It is widely recognised by MBR practitioners that membrane bioreactors, and specifically those treating municipal wastewater, are subject to what is sometimes referred to as ‘ragging’. When the membrane module is removed, characteristic thick strands of material can be seen hanging from the bottom of the module.
Features - Membrane operation
Fouling in MBRs arises when materials either form a layer on the surface of the membrane or plug its pores. Studies are, however, generally unable to distinguish between coating of the membrane surface and phenomena relating to the agglomeration of solids. The latter has received little or no attention from the scientific community, and yet such irreversible deposition of solids clearly impairs MBR operation.