What is Microfiltration?
The principle of the microfiltration process as
with ultrafiltration, is physical separation. The level to which
dissolved solids, turbidity and micro-organisms are removed is
determined by the size of the pores in the membranes.
Microfiltration, (MF) is typically used
for turbidity reduction, removal of suspended solids, giardia and
PureFlow MF blocks designed for cider filtration
Liquid is passed through a microfiltration membrane (pore sizes between 0.1 – 10µm), separating micro organisms and suspended particles from the process liquid removing all bacteria. Microfiltration is generally operated in the crossflow as well as the dead end mode. In cross flow the raw solution flows along the membrane surface with only a small portion of the liquid passing through the MF membrane as a permeate. The concentrate is circulated in a loop to reduce concentration polarisation continuously and is used to clean the membrane. For this reason, cross-flow filtration is preferably applied for the filtration of liquids with a high solids concentration.
In dead-end filtration, the liquid flows perpendicular to the membrane surface so that the retained particles accumulate at the membrane surface and form a filter cake. The filter cake increases in height throughout the filtration period resulting in a decrease in permeate flux. Therefore the membranes in dead-end operations have to be cleaned at regular intervals either by backflushing or possibly by using chemical or mechanical cleaning methods.
The process fills the gap between ultrafiltration and granular media filtration.
Envirogen has extensive experience of supplying MF treatment units to the food & beverage industry. Please contact us for further details on the PureFlow MF treatment