Membrane and Desalination Technologies - TCE Moodle Website

538 J.P. Chen et al.
Distilled
water
gutter
Inlet
Condensed droplets flow along the inside of
the glass cover and collect in the gutter
Heated by the sun, water
evaporates and condenses
Black heat adsorbent surface
Glass cover
Fig. 12.10. Schematic diagram of solar desalination.
Table 12.3
Comparison of water quality in a single-stage solar desalination system
Overflow
Parameter Quality in desalinated water a Quality in seawater a US EPA/WHO standard
solar distillations are operated by families or small villages in many parts of the world. Solarpowered
desalination plants are used in isolated parts of the world on a small scale, but the
high capital cost, fragility, and complexity of operation have discouraged extensive use.
Outlet
Conductivity 50 mS/cm 49,000 mS/cm –/–
pH 6.8 8 6.5–8/–
Calcium 4 mg/L 411 mg/L –/–
Magnesium 1 mg/L 1,290 mg/L –
Sodium 5 mg/L 10,760 mg/L –/200
Potassium 1 mg/L 400 mg/L –/–
Bicarbonate 12 mg/L 142 mg/L –/–
Carbonate 0 370 mg/L –/–
Sulfate 0 mg/L 2,710 mg/L 250 mg/L/250 mg/L
Chloride 11 mg/L 19,350 mg/L 250 mg/L/250 mg/L
Nitrate 2 mg/L 120 mg/L –/–
Total dissolved solids 30 mg/L 35,000 mg/L 500 mg/L/1,000 mg/L
Total hardness 15 mg/L as CaCO 3 4,300 as mg/L CaCO 3 –/–
Total alkalinity 10 mg/L as CaCO 3 2,150 as mg/L CaCO 3 –/–
Dissolved oxygen 7.6 mg/L 13 mg/L –/–
a Ref. (14).