The MBR Book: Principles and Applications of Membrane

Case studies 227
membranes, assembled so as to form a complete hexagonal plate (Fig. 5.15), with
the module providing a total membrane area of 756 m 2 . The total investment costs
amounted to approximately €400 000. The plant was commissioned in August
2002 following a test period lasting most of July 2002 which successfully demonstrated
the system robustness. Fluxes of up to 28 LMH were maintained at a constant
permeability of 300 LMH/bar (and hence a TMP below 0.1 bar). The membrane
is aerated at a rate of 265 Nm 3 /h, corresponding to a SAD p of 14.4 at the maximum
throughput and 22 at the nominal flow rate, which equates to a flux of 16 LMH and
contributes to an energy demand for membrane filtration (MF) of 0.54–0.59 kWh/m 3 .
The total energy (including aeration and pretreatment) demand of the plant is
�1.3 kWh/m 3 . The membrane units are operated on a 9 min filtration/1 min relaxation
cycle, the efficacy of the physical cleaning being affected by rotation of the stack
at 2 rpm (0.033 Hz). The plant operates at an SRT of 25 days and an HRT of 14 h,
providing an MLSS of 8–14 g/L.
In addition to the municipality’s domestic wastewater, the influent contains a
small amount of industrial wastewater from an industrial kitchen. Pollutants and
nutrients in the wastewater are reliably reduced by the process. The system achieves
a COD reduction of 96%, from a mean feed concentration of 750 mg/L, nitrification
down to 1 mg/L N-NH � 4, and around 30% phosphorous removal. No measurable
amounts of solids or Escherichia coli have been detected in the outlet.
5.2.4.2 Other Huber plant
A number of other Huber plant have subsequently been installed in Europe, including
a starch products production facility at Veurne in Belgium (formerly Raisio Chemicals
Figure 5.15 The VRM ® 20/252 membrane stack at Knautnaundorf