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This page was last edited on 05/14/2007

City of St. Marys Wastewater Treatment Plant

St. Marys, OH  45885

Telephone:    419-394-5193

Flow Equalization

An overflow structure at the head end of the Wastewater Treatment Plant controls the volume of wastewater brought into the plant for treatment.  During high flow conditions when the plant cannot treat all of the flow, an electric valve diverts a portion of the flow to an equalization basin.  The contents of the equalization basin automatically return to the treatment plant for treatment when flows return to normal.  A computerized process control system controls all aspects of flow equalization.

Wastewater Treatment

Polluted wastewater pumped into the Wastewater Treatment Plant goes through a complex, multi-stage treatment process that takes about 12 hours.  The treatment plant uses physical, biological, and chemical treatment processes to remove pollution, producing a high quality discharge.

Wastewater Treatment Stages:
bullet Grit Chambers - heavy inorganic matter, such as sand, is removed.
bullet Communitor - grinds paper and other material into smaller pieces.
bullet Phosphorus Removal - ferrous chloride reacts with and settles phosphorus.
bullet Primary Settling - removes solids and floating material.
bullet Trickling Filters - biological process where dissolved and suspended material is consumed.  The majority of biological oxygen demand (BOD) is removed here.
bullet Activated Sludge - biological process where microorganisms feed on organic matter.  The majority of ammonia is removed here, a process known as nitrification.
bullet Secondary Settling - final separation of solids before wastewater is discharged to the river.
bullet Chlorination - addition of chlorine to disinfect the wastewater.
bullet Dechlorination - removal of chlorine to prevent harm to river organisms.
bullet Primary Digestion - solids removed or generated during wastewater treatment are pumped here and anaerobically (without oxygen) treated to reduce organic material.
bullet Secondary Digestion - used to thicken and store treated solids (biosolids).  Biosolids are applied to farmland as a soil conditioner.

Laboratory

The Wastewater Treatment Plant Laboratory contains all the various equipment and chemicals needed to monitor the wastewater.  Thoroughly trained lab analysts check water quality during all stages of the treatment process to insure optimum treatment and to protect the water quality of the St. Marys River.  Tests include pH, phosphorus, ammonia, nitrate, alkalinity, dissolved oxygen, biological oxygen demand (BOD), carbonaceous biological oxygen demand (CBOD), chlorine residual, total, fixed, and volatile solids, and bacteriological.

Maintenance

Regular maintenance is a very important part of operating a public wastewater utility.  Personnel are charged with many tasks and projects in order to keep the treatment plant operating at peak levels.  Examples include: preventative maintenance of treatment plant and lift station equipment, regular inspections of the plant and lift stations, and many other activities.

Staff

Two full time operators staff the St. Marys Wastewater Treatment Plant eight hours per day, seven days per week.  Two supervisors, a laboratory technician, and two maintenance men split time between the plant and other duties.  All employees are Ohio EPA certified operators.  The increasingly technical nature of Federal and State regulations requires continuing training on the part of all employees.

2006 Operating Data
bullet Wastewater Treated:    724.553 million gallons; 1,987,000 gallons per day
bullet Wet Weather Overflows:    29.016 million gallons total for year
bullet Biosolids Applied to Farmland:    2.014 million gallons; 353 Dry Tons
bullet Total Organic Pollution:    95% removal; EPA requires 85%
bullet Carbon Organic Pollution:    96% removal; EPA requires 85%
bullet Suspended Solids Pollution:    95% removal; EPA requires 85%
bullet Ammonia Pollution:    93% removal; no EPA requirement
bullet Phosphorus Pollution:    83% removal; no EPA requirement

 

 
Send mail to dsprague@cityofstmarys.net with questions or comments about this web site.