Use of nano technology in ervironmental engineering

1. APPLICATION OF NANOTECHNOLOGY IN
WATER AND WASTE WATER TREATMENT
VISHNU RAJ R
14CE63R09

2. 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

3. 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

4. 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

5. 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

6. 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

7.  PR-MNPs can be recovered after use by external
magnetic field followed by treatment with HCl
http://nanowatertreatment.wikispaces.com

8. 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)

9.  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)

10. 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.

11. 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.

12. 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)

13. 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.

14. 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

15. 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

16.  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)

17. Groundwater remediation using nZVI (Wei et al )

18. 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

19.  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 Resonance
Jordi et al

20. 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

21. 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.

22. 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

23. 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

24.  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