Water Plant Division
ABOUT USThe City of Akron Water Plant Division is responsible for treating water from Lake Rockwell Reservoir. The average daily pumping rate is 35 MGD, with a plant capacity rating of 67 MGD. The primary reservoir, Lake Rockwell, located in Franklin Township; Portage County, Ohio is supplemented by two Upper Cuyahoga Reservoirs Wendell R. Ladue Reservoir and East Branch Reservoir. Total storage capacity of the three reservoirs is over 10 billion gallons.
The Akron Water Treatment Facility is an enhanced coagulation, rapid sand filtration treatment plant which has been in service since 1915. The Akron Water Treatment Facility continuously provides its customers with high quality water which exceeds all regulatory requirements.
The Akron Water Treatment Facility treats potable water to the City of Akron and all or parts of the cities of Tallmadge, Stow, Fairlawn, Cuyahoga Falls, Twinsburg, Hudson, Mogadore; and Bath, Boston, Copley, Coventry, Springfield, and Twinsburg Townships. Akron serves approximately 90,000 customer accounts with an estimated 300,000 service population.
Treatment Process
The intake is fed from Lake Rockwell Reservoir. Water travels approximately 1000ft to the Treatment Plant through the 72" intake pipe.FINE SCREENING
Within the intake structure of the water treatment facility, fine screens prevents items larger then ½" in size from entering the treatment plant. This would include fish, leaves, and other miscellaneous debris.
Several Chemicals are added in the intake as the water flows to the basins
Sodium Permanganate
Sodium permanganate (NaMnO4) is an oxidant which aids in the removal of iron, manganese, taste, and odor. Iron and manganese metals are dissolved naturally in surface water sources and pose no health risks but can cause staining of plumbing fixtures and laundry. Sodium permanganate also oxidizes organic chemicals that cause taste and odor problems.
Chlorine Dioxide
Chlorine Dioxide (ClO2) is generated on site. ClO2 is an oxidant used for taste and odor, disinfection and organic removal.
Powder Activated Carbon
Powder Activated Carbon (PAC)removes taste and odor compounds, algal toxins, and organics that would otherwise generate disinfection biproducts.
SETTLING BASINS
Four (4) settling basins of varying size are operated to treat flows ranging from 4 MGD to 20 MGD each.
After traveling 1,000 ft through the intake the partially treated water enters the mixing zones of the settling basins. At this point Aluminum Sulfate is added to begin to coagulate particles for flocc formation.
Sedimentation occurs as the large particles of floc become heavy enough that the water can no longer support their weight and the floc begins to settle out. The water has lost much of its turbidity by the time it has traveled to the end of the sedimentation basin. The accumulated floc is regularly pumped out of the bottom of the basin, dried in drying basins and hauled away to be beneficially reused as topsoil.
Alum is the common name for aluminum sulfate (Al2(SO4)3). Alum is used as a coagulant to bind together fine suspended particles into larger particles. These larger particles, called floc become heavy enough to settle out of the water. This settling removes suspended solids, color, turbidity (cloudiness), and the alum.
After sedimentation, the partially treated water requires an additional step to remove particles that were not settled out. This is accomplished by flwoing the water through gravity sand filters
RAPID SAND FILTERS
Twenty-five (25) rapid sand filters operate at up to 3 million gallons a day (MGD) each. The filters are made up of layers of anthracite coal, sand, fine gravel and coarse gravel. Because particles get trapped in the filters, it is necessary to clean, or backwash, them on a regular basis.
Depending on the water temperature, the filter media is cleaned between 20 to 80 hours of operation by backwashing the filtered particles to wash water lagoons. Frequency of backwashes are determined by head loss of the filter, run time, and turbidity (clarity) of the water measured after each filter.
FINAL CHEMICALS
During the final stage of the water treatment process, different chemicals additives including Zinc Orthophosphate, Fluoride, Caustic Soda and Sodium Hypochlorite are fed into the filtered water.
ZINC ORTHOPHOSPHATE
Zinc orthophosphate (Zn(PO4)), is used in small amounts as a corrosion inhibitor. It coats the inside of water mains, and internal house plumbing to prevents corrosion of iron and lead pipes.
CAUSTIC SODA
Caustic soda, also known as sodium hydroxide (NaOH), is used to adjust the pH of the water. Adding alum and chlorine lowers the pH to between 6.6 and 6.8. Caustic soda brings the pH back to a neutral state of 7.0. Neutral pH helps prevent the release of lead in home plumbing and fixtures
SODIUM HYPOCHLORITE
Sodium Hypochlorite is added to the water as a final disinfectant after most of the organic chemicals have been removed through settling and filtering. Enough chlorine is used that excess (residual chlorine) remains in the water throughout the distribution system. This ensures that there will be no re-growth of bacteria or pathogens in the water mains and pipes. Water Supply uses liquid sodium hypochlorite as the source of chlorine.
FLUORIDE
Fluoride in the form of hydrofluorosilicic acid (H2SiF6), is added to the drinking water to reduce tooth decay. Akron Water supply is required to add fluoride by Federal and Ohio law. Ohio Rule 3745-82-04.
High Lift Pumps
The plant is equipped with four 25 MGD pumps and two 15 MGD pumps which are alternated as needed. On average the plant pumps 35 million gallons of water a day (MGD) to approximately 300,000 customers.
WASH WATER LAGOONS
The filter backwash water is collected and pumped to lagoons located on Akron Water Supply property. These lagoons provide an opportunity for solids in the backwash water to settle out. The settled solids are then periodically dredged from the lagoons and transferred to the drying basins for drying and beneficial reuse removal. The settled water returns to the Cuyahoga River downstream of the intake.
COAGULANT RESIDUALS DRYING BASINS