Compatibility of MP membranes and O3

1
Compatibility of MP membranes and O3

• Membranes as O3 contactors
• Materials under study
• Experimental Procedure
• Compatible or not compatible ?
• Conclusions

2
Membranes for O3 contacting Several benefits!

• O3 in water treatment
• MP membranes feasible for O3 mass transfer?

off-gas treatment

• - Different contactor types, characteristics
  performance
• - Membrane contactors
• off-gas can be recycled,
• bubble-free,
• scaling,
• moderate to fast mass transfer (high kLa values)

3
Compatibility of MP membranes and O3

• Membranes as O3 contactors
• Materials under study
• Experimental Procedure
• Compatible or not compatible ?
• Conclusions

4
Original and chemically modified membrane
materials under study

• MP polymeric ultra-filtration membrane tubes
• Membrane test assembly
• PVC outer tube, MP membranes inside
• Water flow inside the membranes, O2/O3 flow
  outside the membranes
• 1 Assembly with original membrane tubes
• 1 Assembly with chemically modified membranes

5
Compatibility of MP membranes and O3

• Membranes as O3 contactors
• Materials under study
• Experimental Procedure
• Compatible or not compatible ?
• Conclusions

6
Methods Ozonation of membrane tubes

• Set-up Batch ozonation of MP membrane tubes

7
Methods Ozonation of membrane tubes

• Experimental conditions
• 5 pieces from 3 different membrane tubes
• Visual observation of damage ? weigth before -
  after
• Milli-Q water, near-neutral pH, RT
• Ozonation 3.5 7.3 6.0 hours, O3liq
  8.28.6 mg/L
• Monitoring of pH, ORP, conductivity, O3gas,
  O3liq, T,
• UV/VIS

8
Methods Test assembly

• Test assembly
• Milli-Q water, near-neutral pH, RT
• Water flow peristaltic pump
• O3gas 50 g/m3
• Set-up

9
Compatibility of MP membranes and O3

• Membranes as O3 contactors
• Materials under study
• Experimental Procedure
• Compatible or not compatible ?
• Conclusions

10
Ozonation of membrane tubes clear indication
of degradation

• Visual observations (after 17 hours ozonation)
• Dispersion of white particles in solution
• Increased surface roughness, loss of flexibility
• Mass balance
• mass loss after ozonation periods points at
  degradation
• UV/VIS Conductivity
• build-up of degradation products in solution
• pH
• decrease in pH caused by formation of
  carboxylic acids (?)

11
Test assemblies MP membranes incompatible
with O3

• Both test assemblies damage after lt 50 minutes
  O3 flow!

12
Compatibility of MP membranes and O3

• Membranes as O3 contactors
• Materials under study
• Experimental Procedure
• Compatible or not compatible ?
• Conclusions

13
MP membranes and O3 incompatible ?

• Nor original, neither modified MP
  ultra-filtration membranes are resistant to O3
• MP membranes cannot be used for O3 contacting
  despite low O3liq in disinfection (typically
  0.1 1 mg/L)
• ? degradation concentration exposure !
• Ozonated water streams need to be separated from
  filter units in the dishwashers!