It describes principle, mode of operation, mode of cleaning of membrane, integrated membrane system, lactose separation using ultrafiltration etc

1. Application of Ultrafiltration in Lactose Separation
Presented by
Rajpal Raj Bhaskar
AGRICULTURAL AND FOOD ENGINEERING DEPARTMENT
IIT KHARAGPUR

2. CONTENTS
 Introduction
 Principle
 Mode of operation
• Dead-end operation mode
• Cross-flow operation mode
 Mode of cleaning
• Cleaning in backwash – mode
• Cleaning in forward flush mode
 Integrating membrane systems
 Lactose separation
 Conclusions
 References

3. INTRODUCTION
 Ultrafiltration is a part of membrane separation.
 It is a pressure driven filtration technology.
 It is used to separate the lactose from milk.
 It leads the separation through semipermeable membrane.
 Playing wide role in waste water treatments.
 It is applied in “cross-flow” mode or “dead-end” mode.

4. PRINCIPLE
 The basic operating principle of ultrafiltration uses a
pressure induced separation of solutes from solvent
through semi-permeable membrane.
 The flux through a membrane is described by Darcy’s
equation.
J= TMP/μRt
Where J is the flux, TMP is the transmembrane
pressure, μ is solvent viscosity and Rt is the total
resistance.

5. MODE OF OPERATION
There are two modes:
 “Dead-end” mode.
 “Cross-flow” mode.
In both cases the ratio of feed and filtrate is called
“Recovery” and is calculated as:
R= Filtrate flow/Feed flow

6. Fig 1. Dead-End process schematics

7.  Dead-End operation mode:
• No circulation of the water takes place.
• This mode is mainly used with raw water of
high quality and less turbidity
 Cross-Flow operation mode:
• Concentrate is circulated at a higher flush speed.
• Turbulences over the membrane.

8. Fig. 2 Cross-Flow operation mode

9. To avoid the formation of a thick fouling layer, the
system needs to be cleaned in defined intervals.
There are two modes:
1. Cleaning in backwash mode
2. Cleaning in forward flush mode
MODE OF CLEANING
1. Cleaning in backwash mode:
Filtrate is pressed from the filtrate to the concentrate side
filtrate is either stored in tanks, or is supplied by other
filtrations units.

10. Fig. 3 Cleaning in Backwash - mode

11. Fig. 4 Cleaning in forward flush mode

12. 2. Cleaning in Forward Flush mode:
As this process is not carried out with filtrate but regular
feed water, it does hardly influence the overall recovery of
the system.
Chemical Cleaning:
Taking into consideration the type of foulant, the appropriate
chemical substance is chosen, e.g. Acid, Caustic
(Sodiumhydroxide) or varied disinfection and cleaning
solutions.

13. 1. Flocculation and ultrafiltration:
The removal efficiency of organic carbons that are very
difficult to remove from the raw water in general, can be
increased significantly by dosing of flocculants in front
of the ultrafiltration system.
2. Active carbon and ultrafiltration:
Adding active carbon in front of the ultrafiltration,
substantially improves the removal efficiency of the
system for humic substances and pesticides
INTEGRATING MEMBRANE SYSTEMS

14. 3. Ultrafiltration and nano-filtration:
• Polar pesticides can be reliably removed by applying
a process combination of ultrafiltration and nano-
filtration.
• As a positive side – effect, the water will also be
softened and sulphate will be removed.
4. Ultrafiltration and reverse osmosis:
• To desalinate water, a reverse osmosis treatment step
can be applied after the ultrafiltration process.
• With ultrafiltration as pre-treatment, the reverse
osmosis system can be operated more reliably and
with higher flux rates.

15. • Ultrafiltration as a pre-treatment for reverse osmosis is a
reliable barrier for microorganisms and particles.
• It almost completely removes fouling causing
substances.
 ADVANTAGES:
I. Ultrafiltration provides a full barrier against
microorganisms and particles
II. The quality of the filtrate is not depending on the feed
water quality
III. Ultrafiltration is able to eliminate chlorine - resistant
pathogens.
IV. Ultrafiltration can be automated easily.

16. V. Concentrate originated by the ultrafiltration process is
only consisting of the water contaminants. The amount
of created and to be disposed sludge is significantly
lower than with conventional treatments.
VI.Compact construction of systems provides lower
investment for buildings and space than with
conventional treatment.
VII.Downstream treatment steps will have higher
productivity due to the fact that nearly all foulants will
have been already removed by ultrafiltration.
VIII.Investment and operation costs for downstream
nanofiltration or reverse osmosis systems are will
decrease substantially, since the systems can be
operated at higher flux rates and with less cleaning
efforts.

17.  Ultrafiltration membranes (UF) have molecular weight
cut-off in the range of 1,000-500,000 Daltons.
 Lactose can easily pass through the membrane while
retain all fat and milk proteins in the retentate.
 The separated lactose in the permeate can be used for
functional foods.
 The milk retentate from ultrafiltration is considered to be
concentrated milk which is suitable for cheese and
yoghurt production.
 Lactose and proteins concentrations in both permeate
and retentate were measured in order to analyse the data
in terms of permeate flux (J), rejection (R) and %
recovery (R) using the following equation
SEPARATION OF LACTOSE FROM MILK BY
ULTRAFILTRATION

18. J= Vp/A.t
where Vp is the permeate volume, A is the membrane effective area
and t is time.
 The rejection of lactose and protein is calculated from the
following equation.
R= ln(Cr/Cf)/ln(VCF)
where Cr and Cf are retentate and feed concentration, respectively.
The equation for volume concentration factor (VCF) is given by
VCF= Vf/Vr
where Vf and Vr are the feed and retentate volume, respectively.
 The % recovery of lactose in permeate is calculated from the
fraction of lactose in the permeate recovered from the original feed.

19. % Recovery= Cp.Vp/ Cf.Vf
where Cp and Vp are permeate concentration and permeate volume,
respectively.
 Effects of transmembrane pressure:
• Graph presents the permeate flux at different transmembrane
pressure while the feed flow rate was maintained constant at 0.64
L/min.
• In general, there was a linear correlation between the
transmembrane pressure difference and the permeate flux up to 4.5
psig.
• Beyond 4.5 psig, there was no significant increase in the permeate
flux, indicating that it reached the limiting flux.
• At pressure beyond 4.5 psig, % lactose recovery decreased
indicating the concentration polarization problem occurred on the
membrane surface.

20. Graph 1. Effect of transmembrane pressure on permeate flux with a constant feed
flow rate at 0.64 L/min.

21. Table 1. Effects of transmembrane pressure on lactose and protein
rejection.

22.  Effects of feed flow rate:
• The transmembrane pressure increased with increasing the feed
flow rate.
• The permeate flux increased with increasing the feed flow rate.
• The concentration polarization effect could be minimized by
operating at high feed flow rate.
• The high recovery of lactose is obtained at the feed flow rate of
1.72 L/min.
• The feed flow rate of 1.72 L/min was considered as the
recommended flow rate because it gave high permeate flux and
high lactose recovery.

23. Graph 2. Effect of feed flow rate on permeate flux.

24. Graph 3. % recovery of lactose in permeate at different feed flow rate.

25. Table 2. Effects of feed flow rate on lactose and protein rejection.

26. 1. .
1. Both transmembrane pressure and feed flow rate affected the
permeate flux, lactose rejection and % lactose recovery.
2. A high degree of removal of lactose from milk could be
achieved by UF with a minimal or no lost of protein in the
permeate.
3. Have consistent product quality, 35-80% protein product
depending on operating conditions.
4. Do not denature proteins as they use moderate operating
conditions.
CONCLUSIONS

27. REFERENCES
• Alvarez F., Arguello M., Cabero M., Riera F. A., Alvarez R., Iglesias J. R. and
Granda J. (1998). Fermentation of concentrated skim-milk. Effects of different
protein/lactose ratios obtained by ultrafiltration-diafiltration. Journal of the
Science of Food and Agriculture, 76, 10-16.
• Geankoplis C.J, (2011), Membrane Separation Process, Transport Processes And
Separation Process Principles, p. 840, PHI Learning Private Ltd, ISBN-978-81-
2614-9.
• Enrique Ortega-Rivas(2012), Membrane Separations, Non-Thermal Food
Engineering Operations, p.199, Springer Science+Business Media, e-ISBN 978-1-
4614-2038-5.
• Novalin S., Neuhaus W. and Kulbe K. D. (2005). A new innovative process to
produce lactose-reduced skim milk. Journal of Biotechnology, 119, 212-218.

28. THANK YOU