Storage and handling systems for lime and soda ash aid water plant improvements
Increasing maintenance and high material costs drove the city of Richfield, Minn., to install new water plant equipment.
The city of Richfield's water plant receives water from seven deep wells with a total pumping capacity of 19,000 million gallons per day [mgd]. Six 125-horsepower pumps and one 150-horsepower pump move the water through 19- and 24-inch pipes to the plant for softening and sterilization. The plant uses dry chemicals including pebble lime and soda ash [with a particle size ranging from that of powdered to crystalline sugar] to soften the water through pH adjustment. This causes carbonates to precipitate out of the water. The plant further treats the water by adding liquids such as ferric chloride, coagulating polymer, and fluoride, as well as carbon dioxide gas. Upon entering the plant, the water splits between two softening basins and flows through a softening reactor, then to a clarifier, through a filter for solids removal, into recarbonation, and through final filtration.