Streamers in Water Filled WireCylinder and PackedBed Reactors

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Overview

• Papers that will be discussed
• Streamers in Water Filled Wire-Cylinder and
  Packed-Bed Reactors
• Bacterial Decontamination of Water by Means of
  Pulsed-Corona Discharges
• Low-pressure Microwave Plasma Ultraviolet Lamp
  for Water Purification and Ozone Applications
• Inactivation of Viruses and Bacteria by Ozone,
  with and without sonication
• Ozone Inactivation in Flowing Water of Indicator
  Organisms
• Disinfection of Deionised Water using AC High
  Voltage
• Lethal Effect of the Gliding Arc Discharges on
  Erwina spp.
• Water Purification by Electrical Discharges
• Generation of Chemically Active species by
  Electrical Discharges in Water
• Water Treatment by Pulsed Streamer Discharges

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Streamers in Water Filled Wire-Cylinder and
Packed-Bed Reactors

• Investigated streamers in a coaxial reactor
  filled with tap water
• Applied a positive high-voltage pulse to center
  electrode over a short amount of time to generate
  plasma channels and discourage arc formation in
  discharge gap
• Streamers generated active species (H, OH)
  within the water but were likely consumed prior
  to interacting with dissolved pollutants
• Investigated an alternative method for a more
  homogeneous distribution of the plasma

Discharges generated between tungsten wire and
stainless steel mesh
EXPERIMENTAL PARAMETERS

• center electrode Ø 0.075 mm
• applied voltage 90 kV
• pulse duration 500 ns
• deposited energy 11 J
• water conductivity 120 µS/cm

• chamber ID 44 mm
• chamber length 100 mm
• channel Ø 0.2-0.3 mm

Observed streamers without gel packing
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Streamers in Water Filled Wire-Cylinder and
Packed-Bed Reactors

• Constructed a packed-bed reactor utilizing 3-5
  mm diameter silica gel beads
• Observed a homogeneous plasma distribution when
  running experiment
• Results suggest that plasma spreads due to
  surface discharges along beads
• Suspect that silica bead packing absorbs and
  retains pollutants and their byproducts and
  functions as a catalyst in the decomposition of
  pollutants

Plasma distribution in packed-bed reactor using
silica gel beads
Note experiment utilizing packed-bed reactor
type was performed at same parameter values
REFERENCE
M.A. Malik, Y. Minamitani, S. Xiao, J.F. Kolb,
and K.H. Schoenbach, Streamers in Water Filled
Wire-Cylinder and Packed-Bed Reactors, IEEE
Tans. on Plasma Sci., vol. 33, no. 2, pp.
490-491, Apr. 2005.
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Bacterial Decontamination of Water by Means of
Pulsed-Corona Discharges
EXPERIMENTAL SETUP

• tungsten wire Ø 75 µm
• SUS plate 20 x 12 mm
• discharge voltage 120 kV
• pulse duration 600 ns
• conductivity of bio suspension 1.6 mS/cm

• energy delivered 13.5 J/Shot
• pulse frequency 0.1 Hz

• Investigated biological effects of streamer
  discharges generated in water without bubbling
  for Escherichia coli and Bacillus subtilis
  (vegetative and spore)
• 2 sets of experiments consisting of 3
  independent trials with 2 samples per trial

Appearance of pulsed-corona discharge in water
Experiment One
Experiment Two
Bacteria E. Coli and B. subtilis (vegetative and
spore) No. of Discharges 0, 10, 20, 30, 40, 50
Bacteria E. Coli and B. subtilis
(vegetative) No. of Discharges 0, 1, 2, 4, 6,
16, 32
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Bacterial Decontamination of Water by Means of
Pulsed-Corona Discharges

• Decontamination effect increased after 10
  discharges concentration decreased twice as
  fast up to approx. 30 discharges (energy
  expenditure 40 J/cm3)
• No effect on B. Subtilis spores, even at 50
  discharges

• Overall concentration reduced by 3 orders of
  magnitude (energy expenditure 10 J/cm3)
• Decontamination rate decreased significantly
  after 15 electrical discharges
• Residual concentration of 10-4(Co)

TYPICAL EXPERIMENTAL RESULTS

• Homogeneous distributions ensured by stirring
  suspension after every 10 shots
• Increasing level of peroxides with increasing
  number of discharges
• pH level of solution dropped after 100 pulses
  from 7.6 to 7.2

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Bacterial Decontamination of Water by Means of
Pulsed-Corona Discharges
REFERENCE
A. Abou-Ghazala, S. Katsuki, K.H. Schoenbach,
F.C. Dobbs, and K.R. Moreira, Bacterial
Decontamination of Water by Means of
Pulsed-Corona Discharges, IEEE Tans. on Plasma
Sci., vol. 30, no. 4, pp. 1449-1453, Aug. 2002.
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Low-pressure microwave plasma ultraviolet lamp
for water purification and ozone applications

• Microwave plasma ultraviolet lamp
• UV lamps are commonly used for germicidal
  applications
• Limited power output of 30 W/m
• Paper compares MPUVL to conventional lamps
• Microwave plasma UV lamp
• Output 0.1 to 1 kW/m
• 2.45 GHz
• 254 nm wavelength kills or renders bacteria
  unable of reproduction

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Low-pressure microwave plasma ultraviolet lamp
for water purification and ozone applications

• Positioned in a 1 m radius circle to determine
  best postion
• Optimal position (3) perpendicular to lamp (39.6
  mV)
• Temperature Control
• Optimal temperature range was around 40-55 degree
  celisus depending on the operating powr ranges
• Without cooling the intensity efficiency is only
  55 with cooling the intensity efficiency is 90
• Optimization of carrier gas pressure
• Argon pressure in the UV lamp effects the
  efficiency of the lamp
• Gas pressure of lt0.1 torr is most efficient

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Inactivation of Viruses and Bacteria by Ozone,
with and without sonication

• Viruses and Bacteria used
• Staphylococcus aureus, Samonella typhimurium,
  enteropathogenic E. coli, Shigella flexneria, and
  Pseudomonas dluorescens
• Ozone produced by corona-type ozone generator
• Added through porous diffuser 5 cubic ft per
  hour.
• Oxygen was added at the same flow rate for
  control
• Ultrasonic system
• 40-KHz ultrasonic generator with 150 W output

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Inactivation of Viruses and Bacteria by Ozone,
with and without sonication

• Results
• Bacteria
• 15 s of treatment with ozone alone or with
  sonication were inactivated.
• Experiment was also run with bacteria suspended
  in secondary effluent from a wastewater treatment
  plant
• Required longer contact time
• Combined treatment enhanced inactivation
• Sonication at fixed intensity for 10 mins did not
  inactivate bacteria
• Viruses
• Encphalomyocarditis virus and CDVII were
  inactivated after 15 s contact time when
  suspended in sterile PBS
• Sonication reduced or altered oxidizable organic
  material thus reduced the ozone demand of the
  secondary effluent.
• May also break up particulate organic material
  and clusters of bacteria so they will be exposed
  to ozone.
• Cavitations may also enhance inactivation by
  reducing high surface tension.

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Ozone Inactivation in Flowing Water of Indicator
Organisms
Organisms Tested Hepatitis A Virus Poliovirus E
. Coli Legionella pneumophila Bacillus subtilis
spores
Experimental Setup Data Water supply phosphate
buffered saline solution (pH 7.2) Ozone
concentration 10 to 30g of O3/m3 of air in
bubble form Reaction Vessel 100-ml with max
possible ozone concentration of 1.4 to 1.6 mg/l
of O3
NOTE The effectiveness of ozone in inactivation
the various organisms was quantified by
calculating the time required for reduction by a
factor of 104.
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Ozone Inactivation in Flowing Water of Indicator
Organisms

• E. Coli needed 0.6 minutes at 20ºC and 0.1 mg/l
  O3 to reduce by a factor of 104
• Inactivation of E. coli was much faster at 10ºC
  than 20ºC creating a very recognizable
  temperature dependency

• B. subtilis experiments were undertaken but there
  was no significant reduction of the number of
  spores with the ability to propagate at 0.18 or
  1.2 mg/l of O3
• Resistances to ozone for various micro-organisms
  at 20ºC appear in the following order

PV1 lt E. coli lt HAV lt L. pneumophila lt B.
subtilis spores
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Ozone Inactivation in Flowing Water of Indicator
Organisms
Reference Herbold, K., Flehmig, B., and
Botzenhart, K. 1989. Comparison of Ozone
Inactivation, in Flowing Water, of Hepatitis A
Virus, Poliovirus 1, and Indicator Organisms.
Applied and Environmental Microbiology, Nov. 1989
, p 2949-2953.
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Disinfection of deionised water using AC high
voltage

• Designed for domestic household usage at 1 L/min
  flow rate
• 50 Hz, 4.75 kV RMS chosen over DC voltage because
  of electrolysis problems
• By deionizing the water, conductivity is reduced
• Electrode chamber consists of two parallel plates
  (10x10mm) and 1.5mm gap
• Killing effectiveness of the electrodes was
  tested on Serratia marcescens and Giardia lamblia
  cysts

SV solenoid valve DIR deionizing resin
cartridges AT air trap EC electrode
chamber ARV air release valve HVT high
voltage transformer CE control electronics FS
- electro-mechanical flow switch
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Disinfection of deionised water using AC high
voltage

• Critical design parameters for killing
  micro-organisms were found to be electric field
  and application time
• Three log reduction of Serratia required an
  electric field strength of 30kV/cm and
  application time of 17ms.

• For the demonstration model, a total of 1000
  nonviable Giardia cysts were counted giving a
  three log decrease in viability
• The low untreated cyst viability was due to a
  poor initial cyst culture
• The commercial and demonstration experiments were
  performed on different dates and different cyst
  cultures

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Disinfection of deionised water using AC high
voltage

• Reference
• Johnstone, P.T., and Bodger, P.S. Disinfection
  of deionised water using AC high voltage. IEE
  Proc.-Sci. Meas. Technol., Vol. 147, No. 3, May
  2000.

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Lethal Effect of the Gliding Arc Discharges on
Erwina spp.
- This system operates at atmospheric
pressure and close to ambient temperature. Once
the arc forms at the minimum gap distance it is
pushed down the axis of the reactor until it
breaks and a new arc forms. The plume of gasses
from the plasma then reacts with the liquid
surface. - NO and OH main species formed by
plasma in humid air. -Supplied gas N2 and O2
(from compressor)
-Voltage 9kV
-Current 100mA
-Gas flow rate L min-1
Reference M. Moreau, M.G.J. Feuilloley, N.
Orange and J.-L. Brisset Laboratory of Cold
Microbiology, University of Rouen, Evreux,
Laboratory of Electrochemistry, University of
Rouen, Mont-Saint-Aignan, and GIE Comité Nord,
Paris, France (accepted 13 September 2004)
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Lethal Effect of the Gliding Arc Discharges on
Erwina spp.
- No significant decrease in population within
the first 4 minutes of process, however as the
graph represents there is a difference between
the 3 types of Erwinia between the 4th and 8th
minute. That is significant because it
represents how some strains may be less
susceptible to the treatment.
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Water Purification by Electrical Discharges
Investigates contact glow discharge electrolysis,
dielectric barrier discharges and pulsed corona
discharges. However the focus largely on pulsed
corona. Free electrons in the streamers have an
average energy at approximately 5 eV with an
electron density of 1013 cm-3. Streamer may
bridge the gap between the electrodes resulting
in a spark discharge. That discharge channel may
reach temperatures of 14,000-15,000 K. It will
also emit UV radiation and create intense shock
waves all of which have a destructive force on
bio-material. Article claims that spark
discharges have higher efficiencies over streamer
discharges.
Reference Muhammad Arif Malik, Abdul Ghaffar and
Salman Akbar Malik Applied Chemistry Division,
PINSTECH, PO Nilore, Islamabad, Pakistan

Department of Biological Sciences,
Quaid-i-Azam University, Islamabad, Pakistan
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Water Purification by Electrical Discharges
Conductivity In the range of 10-80 µS cm-1.
Values of conduction in that range enhance the
resulting discharge, provide for a higher current
flow and increase the streamer length which in
turn creates more chemically active species.
Commercial ozone generators can produce up to 200
g O3 kWh-1 from an oxygen feed and 90 g O3 kWh-1.
A study of a plate-to-plate corona discharge
system in water (30 kV) could create 40 g O3
kWh-1. In comparison to the efficiencies of the
commercial ozone generators the statistic may
sound disappointing, however the efficiency is
still quite significant.
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Generation of Chemically Active Species by
Electrical Discharges in Water

• Overview
• Investigated the generations of chemical species
  in two types of reactors Needle-plate and
  Coaxial
• Both reactors used pulse positive streamer corona
  discharges in water solutions (with different
  conductivity)
• Production of H, O and OH radicals by the
  discharge was proved through spectroscopy and
  formation of H2O2 and degradation of phenol was
  demonstrated through chemical experiment.

• Experimental Parameters
• Needle-Plate Distance (d) 28 mm
• NaH2PO4, NaCl, and FeCl2 used to adjust distilled
  water conductivity
• sc 110 µS cm-1 and ss 50-1000 µS cm-1
• Applied Voltage 0-50 kV DC (average 20 kV)
• Pulse Frequency 50 Hz
• Mean Power 200 Watts

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Generation of Chemically Active Species by
Electrical Discharges in Water

• Conclusions
• Electric field on order of 1MV cm-1 is necessary
  for initiation of corona discharge
• Sharp tip of needle in needle-plate reactor
  eroded quickly
• Thin porous ceramic layer on wire enhanced
  electric field by factor of 10
• Plasma with similar spectral features were
  generated in very different electrode geometry
• Water conductivity of lt 100 µS cm-1 is most
  efficient in the production of OH and O radicals

• Experimental Parameters
• SS wire diameter 6 mm
• Ceramic coating on wire .2 - .3 mm
• Inner tube diameter 30 mm
• Length of SS tube 200 mm
• Reference
• P. Sunka, V. Babicky, M. Clupek, P Lukes, M.
  Simek, J. Schmidt and M. Cernak, Generation of
  chemically active species by electrical
  discharges in water, Plasma Sourves Sci.
  Technol., vol. 8, pp. 258-265, 1999.

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Water Treatment by Pulsed Streamer Discharges

• Overview
• Used a needle-plate reactor to create cold plasma
  in a liquid chamfer of 1 liter
• Both tap water and distilled water were used in
  the experiment to see the effects on the steamer
  prorogation in both types of water
• Uniform or homogenous streamer discharges were
  achieved for the majority of the experimental
  conditions

• Experimental Parameters
• Needle-Plate Distance (d) 28 mm
• Applied Voltage 200 kV DC
• Average Power (per streamer) 217 kW

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Water Treatment by Pulsed Streamer Discharges

• Conclusions
• Homogenous discharge streamers can be produced in
  both distilled and tap water. Where good
  uniformity is a radius of 90 or higher of the
  interelctrode distance and fair uniformity is
  70-90
• The velocity of the streamers were found to be 3
  x104 m/s
• Streamer propagated in a spherical ball

• Reference
• I.V. Lisitsyn, H. Nomiyama, S. Katsuki, and H.
  Akiyama, Water Treatment by Pulsed Streamer
  Discharges, IEEE., vol. 2, pp. 468-471, 1999.

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