Page 199 - ro membanes

182 8. GRANULAR MEDIA FILTRATION
TABLE 8.5 Example of Single-Stage Dual Granular-Media Pressure Filtration System for 50,000 m3/day
(13.2 MGD) Desalination Plant
Component/Parameter
FEED WATER
• Design flow rate, m3/day (MGD) • Turbidity, NTU
• SDI5
DESIGN CHEMICAL DOSAGES
• Ferric chloride, mg/L
• Polymer, mg/L
• Sulfuric acid, mg/L: Target pH: 6.7
FILTER CELLS
• Number
• Diameter, m (ft)
• Length, m
• Filter vessel area
• Total filter media depth
TOP-LAYER FILTER MEDIA
• Type
• Depth
• Effective size
• Uniformity coefficient
• Specific density, tons/m3
BOTTOM-LAYER FILTER MEDIA
• Type
• Depth
• Effective size
• Uniformity coefficient
• Specific density, tons/m3
FILTER PERFORMANCE PARAMETERS
• Average surface loading rate
• Maximum surface loading rate with 2 units out of service • Filtration cycle
BACKWASH RATE
• Average
• Maximum
Specifications/Design Criteria
119,767 (31.6 MGD) 0.2e2 (max 5)
3e6 (max 8)
1 (0.5e5 mg/L) 0.15 (0.0e0.5 mg/L) 8 (0e30 mg/L)
10
3.5 (11.5 ft)
12 (39.4 ft)
42 m2 (452 ft2) 1.2 m (4.0 ft)
Pumice
0.6 m (3.3 ft) 0.6 mm
1.3
1.15
Sand
0.6 m (3.3 ft) 0.4 mm
1.3
2.65
11.9 m3/m2 h (4.9 gpm/ft2) 14.9 m3/m2 h (6.1 gpm/ft2) 24e48 h
35 m3/m2 h (1 gpm/ft2) 60 m3/m2 h ( 25 gpm/ft2)
The source water SDI5 is in a range of 10e16. Maximum algal count is <40,000 cells/L and total hydrocarbon level is below 0.10 mg/L at all times.
Similar to the other two examples, in this example, it is also assumed that the source water does not contain elevated contents of silica, iron, and manganesedtherefore, these fouling