Water defluoridation, water denitrification and water desalination in rural areas in South Africa

Abstract

Many borehole waters in rural areas in South Africa are unfit for human consumption because the fluoride (>1,5 mg/ℓ), nitrate-nitrogen (>6 mg/ℓ) and salinity (>1 500 mg/ℓ) concentrations are too high. Ion exchange (IX) and reverse osmosis (RO) technology are available that can be used for defluoridation, denitrification and desalination of water. However, methodology, guidelines and the economics for the use of these technologies in rural areas are not readily available. Therefore, the objectives of this investigation were to develop methodology, guidelines and the economics for the defluoridation, denitrification and desalination of water in rural areas. The capital costs of ion-exchange household defluoridation and denitrification units are estimated at R5 000 each. Operational costs vary from R0,43 to R3,99/kℓ depending on the feed water concentration. The capital cost of a small RO unit to produce approximately 50 ℓ/d defluoridated water is estimated at approximately R3 000. (Operational cost R3,00/kℓ). The capital cost of an RO unit to produce approximately 5 kℓ/d desalinated water is estimated at approximately R20 000. (Operational cost R1,69/kℓ). The capital cost of an RO unit to produce approximately 50 kℓ/d denitrified water is estimated at approximately R150 000. (Operational cost R2,17/kℓ).

Paper presented at the the Third IASTED African Conference Power and Energy Systems (AfricaPES 2010), September 6-8, Gaborone, Botswana.