plasma water treatment - PlasTEP

PLASMA FOR WATER TREATMENT

Mirosław Dors

Part-financed by the European Union(European Regional Development Fund)

Centre for Plasma and Laser EngineeringThe Szewalski Institute of Fluid-Flow Machinery

Polish Academy of SciencesGdaosk, Poland

9.00 – 10.3011.00 – 12.30

Outline

• Plasma technologies for water cleaning

– Plasma sources for water treatment

• Types of electrical discharges used for water treatment

– Discharges in gas

– Discharges in water (electrohydraulic discharges)

• Reactors

• Diagnostics

– Physics of electrohydraulic discharges

• Plasma processes in water cleaning technologies

– Plasma processes and plasma-induced processes in destruction of organic compounds and microorganisms

• Chemical reactions

• Biocidal effects

• Comparison to other water treatment technologies

Prof. Mirosław Dors, [email protected] 2

3

Plasma technologies for water cleaning

Remote

Indirect

Direct

UV,

electron beam

Ozone

Electrical discharges in water

Plasma

injectionElectrical discharges above water

Different approach

Plasma technologies for water treatment - Remote

Ozonation – fully commercialized method

• Ozone is generated in a Dielectric Barrier Discharge

• Absorption of ozone in water

• Used in drinking water plants

• Ballast water management

NK-O3 Blue Ballast System, USA/Korea

“Alternative Disinfectants and Oxidants Guidance Manual,“ United States Environmental Protection Agency, 1999

4

Plasma technologies for water treatment - Indirect

UV sources

• LP mercury vapor lamps• Low-pressure high-output (LPHO)

mercury vapor lamps• MP mercury vapor lamps• Electrode-less mercury vapor lamps

• Metal halide lamps• Xenon lamps (pulsed UV)• Eximer lamps• UV lasers• Light emitting diodes (LEDs)

Efficiency means electrical to germicidal UV conversion

5


UV irradiation - disadvantages

Mackey et al. (2004)

Linden et al. (2004)

Chang et al. (1985)

6


UV irradiation – reactors and systems

WEDECO UV Systems, USA

ST110P system by SEN Lights Co., Japan

7


Electron beam

8

3-7 MV Electron Beam Water Treatments University of Poitiers (2003-present) & Australia Nuclear Laboratory (1998-2003)

few cm depth water flow

Thermal electron emission from filaments in vacuum then accelerated by a high electric field. Then through Ti or BN thin film by tunnel effects.

Electrical discharges used for water treatment

Discharges in gas phase with liquid electrode – Plasma injection


• needle-to-plate• hollow needle-to-plate

• mesh-to-plate • multiple needle-to-plate

• DC, AC or pulsed corona

• wire-to-plate (pulsed corona only)

• wire-to-cylinder (water layer on the inner wall; pulsed corona only)

HV


Discharges in gas phase with liquid electrode – DC glow corona


45 A 50 A

55 A

75 A

65 A

85 A

Hollow needle Hollow needle

Water surface Water surface

20 mm

20 mm

20 mm

200 400 600

0

2

4

6

8

10

12

Curr

ent (m

A)

Time (ns)

200 400 600

0

50

100

150

Pow

er

(W)

Time (ns)

Repetition rate

50 kHz

Pulse energy

29.2 x 10-6 J


Discharges in gas phase with liquid electrode – pulsed corona


Wire-to-plate

Wire-to-cylinder

-2

0

2

4

6

8

10

12

400 500 600 700 800

Volt

age

(kV

)

Time (ns)

-5

0

5

10

15

20

400 500 600 700 800

Curr

ent

(A

)

Time (ns)

-10

20

50

80

110

140

170

400 500 600 700 800

Pow

er (

kW

)

Time (ns)

Repetition rate

250 Hz

Pulse energy

2.76 x 10-3 J


Gliding Arc

Gas (air, O2, N2) flow: 10-12 L/min. AC supply: 250 W, 100 mA. Water: 400 mLfor 5 min, pH=5.4, 40 S/cm.


Direct liquid phase discharges – “electrohydraulic discharges”


• needle-to-plate• hollow needle-to-plate

(gas injected into water)(pulsed corona, pulsed spark discharge)

• needle-to-needle(pulsed arc discharge)

• pinhole(pulsed corona)


General physical properties


The reason why the breakdown mechanism in liquids is more complicated than solids and gases is evident:

Liquids are much denser in comparison with gases and do not exhibit the long range order as in most solids.

Additionally, the purity of the liquid, such as dissolved gases which form micro-bubbles in the liquid, plays a significant role in the breakdown process.

0a0

2

0p

R

L

E

TDCV

V – breakdown voltageD – thermal diffusivity of water (ca. 1.5e-7 m2/s)Cpρ – specific heat per unit volumeT0 – temperatureσ0 – water conductivityEa – Arrhenius activation energy for the water conductivityL – breakdown channel lengthR0 – breakdown channel radius


Direct liquid phase discharges – pulsed corona and spark


• Inception voltage increases with protrusion length

• Discharge type changes when decreasing distance

• Streamer propagation velocity: 30 000 m/s (2 orders slower than in air)




A typical order of magnitude of the local electrical breakdown field of water is 1 MVcm−1 (in the case of microsecond pulsed breakdown), which is more than 30 times the breakdown electrical field of atmospheric pressure air.

For large pulse widths (i.e. several microseconds to dc), especially in high conductive water solutions, the process of breakdown is preceded by vapour formation due to heating by the pre-breakdown current in the liquid.




Historically, two principal schools:

The first favours an electron multiplication theory in the liquid - In the past, it was often believed that a current multiplication mechanism such as the development of electron avalanches in gas discharges to initiate breakdown. It is interesting to note that electron avalanches have been observed in cyclohexane. Even more direct correlation between these avalanches and the consequent formation of vapour bubbles in the liquid has been demonstrated. However, electron avalanche processes in bulkwater are nearly negligible due to the usual small high electrical field region near the metal electrode and the large scattering cross sections which make it almost impossible for the electrons to gain sufficient kinetic energy for impact ionization. Additionally, free electrons are generally absent in water because even if they are present, they are quickly solvated within 1 ps time scales. Hence, the probability of free electrons in the bulk water is negligible, although one must be careful not to generalize ideas for different liquids and not to exclude electron avalanche processes without a good motivation.




The second school favours a bubble mechanism breakdown theory or more generally a phase change mechanism breakdown theory - a general acceptance is growing that pre-existing bubbles and field enhancement effects in the near electrode region are involved even for nanoseconds voltage pulse widths. Bubbles can pre-exist due to dissolved gases or can be generated by local heating (energy injection from the electrode by pre-breakdown currents) and cavitation.




Corona discharge Spark discharge


Direct liquid phase discharges – pulsed corona – gas production



Discharge development


Electrical breakdown is generally defined as the moment when a conductive plasma channel forms an electrical connection between the two metal electrodes inside the liquid. This leads to the formation of a spark or arc. A time lag between application of the high voltage and breakdown is always observed.

This time lag consists of three successive steps: • initiation phase or streamer inception, • streamer propagation phase,• spark and arc phase.


Streamer propagation mechanisms


Different streamer modes are observed depending on polarity of the powered electrode and the pulse width and amplitude of the applied voltage pulse.

At first a bushlike hemispherical primary streamer (PS) can be observed showing 100–200 filaments.

Then, a fast secondary streamer (SS) appears above a certain threshold voltage (which depends on the geometry of the setup) and can be considerably longer.




1. Primary streamer (subsonic streamer):• low electron density, • low temperature,• low pressure.• its propagation mechanism: series of current pulses and electron avalanches

in successive vapour bubbles,• appear at low amplitude voltage pulses often filling a hemisphere with a size

of a few hundred micrometres (at least for positive streamers) or have a bush-like shape (negative streamers have many short side branches and are shorter in length than positive streamers. Bubble production during the discharge is also much lower for negative voltages than for positive ones under the same conditions).

• propagation velocity of 100ms−1 to a few km s−1




2. Secondary streamer:• high electron density,• high temperature,• high pressure,• its propagation mechanism: field induced dissociation and ionization of

molecules in the bulk liquid, • propagation velocity in the range 10–100 km s−1.



Zoom on the current waveform, (0) beginning of the applied voltage pulse, (1) initiation (or pre-initiation) current due to conductivity of water ∼300mA here, (2) current ramp of the plasma primary positive streamer ∼50 mA, (3) current increase of the secondary positive streamer ∼1A, (4) reilluminations (7μS cm−1, 40 kV)

Streamer propagation – current waveform



Current waveform in distilled water, (0) stray displacement current, (1) pre-initiation current due to water conductivity, (3) large pulse of the secondary positive mode followed by (4) reillumination spikes with decaying amplitude (4 cm gap, 40 kV)




Current waveform in 500 μS cm−1 water, there are no reillumination spikes, (1) initiation current, (3) propagation, (4) decay; there is a large current even when the discharge has stopped propagating and just decays according to the voltage pulse decay (4 cm gap, 40 kV).


Transition to spark: when the plasma filament reaches the opposite plane electrode a thermalization return stroke propagates back to the pin electrode (2n gate, 4μs delay, distilled water, 40 kV).


Direct liquid phase discharges – pulsed corona – conductivity


In the pulsed corona the current is mostly transferred by ions. In water of high conductivity:

large current

faster compensation of space charge

streamer length shortening

higher power density in the channel

higher plasma temperature, UV and acoustic waves




0,0

0,5

1,0

1,5

2,0

0 100 200 300 400

0

10

20

30

40

Cu

rrent (A

)

Voltage (

kV

)

Time (s)

1 S/cm 200 S/cm 600 S/cm

0

10

20

30

40

50

0 5 10 15 20

0

10

20

30

40

Cu

rrent (A

)

Voltage (

kV

)

Time (s)

0

10

20

30

40

50

0 5 10 15 20

0

10

20

30

40

Curr

ent (A

)

Voltage (

kV

)

Time (s)

FWHM = 36 s(voltage pulse)

FWHM = 1.2 s(voltage pulse)

FWHM = 0.8 s(voltage pulse)




Effect of the solution conductivity on temporal evolution of the integral light emission from the discharge (U = 21 kV).

Ph

oto

mu

ltip

lier

sugn

al[a

.u.]


Direct liquid phase discharges – pulsed corona – conductivity and spectra


0 200 400 600 800

0,0

0,2

0,4

0,6

0,8

1,0

Puls

e e

nerg

y (J

)

Water conductivity (S/cm)

Hydrogen Balmer lines are responsible for thetypical magenta or blue–red colour.




600 μS/cm 1.5 mS/cm

6 mS/cm 15 mS/cm

Role of ceramics: increasing the electrical field strength on the anode wire surface due to the redistribution of the field inside the interelectrode space during the prebreakdown stage, thus generating a larger number of discharge channels per pulse.

20 kV


Direct liquid phase discharges – pulsed corona – wire-to-plate



Direct liquid phase discharges with gas bubbles – pulsed corona


Pulsed High

Voltage Wire


Direct liquid phase discharges with gas bubbles – pulsed corona


100–200 μS/cm


Direct liquid phase discharges – pulsed arc


Development of arc

In the pulsed corona the current is mostly transferred by electrons

High current heats a small volume of plasma (quasi-thermal plasma)


Direct liquid phase discharges – pulsed arc, pulsed spark, pulsed corona


0 5 10 15 20-6000

-4500

-3000

-1500

0

1500

3000

時間 (s)

電圧

(V

)

（1mm）（5mm）（3mm）

Ton TonToff

0 5 10 15 20

時間 (s)

0 5 10 15 20

時間 (s)

-1.0

-0.5

0.0

0.5

1.0

1.5

2.0

電流

(A

)




200 400 600 800 1000

Inte

nsi

ty (

a.u

.)

Wavelength (nm)200 400 600 800 1000

Inte

nsi

ty (

a.u

.)

Wavelength (nm)

150 V - arc 175 V - arc 200 V - arc

200 400 600 800 1000

Inte

nsi

ty (

a.u

.)

Wavelength (nm)

Ha

HbO

OOH

Ha

HbO

OOH

Ha

HbO

OOH

Applied Voltage Effect at d = 0.3 mm




Applied Voltage Effect at d = 5 mm

200 400 600 800 1000

Inte

nsi

ty (

a.u

.)

Wavelength (nm)

200 400 600 800 1000

Inte

nsi

ty (

a.u

.)Wavelength (nm)

200 400 600 800 1000

Inte

nsi

ty (

a.u

.)

Wavelength (nm)

Ha

Hb OO

OH

150 V - corona 175 V -spark

200 V - arc

Ha

Hb

O

OOH

Ha

HbO

OOH


Direct liquid phase discharges – pulsed arc – UV radiation


UV-A – 315-400 nm UV-B – 280-315 nm


Direct liquid phase discharges – pulsed arc – pressure wave


Ps – shockwavePe – reflection wave

Measured 16 cm from the pulsed arc


Direct liquid phase discharges with gas bubbles – pulsed arc


1 – Quartz cylinder

2 – Al top and bottom

3 – Copper electrodes

4 – Quartz gas tubes

5 – Arc discharge

6 – Liquid

7 – Drain hole

8, 9 – Sampling tubes


Diaphragm discharge in water


negative streamers

(negative discharge)

positive streamers

(positive discharge) discharge reactor

Experimental conditions:

High voltage: 1-3 kV

Discharge current: 90-250 mA

Input power: 90-300 W

Solution: water + electrolyte (+ dye)

Optimal solution conductivity: 100-1000 μS∙cm-1


Hybrid reactors – combined discharges


Separate charging by

two HV sources Charging by one HV source

Hybrid-series Hybrid-parallel


Hybrid-Series Gas-Liquid Electrical Discharge Reactor


Simultaneous formation of discharge in water and in the gas above water surface (gap~5 mm)

HV: DC pulsed power supply (positive polarity U = 0-100 kV, C = 2 nF, f = 60 Hz)

Liquid phase point electrode: tungsten sharpened wire (curvature radius ~ 100 μm)

Gas phase planar electrode: Reticulated vitreous carbon (RVC) disk

Gas phase discharge

Liquid phase discharge


Summary


Parameter Pulsed corona Pulsed arc

Repetition rate 102-103 Hz 10-2-10-3 Hz

Voltage pulse 10-103 kV 1-10 kV

Current pulse 10-102 A 103-104 A

Voltage pulse rise time 10-7-10-9 s 10-5-10-6 s

Gap of cm of mm

Pulse energy ≈ 1 J ≈ 1 kJ

Electric field at electrode 100-10 000 kV/cm 0.1 -10 kV/cm

Current transfer Ions Electrons


Summary


Parameter Pulsed corona Pulsed arc

Plasma nature Non-thermal Quasi-thermal

Shockwave Week-moderate Strong

UVWeek-moderate

(conductivity dependence)Strong

Heat production Week Strong

Conductivity influence Strong Week

Electrode erosion Week Strong

Plasma technologies for water treatment - Remote

Ozone reactions

Low pH

High pH

50

F2

OHO

3.03

2.802.422.07 O3

[V]H2O21.78

Oxidation potential

Chemical processes induced in water

UV and Electron beam


P. Gehringer, H. Eschweiler (2001)


Removal of organic compounds – Electron beam


Project of a commercial plant (Austria), 1993:

20 kW accelerator (500 keV) with ozone (1kg/h) treating 108 m3/h of groundwater forming 3 mm layer in the reactor

perchloroethylene (PCE): 61 µg/L => 1 µg/L using 200 J/L and ozone ≥ 6 mg/L

P. Gehringer, H. Eschweiler (2001)


Processes induced by gas discharge to water surface


Formation of OH radicals via electron impact dissociation of H2O in vapor

Vaporization of water surface=> formation of water vapor

Formation of ozone and its dissolution in water

Formation of OH radicals via reaction of excited O atoms with H2O in vapor

MOMOP)O( 323

ee H·OH·OH2OH·OH·OHD)O( 2

1

Formation of OH radicalsfrom ozone dissolved in

water


Oxidative species from secondary reactions - diagnostics


OH + OH → H2O2

OH + O3 → HO2 + O2

H + O3 → OH + O2

HO2 + O3 → OH + 2O2

HO2 + H → H2O2

Indirect measurements of short lived species (e.g. OH

radicals) through chemical changes of model organic

compounds in water

phenol and substituted phenols

Direct measurements of produced long-lived chemical active species

simultaneous production of ozone decrease in the gas and H2O2 production in water


Diagnostics


HPLC (High Performance Liquid Chromatography) - for organic compounds measurements,

UV-VIS spectrometry - analysis in UV range and visible range of light for diagnostics of inorganic compounds, like O3, H2O2 and OH radicals:

O3 – iodometric method: O3 + 2KJ + H2O J2 + 2KOH + O2 (give pink complex with N,N-dimethyl-p-phenylenediamine), λ=515 nm; or reaction with Indigodye, λ=600 nm

H2O2 – reaction with titanyl ions: Ti4+ + H2O2 + 2 H2O TiO2.H2O2 + 4 H+ (give yellow complex), λ=407 nm

TOC analysis - which Total Organic Carbon analysis - for the measurement of the sum of organic compounds:

mineralization and measurement of produced CO2 (e.g. IR measurement)

Microbiological analysis – different for specific microorganisms.


Diagnostics – OH radicals


in plasma -> Optical Emission Spectroscopy (OES), λ=309 nm

in water -> fluorescence:

with terephthalate, λ=426 nm (excitation at λ=312 nm)

with coumarin 3-carboxylic acid (CCA), λ=450 nm (excitation at λ=396 nm)

with benzoate, λ=350 nm (excitation at λ=300 nm)

with phenoxazinone, λ=585 nm (excitation at λ=570 nm)

with indoxyl-β-glucuronide (IBG)


Gas phase discharge - oxidation reactions


0 20 40 60 80 100

0,00

0,05

0,10

0,15

0,20

0,25

0,30

O3 a

qu

eo

us (

mM

)

Processing time (min)

H2O

H2O + Phenol

0 20 40 60 80 100

0

50

100

150

200

250

O3 g

ase

ou

s (

pp

m)


H2O

H2O + Phenol

O3 => OH => Phenol


Oxidation reactions in water


0 20 40 60 80 100

0,00

0,05

0,10

0,15

0,20

0,25

0,30

H2O

2

(mM

)


H2O

H2O + Phenol

0 20 40 60 80 100

0,000

0,005

0,010

0,015

0,020

0,025

0,030

Co

nce

ntr

atio

n

(mM

)


Phenol

Dihydroxyphenols

Consumption of OH leads to decreased production of H2O2

Phenol => Dihydroxyphenols(Catechol, Hydroquinone, Resorcinol)

Organic acids


Oxidation reactions – OH attack on Phenol ring


- HO2.

OH

OH O

O

OH OH

OH

OH

OHOO.

OH

OHOO.

OH

OH

O

O

OH.

HCHD .

- 2 H+

+ 2 H+

- 2 H+

+ 2 H+

O2 O2 Ring opened

products. O

O

- HO2.


Oxidation reactions – O3 attack on Phenol ring


OH

O

O

OOH

H

O3

O3

OO

OOH

H

+

OH

OH

- H2O

2- H2O

- O2

O3

O

O

OOH

OH

O3

OH

OH

C

C

O

O

OH

OH

C

C

O

O

OH

H

C

CH

O

OH

OH

OOH

muconaldehydecis,cis-muconic acid

H2O


Hybrid gas-liquid discharge – influence of gas


0

100

200

300

400

500

0 10 20 30 40 50 60 70

Ph

en

ol co

ncen

trati

on

[

M]

Degradation time [min]

liquid-only

hybrid-O2

hybrid-Ar

Initial conditions: pH=3.6, σ=100 μS/cm


Hybrid gas-liquid discharge – influence of gas


Argon atmosphere

Oxygen atmosphere

OH

OH

OH

OH

O

O

COOH

COOH

hydroquinonecatechol 1,4-benzoquinone maleic acid

OH

OH

OH

OH

O

O

COOH

COOH

COOH

COOH

COOH

COOH

cis,cis-muconic acidhydroquinonecatechol 1,4-benzoquinone maleic acidcis,trans-muconic acid


Hybrid gas-liquid discharge – influence of pH


Hybrid-O2 atmosphere Hybrid-Ar atmosphere

-2.5

-2

-1.5

-1

-0.5

0

0 1000 2000 3000 4000

Treatment time [s]ln

(c/c

0)

H2SO4

(pH=3.6)

Na2SO4

(pH=5.1)

NaOH

(pH=10.2)

pH=5.1

pH=10.2

pH=3.6

-2.5

-2

-1.5

-1

-0.5

0

0 1000 2000 3000 4000

Treatment time [s]

ln(c

/c0)

pH=5.1

pH=10.2

pH=3.6


Hybrid gas-liquid discharge – influence of pH


OH O

0

0.2

0.4

0.6

0.8

1

7 8 9 10 11 12 13

pH

a

OH O

OH-

H+

pK = 9.89

OH

O

3O kO3 = 1.4 x 109 M-1 s-1

3O kO3 = 1.3 x 103 M-1 s-1


Hybrid gas-liquid discharge – additional source of OH


25pH

223 O3OH·2OHO2

Production of additional

OH radicals through decomposition

of ozone by H2O2 at high pH

Peroxone O3/H2O2 process


Liquid phase discharge – no O3



Liquid phase discharge – no O3


0 20 40 60

0,0

0,5

1,0

1,5

H2O

2 (m

M)


1 S/cm

303 S/cm

606 S/cm

Tap water (580 S/cm)

- OH as the only oxidative species- dependence on the conductivity

)sthermolysiphotolysis(iondecompositreaction)order -zero(productiondt

]OH[d 22

ph

oto

lysi

sra

te/a

ll d

eco

mp

osi

ton

rate

1 S/cm 200 S/cm


Liquid phase discharge – Phenol oxidation


0 20 40 60 80 100

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

Phenols

concentr

ation (

mM

)


Phenol, without Fe2+

Phenol, with Fe2+

Dihydroxyphenols, with Fe2+

0 20 40 60 80 100

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

Phenols

concentr

ation (

mM

)



Phenol, with Fe2+


0 20 40 60 80 100

0,0

0,1

0,2

0,3

0,4

0,5

0,6

0,7

Phenols

concentr

ation (

mM

)



Phenol, with Fe2+


200 S/cm 600 S/cm1 S/cm

Fe2+ + H2O2 Fe3+ + OH- + OH

Enhancement by Fenton reaction:


Removal of organic compounds – Pulsed Arc Electrohydraulic Discharge


Reduction of TOC in Sludge-Water (d = 0.5mm, V = 1-2.2kV)

0

50

100

150

200

250

300

350

0 20 40 60 80 100 120

TOC

co

nce

ntr

atio

n (

mg

/L)

PAED treatment time (min)

Sludge-water

Pond surface water

Pond bottom water with 33g/L sediment

Pondbottom water with 100g/L sediment




Generations of gaseous by-products (CO, CO2, CxHy, SO2 and H2S (sludge-water, Initial TOC =120mg/L)

0

1

2

3

4

5

6

7

8

9

0 50 100 150

Acc

um

ula

ted

CO

, CO

2an

d C

xHy

(mg/

L)

Treatment time (min)

[CO]

[CO2]

[CxHy]

0,00

0,05

0,10

0,15

0,20

0,25

0,30

0,35

0 50 100 150

Acc

um

ula

ted

SO2

and

H2S

(mg/

L)

Treatment time (min)

[SO2]

[H2S]

d = 0.5mm, V = 1kV




Change in Water Quality (Dissolved Oxygen)

0

1

2

3

4

5

6

7

0 20 40 60 80 100 120Dis

solv

ed

oxy

gen

co

nce

ntr

atio

n (

mg

/L)


Pond water

Pond water with 33g/L sediment




Change in Water Quality (pH)

6,8

6,9

7

7,1

7,2

7,3

7,4

7,5

7,6

7,7

7,8

7,9

0 20 40 60 80 100 120

pH


Pondwater

Pondwater with 33g/L sediment

Pondwater with 100g/L sediment




Change in Water Quality (Conductivity)

200

250

300

350

400

450

500

550

600

650

700

0 20 40 60 80 100 120

Co

nd

uct

ivit

y (m

S/m

)


Pond water

Pond water with 33g/L sediment"

Pond water with 100g/L sediment"Sludge-water

Organic compounds decomposition


phenols trichloroethylene polychlorinated biphenyl perchloroethylene pentachlorophenol acetophenone organic dyes (such as methylene blue) aniline anthraquinone monochlorophenols methyl tert-butyl ether (MTBE) benzene toluene ethyl benzene (BTEX) 2,4,6-trinitrotoluene 4-chlorophenol 3,4-dichloroaniline

Biocidal effects

Disinfection mechanisms – UV irradiation


• 240 to 280 nm - damaging nucleic acids of microorganisms

(Tchobanoglous, 1997)

HOWEVER,

Under certain conditions, some organisms are capable of repairingdamaged DNA and reverting back to an active state in which reproduction is again possible – “Dark repair mechanisms”

UV irradiation – requirements for disinfection

Surface Water Treatment Rules – Minimum Treatment Requirements1

Regulation Giardia Virus Cryptosporidium

US EPA Long Term 2 Enhanced Surface Water Treatment Rule

3-log removal (99.9%)

4-log removal (99.99%)

2.5-log additional treatmentfor filtered systems

3-log additional treatmentfor unfiltered systems

UV Dose Requirements (mJ/cm2)

Target pathogensLog inactivation

0.5 1.0 1.5 2.0 2.5 3.0 3.5 4.0

Cryptosporidium 1.6 2.5 3.9 5.8 8.5 12 15 22

Giardia 1.5 2.1 3.0 5.2 7.7 11 15 22

Virus 39 58 79 100 121 143 163 186most viruses can be easily inactivated with chlorine so UV disinfection for virus inactivation may not be necessary

76

Biocidal effects

Biocidal effect of electrohydraulic discharges


Spark/Arc Corona Ozonation Fenton Peroxone

• OH, HO2,

H2O2

• UV

irradiation

• shock wave

• heat

• OH, HO2,

H2O2, O3

• UV

irradiation

• O3

• OH

• OH • OH

• O3

2 O3 + H2O2 → 2 OH + 3 O2

O3 + OH- → O3- + OH

Fe2+ + H2O2 → Fe3+ + OH + OH−


River water disinfection - number of microorganisms


Microorganismsgrown in 360C

Microorganisms grown in 220C

0 100 200 300 400 500 600 700

0,01

0,1

1

10

Tota

l num

ber

of m

icro

org

anis

ms in 3

60C

(10

3 c

fu/m

l)

Processing time (s)

Ozonation

Spark

Corona

Before

0 100 200 300 400 500 600 700

0,01

0,1

1

10

Tota

l num

ber

of m

icro

org

anis

ms in 2

20C

(10

4 c

fu/m

l)

Processing time (s)

Ozonation

Spark

CoronaBefore


River water disinfection - number of microorganisms


E. coli Total coli

0 100 200 300 400 500 600 700

0,01

0,1

1

10

100

Tota

l num

ber

of E

. C

oli

bacte

ria (

cfu

/ml)

Processing time (s)

Ozonation

Spark

Corona

Before

0 100 200 300 400 500 600 700

0,01

0,1

1

10

Tota

l num

ber

of C

oli

bacte

ria (

10

3 c

fu/m

l)

Processing time (s)

Ozonation

Spark

Corona

Before


Disinfection mechanisms – O3 and OH action


• destruction of bacterial membrane through alteration of:- glycoproteins or glycolipids (Scott and Lesher, 1963)- certain amino acids such as tryptophan (Goldstein and McDonagh, 1975)

• disruption of enzymatic activity of bacteria by acting on the sulfhydryl groups of certain enzymes (Giese and Christensen, 1954)

• affection of both purines and pyrimidines in nucleic acids (Scott and Lesher, 1963)

Bacteria

Virus

• modification of the viral capsid sites that the virion uses to fix on the cell surfaces. High concentrations of ozone dissociate the capsid completely (Cronholm et al., 1976 and Riesser et al., 1976)

Protozoa

• modifications in the oocyst structure …


Principal known disinfection byproducts


• Formaldehyde

• Acetaldehyde

• Glyoxal

• Methyl glyoxal

Aldehydes Acids

• Oxalic acid

• Succinic acid

• Formic Acic

• Acetic acid

Aldo- and Ketoacids

• Pyruvic acid


Pulsed Arc Electrohydraulic Discharge


0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

0 100 200 300 400 500 600

Lo

g R

em

ova

l

Number of Pulses

8.05 mS/m

4.3 mS/m (1)

4.3 mS/m (2)

532 uS/m (1)

532 uS/m (2)

532 uS/m (3)

E. coli inactivation

•V = 4kV•PAED: 5 sec/pulse, 100 pulse = 9min•Accumulative energy for 100pulses for high conductivity water = 2.8 kWh/m3•Accumulative energy for 100, 300, 400, 500 pulses for low conductivity water = 6.3, 19, 25.3 and 31.6 kWh/m3

0,0

0,2

0,4

0,6

0,8

1,0

1,2

1,4

1,6

1,8

2,0

0 100 200 300 400 500 600

Lo

g R

em

ova

l

Number of Pulses

588 uS (1)

588 uS (2)

588 uS (3)

588 uS (4)- LP




Bacillus subtilis inactivation

•V = 4kV•PAED: 5 sec/pulse, 100 pulse = 9min•Accumulative energy for 100pulses for high conductivity water = 2.8 kWh/m3•Accumulative energy for 100, 300, 400, 500 pulses for low conductivity water = 6.3, 19, 25.3 and 31.6 kWh/m3


Pulsed arc in the sea water – removal of algae and mussels


Before After




0

20

40

60

80

100

120

0 20 40 60 80 100 120 140 160 180

Time (hrs)

Mo

rta

lity

(%

)

Lake Ballast Water 1 with10 minutes treatment

Lake Ballast Water 1 with 2pulsed treatment

Lake Ballast water 1 forcontrol

Lake Ballast Water 2 with10 minutes treatment

Mortality of Zooplankton (Lake Ballast Water, 30 animals/L, V =2.3kV, d =0.5mm)

Time after PAED treatment (hrs)

1mm


Pulsed arc in the sea water – disinfection, pilot station


d

l

#

2

dl

1m 1mWater Out

Water In

50L/min

235mm

185mm

185mm

Ti Electrodes

I.D =

82.5mm

Regional Municipality of Waterloo’s Mannheim Drinking Water Treatment Plant, Canada – Pulsed arc discharge in water ● 50 L/s● E. coli● B. subtilis● Natural Organic Matter● MTBE

Comparison to other water treatment technologies


Comparison to other water treatment technologies


Chemical Optical RadiolysisGas

Discharges

Electrohydraulic

Discharges

Ozone Cl/ClO2 UV-C

UV-

Photo-

catatyst

E-

beam-Ray Corona Barrier

Pulsed

Spark

Pulsed

Arc

Micro-organisms O O O O

Oxidation Power X

Algae Destruction X O X X X X X

Urine Components

Destruction O X O

VOCs Destruction O X X O O O

Removal of Inorganics X X O O

- Good O - Adequate - Partial x - None

Summary

Energy efficiency of plasma in water cleaning


AC-GlidArc AC gliding arc discharges, Ar argon, Co initial concentration of dye in treat-water, CGDE contact glow discharge electrolysis, DD diaphragm discharges, GDE glow discharge electrolysis, G50 energy yield at 50% conversion, HS-PCD hybrid-series pulsed corona discharges, MWD microwave discharges, DBD dielectric barrier discharges, DC direct current, O2 oxygen, O3 ozone, PCD pulsed corona discharges, RFD radio-frequency discharges, RT refers to the number of row from which values of ‘REEr’ and ‘G50r’ are taken to calculate ‘REE’, REE relative energy efficiency, SD spark discharges, SSD streamer and spark discharges, UV ultraviolet radiations

Other applications

As a source of seismic waves – sea bed mapping


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water treatment Indust. Eng. Chem. Res. 45 882–905

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• An W, Baumung K and Bluhm H 2007 Underwater streamer propagation analyzed from detailed measurements of pressure release J. Appl. Phys. 101 053302

• Sato K and Yasuoka K 2008 Pulsed discharge development in oxygen, argon, and helium bubbles in water IEEE Trans. Plasma Sci. 36 1144–5

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• J. S. Chang, “Thermal Plasma Solid Waste and Water Treatments: A Critical Review,” Int. J. Plasma Env. Sci. Techn., vol. 3, no. 2, 2009

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• P H Ceccato, O Guaitella, M Rabec Le Gloahec and A Rousseau, Time-resolved nanosecond imaging of the propagation of a corona-like plasma discharge in water at positive applied voltage polarity, J. Phys. D: Appl. Phys., 43 (2010) 175202

• A.A. Joshi, B.R. Locke, P. Arce, W.C. Finney, ”Formation of hydroxyl radicals, hydrogen peroxide and aqueous electrons by pulsed streamer corona discharge in aqueous solution”, Journal of Hazardous Materials, vol. 41, pp. 3-30, 1995

• N. Karpel Vel Leitner, G. Syoen, H. Romat, K. Urashima, J.-S. Chang, Generation of active entities by the pulsed arc electrohydraulic discharge system and application to removal of atrazine, Water Research 39 (2005) 4705–4714

• Sugiarto, A. T.; Sato, M. Pulsed plasma processing of organic compounds in aqueous solution. Thin Solid Films 2001, 386, 295

• A. Abou-Ghazala, S. Katsuki, Karl H. Schoenbach, F. C. Dobbs, and K. R. Moreira, Bacterial Decontamination of Water byMeans of Pulsed-Corona Discharges, IEEE Trans. Plasma Sci. , 30 (2002) 4, 1449-1453

• M. Dors, J. Mizeraczyk, Y.S. Mok, Phenol Oxidation in Aqueous Solution by Gas Phase Corona Discharge, Journal of AdvancedOxidation Technologies, 9, 139-143, 2006

• M. Dors, E. Metel, J. Mizeraczyk, Phenol Degradation in Water by Pulsed Streamer Corona Discharge and Fenton Reaction, Int. J. Plasma Environ. Sci. Technol., 1, 76-81, 2007

• M. Dors, E. Metel, J. Mizeraczyk, E. Marotta, Coli bacteria inactivation by pulsed corona discharge in water, Int. J. Plasma Environ. Sci. Technol., 2, 34-37, 2008

• Fridman A., Plasma Chemistry, Cambridge University Press, 2008Prof. Mirosław Dors, [email protected] 91

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