APPLICATION OF NANOTECHNOLOGY IN

WATER AND WASTE WATER TREATMENT

VISHNU RAJ R

14CE63R09

INTRODUCTION

Nano Science

Nano means a factor of one billionth

Size of 7 oxygen atoms or 3-4 water molecules

Nanomaterials don’t obey

the normal laws of

physics and chemistry.

Manufactured either by

top down or bottom up

approach

WHY TO USE NANOTECHNOLOGY IN WATER

TREATMENT ?

Present scenario

Water scarcity & pollution of water bodies are

increasing

Current water treatment & distribution technologies concepts are mostly inefficient

Draw backs include

-- Formation of DBPs during chlorination

-- Possibility of contamination during water

transport

-- High Cost of operation during RO process

-- Low adsorption capacities.

-- Inability to reuse Activated carbon after one

cycle

-- Membrane fouling

NANATECHNOLOGY – A SOLUTION ?

Nano technology have the potential to resolve the

current problems in water sector.

Their unique properties of materials when they

are at nanoscale are utilized for environmental

applications

This includes

-- Very large specific surface area

-- High degree of functionalization

-- High reactivity

-- Super magnetism

-- Anti microbial properties

-- Photo catalysis

NANOADSORPTION

Efficiency of conventional adsorbants limited by lesser

surface area and lack of selectivity

Nanoadsorbants provide better adsorption properties

Carbon‐based nano adsorbents

-- CNTs comes under this category.

-- In aqueous phase, CNT form aggregates, containing

interstitial spaces accessible for bulky organic

molecule [Xiaole et al ]

-- The surface functional groups (carboxyl, hydroxyl &

phenol) of CNTs are the major adsorption sites for

metal ions

-- Mainly through electrostatic attraction and chemical

bonding

METAL BASED NANO-ADSORBENTS

Metal oxides like alumina, iron oxide are effective

for metal based nano adsorbants

Wastewater treatment using polyrhodanine-

magnetic nanoparticles

Manufactured using aqueous solution of rhodanine

,iron chloride & sodium borohydride

Adsorbtion is due to metal-binding functional groups

of Rhodanine monomeric unit

Higher adsorption observed for mercury ions

Song et al

PR-MNPs can be recovered after use by external magnetic field followed by treatment with HCl

http://nanowatertreatment.wikispaces.com

NANOCATALYSTS

Under UV light illumination, TiO2 produces

electron-hole pairs on the surface.

Charged points on reaction with electron donors,

such as water or hydroxide ions forms hydroxyl

radicals

TiO2 application limited due to its higher band

gap energy- 3-3.2eV(Jatinder et al)

Nitrogen-doped TiO2 nanocatalysts emerged as a

possible solution by narrowing band gap (Liu et al)

E Coli removal with N-doped TiO2 nanoparticles

under the solar light was studied (Liu et al)

The initial cell counts was about 109 CFU/ml.

At the end of reactions, the residual cell counts for

E.coli were almost non detectable.

(Liu et al)

NANO FILTRATION

Pressure driven process wherein the pore size of the

membrane (0.5-1 nm) & trans-membrane pressure

(5-10 bars)

Nanofilters soften water by retaining scale-forming,

hydrated divalent ions such as Ca2+, Mg2+ while

passing smaller hydrated monovalent ions.

CNT filters were effective at removing bacteria

(Escherichia coli and Staphylococus aureus) from

contaminated water (Srivastava et al)

The carbon nanotube filters are readily cleaned by

ultrasonication and autoclaving.

NANO ALUMINA FIBERFILTERS

A 2 nm alumina fiber is combined with a microglass

fiber to produce a nonwoven filter(pore size of 2

microns)

Microglass- nano alumina mixture is highly

electropositive ( zeta potential of 32 mV)

They adsorb negatively charged contaminants such

as viruses, bacteria, and organic and inorganic

colloids

Capable of adsorbing > 6 LRV of MS2 virus (Fred et al)

Flow rate of about 1 to 1.5 liters per hour per square

centimeter of media.

ANTIMICROBIAL NANOMATERIALS

Chemical disinfectants currently used can react

with various constituents in natural water to form

DBPs-which are potential carcinogens.

The resistance of some pathogens to conventional

chemical disinfectants requires extremely high

disinfectant dosage ,leading to aggravated DBP

formation

Nanomaterials like chitosan, silver nanoparticles

,photocatalytic Ti02, aqueous fullerene

nanoparticles and CNTs have strong antimicrobial

properties.(Qilin et al)

Antimicrobial Peptides & Chitosan

Charge interaction between chitosan particles &

cell membranes causing an increase in membrane

permeability and eventual rupture

Applications of nanoscale chitosan and peptides

include surface coatings of water storage tanks or as

an antimicrobial agent in membranes

ZnO Nanoparticles

ZnO shows high UV absorption efficiency

Mechanism of photocatalytic degradation by ZnO is

due to the generation of hydrogen peroxide within

the cells.

Silver Nanoparticles

Nanoparticles of silver release large quantities of

silver ions when they interact with bacterial cells.

These ions are very reactive and form ROS within

the cells by reacting with thiol groups in the

enzymes.

ROS formation renders the respiratory enzymes

inactive leading to cell death

Economic analyses must be done before decision

regarding lower DBP formation as well as the cost

associated with escape of nanoparticles

NANOREMEDIATION

Iron nanoparticles can be used nano remediation

particularly groundwater contamination problems

Preferred for nanoremediation

-- Posses dual properties of adsorption and reduction

-- Non toxic

nZVI is also efficient in removing dissolved metals from

solution -Cr (VI) to Cr (III) (Wei et al)

Synthesis of nanoscale iron

4Fe3+ + 3BH4- + 9H2O → 4Fe0↓ +3H2BO3

- + 12H+ + 6H2

nZVI is very effective in destroying halomethanes,

polychlorinated hydrocarbons pesticides and dyes

C2Cl4 + 4Fe0 + 4H+ C2H4 + 4Fe2+ + 4Cl−(Andrew et al)

Groundwater remediation

-mobile nZVI is injected to form a plume of reactive

Fe particles that destroy organic contaminants that

dissolve from a DNAPL source in the aquifer

-With this technique, the formation of a pollutant

plume is inhibited.(Bernd et al)

Groundwater remediation using nZVI (Wei et al )

NANO SENSORS

Conventional indicator -slow and can’t monitor the

presence of viruses

Pathogen detection is the key component of

diagnosis-based water disinfection approach, in

which disinfection is triggered by the detection of

target microorganisms.

Sensors consist of recognition agents, nanomaterials

& signal transduction mechanism

Recognition agents interact with antigens

Sensitivity and fast response achieved by the

nanomaterial related signal transduction upon the

recognition event

LSPR biosensors made from noble metal NPs

LSPR spectra are extremely sensitive to changes in

the local refractive index.

When foreign molecule attaches , shift in the LSPR

spectrum is used to detect molecules attached to

the noble metal NPs.

Biosensing mechanism using Localised Surface Plasmon ResonanceJordi et al

ECONOMIC ANALYSIS

nZVI based nano remediation for 100 m2 area

--6 kL of slurry containing 11kg of nZVI required

--cost ranging US$40 to $50 per kg

Titanium dioxide nanopowders

-- US$1.10 per kilogram.

Nanofibrous Alumina Filters

-- US$3 per square meter

Adsorbent resin made of hydrous iron oxide

nanoparticles with polymer substrate

-- US$0.07 to $0.20 per thousand liters

Global Dialogue on Nanotechnology and the Poor: Opportunities and Risks

ENVIRONMENTAL RISKS

Studies were conducted to analyze mobility, toxicity

& persistence of nanoparticles (Talia et al)

Ag, ZnO & TiO2 nanoparticle effects were studied

Adverse health effects where observed from

exposure to nanoparticles through in vitro and in

vivo experiments.

The observed effects in aquatic organisms ranged

from higher activity of certain stress-related genes

,glutathione depletion & lipid peroxidation to reduced

fertility at high particle concentrations

(Bernd et al)

After 5 days of ingesting TiO2 nanoparticles in

drinking water, rats had detectable DNA damage.

CONCLUSION

Current water treatment & distribution system

have a lot of drawbacks.

Nanotechnology have the potential to replace

them and increase the efficiency

However most of techniques for the treatment of

wastewater involving nanotechnology so far have

been done in laboratory scale only

Development of cost effective nanomaterials

with proven non toxicity effects on environment

could revolutionize water treatment domain

REFERANCES

Antimicrobial nanomaterials for water disinfection and microbial control: Potential

applications and implications- Qilin Li, Shaily Mahendra, Delina Y. Lyon, Lena

Brunet, Michael V. Liga, Dong Li, Pedro J.J. Alvarez

Meridian Institute, Global Dialogue on Nanotechnology and the Poor:

Opportunities and Risks

Role of nanotechnology in water treatment and purification: Potential applications

and implications Sayan Bhattacharya, Indranil Saha

Applications of nanotechnology in water and wastewater treatment - Xiaolei Qu,

Pedro J.J.

Photocatalysis by Nanoparticles of Titanium Dioxide for Drinking Water

Purification: A Conceptual and State-of-Art Review- Jatinder Kumar , Ajay Bansal

Novel TiO2 Nanocatalysts for Wastewater Purification-Tapping Energy from the

Sun- Y. Liu, J. Li, X. Qiu, C. Burda

Particle removal efficiency of nano alumina fiber Filter- Fred Tepper, Leonid

Kaledin, Argonide Corp., Sanford, FL

Adsorption of heavy metal ions from aqueous solution by polyrhodanine-

encapsulated magnetic nanoparticles- Jooyoung Song, Hyeyoung Kong, Jyongsik

Jang

Nanosensors in environmental analysis - Jordi Riu, Alicia Maroto, F. Xavier

Long-Term Performance of Zero-Valent Iron Permeable Reactive Barriers: A

Critical Review Andrew D. Henderson and Avery H. Demond

Nanoscale iron particles for environmental remediation: An overview -Wei-xian

Zhang

Carbon nanotube filters - Srivastava, Talapatra, R Vajtai and P M. Ajayan

Pollution Prevention and Treatment Using Nanotechnology-Bernd Nowack

Evaluating Nanoparticle Breakthrough during Drinking Water Treatment.-Talia E.

Abbott Chalew, Gaurav S. Ajmani

Antimicrobial nanomaterials for water disinfection and microbial control: Potential

applications and implications :Qilin Li, Shaily Mahendra, Delina Y. Lyon, Lena

Brunet

Online Sources

http//superparamagnetic-nanoparticles-and-the-separation-problem

http//clu.in.org- clean up information USEPA

http://nanowatertreatment.wikispaces.com