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Projects Involving Nanotechnology at
The Oxford Centre for
Sustainable Water Engineering
Dr Nick Hankins
• Introduction to Centre for Sustainable
Water Engineering
• Adsorptive Micellar Flocculation
• Forward Osmosis
• Nanocatalysts
• Macromolecular Complexation-Flocculation
Outline
Water Problems
1.1 billion people have no access to safe water
2.6 billion people have no proper sanitation
as a result...
...2.2 million deaths per year are
related to water/hygiene/sanitation; many of these
are children
In the United Kingdom, one in six households may
be adversely affected by “water poverty”.
Data: Wateraid, Chartered Institute for Environmental Health; Photo: CEH Wallingford
Prioritization of Activity
• IChemE Roadmap for the 21st Century specifically
highlights water in priority position statements:
Water as a Resource
Sustainability and New technology
Industrial Usage
Prioritization of Activity
Sustainability and New Technology:
Develop existing and implement novel potable
water and waste-water treatment processes with -
low cost, low energy, low environmental impact and
low footprint eg membrane processes
Effective removal of micro-contaminants and
nitrates/phosphates from waste-water
Prioritization of Activity
Industrial Water Usage:
Seek the potential to:
Reduce consumption of
Recycle
Recover
- Water, Raw materials and Energy
Beneficial sludge reduction/disposal
Focus of Research ActivityMarket Driven:
Potable Water Treatment and Desalination
• Development of Novel Osmotic Agents for Forward
Osmosis
• Visible-light Photocatalytic Oxidation/Disinfection
Waste Water Treatment
• Application of Synthetic Sludge to Study Activated
Sludge Process
• Use of Micellar Enhanced Ultrafiltration and
Polyelectrolyte Complexation for Removal and
Concentration of Dilute Heavy Metal Ions
Focus of Research ActivityMarket Driven:
Waste Water Treatment
• Removal of Emerging Micro-contaminants eg
EDCs, APIs eg ibuprofen, diclofenac (CEH)
Process Stream Treatment
• Adsorptive Micellar Flocculation to Remove/Reuse
Organic Acids and Bases
Focus of Research ActivityTechnology Driven:
Membrane Processes
• MBRs, Pre-coagulation, Forward Osmosis
Nanostructures – Colloids and Interfaces
• Micellar/Colloidal Complexation, Ion-Exchange,
Coagulation/Flocculation, Adsorption
Environmental Microbiology – Ian Thompson
SWT: Goals
• Establish an internationally leading, state-of-the-art
centre of excellence in fundamental and applied
research in potable, waste-water & process water
treatment
• Be interdisciplinary: engineers, microbiologists,
chemists, social scientists
• Leverage external support: Government, Industry
EC/international organizations
Nanotechnology: Adsorptive Micellar
Flocculation
•Remove and recycle valuable components -
weak organic acids/bases -from aqueous
effluent and process streams
•Develop a novel surfactant-based process:
Adsorptive Micellar Flocculation (AMF)
•Perform pilot-plant studies to validate the
process
Concept of Adsorptive Micellar Flocculation
Micelles
Micelles
Heavy
metal ion
FlocculantOrganic acid
anion
Coarse filter
UF membrane
Experiments on Pilot Plant
Pilot Plant Results
Optimum Flocculant Dosage
• Optimum molar ratio of flocculant:surfactant for phenol
removal = 0.75 (pilot rig, bench tests)
• Highest removal = 68.8 % (one stage)
0
20
40
60
80
100
120
0 0.5 1 1.5 2 2.5
ratio of floculant and SDS (-)
rem
ova
l e
ffic
ien
cy (
%)
Pilot tests
Bench tests (distilled water, from Salvation Anthony, Mres disertation, 2002)
Bench tests (tap water)
Nanotechnology: Micellar-based Techniques
• Micellar Enhanced Ultrafiltration
- Involves metal binding to micellar surface
or solubilization within hydrocarbon core
- Micelles and target species trapped by UF
• Problems:
- membrane fouling and large retentate stream
Micelle
Pollutant
Pollutant
Pollutant
Nanotechnology: Forward Osmosis
• Emerging alternative to reverse osmosis
for desalination
• Exploit natural osmotic pressure gradient from saline feed through membrane to concentrated draw solution
(higher concentration) FO
Osmotic
pressure
gradientH2O
MembraneMembrane
FO
Osmotic
pressure
gradientH2O
MembraneMembrane
Draw
solu
tio
n
Mix
ed
liq
uor
MembraneMembrane
Draw
solu
tio
n
Mix
ed
liq
uor
MembraneMembrane
Draw
Solution
Draw Solution
Forward Osmosis
Separation
Unit
Potable Water
Membrane Unit
Concentrated Draw Solution
Raw Feed Solution
Clean Water
Draw Solution
Lower concentration/
osmotic potential
Higher concentration/
osmotic potential
Contaminant Water
Magnetic
Nanoparticle
Field
Gradient
Forward Osmosis
Forward Osmosis
Key Challenges:
•Develop an effective draw agent: high osmotic pressure, high diffusivity, low toxicity
•Draw agent easily regenerable from product water
•Develop an effective membrane to minimise internal concentration polarisation
Nanotechnology: Visible Light
Photocatalysts• Ultra-Violet only about 5% of sunlight
• Develop wide gap semiconductors: work in
visible light
• Dope titanium with N2 and Sn; phosphate
materials – good stability and activity
• Test capacity to degrade organic
contaminants and kill microbial cells
Visible Light Photocatalysts
Nanotechnology:Complexation-Flocculation
Micelles or Macromolecules
Micelles or Macromolecules
Heavy
metal ion
Flocculant (metal ion or
polyelectrolyte)
Heavy metal
ion
MEUF
CF
•Remove Heavy Metal ions from aqueous
solution by complexation-flocculation
•Complex heavy metal ions to macromolecular
humic substances by electrostatic interactions
•Flocculate humic acid and bound heavy metal ions
by polyelectrolyte: charge neutralisation and
polymer bridging
•Filter or settle flocs – remove heavy metal!
Complexation-Flocculation Process
Complexation-Flocculation Process
+
Metal ions
HS
Cationic polymer flocculent
Ultrafiltration membrane
+
+
+
+
++
+
+
+
+ +
- -
--
--
- -
+
+
+
+
+ + +
+
-+
+
+ +
- +
+
+
+
-+
-
+
+
+
+
-
+
-
+-
+-
+
+
+
Complexation-Flocculation Process
Humic Acid- PolyDADMAC Flocculation
• Flocculation passes through a maximum
• Optimum dosage increases with pH
Effect of PolyDADMAC dosage Effect of pH
0.1 0.2 0.3 0.4 0.5
0
20
40
60
80
100
Rem
oval eff
icency (
%)
Ratio of PDADMAC to HA (mass/mass)
pH7
0.0 0.1 0.2 0.3 0.4 0.5
0
20
40
60
80
100
Rem
oval eff
icency (
%)
Ratio of PDADMAC to HA (mass/mass)
pH3
pH5
pH7
pH9
Thank-you for your Attention!