1. A well water with a total hardness of 10.76 ppm is to be used for a pharmaceutical industry, which requires finished water hardness to be 3 ppm. An ion exchange resin is selected requiring 0.3 pounds of salt per kilo-grain of hardness removed to regenerate. What is the salt usage for each regeneration if the system regenerated every 10 days? What size resin tanks (diameter, height) would be required for a duplex system with no redundancy?
Assumptions:
Limit water loading rate to 8 gpm/sf
Resin capacity is 20,000 grains per cubic foot of resin
Grains per gallon: 17.1 = 1 mg/L
Water production is 1.0 mgd
Resin void is 50%
2. What is the annual power cost for a 10-mgd water plant using ozone for oxidation as well as disinfection at a rate of 5 mg/L? Assume the city gets a bulk power rate of ten cents per kilowatt hour.
3. A brackish water Reverse Osmosis (RO) system has one skid with 36 vessels each containing six membrane elements. The plant produces one million gallons per day of desalted water. Is the system within membrane manufacturer's warranty requirement of maximum flux rate of 14 gfd? What is the annual power cost of the RO system?