Introduction to Desalination. Fuad Nesf Alasfour

Чтение книги онлайн.

СКАЧАТЬ 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
NO3−	<50	100
Cu2+	0.05	1.5
Fe3+	0.10	1.0
NaCl	250	—
pH	7–8	6.5–9

Table 1.5 Thermo‐physical properties of typical seawater at 40 000 ppm and 20 °C.

Density	1.0288 kg/m3
Specific heat capacity	3.973 kJ/(kg °C)
Boiling point elevation, at 20 °C	0.344 K
Boiling point elevation, at 90 °C	0.565 K
Thermal conductivity	0.601 W/(m K)
Dynamic viscosity	1.089 × 10−3 kg/(m2 s)
Kinematic viscosity	10.58 × 10−7 m2/s
Latent heat of vaporization	2355.4 kJ/kg

      1.6.2 Seawater

Table 1.5 shows thermo‐physical properties of standard seawater at 40 000 ppm and 25 °C.

      Note that the comprehensive thermo‐physical properties of seawater as a function of temperature and salinity are presented in Appendix A.

The major six elements that comprise about 99% of seawater are chlorine (Cl⁻), sodium (Na⁺), sulfate (SO₄²⁻), magnesium (Mg⁺²), calcium (Ca⁺²), and potassium (K⁺), and standard seawater composition at 35 000 ppm are presented in Table 1.6.

Table 1.6 Standard seawater composition at salinity equal to ≈35 000 ppm.

СКАЧАТЬ

---

Chemical ion	Concentration (ppm)	Valence	Total salt content (%)	mmol/kg	Molecular weight
Chlorine Cl−	19 345	−1	55.03	546	35.453
Sodium Na+	10 752	+1	30.59	468	22.990
Sulfate SO42−	2701	−2	7.68	28.1	96.062
Magnesium Mg2+	1295	+2	3.68	53.3	24.305
Calcium Ca2+	416	+2	1.18	10.4