The MBR Book: Principles and Applications of Membrane

170 The MBR Book
industrial and municipal sectors, concentrating mainly on small- to medium-scale
plants. The company has been developing the MBR technology since 2001. The CES
Sub Snake system is unusual in that the membrane modules are bespoke and fabricated
from a continuous 0.04 �m PES membrane sheet which is cut to size and then
glued at the edges to form a FS module. The membrane is then wrapped, snake-like,
around a purpose-built steel or plastic frame comprising a number of rigid vertical
poles at each end to make a multiple FS module with a membrane sheet separation of
10 mm. A single tube is inserted into the permeate channel of each FS element for
permeate extraction under suction into a common manifold (Fig. 4.7b).
The maximum depth of the module is dictated by the width of the sheeting, and
the total membrane area of the module by its overall length. Thus far, the largest
modules offered by the company are 10 m 2 , provided by 10 elements of 1 m depth
and 0.5 m width (double-sided), the total length of the FS being 5 m in this case.
4.2.4 Huber Technology
(a) (b)
Figure 4.7 The CES Sub Snake system: (a) FS elements and (b) permeate extraction and module ends
The Huber VRM ® (Vacuum Rotation Membrane) product is differentiated from all
the other iMBR systems by having a moving membrane module, which rotates at a
frequency of 1–2 rpm. The small shear created by this, combined with scouring of
the membrane surface by air from the central coarse bubble aeration, apparently
obviates all cleaning; the rotary action means that solids do not collect in any region
of the module. The membrane elements themselves comprise a four-plate segment of
a hexagon or octagon (Fig. 4.8a), thereby making up one sixth or one eighth of a
complete plate. The membrane material itself is based on 0.038 �m pore-size PES
material of around 300 �m in thickness (Fig. 4.8b). The individual elements are
thus relatively small (0.75 m 2 for four parallel plates, hence 0.19 m 2 /element) and,
since each are fitted with a permeate extraction tube, the permeate flow path is relatively
short. The plates themselves are 6 mm thick and separated by a 6 mm channel.
The membrane modules are hand-assembled into the VRM ® units of 2 m (VRM ® 20)
or 3 m (VRM ® 30) diameter. Each module is positioned and fixed in a drum and