liquid Oxygen is vaporized and released during periods of possible low D.O. events such as during the beginning of a high flow event.

Mixing & Holding Tank Mixing & Holding Tank

SOLIDS HANDLING AND DISPOSAL 


PRIMARY GRAVITY THICKENERS
Solids removed from the Primary Settling Tanks are pumped to the Primary Gravity Thickeners, where they are thickened by gravity settling. The thickened solids are then pumped to the Mixing and Holding Tanks.

GRAVITY BELT THICKENING
Waste activated solids from the Activated Sludge Process flow to the Gravity Belt Thickeners. Gravity belt thickening concentrates conditioned solids through the gravity separation of water and solids on a continuously moving porous horizontal belt. The thickened solids are then pumped to the Mixing and Holding Tanks.

MIXING and HOLDING TANKS
Thickened Primary and Waste Activated solids are pumped to the Mixing and Holding Tanks and blended together and stored for further processing. There are a total of six tanks, each with a one million gallon capacity.

Water Reclamation Facility

Water Reclamation Facility

2460 Akron-Peninsula Road
Akron, OH 44313
p (330) 375-2963 f (330) 375-2966



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