Forward Osmosis in India: Status and Comparison with Other Desalination Technologies

Table 1

Comparison of different desalination techniques.

Desalination technique	MSF	MED	RO	VC	SHDH	EDR	FD	NF	FO
Energy consumption (kWh/m^3)	Electrical: 4–6 Thermal: 55–120 [30]	Electrical: 2–2.5; Thermal: 30–120 [31]	Electrical: 3.5–4.5; Thermal: None [30]	Electrical: 7–12; Thermal: None [32]	140–550 [33]	<0.6 [34]	90–120 [35]	0.3–1 [36]	Total: 0.84 [37]
Product water quality (mg/L TDS)	1–50 [30]	1–50 [38]	1–350 [30]	1–50 [39]	50–90 [40]	0–10 [41]	Not available	30–45 [42]	120–200 [43]
Total capital costs	Very high	High	Low-medium	Medium	Very high	Low-high	Very high	Low	Low
Tolerance to changes in seawater composition	Medium-high	High	Very low	High	Very high	Very high	high	Very low	Very low
Maintenance requirements	Medium	Low	High	High	Higher than RO	High	Very high	low	High but with less frequent cleaning than RO
Scaling potential	Low-medium	Low	High	Medium	Low	Very low	Very low	Less than RO	High but lower than RO
Chemical consumption	High	Medium	High	Medium	—	Low	Low	Low	Medium
Ratio between product to total seawater flow	0.1-0.2 [30]	0.1–0.25 [30]	0.3–0.5 [30]	0.7 [44]	0.85 [45]	0.8-0.9 [41]	0-1 [46]	0.7 [47]	0.3–0.85 [48]
Technical know how	High	High-medium	Medium	Medium	Low	Medium	Medium	Low	Low
Membrane fouling	NA	NA	High	NA	NA	Low	NA	High	Low
GHG emission	Yes	Yes	Negligible	Yes	No emission	Can't say	Can't say	Negligible	Negligible
Fully automatic operation	Possible	Possible	Possible	Possible	No information available	Possible	No information available	Possible	Possible
Limiting factors	Pumps, valves, and vacuum unit [30]	Erection and construction aspects; plant reliability [30]	Pumps [30]	Volumes of vapour to be handled are large, thus demanding high volumetric capacity centrifugal compressors. [44]	Low productivity and thermal efficiency, and large land area required [49]	Microbial contamination [34]	High capital cost and operating cost, and retention of aroma from original water [50]	Membrane fouling, limited lifetime of membranes, and low chemical resistance [51]	Lack of an optimized membrane to produce high water flux, and lack of ideal draw solution [52]