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The MBR Book: Principles and Applications of Membrane

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194 <strong>The</strong> <strong>MBR</strong> <strong>Book</strong><br />

Leachate<br />

Air<br />

Inflow<br />

Air<br />

Figure 4.37 <strong>The</strong> Wehrle BIOME<strong>MBR</strong>AT ® Airlift <strong>MBR</strong><br />

Sludge<br />

Figure 4.38 <strong>The</strong> Wehrle BIOME<strong>MBR</strong>AT ® -LE <strong>MBR</strong><br />

Exhaust air<br />

Treated<br />

leachate<br />

Exhaust<br />

Effluent<br />

higher crossflows, <strong>and</strong> thus a higher energy dem<strong>and</strong>, rather than having redundant<br />

membrane area at low-to-normal loads. So far, this process has been piloted at bioreactor<br />

process flows <strong>of</strong> ~0.15 m 3 /h (up to ~0.4 m 3 /h permeate flows). Net fluxes <strong>of</strong><br />

~55 LMH have been achieved at specific energy dem<strong>and</strong>s <strong>of</strong> around 1.5 kWh/m 3<br />

arising at moderate crossflow velocities (1–2 m/s). It is thought that the<br />

BIOME<strong>MBR</strong>AT ® -LE will be more suited to industrial effluents with low to average<br />

COD than the airlift process, though it operates at a slightly higher energy dem<strong>and</strong><br />

than the latter. <strong>The</strong> airlift configuration will continue to be employed for municipal<br />

effluents.<br />

Wehrle have also developed integrated post-treatment processes to provide additional<br />

purification. Unit operations have included both activated carbon (AC) <strong>and</strong><br />

nan<strong>of</strong>iltration (NF) where the NF concentrate is fed to the AC for organics removal,<br />

with the AC effluent (Fig. 4.39).

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