This groundwater treatment plant is the first municipal membrane treatment plant in Ohio. The Tonka Water system is designed for conventional iron removal coupled with membrane treatment for hardness reduction. Special attention was given to provide the highest quality potable water without the generation of brine waste; a disposal problem often associated with ion exchange softening treatment.
The water supply is received from two wells. Sodium hypochlorite and potassium permanganate are added for disinfection and iron oxidation prior to detention. Four 4’ diameter VertaCell™ pressure filters manufactured by Tonka Water are employed to remove the iron. Dual media within the filters consists of 18 inches of silica sand capped with 12 inches of anthracite.
Sodium bisulfite and antiscalant chemicals are added to the filtered water prior to reaching one of two of Tonka Water’s Flux RO/NF™ nanofiltration membrane skids for hardness removal. Special criteria were set for the removal of sulfate and TDS, as well as total hardness. Softened water is blended with a bypass stream to produce water with a total hardness of 150 mg/L. Sodium bicarbonate and caustic soda are added for pH adjustment to the finished water. The water is collected in clearwells where it is pumped to the distribution system using two high service pumps.
Controls consist of multiple Allen Bradley PLC-based automatic control panels. The main control panel operates all filter functions, chemical feed pumps, and the Flux RO/NF skid. All controls are networked together to ensure total system responsibility.
The treatment process has been highly efficient in the removal of iron, hardness, sulfate, and TDS.
Finished Water (mg/L)