nanotechnology-enabled water treatment:

Nanotechnology-Enabled Water Treatment: A Vision to Enable Decentralized

Water Purification and Reuse

Pedro J.J. Alvarez

McGill University22 September 2015

2

“Whiskey is for Drinking;

Water is for Fighting Over”

43 million Americans lack access to municipal water; 800 million worldwide lack access to safe water Global market for drinking water ~ $700 billion Larger market for industrial wastewater reuse

Clean Water Is Critical for Enhancing Human Capacity

78

47

http://www.prb.org/Publications/Articles/2011/biodemography.aspx

American’s life expectancy at birth• Public health• Energy production• Food security• Economic development

WTP

Source

Drivers for Decentralized (Distributed) Treatment

• Lack of adequate infrastructure (distribution systems, electricity)

• Match water supply with consumer location (avoid contamination during transport & storage)

• Reduce water losses in large and complex distribution systems.

• Reduce energy requirements

Network topology analysis to exploit the interconnectivity of complex water systems (e.g., integrated drinking water, wastewater & storm water networks to enhance water availability and reuse).

Advanced materials and technologies to obtain drinking water from unconventional sources, and to enable reuse and resource recovery (e.g., drinking water, energy, nutrients) from challenging wastewaters.

Research Needs and Opportunities

Nano = Dwarf (Greek) = 10-9

“Nanotechnology is the understanding and control of matter at dimensions of roughly 1 to 100 nanometers, where unique phenomena enable novel applications.”-National Nanotechnology Initiative

Why Nano?Leap-frogging opportunities to:• Develop high-performance multifunctional materials and

systems that are easy to deploy, can tap unconventional water sources, and reduce the cost of remote water treatment

• Transform predominantly chemical treatment processes into modular and more efficient catalytic and physical processes that exploit the solar spectrum and generate less waste

8

Desirable ENM Properties

Examples of Enabled Technologies

Large surface area to volume ratio

Superior sorbents (e.g., nanomagnetite or graphene oxides to remove heavy metals and radionuclides)

Enhanced catalytic properties

Hypercatalysts for advanced oxidation (TiO2 & fullerene‐based photocatalysts) & reduction processes (Pd/Au)

Antimicrobial properties Disinfection and biofouling control without harmful byproducts

Multi‐functionality (antibiotic, catalytic)

Fouling‐resistant (self‐cleaning and self‐repairing) filtration membranes that operate with less energy

Self‐assembly on surfaces

Surface structures and nanopatterns that decrease bacterial adhesion, biofouling, and corrosion

High conductivity Novel electrodes for capacitive deionization (electro‐sorption) and energy‐efficient desalination

Fluorescence Sensitive sensors to detect pathogens, priority pollutants

Opportunities for Engineered Nanomaterials (ENMs) in Water Treatment and Reuse

SUNContaminated Water

Drinking or Reclaimed Water

INTERFERING SPECIES &

SCALE CONTROL

LOW-ENERGY DESALINATION (Solar membrane distillation, high-flux RO)

PRIORITY CONTAMINANT REMOVAL (Nanosorbents, Nanophotocatalysts, etc.)

Modular Treatment SystemsMatch treated water quality to intended use

• High Performance Modules• Lower Chemical Consumption• Lower Electrical Energy Requirements • Less Waste Residuals• Flexible and Adaptive to Varying Source Waters

OR

SUN

10

Example: Enhancing Membrane Distillation

www.desalination.biz

Tp

T1T2

Tf

Q1 Q2 Q3

T1 T2

Tf Tp

Temperature polarization:

Can reduce transmembrane temperature gradient by up to 70%

Photonics of Nanoparticles for Solar-Thermal Applications

Light localization by multiple scattering confines solar energy, enabling high efficiency heat transfer

(Hogan et al., Nano Lett. 2014, 14, 4640-4645)

VaporT2

MEMBRANE DISTILLATEHOT FEED

nano

parti

cles

T1

Higher T gradient = higher flux

Multifunctional membranes: Fouling-resistant, High-flux Self-cleaning

Enabling TechnologyDirect solar membrane distillation for low-energy desalination

Enabling Technology(Photo)Disinfection & Advanced Oxidation

Nano(photo)catalysts that use solar radiation to generate ROS that destroy resistant microbes and recalcitrant pollutants without generating harmful disinfection byproducts Sunlight

H2O, O2

OH•, 1O2

ImmobilizedPhotocatalyst

++

ROS:

++

Advantages of Amino-C60 as Photocatalytic Disinfectant

0 50 100 150 200 250-5

-4

-3

-2

-1

0

0 15 30 45 60

-3.0

-2.5

-2.0

-1.5

-1.0

-0.5

0.0

MS

-2 R

emov

al L

og (N

/N0)

Irradiation Time (min) Irradiation Time (min)

HC4TiO2

No Sunlight

Sunlight Alone

190 μW/cm2 / 28 oC

430 μW/cm2 / 32 oC430 μW/cm2 / 22 oC

HC4 vs TiO2 under UV HC4 Activated with Sunlight

30 × Faster

Immobilization of aminofullerene onto silica beads facilitates separation, reuse and recycling

FFA

Con

c. (C

/C0 )

0 2 4 6 8 100.0

0 .2

0 .4

0 .6

0 .8

1 .0

1 .2

Irradiation Time (hr)

1st 2nd 3rd 4th 5th

REPETITION TEST

No loss ofphoto-activity

Lee, Mackeyev, Cho, Wilson, Kim and Alvarez (2010). Environ. Sci. Technol.44: 9488–9495.

NO C60 AGGREGATION ON THE SILICA SURFACE

(HIGHER CATALYTIC AREA)

0.2 - 0.3 mmEASILY SEPARABLE

Photocatalytic treatment of emerging contaminants (pharmaceuticals, endocrine disruptors)

Lee J., S. Hong, Y. Mackeyev, C. Lee, L.J. Wilson, J-H Kim and P.J.J. Alvarez (2011). Environ. Sci. Technol. 45: 10598–10604.

0 20 40 60 80 100 1200.0

0.2

0.4

0.6

0.8

1.0

Con

c. (C

/C0 )

Irradiation Time (min)

Ranitidine

CimetidinePropranolol

Sulfioxazole

Nanotechnology for Biofouling Control

Discourage adhesion Nano-patterned topology Surface chemistry Interrupt quorum sensing

Incorporate antimicrobial NPs Nano silver Carbon nanotubes Porous nano-carriers

Photocatalytic ROS Semiconductors, e.g., TiO2 Fullerene derivatives

(self-cleaning surfaces)

X

Enabling Technology Electrosorption for Scaling Control

Nanocomposite electrodes to remove multivalent ions from brines, and generate smaller waste streams

Cathode

Anode

+

+

‐

+

‐+

‐

‐

+‐

19

NaCl adsorption capacity > 1.3 mmole/g

VerticallyAlignedCNTs

CNTs/graphene enhance sorption capacity, kinetics, mechanical

strength and electrical conductivity.

Nano-Enabled CDI for Scaling ControlIX polymers enable preferential

removal of divalent cations that cause scaling

Enabling Technology Multifunctional nanosorbents

Selective removal of target contaminants by functionalized nanoparticles supported in macroscale structures or subject to magnetic separation for enhanced removal kinetics and easier reuse

Pd+

Functionalization

Magnetic core (e.g., magnetite, Fe3O4)

Silica shell

Catalysts

Bactericidal NP

Pd+

Specific adsorbents

Pd+

SUMMARY OF APPLICATIONS• Low-energy desalination by

nanophotonic MD or electrosorption• DBP-free disinfection• Advanced (photo)oxidation• Selective nano-sorbents• Multi-functional membranes• Fouling- & corrosion-resistant surfaces

• Innovation across value chain (nanomaterial and equipment manufacturers, service providers, R&D and deployment partners, and users)

Some of Our NEWT Partners

• Co-development and production of advanced multifunctional materials• Globally-relevant research and education experiences for students• Testbed sites for applications in fast-growing water markets

International Partners

24

Responsible Nanotechnology

25

"With Great Power, Comes Great Responsibility”Uncle Ben to Peter Parker in Spider Man

Paul Hermann MullerThomas Midgley

Nanoparticle Modifications in the Environment

Alvarez P.J.J., V. Colvin, J. Lead and V. Stone (2009). Research Priorities to Advance Eco-Responsible Nanotechnology. ACS Nano 3(7): 1616-1619.

Example: Silver Nanoparticles

Silver

Num

ber o

f pro

duct

s

0

50

100

150

200

250

300

350

March 8, 2006March 10, 2011

Most Widely Used Nanomaterials In Commercial ProductsSource: Woodrow Wilson-The project on emerging nanotechnologies

CNTs TiO2 Silicon Zinc Gold

313

9159

4331 28

Is the antimicrobial activity of silver due to the nanoparticles themselves, or to the released Ag+ ions, or both?

• And how do environmental conditions affect their relative influence?

O2

nAg(0)

O2

Ag+ BacteriaToxic

Bioavailable? Toxic?

Cl‐, S2‐, Cysteine, CO3

2‐, HCO3‐,

SO42‐, PO4

3‐

Complexation?Precipitation?

Toxic?

Ag+

Bacteria

Ligands

Bioavailability and Toxicity of AgNPs

Ag+ is released only if Ag(0) is oxidized: 4Ag0 + O2 +4H+ ↔ 4Ag+ + 2H2O(Solubility of Ag0 ≈ 0)

OxidizedNPs

(Ag2O)

H+

H+

Ag+

No Ag+ release under Anaerobic Conditions(Faster release for air-exposed smaller particles)

0 20 40 60 80 100 1200

500

1000

1500

2000

2500

Ag+ d

isso

lutio

n (

g/L)

Time (h)

5 nm (Aerobic) 11 nm (Aerobic) 5 nm (Anaerobic) 11 nm (Anaerobic)

Xiu Z., Q. Zhang, H.L. Puppala, V.L. Colvin, and P.J.J. Alvarez (2012). Nanoletters. 12, 4271−4275.

No Toxicity Without Ag+ Release

0 30 60 90 120 150 180 2100

20

40

60

80

100

120

E.

col

i aliv

e (%

)

PEG-AgNPs concentration (mg/L)

Anaerobic exposure

Outside anaerobic chamber

AeratedFor 48 h


Ag+ concentration (g/L)

0 100 200 300 400 500

E. c

oli k

illed

(%)

020406080

100120

PVP-nAg-25nmPVP-nAg-37nmPVP-nAg-86nmPEG-nAg-2nmPEG-nAg-5nmPEG-nAg-10nmAgNO3

AgNP Toxicity Can Be Explained by Dose-Response of Released [Ag+]


R2 = 0.95

“What does not kill you makes you stronger”Friedrich Nietzsche

0 5 10 15 20 25 30

60

80

100

120

140

*

**

Via

ble

E. c

oli (

%)

Ag+ concentration (g/L)

(a)

Stimulatory effect after 6 h exposure to low Ag+ concentration (Hormesis?)


Wang J., Y. Koo, A. Alexander, Y. Yang, S. Westerhof, Q. Zhang, J. Schnoor, V. Colvin, J. Braam, and P.J. Alvarez (2013). Environ. Sci. Technol. 47 (10): 5442–5449.

Sub-Lethal Concentrations of AgNPsCould Also Stimulate Plants

Sublethal Exposure to AgNPs (but not Ag+) stimulated biofilm development

C

50 µm

0.02 mg/L of Ag+ 0.02 mg/L of AgNPs Control

Mixed culture from the effluent of a WWTP, forming biofilm on a glass slide

Yang & Alvarez (2015). ES&T Letters. DOI: 10.1021/acs.estlett.5b00159

Sub-lethal Exposure of PAO1 to AgNPs also Upregulates Quorum Sensing, LPS, and Antibiotic Resistance Genes

Why is nAg sometimes a stronger bactericide?

• Cl- (& other ligands, NOM) reduce Ag+ bioavailability and preferentially decrease its toxicity, even without precipitation

• nAg may then be more bioavailable & effectively deliver Ag+

Max [Ag+]: 3µM; [Cl‐]: 3µM Max [nAg]: 57µM; [Cl‐]: 57µMAg+ concentration (mg/L)

0.0 0.1 0.2 0.3

E. c

oli k

illed

(%)

0

20

40

60

80

100

Ag+

Ag++Cl-

nAg concentration (mg/L)0 2 4 6

E. c

oli k

illed

(%)

0

20

40

60

80

100

nAgnAg+Cl-

More Effective Deliveryof Ag+ to Membrane and Cytoplasm

Morones et al.,2005

Ag+nAg

Ag+

Ag+

Ag+

Ag+

nAg

Natural ligands

Natural ligands

pH=3.0

pH=5.5

Risk = Hazard × Exposure

Hazard, but no exposure

Hazard as well as exposure

Exposure but no hazard

Safer Use of ENMs

Hazard• Prioritize use of ENMs of benign, low‐cost, and earth‐abundant compositions (GRAS); Green Chemistry and Green Engineering

• Experts panel to select ENMs before incorporation into products

• Interface with TSCA in the US and REACH in the EU

Exposure• Immobilize ENMs to minimize release and exposure and enable reuse (no free NPs)

• Model & monitor treated water for leaching

• Foster safety in manufacturing by iterating with OSHA on best practices

• Independent certification for meeting health & safety stds.

Risk = Hazard x Exposure

CONCLUSIONS

• Implications: Ecotoxicology-Ecosystem services (primary productivity, food webs, nutrient cycling?) biodiversity? Toxicity to higher organisms? Mitigated by NOM, salts

• Applications: DBP-free disinfection, advanced (photo) oxidation processes, anti-fouling/corrosion coatings? functionalized membranes

Ph.D. M. Vermace; Craig Hunt; Marcio da Silva; Nanh Lovanh; Alethia Vazquez; Roopa Kamath; Michal Rysz; Natalie Capiro; Delina Lyon; Rosa Dominguez, Dong Li; Diego Gomez, Jacques Mathieu, Leti Vega, Xiaolei Qu, Jon Brame, Jiawei Ma, Pingeng Yu, Mengyan Li, Jing Wang, Ana McPhail, O. Monzon

M.S.E. Gary Chesley; Sang-Chong Lieu; Pete Svebakken; Phil Kovacs; Rod Christensen; Marc Roehl; Ken Rotert; Brad Helland; Leslie Cronkhite; Annette Dietz; Bill Schnabel; Ed Ruppenkamp; Leslie Foster; Bryan Till; Nahide Gulensoy; Rebecca Gottbrath; Matt Wildman; Chad Laucamp; Todd Dejournet; Sascha Richter; Nanh Lovanh; Sara Kelley; Eric Sawvel; Jennifer Ginner; Sumeet Gandhi; Richard Keller; Jennifer Wojcik; Anitha Dasappa; Leslie Sherburne; Brett Sutton; Russ Sawvel; Andrea Kalafut; Roque Sanchez; Amy Monier; Isabel Raciny; Katherine Zodrow; Robert O’Callaham; Bill Mansfield

Postdocs Graciela Ruiz; Jose Fernandez; Byung-Taek Oh; D. Kim; Joshua Shrout; Laura Adams, Sufia Kafy; Lena Brunet; Jaesang Lee, Jiawei Chen; Shaily Mahendra; Zongming Xiu; Yu Yang

Thanks! - Graduate Students and PostdocsNSF, EPA, CBEN, FAO, NERC, BP

Any Questions?Any Questions?

“Nanohype” - Berube

Trough ofDisillusionment

Slope ofEnlightenment

Plateau ofProductivity

Maturity

TechnologyTrigger

Peak ofInflated

Expectations

PositiveHype

Quo Vadis, Nano?Vi

sibi

lity

NegativeHype

Cos

t

Purity

Cost of Purification

High purity requirements increase separation cost due to higher energy, solvent, & process time requirements

Most production is done for research (small quantities of highly purified material)

Few commercial applications = low supply prices stay high

Need market-driven decrease ENM price

Avoid the diminishing returns of ultra high purity

Less pure amino-C60 cost less (20x) without significantly sacrificing reactivity

0

0.2

0.4

0.6

0.8

1

0 40 80 120

Rel

ativ

e C

once

ntra

tion

Time (min)

FFA-probe for 1O2

Purified

Unpurified-Soot

Outlook for Developing NationsDespite current barriers (technical capacity, cost) the use of ENMs will increase in developing nations (similar to cell phones) for point-of-use water treatment and reuse, due to:

Decreasing cost:• Economy of scales• Recyclability of immobilized NPs• Avoid diminishing returns of ultra high purity• Valuable properties imparted at low additive ratios

Savings on capital investment for new infrastructure in expanding mega-cities

When Does NEWT Make Sense?

• Where current technologies do not meet current or upcoming DWT or WWT regulations;

• To treat recalcitrant compounds (e.g., pharmaceuticals) that escape WWTPs and hinder reuse (e.g., irrigation);

• Where there is insufficient infrastructure and one must rely on POU devices

• When NEWT enhances cost-effectiveness (e.g., faster, less energy, and less material)

Feasibility Is within Reach(Photo-disinfection with TiO2 is feasible

for small villages if recycled)

10

20

50

200

TiO2 C

ycles Needed

Recycling makes photo-disinfection with TiO2 competitive with traditional treatment processes at small scales

(Assumes $0.15/g TiO2, 50 g/L used for treatment)

Photocatalyst

Photocatalytic Hydroxylation of Weathered Oil to Enhance Bioavailability and Bioremediation

WeatheredOil

(Recalcitrant)

HydroxylatedResidue

(Bioavailable)

OHOH

OH

CO2

ROSFoodGrade

Photocatalysis Increased Solubilization and Biodegradation of Weathered Oil

0

30

60

90

No PC P25 FG

TOC (m

g/L)

Dark

WithUV

*

*

*

* statistically significant (p <0.05)after 1-day exposure

0

100

200

300

400

0 50 100 150

BOD Con

sumed

(mg/L)

Time (h)

UV+PC

UV

Dark

37% more BOD removed

Brame J., S.W. Hong, J. Lee and P.J.J. Alvarez (2013). Chemosphere 90: 2315–2319.

Conceptual Improvements to Water Treatment Through Nanotechnology

52Qu X., J. Brame, Q. Li and P.J.J. Alvarez (2012). Acc. Chem. Res. doi:10.1021/ar300029v

SUMMARY Antimicrobial NPs can enable

microbial control (e.g., DBP-free disinfection, fouling resistant surfaces and membranes, etc.)

Sub-lethal concentrations of Ni2+

and Cd2+ hinder biofilm formation by inhibiting quorum sensing at the transcription level.

Nanotechnology could offer opportunities for controlled released of bactericidal or QS-interrupting metals

Qu X., J. Brame, Q. Li and P.J.J. Alvarez (2012). Acc. Chem. Res. doi:10.1021/ar300029v

Microbial-Induced

Corrosion& Souring

Flow obstruction,transformation of

light oil to bitumen

Gas Production Obstructs Flow

Clogging by Mineral

Precipitation

BiofilmSediment grains in porous media

N2 Gas bubbles

Biogenic minerals

(e.g., FeS)

Microbial Processes of Concern to the Oil and Gas Industry

3. O&G Reservoir Souring Control

Scale

Wax

Hydrates

Asphaltenes

Naphthenates

Souring (H2S)

ManageabilityLow Medium High

Prod

uctio

n Im

pact

Low

M

ediu

m

H

igh

50%

26%

15%

20%

71%

28%

Responsive NPs for Selective Biocide Delivery

H2S

Biocide

• Mesoporous silica filled with biocides & coated with polymers to enhance stability under high salinity/temperature

• Trapdoors made by Mike Wong (hexahydro-s-triazines) fall off due to nucleophilic attack by H2S, to release the biocide

• This triggers a burst release of biocide “on demand”

In Situ Control of Sulfidogens with Bacteriophages (Reservoirs & Pipelines)

• Prevent souring by H2S, corrosion, & clogging by FeS2

• Advantageso Self-replicating → low production

costs, persistent protectiono Penetrating → degrade biofilms,

can enhance transport properties- encapsulation- targeting through triggered

release (increased local MOI)o Green technology

Strategy: isolate and enrich polyvalent (broad-host-range) phages for “vaccination” inoculation of reservoirs.

Inhibition of Desulfovibro salexigensATCC 14944 by a phage from WWTP

With and without phage


0%

20%

40%

60%

80%

100%

0 4 8 12 16 20 24

Resid

ual SO

42‐

Time /h

Control(no phage)

1 phage per 10 bacteria

FeS

60

http://ww

w.bigelow.org/bacteria/land.jpg

Microbial-nanoparticle Interactionsto Inform Risk Assessment

• Bacteria are at the foundation of all ecosystems, and carry out many ecosystem services

• Disposal/discharge can disrupt primary productivity, nutrient cycles, biodegradation, agriculture, etc.

• Antibacterial activity may be fast-screening indicator of toxicity to higher level organisms (microbial sentinels?)

0

20

40

60

80

100

0 10 20 30 40 50

QD (nM)

% M

orta

lity

Weathered

Coated

Bacillus subtilis exposed to QD 655

Example 2. Artificial Coatings:Quantum Dot Weathering

Coated QDs

Weathered QDs

Cd2+ and Selenite Release after pH change (pH <4 & pH >10) Explains Dose-Response

0

20

40

60

80

100

120

0 50 100 150 200

Cadmium (mg/L)

% C

ell m

orta

lity

Coated QDs Weathered QDs Cd(NO3)2

Mahendra S., H. Zhu, V. Colvin and P. J. J. Alvarez (2008). Environ. Sci. Technol. 42 (24), 9424-9430

pH 2 pH 7 pH 12

Organic ligands mitigate toxicity

0

0.1

0.2

0.3

0.4

Weathere

d

W + NTA

W + ox

alate

W + EDTA

W + cit

rateW +

cyste

ineW +

humic

acid

W + BSA

Coated

B. s

ubtil

isA 6

00 a

fter 4

8h

Cd

(mg/

L)

0

25

50

75

100

W

W+NW+OW+EW+citW+cy

sW+HA

W+B C

Mahendra S., H. Zhu, V. Colvin and P. J. J. Alvarez (2008). Environ. Sci. Technol. 42 (24), 9424-9430

Potential Impacts to the N cycle:

N2

NH4+

NO2-, NO3

-Organic Nitrogen

Nitrogen fixation

Ammonification Nitrification

DenitrificationA.vinelandii

(amoA1, amoB2,amoC2, hao2,

cycA1)

N. europaea(nifH, vnfH,

anfD)

P. stutzeri(nirH, narG, napB, norB)

N2O

N2O

Gene name

narG napB nirH norB nifH anfD vnfH amoA1 amoB2 amoC2 hao2 cycA1

Gen

e ex

pres

sion

fold

cha

nge

(log 2

)

-2

0

2

4

6 100 nM PMAO QDs (1 nM for N. europaea) 10 nM PEI QDs (1 nM for N. europaea)

P. stutzeri A. vinelandii N. europaea

*

*

* ** * *

*

*

Sub-lethal concentration of PEI QDs up-regulated denitrification and N2 fixation genes

Yang Y., J. Wang, H. Zhu, Vicki L. Colvin and P.J.J. Alvarez (2012). Environ. Sci. Technol. 46(6): 3433−3441

Biofilms and Biofouling Control• Attached microorganisms

in a “slimy” matrix that are very difficult to eradicate.

• Preferred lifestyle of microorganisms in the environment

• Can harbor pathogens and increase energy consumption (headloss)

• Can cause corrosion through– production of organic acids– cathodic depolarization– direct oxidation of metal

66

Source: http://www.biofilm.montana.edu/resources/images/biofilm

s-nature/oxidation-late-stage.html

ConclusionsNanotechnology offers great potential for meaningful disruptive innovation in water & wastewater treatment and reuse:

• DBP-free disinfection• Advanced (photo) oxidation• Selective adsorption and

energy-efficient desalination• Fouling- and corrosion-

resistant surfaces• Multi-functional membranes• Responsive materials

Dissolved NOM Enhances C60 Dispersion

C60+ DI

C60 + SRHA

SRHA C60 + SRFA

SRFA

0

1

2

3

4

5

0 10 20 30 40 50 60 70 80

20 m g/L S R H A 10 m g/L S R H A5 m g/L SR H A

C60

con

cent

ratio

n (m

g/L)

M ixing tim e (h r)

No HA after 72 hr

1 mM NaCl

• Dispersed C60was measured as dissolved TOC

Li, Q. et al., ES&T, 2009, 43(10): 3574-3579.

Dissolved NOM Decreases nC60 Deposition onto a Quartz Surface, Increases Mobility in Water

0

5

10

15

20

25

30

-5 0 5 10 15 20 25

15 mM Ca, HA15 mM Ca, FA10 mM Ca, HA10 mM Ca, FA

Mas

s D

epos

ition

Rat

e dm

/dt (

ng h

r-1)

NOM Concentration (mg/L)Oscillating quartz crystal detector

Depositing Nanoparticles

~

Quartz Crystal Micro Balance

Four Strategies to Interrupt QS1. Block production of autoinducers (repress

gene transcription)

2. Inactivate or degrade autoinducers (enzymes)

3. Use autoinducer analogues to block receptors

4. Disrupt the autoinducer receptor

Autoinducers and receptors are species specific, which makes strategies 2, 3 and 4 narrowly applicable

Suspended Solids

1) Water Treatment Membranes

Multivalent Ions

Macromolecules

Water

Monovalent Ions (salt)

UF NF ROMF

Higher ∆P (energy), lower H2O recovery

–QS is a cell-to-cell communication via signal molecules (e.g., HSLs)

–Influences• Bioluminescence• Sporulation• Biofilm formation

72

Source:http://www.biofilm.montana.edu/resources/images/multicellularextracellular/quorum‐sensing.html

2) Biofouling Control through Quorum Sensing Interruption

Serendipitous Finding:Biofouling Resistant Heat Exchanger

• NASA’s Service and Performance Check Out Unit Heat Exchanger (SPCU HX)• Provides thermal control to the spacesuits before and

after a spacewalk • Used at International Space Station US Airlock

– Results from ground testing suggested that biofilm formation was occurring within the on-orbit HX (CO2↑, pH↓, metal dissolution↑)

73

Evaluation of Flight Unit• Heat exchanger was analyzed

for biofilm &MIC –Expected significant fouling, corrosion–Evaluated using scanning electron

microscopy (SEM), epifluorescencemicroscopy, auger microscopy

• Results–Planktonic growth without biofilm

BacLight Live/Dead staining of HX Control(top) and SPCU (bottom) samples. Thecontrol sample is fouled with bacteriawhile the SPCU sample has little growth74

Hypothesis: Trace elements (e.g., Ni) prevented biofouling through QS inhibition

Ni2+ & Cd2+ Inhibit Burkholderia Biofilm

• B. cepacia planktonic viability not affected (no bactericidal effect)

• Biofilm formation decreased with increasing Ni conc.

• HSL addition stimulated biofilm formation (no effect on planktonic), implicating QS inhibition

0.000

0.200

0.400

0.600

0.800

1.000

1.200

0 0.1 0.2 0.3

Absorban

ce600n

m

mM

Planktonic Viability

No Signal

HSL

0.000

0.050

0.100

0.150

0.200

0 0.1 0.2 0.3

Absorban

ce570n

m

mM

Biofilm Attachment

No Signal

HSL

Implication:If you can get bacteria to stop HSL production (by repressing QS gene expression) you would mitigate biofilm formation

QS Gene Repression

• Quantified QS gene expression (5x down-regulation of cep in B. cepacia at 0.3 mM nickel)

• Downregulation of QS gene expression (cep) coincided with no biofilm formation

76

0.000

0.050

0.100

0.150

0.200

0 0.1 0.2 0.3

Absorban

ce570n

m

mM

Biofilm Attachment

No Signal

HSL

Complete Biofilm Inhibition

Potential Mechanistic Explanation

• Ni2+ and Cd2+ are competitive antagonists of both Mg2+ & Ca2+, which are essential cofactors for many enzymes (including DNA & RNA polymerases, thus QS inhibition at transcription level) and help adhesion by cationic bridging.

Nanotechnology could offer opportunities for controlled released of QS-interrupting metals (e.g., control NP size and coating to modulate dissolution and ion release so that the MCL for the metal is not exceeded)

Fast Screening of QS Inhibitors(Microtiter Plate Method)

• Tested different concentrations of Nickel using the model bacterium, Chromobacteriumviolaceum (turns violet when QS is induced)

Quorum Sensing Inhibition (QSI) by Ni in Chromobacterium violaceum

QS+ QS‐Baseline

Water is by far the largest byproduct of the fossil fuel industry Water/Oil Ratio = 10 (US), 14 (Can.) $1 trillion/yr challenge*

Importance of Water for Energy Production

Residual AdditivesRadionuclidesHeavy MetalsScaling ions

OrganicsSalt

*http://www.twdb.state.tx.us/Desalination/TheFutureofDesalinationinTexas-Volume2/documents/B3.pdf

25000260002700028000290003000031000

Prod

uctio

n x

1000

B/D

Water

500060007000

1976 1978 1980Year

Crude

Fracking in drought-prone regions represents both a water supply and pollution control challenge

Use Brackish Groundwater for Fracking?(Geospatially consistent)

Nano = Dwarf (Greek) = 10-9

“Nanotechnology is the understanding and control of matter at dimensions of roughly 1 to 100 nanometers, where unique phenomena enable novel applications.”-National Nanotechnology Initiative

1) Need for Low-Energy Desalination

• High TDS represents a beneficial disposition challenge (discharge regulations)

• Multivalent cations (Ca2+, Ba2+, Sr2+, Fe2+/Fe3+) interfere with performance of friction reducing polymers and also form scale (flow assurance)

• Naturally occurring radioactive materials

• Toxic inorganic contaminants (e.g., Zn2+)

Desalination Technologies: Applicability and Water Recovery

0 20,000 60,00040,000 100,00080,000 120,000 Solubility

IX ‐ >98%

NF – 75‐90%

MSF – 10‐20%

MED – 20‐35%

RO – 30‐60%

MVC – 98% to ZLD

aqwatec.mines.edu TDS (mg/L)

CDI ‐ ~80%

ED – 80‐90%

MVC – 98% to ZLD

CDI ‐ ~80%

MD– near ZLD

MD – Membrane DistillationMVC – Mech. Vapor CompressionMED – Multi Effect DistillationCDI – Capacity DeionizationRO – Reverse OsmosisMSF – Multi Stage FlashNF – NanofiltrationED – ElectrodialysisIX – Ion Exchange

Microbial-Induced

Corrosion& Souring

Flow obstruction,transformation of

light oil to bitumen

Gas Production Obstructs Flow

Clogging by Mineral

Precipitation

BiofilmSediment grains in porous media

N2 Gas bubbles

Biogenic minerals

(e.g., FeS)

2) Need for Microbial Control

Microbial Control Strategies for Oil and Gas Reservoirs

• Biocides & bacteriostats– glutaraldehyde, nitrite

• Nutrient control– SO4 removal (RO)

• Competitive inhibition– nitrate (NRB stimulation)

Biocides

Oxidizing Non‐oxidizing

Electrophiles

Lytic

Protonophores

In Situ Control of Sulfidogens with Bacteriophages (Reservoirs & Pipelines)

• Prevent souring by H2S, corrosion, & clogging by FeS2

• Advantageso Self-replicating → low production

costs, persistent protectiono Penetrating → degrade biofilms,

can enhance transport properties- encapsulation- targeting through triggered

release (increased local MOI)o Green technology

Strategy: isolate and enrich polyvalent (broad-host-range) phages for “vaccination” inoculation of reservoirs.

Inhibition of Desulfovibro salexigensATCC 14944 by a phage from WWTP



0%

20%

40%

60%

80%

100%

0 4 8 12 16 20 24

Resid

ual SO

42‐

Time /h

Control(no phage)

1 phage per 10 bacteria

FeS

Nanotechnology has a great potential for enabling exploitation of a broader range of water sources (e.g., sea water, flowback-water, wastewater)

Could help transform some infrastructure-, chemical- and energy-intensive treatment approaches towards catalytic & physical systems that obviate current tradeoffs between cost & performance, and between energy consumption & treatment rate

CONCLUSIONS

Example 1. C60, nC60 and NOM

Photocatalystand Antioxidant(sp2 hybridized)

R. Buckminster Fuller (Bucky)

Solid or solution nC60 (20-200 nm)

_ _ _

_

__

_

_

_ _ _ _

__

__

NaCl adsorption capacity > 1.3 mmole/g

VerticallyAlignedCNTs

CNTs/graphene enhance sorption capacity, kinetics, mechanical

strength and electrical conductivity.

Nano-Enabled CDI for Scaling ControlIX polymers enable preferential

removal of divalent cations that cause scaling

Ex. 3. Low-Energy Desalination byMembrane Distillation


Tp

T1T2

Tf

Q1 Q2 Q3

T1 T2

Tf Tp



Nanophotonics-Enhanced Membrane Distillation for Solar Desalination

Plate-and-Frame Configuration

http://www.wassertech.net/content/view/34/29/lang,thai/

• Thin, patterned transparent poly(methyl methacrylate) sheet serves simultaneously as the top plate of the module, the optical window and the spacer that forms the feed flow channels.

• Mount it on a solar tracker to maximize sunlight collection.

95

Nano-Enabled Water Treatment @ Rice

• Sand filter coated with nano-magnetite to remove As (pilot in Guanajuato, Mexico, reported by BBC, NY Times, Forbes and CBC).

• Fouling-resistant membranes that also inactivate virus (nAg, nano-TiO2)

• Pd/Au hypercatalysts to treat TCE (Pilot at Dupont site)

• Novel amino-fullerene photocatalysts to enhance UV and solar disinfection and advanced oxidation processes

Proliferation of Multi-drug Resistant “Superbugs” (NDM-1 positive) from Sewage Treatment Plants

Yi L., F. Yang, J. Mathieu, D. Mao, W. Qing, and P.J.J Alvarez (2014). ES&T Letters. (1), 26−30

PCT1.0E+16 1.9E+17 1.8E+17 3.0E+17 1.0E+15

6.1E+16

7.8E+16

Recycled Sludge

(1.7E+21) (5.6E+22) (4.6E+22) (9.9E+22) (6.5E+19)

(2.0E+22)

(2.3E+22)

NDM‐1 gene(16S rRNA gene)

RIAaT AT AeT SCT DU FE

WS DS 2.3E+15(2.9E+20)

5.7E+14(7.1E+18)

6.1E+14(2.3E+19)

2.2E+17(6.4E+22)

NDM-1 flow output (genes/day) was 4.6-fold greater than influent values

Disinfection (Cl2) Efficiency:892% for Total Bacteria434% for NDM1 carriers

Why Nano?Leap-frogging opportunities to:• Develop high‐performance multifunctional materials and systems that are easy to deploy, can tap unconventional water sources, and reduce the cost of remote water treatment

• Transform predominantly chemical treatment processes into modular and more efficient catalytic and physical processes that exploit the solar spectrum and generate less waste

97

Example 3. Low-Energy Desalination (and Disinfection) by Membrane Distillation


Tp

T1T2

Tf

Q1 Q2 Q3

T1 T2

Tf Tp



Photonics of Nanoparticles for Solar-Thermal Applications

Light localization by multiple scattering

confines solar energy, enabling high

efficiency heat transfer(N. Hogan et al., TBP)

Inhibition on biofilm development increased from PEG‐AgNPs to PVP‐AgNPs to Ag+

silver concentration (ppm)0.0 0.1 0.2 0.3 0.4 0.5 0.6

Inhi

bitio

n on

bio

film

gro

wth

(%)

-20

0

20

40

60

80

100

120

Ag+PVP-AgNPsPEG-AgNPs

IC50,Ag+= 0.044 ppm

IC50,PEG-AgNPs= 0.182 ppm

IC50,PVP-AgNPs= 0.114 ppm

Photocatalyst

Photocatalytic Hydroxylation of Weathered Oil to Enhance Bioavailability and Bioremediation

WeatheredOil

(Recalcitrant)

HydroxylatedResidue

(Bioavailable)

OHOH

OH

CO2

ROSFoodGrade

Photocatalysis Increased Solubilization and Biodegradation of Weathered Oil

0

30

60

90

No PC P25 FG

TOC (m

g/L)

Dark

WithUV

*

*

*

* statistically significant (p <0.05)after 1-day exposure

0

100

200

300

400

0 50 100 150

BOD Con

sumed

(mg/L)

Time (h)

UV+PC

UV

Dark

37% more BOD removed

Brame J., S.W. Hong, J. Lee and P.J.J. Alvarez (2013). Chemosphere 90: 2315–2319.

103

http://ww

w.bigelow.org/bacteria/land.jpg

Microbial-nanoparticle Interactionsto Inform Risk Assessment

• Bacteria are at the foundation of all ecosystems, and carry out many ecosystem services

• Disposal/discharge can disrupt primary productivity, nutrient cycles, biodegradation, agriculture, etc.

• Antibacterial activity may be fast-screening indicator of toxicity to higher level organisms (microbial sentinels?)

Selected Antimicrobial Mechanisms

Disruption of membrane/ cell wall by carboxyfullerene

DNA damage

ROS

Protein oxidation

e-

e-

Release of toxic ionsby QDs, nano-silver, nZnO

Generation of Reactive Oxygen Species by TiO2 & aminofullerenes

Ag+

Cd2+ Zn2+

Interruption of respiration and protein oxidation upon contact (e.g., nC60 , CeO2)

Example 1. C60, nC60 and NOM

Photocatalystand Antioxidant(sp2 hybridized)

R. Buckminster Fuller (Bucky)

Solid or solution nC60 (20-200 nm)

_ _ _

_

__

_

_

_ _ _ _

__

__

nC60 may be more toxic to bacteria than many other common nanomaterials

Incr

easi

ng to

xici

ty

THF/nC60 son/nC60 aq/nC60 PVP/nC60 Ag+ nano-Ag NaOCl nZnO nZVI nTiO2(sunlight)

nSiO2

0.01

0.1

1

10

100

1000

10000

MIC

(ppm

)

NOM reduces bioavailability & toxicity of nC60

200 nm

nC60

nC60 trapped by humic colloids

0

200

400

600

800

1000

1200

0 10 20 30 40 50Time (h)

Cum

ulat

ive

CO

2pr

oduc

tion

(μm

ole) 1400

0.27 mg humic acid+nC60

100 mg soil+nC6092 mg sand+nC60

nC60-free controlnC60 only

Humic acid concentrations as low as 0.1 mg/L eliminated toxicity

Li, D., Lyon D.Y., Q. Li, and P.J.J. Alvarez (2008). Environ. Toxicol. Chem. 27(9):1888-1894


108

Example 3. Direct Solar Desalination by Membrane Distillation

Direct solar (membrane) distillation

– Uses nanophotonics to convert sunlight to heat efficiently

– NPs create plasmon resonance to generate vapor on membrane surface

T2

MEMBRANE DISTILLATEHOT FEED

Solar-enhanced MD

nano

parti

cles

T1

Higher T gradient = higher flux

The exposure concentration was 0.0216 ppm for all the silver treatments. Treatment

Control AgNO3 PVP-AgNPs

Am

ount

of p

rote

ins

(mg/

g dr

y w

eigh

t)

0

20

40

60

80

100

Am

ount

of c

arbo

hydr

ates

(mg/

g dr

y w

eigh

t)

0

50

100

150

200

250

300

350

ProteinCarbohydrate

* *

AgNO3

Sub-lethal Exposure of P. aeruginosa PAO1 to AgNPs Stimulates Production of Biofilm Proteins & Carbohydrates

AgNPs also had higher impact than Ag+ on activated sludge!

AgNPs damaged AS floc, which can affect clarification and recycling

Control35‐nm AgNPs (40 ppm)

Yang Y., J. Quensen, J. Mathieu, Q. Wang, J. Wang, M. Li, J. Tiedje, and P. Alvarez (2014). Wat. Res. 48:317‐325.

20 µm 50 µm

10 µm 20 µmControl AgNO3 35-nm AgNPs

Cop

y nu

mbe

r of n

itrify

ing

gene

am

oA(x

107

per

ng

DN

A)

0

10

20

30

40

Control AgNO3 35-nm AgNPs

*

AgNPs decreased abundance of nitrifiers, hinders N removal

cracked & pittedgranule

broken cells

Nanoparticle Modifications in the Environment

Alvarez P.J.J., V. Colvin, J. Lead and V. Stone (2009). Research Priorities to Advance Eco-Responsible Nanotechnology. ACS Nano 3(7): 1616-1619.

Background on Biofouling

$‐

$100,000

$200,000

$300,000

$400,000

$500,000

$600,000

CorrosionCosts (Yearly)

Market ValueExxon‐Mobil

Market ValueApple

US Dollars (M

illions)

• Biofouling impairs membranes, water distribution and storage systems cooling towers, heat exchangers., etc.

• Biofouling and microbial-induced corrosion costs 3.1% of US GDP* (~$500 billion/year), which is close to the value of the two most valuable companies in the world

Fluidized Bed Photocatalytic Reactor for Point-of-Use Disinfection and Pesticide Removal

Air in

Water in

Clean Water

out

Light Source

Photocatalyst attached to suspended

beads

Brame J., V. Fattori, R. Clarke, Y. Mackeyev, L. J. Wilson, Q. Li and P.J.J. Alvarez (2014). Environmental Engineer and Scientist: Applied Research and Practice. 50(2), 40-46).

5 gal10 gpm

114

nAg-PSf Membranes Enhance Virus Removal 5 x 105

PFU/mL

6 x 102

PFU/mL 0 PFU/mL

Surface Water Treatment Rule:

99.99% Virus Removal

Removal of MS2:

PSf: 99.9%

nAg-PSf: > 99.999%

PSf nAg-PSf

115

Vision: Nano-Enabled Water Treatment & Reuse

“Nano” particles:• High surface areas• Hyper-catalytic functions• Tunable physical properties• Multifunctional membranes• Faster kinetics

Enable high-performance water treatment and remediation systems with(1) Less infrastructure, (2) Less materials/reagents

(selective targeting)(3) Lower costs & energy

clean water, enhance water

infrastructure, &enable integrated water management & reuse

Transformative Technologies to

Example 1: Enhancing UV/Solar Disinfection

• UV disinfection of DW is increasingly used to inactivate cyst-forming protozoa such as Giardiaand Cryptosporidiumwithout harmful DBPs.

• However, UV is relatively ineffective to treat virusunless the contact time and energy output are significantly increa$ed

UV Light

Energy Level

O2

O21

Light excites C60 to triplet state. Energy transfer between 3C60* and molecular oxygen gives rise to singlet oxygen (1O2)

Hotze M., J. Labille, P.J.J. Alvarez and M. Wiesner (2008). Environ. Sci. Technol. 42, 4175–4180

3C60*

1C60

“Water Soluble” Derivatized Fullerenes

O

O

HN

OHOH

HN

OHOH

HC3

O

OO

NH3

O

NH3

HC4

vs

* Synthesized in Lon Wilson’s lab, Dept of Chemistry, Rice University (Bingel reaction)

* Commercially Available, MER Corp.

Superior 1O2 Production confirmed by EPR & Laser Flash Photolysis

Example 2: Biofouling ofWater Treatment Membranes

NMP + nAg

1. Collodion preparation :

• Nanoparticle solubilisation in NMP. Ultrasonication (100 W, 4 min)

• Addition of PVP at 70 °C

• Slow addition of PSF while stirring at 120 °C

2. Film casting at room temperature

3. Immersion in water

Water at 25 °CGlass plate

PVP + PSf

120 °C

NMP = N-methylpyrrolidone ; PSf = Polysulfone ; PVP=Poly(vinylpyrrolidone)

Fouling-Resistant UF Membrane Fabrication (Wet Phase Inversion)

20 μm

PSf

*nAg-PSf

0

2000

4000

6000

8000

10000

12000

Type of Membrane

Cells

/ m

m2

Bacteria deposited by filtrationMembrane

LB Agar

Bacterial growth inhibition test

Inhibition of E. coli attachment onto membrane surface

Inhibition of growth of E. coli

PSf

*nAg-PSf

0

5

10

15

20

25

30

Type of Membrane

Col

ony

Form

ing

Uni

ts ,

Zodrow K., L. Brunet, S. Mahendra, Q. Li, and P.J.J. Alvarez (2009). Wat. Res doi:10.1016/j.watres.2008.11.014

nanotechnology-enabled water treatment:

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