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!