Membrane plant for concentration
The REDA membrane filtration plant consists
of one RO (reverse osmosis) and one
NF (nanofiltration) unit. The membrane
process technology works at maximum
pressures of 34/36 bar to ensure the required
concentration factor and to achieve
an efficient and economical permeation.
The membranes are of spiral type, wrapped
in polyamide.
The plant is fully automatic and operates
continuously, being continuously
supplied with pre-treated whey, which is
divided into two streams:
• Permeate, which consists mainly of water,
part of the monovalent salts (sodium, potassium
and chlorides) and some organic salts
• Retentate, with the most solids (protein, lactose,
divalent salts, other organic substances)
from whey, concentration factor approx. 5.
The key process parameter is the concentration
factor, which is the volumetric ratio between
the feed quantity and the flow rate of
the retentate. The plant reaches whey concentration
values of 28%.
Compared to reverse osmosis (RO), nanofiltration
(NF) shows a small difference in
membrane permeability (slightly higher). Nanofiltration
therefore allows a partial desalination
of the whey. Some of the sodium and
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Via Piave 9, 36033 ISOLA VICENTINA (Vicenza), Italy
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chloride salts and other monovalent salts go
with the permeate, which results in a reduction
of the sodium content of the concentrate.
The unit is supplied pre-assembled on two
base frames: the first base frame is equipped
with the high pressure pumps, supply tank
with level control, pre-filter and control cabinet,
while the second base frame houses the
circulation pumps and membranes.
REDA membrane units
REDA chooses the best membranes on the
market, manufactured by the most reliable
companies. This refers to membrane materials,
geometric configuration and optimal
choice of spacers, in order to obtain the
right flux, the best concentration ratio and
a long membrane life. The optimisation of
these parameters aims to save both investment
and operating costs:
• minimisation of dead volume with consequent
saving of operating fluids
• software/automation developed directly
by REDA and not by external companies.
This allows a better integration of software
and hardware, the development of
optimised automation programs and a
higher efficiency and timeliness in case of
need for technical assistance
• automatic control of filtration and CIP
cleaning operations. The automation
protects the membranes and prevents
their early wear and tear
• pre-assembly of the plant in a compact
design that allows easy maintenance
• start system with initial concentration
control: when the system is started, the
product
needs some time to reach the
required concentration (initial waiting period
during which the product coming out
is not properly concentrated). REDA offers
for this purpose a concentration control
system before the concentrated product is
directed or released into the storage tank
• recovery system in case of system stop: At
system stop there is a discharge system
that avoids dilution of the concentrated
product in the membrane unit
• possibility of remote control of the system
operation by REDA for technical assistance
or software updates.
A second membrane unit (polisher) of the
type RO, which concentrates the resulting
permeate from the RO-NF unit, is installed
parallel to the membrane unit. The permeate
coming from this plant is water of a very
good quality and can be used in the cheese
dairy, for example for cleaning processes.
Concentrate storage
and dispatch
Finally, the whey concentrate is passed
through a second valve manifold with Bardiani
valves and CSF pumps and is then conveyed
to storage for shipping.
The whole plant is controlled by a
fully automatic switchgear from REDA by
means of PLC and its own program.
REDA has equipped the cheese dairy
with a whey pasteuriser and separators
View of the RO unit at the Kranenburg
plant
Bardiani valves and CSF pumps ensure
the flow of raw materials
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