Page 299 - Membranes for Industrial Wastewater Recovery and Re-Use

268 Membranesfor Industrial Wastewater Recovery and Re-use

Table 5.17 Reclaim and raw water quality (parameters requiring treatment in bold type)

Parameter Reclaim water Raw water
Min. Max. Min. Max.
Bacteria (cells 1-l) 5 73 5 2000 94 000
Conductivity (pS cm-') 250 600 44 179
Silica (mg 1-') 0.5 32 0.903 0.73
Iron (mg I-') 0.01 0.1 0.01 0.1
Sodium (mg 1-I) 0.004 4.9 1.34 7.4
Alkalinity (mg I-') 0 0 3 147
Calcium (mg 1-l) 0.01 0.67 7.2 8.9
Potassium (mg I-' 0.01 0.73 0.37 0.66
Magnesium (mg 1- ) 0.01 0.07 1.02 1.6
Chloride (mg 1-I) 0.02 19.8 11 13
Phosphate (mg 1-' 0.05 2.05
Sulphate (mg 1-') 30 110 4 5
Nitrate (mg I-') 0.13 1.2 1.11 1.8
Fluoride (mg 1-I) 1 15.5 0.1 0.13

Anion
GAC

RO
I
Reclaim tank I 1"DI
Reclaim tank
I
screen
screen UV
UV
Drain
c ETP
Figure 5.25 Processflow diagram of the reclaim treatment facility at NEC Semiconductors Ltd

then sterilises the water and removes any trace organics remaining in the flow.
The final stage of the treatment is a reverse osmosis plant consisting of 8 inch x 8
inch modules each fitted with four elements and arranged in a 5:2:1 array.
The plant operates at a 90% recovery generating 130 m3 h-' of treated
reclaim water.

5.113 Performance
Water enters the reclaim plant with a conductivity of 600 pS cm-l. The weak
anion bed reduces the conductivity to 2 5 pS cm-l which is then further reduced
through the RO plant to a final value of 3 pS cm-l. The water then mixes with the
treated raw water before being passed onto the DI production facility where