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106 5. PRETREATMENT BY SCREENING 5.3.2 Design Example
Disk filters have found wide application as microscreens for source seawater prior to membrane pretreatment. The following example illustrates disk filter-type microscreen application for a 50,000 m3/day (13.2 MGD) seawater desalination plant designed for 43% SWRO system recovery and a total plant seawater intake flow of 127,910m3/day (5329 m3/h or 33.8 MGD):
Manufacturer
Model
Unit disk filter (module) capacity Number of arrays
Number of disk filter modules per array Number of disks (spines) per disk filter Number of jets per spine
Filter size
Array inlet- & outlet-piping diameters Inlet and outlet diameters of disk filters Pressure loss (clean filter)
Pressure loss triggering backwash Average pressure loss during operation Number of filters washed at one time Backwash flow
Backwash cycle length
Backwash frequency
Total backwash volume
Backwash pumps (horizontal centrifugal) Backwash pump head
Disk filter material
Amiad/Arkal or equal SpinKlin Galaxy600
16,000 m3/day (667 m3/h) 2
4
8
48
100 mm
300 mm (12 in.) 150 mm (6 in.) 0.15 bars (2.1 psi) 0.30 bar (4.2 psi) 0.22 bar
4 (one array)
16 m3/min per array
6 min
14 washes/day 0.3%e0.5% of intake flow 1 duty รพ 1 standby
3.0 bars
Polypropylene
This example is developed for a particular type of popular disk filter (SpinKlin, manufac- tured by Arkal, Israeldsee Fig. 5.10). These filters have found applications on a number of desalination plants with membrane pretreatment such as the 300,000 m3/day (80 MGD) Ade- laide and Southern (Perth II) Desalination plants in Australia, the 100,000 m3/day (26 MGD) Chennai SWRO Plant in India, and other plants in the Middle East and Europe.
