membrane, which is called hybrid (Chapter 10), is another option of selection.
Table 1.1 shows the range operational energy requirement for main desalination systems.
Table 1.1 Energy requirement for main desalination systems.
Source: Alkaisi et al. 2017 [4]. Reproduced with permission of Elsevier.
| MEE | MSF | MEE‐TVC | MVC | RO | ED | |
| Typical unit size (m3/d) | 5000–15 000 | 50 000–70 000 | 10 000–35 000 | 100–2500 | 24 000 | −145 000 |
| Steam pressure (atm) | 0.2–0.4 | 2.5–3.5 | 0.2–0.4 | — | — | — |
| Electrical energy consumption (kWh/m3) | 1.5–2.5 | 4–6 | 1.5–2.5 | 7–12 | 3–7 | 2.6–5.5 |
| Thermal energy consumption (kJ/kg) | 230–390 | 190–390 | 145–390 | None | None | None |
| Electrical equivalent for thermal energy (kWh/m3) | 5–8.5 | 9.5–19.5 | 9.5–25.5 | None | None | None |
| Total equivalent energy consumption (kWh/m3) | 6.5–11 | 13.5–25.5 | 11–28 | 7–12 | 3–7 | 26–5.5 |
1.6 Thermo‐Physical Properties of Water
1.6.1 Potable Water
Potable water (freshwater) is characterized with salinity less than 500 ppm.
Table 1.2 shows water classification based on salinity, and the standards of WHO for freshwater limit is 500 ppm (0.05 mg/kg).
Table 1.2 Water classification based on salinity content.
| Type | Total dissolved salts (TDS) |
| Freshwater | <1500 |
| Brackish water | 1500–10 000 |
| Salt water | >10 000 |
| Seawater | 10 000–45 000 |
| Standard seawater | 35 000 |
The chemical concentration in fresh water with 500 ppm are shown in Table 1.3.
Table 1.3 Secondary drinking water regulation [5].
| Chemicals | SDWR |
| Aluminum | 0.05–0.2 mg/l |
| Chloride | 250 mg/l |
| Color | 15 color units |
| Copper | 1.0 mg/l |
| Corrosivity | Non‐corrosive |
| Fluoride | 2.0 mg/l |
| Foaming agents | 0.5 mg/l |
| Iron | 0.3 mg/l |
| Manganese | 0.05 mg/l |
| Odor | Three threshold odor numbers |
| pH | 6.5–8.5 |
| Silver | 0.1 mg/l |
| Sulfate | 250 mg/l |
| Total dissolved solids (TDS) | 500 mg/l |
| Zinc | 5 mg/l |
Tables 1.3 and 1.4 show the 2018 Drinking Water Standards and Health Advisories, Secondary Drinking Water Regulations.
Table 1.4 WHO standards for potable water [5].
| Constitutes | Concentration (ppm) | |
| Limited values | Max allowed values | |
| Total dissolved salts (TDS) | 500 | 1500 |
| Cl | 200 | 600 |
| SO42+ | 200 | 400 |
| Ca2+ | 75 | 100 |
| Mg2+ | 30 | 150 |
| F− | 0.7 | 1.7 |
|
| ||