Disinfection of Gram-negative and Gram- positive ... - Dynaflow, Inc.

Disinfection of Gram-negative and Gram- 

positive Bacteria using DYNAD 

YNAJETS 

® 

Resonating Cavitating Jets 

Greg Loraine, Georges Chahine, 

and Chao-Tsung Hsiao 

Dynaflow, Inc. 

www.dynaflow-inc.com ACS-AIChE 4-8-08

Cavitation 

• Gas nuclei in water 

expand & collapse when 

the local pressure changes 

very quickly. 

• Collapsing bubbles 

produce tremendous 

pressures & temperatures 

in localized area. 

• Examples: Ultrasonic 

homogenizers, water 

hammer, propellers, etc. 

Underwater explosion from 

6000 V spark. 

Collapse is analogous 

to cavitation 


Hydrodynamic & Ultrasonic Cavitation 

• Hydrodynamic Cavitation 

is caused by motion of 

fluid. 

• Large pressure 

fluctuations in shear layer 

cause cavitation. 

• Ultrasonic (US) cavitation 

is caused by mechanical 

vibration in a liquid and is 

localized at the face of the 

probe. 

US 

Shear Layer 


• High shear. 

• Shock wave. 

• Temperature and pressure 

spikes near collapsing bubble. 

• Free radicals (OH • & H • ) 

formed in interior of collapsing 

bubble. 

• Collapse near boundaries or 

other objects (e.g. cells) result 

in the formation of very high 

speed reentering micro-jets. 

Bubble Collapse 


Disinfection Mechanism 

• Rupture of cell walls. 

• Loss of osmotic response. 

• Disruption of protein synthesis. 


Gram positive and Gram negative 

• Gram-positive: thick layer of 

peptidoglycan. 

• Gram-negative: thin layer of 

peptidoglycan covered by outer 

membrane of 

lipopolysaccharide. 

• Gram-negative microorganisms 

are in general more susceptible 

to cell wall damage. 

• Gram –positive: Bacillus 

subtilis 

• Gram-negative: E. coli, 

Klebsiella, Pseudomonas. 

• Membrane structure can be 

used to probe kill mechanism. 


DYNAJETS 

® Cavitating Jets 

• DYNAJETS ® hydrodynamic 

cavitation technology. Several 

designs including STRATOJET ® 

and DYNASWIRL ® . 

• Cavitation at lower pump 

pressures than conventional 

jets. Lower energy costs, more 

cavitation. 

• STRATOJET ® passive acoustic 

excitation. 

• DYNASWIRL ® swirling flow 

reduces pressure at center of 

vortices. 

STRATOJET ® 

DYNASWIRL ® 

Shear 

Layer 


Applications of DYNAD 

YNAJETS 

® 

• Disinfection- no chemical residual, no chemical 

addition. 

• Pump energy is only input. 

• Previous work – Wastewater, Stormwater, 

Aquaculture recirculation water. 

• Oxidation of pesticides, pharmaceuticals, & 

solvents in water. 

• Other applications – emulsions, aeration, rock 

drilling, etc. 


Reservoir Chamber 

Experimental Methods 

Batch Test Loop 

• Two nozzle designs 

STRATOJET ® and 

DYNASWIRL ® . 

• 4 Gram (-) and 1 

Gram (+) species 

tested. 

• E. coli & B. subtilis 

used to examine 

effects of nozzle type 

and nozzle pressure. 

• Matrix effects. 

• Initial Concentration 

of Microorganisms. 

5 hp piston pump 

Reaction 

Chamber 

DYNAJETS ® 

nozzle 

www.dynaflow-inc.com ACS-AIChEwww.dynaflow-inc.com 

4-8-08

Disinfection of E. coli and Klebsiella 

Gram – negative 

DYNASWIRL ® 

2.1 bar (30 psi) 

5 log 10 

removal 

CFU/ml 

1.E+08 

1.E+07 

1.E+06 

1.E+05 

1.E+04 

Klebsiella 

E coli 

1.E+03 

1.E+02 

1.E+01 

0 20 40 60 80 100 

Disinfection Time (mins.) 


Gram- Negative: Species Differences 

Identical 

cavitation 

conditions. 

1.E+09 

1.E+08 

1.E+07 

1.E+06 

E.coli 

P. Aeruginosa 

P. Aeruginosa 

P. Syringae 

P. Syringae 

STRATOJET ® 

5.2 bar 

CFU/ml 

1.E+05 

1.E+04 

1.E+03 

1.E+02 

1.E+01 

1.E+00 

0 20 40 60 80 100 120 140 

Time (mins) 

Significant differences were observed between species of Pseudomonas 


Disinfection Efficiency: E coli & B subtilis 

Effects of nozzle geometry, and nozzle pressure were investigated 

using E. coli and B. subtilis. 

1.E+08 

1.E+07 

1.E+06 

CFU/ml 

1.E+05 

1.E+04 

1.E+03 

E. coli 

B. subtilis 

1.E+02 

1.E+01 

1.E+00 

0 20 40 60 80 100 120 

Disinfection Time (mins) 

Same conditions - DYNASWIRL ® nozzle at 2.1 bar 


Effect of nozzle geometry 

E. coli – Gram - negative B. Subtilis – Gram - positive 

1.E+00 

1.E+01 

C/C0 

1.E-01 

1.E-02 

1.E-03 

STRATOJET 5.2 

bar 

DYNASWIRL 

5.2 bar 

C/C0 

1.E+00 

1.E-01 

1.E-02 

StratoJet 4.1 bar 

DynaSwirl 4.1 bar 

1.E-04 

1.E-03 

1.E-05 

1.E-04 

1.E-06 

0 300 600 900 1200 

Time *Flow Rate/Volume = Number of Cycles 

1.E-05 

0 200 400 600 800 1000 1200 

Number of Cycles 

DYNASWIRL ® and STRATOJET ® 

Both showed good disinfection rates 

for E. coli. 

B. Subtilis disinfection was more 

dependent on nozzle geometry. 


Nozzle Pressure controls E coli Disinfection 

DYNASWIRL ® nozzle, CFU/ml initial = ~1 x 10 8 

1.E+00 

1.E+01 

1.E-01 

1.E+00 

1.E-02 

1.E-01 

C/C0 

1.E-03 

1.E-04 

1.E-05 

1.E-06 

3.45bar 

2.1bar 

1.0bar 

C/C0 

1.E-02 

1.E-03 

1.E-04 

1.E-05 

1.E-06 

3.45bar 

2.1bar 

1.0bar 

1.E-07 

1.E-07 

1.E-08 

0 200 400 600 800 1000 1200 1400 

Cycles, N 

Cycle = Flow Rate x Time / Volume 

Optimal pressure = 2.1 bar (30 psi) 

1.E-08 

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 

Energy(MJ) 

Hydraulic Energy from pump. 

Higher pressures require more energy 

but may not increase disinfection 

efficiency. 


B. subtilis: Nozzle Pressure Effects 

DYNASWIRL ® nozzle, CFU/ml initial = ~5 x 10 6 

1.E+01 

1.E+01 

1.E+00 

1.E+00 

1.E-01 

1.E-01 

2.1 bar 

4.1 bar 

C/C0 

1.E-02 

1.E-03 

C/C0 

1.E-02 

1.E-03 

6.2 bar 

8.3 bar 

1.E-04 

1.E-05 

2.1 bar 

4.1 bar 

6.2 bar 

8.3 bar 

1.E-04 

1.E-05 

1.E-06 

0 100 200 300 400 500 600 700 800 

N Cycle 

Cycle = Flow Rate x Time / Volume 

1.E-06 

0 0.5 1 1.5 

Input Energy (MJ) 

Hydraulic Energy from pump 

Optimal conditions are the same as for E. coli 


Effect of Initial Concentration of E. coli 

1.E+10 

DYNASWIRL ® 2.1 bar 

Disinfection rate 

increased as 

concentration 

decreased. 

CFU /ml 

1.E+09 

1.E+08 

1.E+07 

1.E+06 

1.E+05 

1.E+04 

C0=1e9 test1 

C0=1e9 test2 

C0=1e7 test1 

C0=1e7 test2 

C0=1e5 test1 

C0=1e5 test2 

C0=1e3 test1 

1.E+03 

1.E+02 

1.E+01 

1.E+00 

0 50 100 150 200 

Time (mins.) 


Matrix Effects 

1.E+07 

E. Coli 

STRATOJET ® 

5.2 bar 

1.E+06 

1.E+05 

In Sewage 

CFU/ml 

1.E+04 

1.E+03 

In growth 

media 

1.E+02 

1.E+01 

0 30 60 90 120 150 180 

Time (min) 

Independent of dissolved organic matter and suspended solids. 

Disinfection effective in highly colored matrix. Hydrodynamic cavitation 

can be applied where UV is not efficient. 


Energy Cost Comparison with Ultrasonic 

P 

Eff. = 

-log10 (C/C 0 

) 

P HC 

= Hydraulic Power = Q*ΔP*t / Vol. 

P US 

= Watt / Vol. 

9000 

Comparison with 

E. coli disinfection 

bench studies 

using Ultrasonic 

W/L per log reduction 

8000 

7000 

6000 

5000 

4000 

3000 

DYNAJETS ® 

10 to 100 times 

more energy efficient 

than Ultrasonic. 

2000 

1000 

0 

StratoJet 5.2 bar DynaSwirl 2.1 bar US 20 KHz -260W/L US- 20Khz-280 W/L US- 20Khz-650 W/L US- 20 Khz 126000 

W/L 

Stanley, 2004; Hua et al. 1995; Furuta, et al, 2004. 


Conclusions 

• DYNASWIRL ® and STRATOJET ® were both effective for 

disinfection. DYNASWIRL ® nozzle at 2.1 bar most 

effective. 

• Nozzle pressure was the most important operating 

parameter for disinfection. Optimal pressure for each 

nozzle configuration. 

• Individual species showed different disinfection rates. 

• E. coli (Gram-negative) showed no dependence on nozzle 

geometry but did depend on pressure. 

• B. subtilis (Gram-positive) disinfection was dependent on 

nozzle geometry as well as pressure. 

• Disinfection rates increased as microorganism 

concentrations decreased. 

• DYNAJETS ® were 10 – 100 times more energy efficient 

than Ultrasonic disinfection. 


Acknowledgements & Contact Information 

• US Environmental Protection 

Agency 

• NASA 

• Dr. Spencer Benson, University 

of Maryland. 

• DYNAFLOW, INC. 

www.dynaflow-inc.com 

10621-J Iron Bridge Road, Jessup, 

MD 20794. USA 

• Dr. Georges L. Chahine 

President 

(301) 604-3688 

glchahine@dynaflow-inc.com 

• Business POC: Dr. Jin-Keun 

Choi 

Principal Research Scientist 

(301) 604-3688 

jkchoi@dynaflow-inc.com

Disinfection of Gram-negative and Gram- positive ... - Dynaflow, Inc.

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