Diesel Fuel Contaminated Water Treatment by Sonication: a

Potential 20-Minute Sump and

Stormwater Remedy Presented by:

Roxanne Bessette, E.I.

Co-author:

Dr. Robert W. Peters, P.E.

UAB Department of Civil, Construction, and Environmental Engineering

Presented at the 2007 Alabama Water Resources Conference, Orange Beach, AL,

September 5-7, 2007.

Situation:Diesel Usage = Diesel Spills =

Receiving Waters Impacted

Current Treatment: Gravity Phase Separation and

Mechanical Recovery

Limitations of Current Treatment

• Cannot handle large spills rapidly;

• Cannot handle peak storm flows of the Southeastern U.S.;

• Minimal removal at <100mg/L, NPDES O&G discharge limit is usually 15 mg/L; and

• Overflow must be sent to local POTW at a per gallon service charge ($$$$!).

Sonochemical Treatment:Unique Aspects

•Organic compounds rapidly oxidized (seconds to minutes)

•Rapid emulsification of immiscible liquids (seconds)

•Extreme conditions on the micro-scale with ambient bulk solution conditions

Acoustically Induced Cavitation

Cavitation: Quick Overview

•Microbubble is spherical at first and then shrinks rapidly•Microbubble formed near solid surface yielding an asymmetric implosion expelling a ~400 kph liquid jet•The jet develops opposite the solid surface and moves towards it•Implosion heats gases to ~5,500ºC •Pressure ~500-1000 atm at collapsing interface•Microbubble shown is ~150 μm …can be much larger depending on kHz

Source: Suslick, Scientific American Feb 1989

Acoustical Cavitation = Micro High Energy Rapidly Quenched

•In less than a μs, implosion energy causes: •Ionization

• N2 NOx NO2-

•Radical Creation • O2 and H2O OH

•Luminescence• Visible and UV

• Pressures of ~500 atm•Temperatures of

• ~5,500oC for gases• ~2,100oC for immediately surrounding liquid

Bench-Scale Treatment Method

•Initial Off Road No. 2 Diesel Fuel Concentration: 195 mg/L

•Volume Treated: 100 mL

•Sonicator Frequency: 20 kHz

•Sonicator Max Power Output:950 W

Experimental Conditions

Sonication Equipment: Branson 910 BC Power Supply and 902 J Converter

Bench-Scale Treatment Method

Experimental Matrix

Rep Time Sonicated (min)

1 CV 0 2 5 5DUP 5MS 10 20 IB Meth BlK2 CV 0 2 5 5DUP 10 10MS 20 IB

3 CV 0 2 5 5DUP 5MS 10 20 IB

CV= Calibration Verification; DUP= Duplicate Sample; MS=Matrix Spike; IB=Instrument Blank; Meth Blk=Method Blank

Bench-Scale Analytical Method

Sample Preparation by SW846 3510C

Separatory Funnel Liquid toLiquid Extraction

Sample Analysis by SW846 8015B

Nonhalogenated Organics Using GC/FID

Bench-Scale Analytical Method

Bench-Scale Diesel Sump Water Treatment Results

Sonocation of No.2 Diesel

y = -0.1859x + 4.5141R2 = 0.8202

0

1

2

3

4

5

6

7

0 5 10 15 20 25

Time (min)

ln(C

)

Electrical Energy per Mass of Contaminate Removed (kWh/kg)

EE/M= (106) P t (60) V (Ci-Cf)

where: P = Power, (kW) t = treatment time, (min) V = Volume of Treated Solution, (L) Ci = Initial Contaminate Concentration, (mg/L)

Cf = Final Contaminate Concentration, (mg/L)

93% removal of No. 2 Diesel Fuel requires 8,203.8 kWh/kg (0.0082 kWh/mg)

This number is approximately 3-4 fold greater than the TCE and CCl4 sonication energy requirements found by Peters, et al. (2005);

Paper presented at the 15th Annual AEHS Meeting and West Coast Conference on Soils, Sediments, and Water, San Diego, CA.

Published Sonochemical Degradation Rates of Various Organic Compounds

(Reality Check)

Compound Sonication Condition

k (min –1) (Mass Transfer Rate Constant)

Source

2,4,6-trinitrotoluene (TNT)

20kHz 0.0010 M.R. Hoffmann et al., Ultrasonics Sonochemistry 3 (1996) S163-S172

Carbon Tetrachloride

20 kHz, 130W

0.1980

2-Chlorophenol 20 kHz, 96W

0.0002 Ku et al., Water Res. 31 (1997) 929-935

Anthracene (PAH)

20kHz, 600W

1.5660 Z. Laughrey et al., Ultrasonics Sonochemistry 8 (2001) 353-357

Phenanthrene (PAH)

0.6600

Pyrene (PAH) 0.6240

Styrene (Hydrocarbon)520kHz, 14.6W

0.0622 De Visscher et al., J. Phys. Chem., 100 No.28 (1996)

Ethylbenzene (Hydrocarbon)

0.0446

Removal Efficiencies Comparison

Belt Strippers (common current technology)

[O&G]* mg/L 10,000 200 100 15

Oil/water removal efficiency per API**

90% 50% Minimal Common NPDES Discharge Limit

*DRO is a subgroup of O&G**Removal time frame commonly on the order of hours to days

Sonication (proposed technology)

198 mg/L No.2 Off-road Diesel 95% removed

10 mg/L in 20 min

Bench-Scale Diesel Sump Water Treatment Conclusions

Sonochemical Treatment Potential

• Rapid treatment to handle storm event runoff (minutes vs. days)

• Exceeds gravity separation treatment efficiency by 45%

• 0.002 kWh/mg removal energy requirement for ~200mg/L initial concentration

• Tested conditions achieves NPDES discharge standard of 15 mg/L

Acknowledgements

Dr. Robert W. Peters, P.E. -for opportunities and encouragement

UAB Department of Civil, Construction,and Environmental Engineering-for research facilities support

Sound Environmental Practice LLC-for funding

Thanks for this opportunity….Questions?