The MBR Book: Principles and Applications of Membrane

192 The MBR Book
Leachate
Air
TSS in g/L
60
50
40
30
20
10
0
4.4.3 Wehrle Environmental
1.5 3 5.2 8 10.2
Tube diameter or channel width in mm
Figure 4.34 Suspended solids level vs. tube diameter (Robinson, 2005)
Denitrification
Nitrification
Ultrafiltration
Figure 4.35 The Wehrle BIOMEMBRAT ® process
Wehrle use off-the-shelf membranes for its MBR designs, including Norit X-Flow
and Berghof. All the membranes used for sMBRs are MTs. Initially, 1� (25mmID)
tubes were used, and these were subsequently replaced by 11.5 and 10.5 mm units.
Since 2000, all the crossflow MBR plants have been designed and built using the
standard 8� (200 mm diameter) � 3 m module incorporating 8 mm diameter
tubes, since this tube diameter appears to be sufficient for moderate to high-MLSS
bioreactor liquors (Fig. 4.34). The 8 mm tubular membrane design was originally
conceived in co-operation between Stork Friesland (now part of Norit X-Flow) and
Wehrle.
The Wehrle BIOMEMBRAT ® process (Fig. 4.35) is an sMBR which can be combined
with either an atmospheric or pressurised bioreactor depending on the process
circumstances. The bioreactors can be operated at up to 25 g/L MLSS, which minimises
14.1
Excess
sludge
Treated
leachate