UF Introduction
UF and RO (NF) are all pressure-driven membrane separation
process. UF filter media is UF membrane, configured as
flat type, tubular type and hollow fiber type. UF process
is the separation process in relation with pore size,
and the pore size is between RO (NF) and MF (0.001-0.1?m),that
is to say UF process the separation from big molecules
to small molecules. In short, ions and small molecules,
dissolved in the raw water, permeate to be the UF permeate,
while particles larger than the membrane pore size are
concentrated as concentrate, such as big protein molecules,
microorganism, colloid, suspending substance etc.
Used in water treatment, the main function of UF is
to remove turbidity, microorganism (purifying water,
or water filtration).
Flux
It reflects the membrane permeability of water, as economic
index of the membrane performance. It always refers
to the water permeated volume in the condition of 25?,
0.1MPa, unit time, unite membrane area, unite membrane
module. (L/H. m2.0.1MPa, T/Mod.0.1MPa).
The membrane flux is related to the operating condition,
such as raw water quality, water temperature, operating
pressure. In addition, flux is also influenced by many
other factors such as membrane material, structure,
MWCO, pore size, pore percentage. All these indexes
are controlled by the membrane manufacture process.
MWCO
It is the index of UF membrane filtration precision.
UF Membrane pore size is the average index.
Separation function is proceed by the multi-pore compact
skin in the UF process, The membrane permeating characteristic
is evaluated by the arrangement of pore size and micropore
diameter size on the multi-pore compact skin.
The figure and size of micropores on membrane wall
are not selfsame, evaluated by PCO and MWCO, PCO refers
to the percentage of the special solute cut off to all
special solute in solution. When 90% solute is cut off,
the minimum MW of the solute showing from cut off curve
is the MWCO. UF membrane pore size is between 0.001
and 0.1?m, and the opposite MWCO is about 1,000-500,000.
MWCO often used in water treatment always is 50,000-100,000,
and the membrane pore size is 0.001~0.01?m.
UF Membrane Operating
Process
Hollow fiber UF membrane module is the most widely used
type in UF technology. It is a kind of self-support
membrane. its geometrical structure makes the big filtration
surface be included into a compact housing, helping
to get the greatest efficiency in a smallest space.
Hollow fiber UF membrane module can flushing, backwash,
make the cross-flow filtration get the greatest benefits.
Flushing and backwash can recover UF membrane flux efficiently
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Drinking water and ice process