1. Optimisation of washing cycle on
ultrafiltration membranes used in treatment
of metalworking fluids
Gerald Busca, Nidal Hilal*, Brian P. Atkin
School of Chemical, Environmental and Mining
Engineering, The University of Nottingham,
Notingham NG7 2RD, United Kingdom.
* Email: Nidal.Hilal@Nottingham.ac.uk
Introduction
•Ultrafiltration membranes are used for separating oil from water and treating waste metalworking fluid.Ultrafiltration membranes are used for separating oil from water and treating waste metalworking fluid.
•Filtration parameters such as feed temperature, concentration ratio in the re-circulation feed stream affects the permeate flux and quality.Filtration parameters such as feed temperature, concentration ratio in the re-circulation feed stream affects the permeate flux and quality.
•Concentration polarisation and fouling occur inevitably in any membrane filtration system and there are factors that limit the process.Concentration polarisation and fouling occur inevitably in any membrane filtration system and there are factors that limit the process.
• To alleviate fouling, membranes have to be cleaned, surfactant have been found efficient to remove oil fouling the membrane surface .To alleviate fouling, membranes have to be cleaned, surfactant have been found efficient to remove oil fouling the membrane surface .
•The performance of each washing cycle is evaluated by measuring after wards the Cold Water Flux on the washed membrane.The performance of each washing cycle is evaluated by measuring after wards the Cold Water Flux on the washed membrane.
CONCLUSION
• 200 kD and 100 kD membranes have shown a similar separation performance with a permeate flux 40% higher for 200 kD.200 kD and 100 kD membranes have shown a similar separation performance with a permeate flux 40% higher for 200 kD.
•The feed temperature has a dramatic effect on permeate flux and quality and should be kept low.The feed temperature has a dramatic effect on permeate flux and quality and should be kept low.
•The necessary surfactant to clean oil from UF membrane has been demonstrated and found effective when used under the right conditions.The necessary surfactant to clean oil from UF membrane has been demonstrated and found effective when used under the right conditions.
• Surfactant has a preventive anti fouling effect.Surfactant has a preventive anti fouling effect.
Ave rag e
o f C WF
X 1 X 2 X 3 X 4 X 5 X 6
536.5 25.5 8 8 .5 35.3 14.1 34.8 -50.5
Evaluation of the factor effect on the cold water flux
A plot of 8 experiments have been done to evaluate the
importance of each factor on the washing.
The efficiency of the washing cycle has been assessed by
measuring after washing the recovery in flux of cold
demineralised water.
Temperature has the greater effect, 45% increase in
CWF when X2 goes from 40°C to 60°C.
0.5 1.5
40 60
15 45
5 15
No Yes
2.7 3.6
s tateFacto rs
Surfactant concentration %v/v X1
Washing temperature oC X2
Washing time minutes X3
Volume of solution litres X4
Application of pressure X5
Re-circulation velocity m/s X6
Factors and values used to evaluate the
washing cycle performances.
1 feed tank, 2 pump
3 Ultrafiltration unit,
4 graduated column
5 temperature control
6 thermometer
P Pressure gage
2
1 4
5
6 Feed
Concentrate
Permeate
P
P
3
Experimental set up
10.00
15.00
20.00
25.00
30.00
35.00
40.00
45.00
50.00
00:00 00:30 01:00 01:30 02:00 02:30 03:00 03:30 04:00
Runing time hh:min
Permeate(fluxl/h/m2)
After surfactant wash
After water wash
Effect of surfactant on metalworking fluid filtration
40
45
50
55
60
0 5 10 15 20 25 30 35 40 45 50 55 60
Time (min)
Permeateflux(l/h/m2)
Pressure applied
for 1 min
Pressure stopped
Permeate flux of a washing cycle and effect of pressure
0
100
200
300
400
500
600
700
800
900
Washing cycle number
COLDWATERFLUX(l/h/m2)
Different washing condition with surfactant
Washing without surfactant
Effect of surfactant on cold water flux
Acknowledgments:We thank the UK Engineering and Physical Sciences Research Council and CARDEV International Ltd for funding this work.
TO C g / l Turb id it y N TU
45 50.5 7.1 4500
20 23.3 4.3 100
Te mp e rat ure
F lux l/ h/ m2 P e rme at e q ualit y
Influence of the feed temperature on the UF permeate PVDF Molecular Weight Cut Off Performances at 20°C
TO C g / l Turb id it y N TU
200 kD 23.3 4.3 207
100 kD 16.1 3.9 50
M WC O F lux l/ h/ m2
P e rme at e q ualit y