The MBR Book: Principles and Applications of Membrane

220 The MBR Book
Permeability (GFD/PSI)
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gfd/psi
flux (gfd)
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Time (min)
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0
1200
Figure 5.9 Flux and permeability with 400 ppm MPE50 at 13.3°C
Table 5.5 Water quality data and permitted limits for discharge,
Running Springs
Parameter Post 2004 limits Ave. influent Ave. effluent*
cBOD 5 (mg/L) �5 223 mg/L �2.0 mg/L
TSS (mg/L) �5 mg/L 165 mg/L �1.0 mg/L
TKN (mg/L) Not permitted 41 mg/L �1.0 mg/L
TN (mg/L) Not permitted Not available �4.0 mg/L
N-NH 4 � (mg/L) �5 mg/L Not available Not available
P-PO 4 (mg/L) �2 mg/L 15 mg/L �5.0 mg/L
Turbidity (NTU) �0.2 NTU – Not available
*Effluent values based on samples taken during September 2003.
0.2 and 0.8 mg/L to ensure that SNdN is optimised. From April 2003 to August
2003, the plant was operated based on DO measurements and conventional treatment
strategy. Following optimisation based on the SymBio ® process during September
2003, effluent TN levels decreased from 14.4 mg/L to 3.9 mg/L and effluent TP levels
from 7.4 mg/L to 4.9 mg/L.
The peak loading rate coupled with limited equalisation demands that the membranes
operate at gross fluxes �50 LMH for up to several hours a day, and in some cases
for 24 consecutive hours. According to operator feedback, during November 2004, a
net flux of 30.5 LMH was sustained, some 8 LMH above the membrane manufacturer’s
recommended limit for normal operation, for 19 days at temperatures of 11.4–12.7°C
with only a small decline in permeability over that period (840 to 500 LMH/bar, arising
from a TMP increase of 0.025 bar). To handle extended higher peak loads during
extreme cold weather conditions (�10°C), a flux-enhancing polymer [PermaCare ®
MPE50] is occasionally added to increase the critical flux. A 20 h trial conducted
40
35
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5
Flux (GFD)