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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
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