|Title of Invention||
A METHOD OF TREATING POLYCHLORINATED BIPHENYL CONTAMINATED MEDIA
|Abstract||A method for treating polychlorinated biphenyl (PCB) contaminated media comprising the steps of: a) combining said media with a fluid containing one or more liquid hydrocarbons to form a media/fluid mixture; b) sonicating said mixture at audio frequency to extract PCB from the media into the fluid; and c) treating said fluid with sodium-containing alkali metal.|
|Full Text||FORM 2
THE PATENTS ACT, 1970 (39 of 1970)
COMPLETE SPECIFICATION (See Section 10, rule 13)
A METHOD OF TREATING POLYCHLORINATED BIPHENYL
SONIC ENVIRONMENTAL SOLUTIONS INC of SUITE 2100-OCEANIC PLAZA 1066 WEST HASTINGS STREET VANCOUVER, BRITISH COLUMBIA V6E 3X2 CANADA, CANADIAN Company
The following specification particularly describes the nature of the invention and the manner in which it is to be performed : -
WO 03/090945 PCT/CA03/00593
mixture for PCB extraction largely avoids wetting of naturally hydrophilic solids by the hydrocarbon containing liquid portion of the fluid. This can be optimized by adjustment of the aqueous phase pH.
The following non-limiting examples illustrate the effectiveness of the invention:
One-Stage Batch Treatment of Soil in Single Vessel with Axial Sonication
A sample of PCB contaminated soil was obtained from a
secure landfill at a Greater Vancouver, B.C., Canada location.
This fill was constructed for the sole purpose of containing
high level (>50 ppm) PCB contaminated soil and debris from
demolition and cleanup of an electrical manufacturing plant
site. Excavated material was sampled for analysis and all
material containing >50 mg/Kg (ppm) of PCBs was placed in the
double lined, covered fill. The sample of approximately 20 Kg
was processed initially over a -6 mesh shaking screen to
separate the sieved soil from coarse cobble rock, concrete,
steel, and debris.
The soil (-6 mesh) was air dried, and then split using a riffle splitter (a device for obtaining representative subsamples of solid materials, see Taggart) to provide representative samples for testwork and analysis.
A 2-kilogram sub-sample of the soil was then mixed with 0.8L of kerosene and placed in a cylindrical steel reaction chamber. Sodium metal in the form of a 10 g block was added to the chamber prior to closure and the chamber was then
mounted on the 20 kW sonic generator. The chamber incorporated a heating jacket which was partially filled with ethylene glycol antifreeze to facilitate heat transfer. The mounted chamber was then heated with a propane torch until a charge temperature (thermocouple measured) reached 10.0°C.
The vent valve on the chamber was then closed and the generator was run at 60% power, 430 Hz resonant frequency for two five-minute periods. After each interval, the vent valve was opened to release accumulated pressure. Temperature was maintained at >102°C. After 10 minutes of sonic mixing the chamber was dismounted, opened and the contents tested for residual sodium. There was none found, so a further 10 g of sodium was added and the test sequence repeated. Product samples were then taken for analysis as follows:
• for solids, exhaustive Soxhlet extraction with hexane/acetone (50/50), followed by gas chromatography with an electron capture detector (GC-ECD)
• for hydrocarbon containing liquid, dilution with hexane followed by GC-ECD
• for solids oil content, overnight air drying at 80°C in a ventilated oven .
Results of PCB analyses were as: follows:
Sample FCB content '
• ■ mg/Kg (solids) or mg/L
Untreated soil 470
Soil, first 10 minute test 98
Soil, second test (total time 20 min) Hydrocarbon containing liquid (second test)
The treated soil contained 15.5% hydrocarbon containing liquid by weight.
The results indicate the feasibility of soil contained PCBs destruction to For the GC-ECD analytical method on heterogeneous samples^ such as soil, the practical detection limit is 2 mg/Kg (ppm) To quantify the extent of the PCB removal in this initial successful test, the final treated soil was reanalyzed by:
Soxhlet extraction (hexane/acetone);
cleanup of extract by treatment over a Florisil absorption column to selectively remove polar and asphaltic components;
analysis of cleaned extract by Gas
Chromatography/Mass Spectroscopy ("GC-MS") operated in the Selected Ion Mode ("SIM") . The GC-MS-SIM .. system differentiates between target and background
response, permitting a detection limit of 0.4 ppm PCBs. By this method, the 30 minute treated sample contained Example 2
Batch. Treatment of Soil in Single Vessel with Axial Sonication
PCB-contaminated soil was air-dried and sieved to -6 mesh. Two kilograms of soil was combined with 0.6 litres; kerosene and 45 grams of solid sodium metal in a 3.2 litre sonication vessel axially mounted to a 20 kilowatt (kW) sonic driver. The sealed sonication chamber was heated to 115°C using heat from a propane torch to melt the sodium metal. The sonic chamber heating jacket was filled half-way with ethylene glycol antifreeze to aid in heat transfer to the sonication chamber ingredients. The sonication chamber was opened to sample soil after interval sonic mixing times of 1, 2, and 5 minutes. The presence of sodium was determined by addition of a few drops of water to the analytical sample and observation^ of effervescence from hydrogen produced by water reaction witt residual sodium. The following table illustrates PCB destruction as a function of time using the above approach on a soil with an initial PCB content of 424 ppm (micrograms/gram) :
Treatment Time (minutes) PCB Content % PCB Destruction
Sample Interval Total (mg/Kg)
Untreated Soil 0 0 424 0
Sample 1 1 1 12.7 97.0
Sample 2 2 3 8.4 98.0
Sample 3 5 8 2.2 99.5 •
These results indicate that initially the rate of PCB destruction is extremely high, but extended time at temperature with excess sodium is required to achieve low soil residual PCB values.
One-stage Flow-through Treatment of Soil in Two Vessels with Probe Sonication
To investigate scale-up of the technology, a test system was
constructed as follows (shown in Figure 3):
• a slurry' reservoir/recirculation tank 46 24 inches
in diameter and 6 feet high was constructed of
schedule 80 steel pipe and plate, and mounted on
legs to permit heating of the tank bottom plate by
• a 10 HP vertical sump pump 48 was installed in the recirculation tank;
• a reaction chamber 44 18 inches in diameter and 3 feet high with a 45° cone bottom was fabricated with 2 side overflow pipe stubs 45 (normal and high level);
the reaction chamber 44 was mounted on an angle iron frame adjacent to the circulation tank 46 and the overflow ports 45 were connected by 4" diameter nitrile rubber hoses to corresponding pipe stubs on the circulation tank 46;
• the 5 kW vertical sonic generator 40 was mounted on
the top of the reaction tank 44 so that vibrating
probe 42 would be 50% immersed when overflowing
through the lower overflow pipe and 75% immersed
when discharging through the high level overflow;
This system illustrated in Figure 3 permitted circulation of slurry 50 through the sonically agitated reaction tank 44 from a relatively large reservoir of process slurry 46.
A new bulk sample from the fill described in Example 1 was obtained and processed in the same manner to prepare 33 Kg of soil for testing.
The test was then concluded as follows:
• 200L (55 gallon drum) of kerosene was loaded into the reservoir by pump
• the sump pump was started and its speed adjusted to circulate fluid at 500 L/min (+/- 10%)
• 33 Kg of soil was loaded into the recirculation tank
the slurry was indirectly heated (while circulating)
by propane burners directed at the bottom and sides of the tank
when the temperature of the circulating slurry reached 105°C, a sample was taken to determine the extent of extraction of PCB from the soil prior to starting the PCB destruction (time =0)
1.5 Kg of sodium metal was added as blocks to the circulation tank, and the 5 kW generator was turned on
• samples of the circulating slurry were then taken! over a period of 105 minutes of extraction/reaction Samples were taken from a drain valve on the pump tank into a steel bucket; drainable hydrocarbon containing liquid (i.e. kerosene plus PCB contaminant extract) was returned to the tank by decantation and solid soil samples (with 15-17% kerosene content) were transferred to sealable glass sample containers for transport to the analytical laboratory.
Results of soil analyses were as follows:
Sonic Treatment Time (minutes) I Soil PCB Content
Sample Interval Total mg/Kg
Feed Soil None None 1043
Slurry t=0 0* 0 217
Slurry t=5 5 5 ...... 104
Slurry t=38 33 38 85
Slurry t=60 22 60 23
Slurry t=105 45 105 * approximate lv 90 minutes of circulation during heatina
Excess sodium remained in the slurry at the end of the 105 minute test. The new bulk untreated soil PCB content of 1043 ppm illustrates the heterogeneous nature of the landfill (compare to the previous sample containing 430-47Oppm) and the desirability of a blended feed for commercial operation.
The final soil PCB content Example 4
One-Stage Flow-through Treatment of Soil in Two Vessels with Axial Sonication
Following the successful flow-through test using the 5 kW
generator, it was determined that commercial feasibility would
be favored by use of the largest and highest powered Sonic
Generator manufactured to date, the 75 kW horizontal unit.
This unit also has the advantage of proven reliability, having
operated for 6 months in a mine environment with minimal
With reference to Figure 4 the pilot test system was altered by:
• Changing the pump / pipe configuration to feed (see below) a new reaction chamber 62 mounted on the 75 kW generator 60. The reaction chamber feed and discharge lines 64, 66 are axial entry / exit;
• The schedule 40 steel pump discharge and return lines 64, 66 are isolated from the generator vibration by 4' lengths of nitrile hose 67, with secondary confinement (in the event of fatigue failure) by a light gauge nitrile rubber tube;
• Design and manufacture of a new reaction chamber 62 to minimize short circuiting and maximize mixing intensity.
A new bulk 0.8 ton sample was also obtained from the site' described in Example 1 and processed in the same manner to provide a uniform feed for tests to investigate a variety of
operating parameters. After shakedown tests to confirm mechanical operability, the initial test on the 75 kW generator was performed as follows:
• Load 200L of kerosene into the pump tank
• With the circulation pump on, load 44 Kg of soil into the pump tank
• Heat the circulating mixture to 105°C using gas fired torches on the bottom and sides of the circulation tank
• Sample oil phase for PCB content (Sample #1)
• Start generator at 105 Hz / 10 kW Power setting (nominal Time = 0 minutes)
• Shut down to repair chamber leaks (mixing time approximately 2 minutes) sample from tank drain valve (sample #2) .
• reheat slurry with circulation and sonication at 105 Hz, 10-11 kW Power (45 minutes to heat from 4°C to 110°C)
• sample #3 at 110°C
• Add 125 g sodium metal (1 block) to pump tank
• Sample #4 after 30 minutes
• Add 125 g sodium (1 block)
• Sonicate for 15 minutes.
• Add 250 g sodium (2 blocks)
• Sample #5, 3 0 minutes after sodium addition
• Add 125 g sodium (1 block)
• Sample #6, 30 minutes after sodium addition
• Add 125 g sodium (1 block)
• Sample #7, 30 after sodium addition
• Add 125 g sodium (1 block)
• Sample #8, 30 minutes after sodium addition
• Add 125 g sodium (1 block)
• Sample #9, 30 minutes after sodium addition
• Add 125 g sodium (1 block)
• Sample #10, 30 minutes after sodium addition. (This sample was for hydrocarbon containing liquid phase plus approximately 4 Kg/2 L of soil solids for hydrocarbon containing liquid - soil separation testing.)
Results of hydrocarbon containing liquid phase analysis were as follows:
Sample No. Solid
Content Hydrocarbon Containing
Liquid Phase PCB Notes
Feed solids 525 - 1.36% Moisture
1 180 PCB extraction during heating cycle to 105°C
2 191 approx. 2 minutes of sonication before shutdown for mechanical problem
3 247 after reheat to 110°C approx. 45 minutes with sonication
4 215 after 125 g sodium addition, 30 minutes sonication at 110-112°C, no excess sodium
5 127 after 250 g sodium addition, 30 minutes sonication at 110-112°C, no excess sodium
6 114 after 125 g sodium addition, 30 minutes sonication
7 90 after 125 g sodium addition, 30 minutes sonication
8 ' 61 after 125 g sodium addition, 30 minutes sonication
9 44 after 125 g sodium addition, 30 minutes sonication
10 39 after 125 g sodium addition, 30 minutes sonication (apparent slight sodium residual).
These results indicate the feasibility of PCB reduction by sodium addition to slurry using the 75 kW generator. The results also indicate that the chemical efficiency of the sodium destruction of PCBs decreases as the hydrocarbon containing liquid phase PCB concentration is decreased below (about) 125 mg/L.
Sonicated Hydrocarbon Containing Liquid-Soil Separation
As previously noted, clean soil recovered by decantation of hydrocarbon containing liquid after extraction and PCB
destruction contains 15-17 wt % of hydrocarbon containing liquid phase. Recovery of this hydrocarbon containing liquid is important in relation to both process economics (cost of hydrocarbon containing extractant) and final disposal of the clean soil.
To investigate recovery of hydrocarbon containing liquid from treated soil (Example 4, Sample #10), an initial froth flotation test was conducted as follows:
• Transfer 500 g of hydrocarbon containing, liquid saturated soil (samplellO decanted) to a 2 L laboratory flotation cell
• Add 1.6 L of hot (60°C) water and mix (condition) the soil - hydrocarbon containing liquid - water slurry for 2 minutes at 1500 rpm using a Denver D4 (Denver Equipment Co.) laboratory flotation machine
• Stop the agitator and - after 2 minutes of quiescent settling - decant the separated free floating hydrocarbon containing liquid phase
• Agitate (condition) for a further 2 minutes
• Add further hot water (approx 0.1 L) to bring the pulp (liquid-solid slurry) level within about 1 cm of the cell overflow
• With aeration controlled by the machine's air intake valve, manually remove froth for 35 minutes, periodically adjusting pulp volume with hot water to
compensate for volume of froth removed until the froth was visually free of solids
• Stop agitation, settle 1 minute
• Decant water
• Record wet weight clean soil • Sample wet soil for analysis
Analysis of the clean soil indicated:
Sample Moisture % PCB
mg/Kg Oil &
(wt % of
tailing) 14.6 1.7 1800 96 >98
These results indicate that froth flotation, a commonly practiced industrial process, is effective for recovery of hydrocarbon containing liquid from.cleaned soil. It is of interest to note to that the residual PCB content of the cleaned soil, although low enough to meet stringent disposal
criteria, is higher than can be accounted for by its residual oil and grease content if it is assumed that the residual hydrocarbon containing liquid contains the same (39 mg/L) PCB content as the bulk hydrocarbon containing liquid separated from the solids at the end of the extraction /destruction
test (Example 4, Sample 10).
These data also demonstrate that complete destruction of PCBs in the hydrocarbon containing liquid phase is not necessary in order to produce acceptably low PCBs content in . cleaned soil for disposal. This is an important factor for process economics, since the results of the Example 4 indicate that the chemical efficiency of sodium destruction of PCBs decreases as the residual PCBs concentration is lowered and becomes prohibitively inefficient below (about) 60 ppm PCB.
■-■■■ ■ ' "' ■ ,» Sonicated Hydrocarbon Containing Liquid-Soil Separation with Additives
The procedure followed in Example 5 was repeated with the
• The water additions were pre-heated to about 90°C
• A commercial frothing agent (Dowfroth 250,
polyglycol, average molecular weight = 250) was added incrementally to a total dosage of 20 g/tonne of feed solids to generate and maintain a better froth than was obtained in the initial tests to
which no chemical was added.
• Pulp (liquid-solid slurry) pH was adjusted to 11.5
with sodium carbonate (0.5 Kg/tonne of feed).
Analysis of clean soil from this test indicated: ,
mg/Kg Oil &
mg/Kg Solids Recovery (wt % of feed dry
These data confirm the utility of froth flotation for . Example 7
Two-Stage Flow-through Treatment of Soil in Two Vessels with Hydrocarbon Containing Liquid Extractant
Soils contain varying quantities of organic matter and
other materials which may compete with PCBs for reaction with
sodium containing alkali. To investigate the effect of
separating the PCB extraction and destruction operations, the
following test sequence was conducted:
• 150 L of used hydrocarbon containing liquid from the test of Example 4 was returned to the circulation tank with 45.7 Kg of PCB soil bulk sample.
• This mixture was heated to 110-115°C and treated
through the 75 kW Sonic generator chamber for 3 hours at 105 Hz, 10-12 kW power. (Note: use of low power settings relative to the generator's 75 kW maximum was based on supplying a mixing power intensity similar to what would be achieved in the next stage of scale up.. Using chambers on each end of the generator (e.g. see
also Figure 9A in US patent 5,005,773) and increasing power to 75 kW will provide the same power1 input (kw/ton) to approximately 15 x as much material, i.e. a
batch size of 0.6 - 1 tonne. Larger batches can be
treated at equivalent power input by extending
treatment time or providing more generators.)
Hydrocarbon containing liquid phase samples from this
test were analyzed, indicating:
Sample No. Sonic Treatment Time (minutes) PCBs mgr/L Notes
0 0 44 Recycled hydrbcarbon containing liquid
1 15 190 Extraction from 45 minutes heat up plus 15 minutes sonic treatment
2 45 215
3 135 215
4 195 219
Since the precision of PCB analytical results is typically +/-10%, these data indicate substantially complete reaction within 45 minutes and >90% extraction within the
heating time + 15 minutes of sonication.
The reacted slurry was drained from the circulation tank and primary hydrocarbon containing liquid-soil separation was performed by manual decantation. Recovered hydrocarbon containing liquid, 140 L, was returned to the circulation tank" along with 60 L of used hydrocarbon containing liquid accumulated from other tests. The combined hydrocarbon containing liquid sample was then heated to 110°C under a nitrogen purge gas flow and pumped through the generator
chamber (10-11 kW, 105 Hz) while adding increments of sodium metal.
Test analytical results were as follows:
Sample No. PCB Sodium addition (g) Notes
(mg/L) interval cumulative ¥'
1 271 0 0 Blended
2 177 200 200
3 90 200 400
4 45 200 600
These data show the same trend as results from Example 4, i.e. the chemical efficiency of sodium reduction of PCBs decreases as the residual PCB decreases, particularly below 100 ppm. However, the overall sodium efficiency for this test is approximately 28% improved relative to results of Example 4.
Since the cost of sodium metal (Canadian Dollars $3/lb in bulk) is estimated to be the largest single component of , treatment operating cost, hydrocarbon containing liquid - soil separation before sodium treatment may thus be a preferred option for process operation on soils with a high parasitic sodium consumption.
Two-Stage Flow-through Treatment of Soil in Two Vessels with Hydrocarbon Containing Liquid/Water Extractant
Since the sodium containing alkali efficiency is better
at higher PCB concentrations in the hydrocarbon containing liquid extractant, consideration was given to conducting the
sonic extraction with a fluid mixture of water and hydrocarbon containing liquid to achieve a higher PCB concentration in the hydrocarbon containing liquid phase. It was also hypothesized that water soluble and more hydrophilic components of the soil (probable contributors to parasitic sodium consumption) might : be retained in the aqueous phase.
A laboratory scale scoping test provided encouraging results (1700 mg/L PCB in the hydrocarbon containing liquid phase), so a pilot scale test was conducted as follows:
• load 110 L of water and 20 L of kerosene to the
• heat mixture to 92°C while circulating with the pump
• load 46.3 Kg of bulk soil sample
• sample (hydrocarbon containing liquid i.e. kerosene rich phase)
• set generator to 10 -11 kW for intensive mixing of
• at 120 minutes, sample circulating slurry for
hydrocarbon containing liquid phase analysis and soil cleanup testing (see below)
Results of hydrocarbon containing liquid phase analyses were as follows:
Sample No. Sonic Extraction
Time (minutes) PCB Content mg/L Notes
1 0 1616 hot pump circulation
2 120 1,747 Sonication
These results confirm the practicality of obtaining a
high hydrocarbon containing liquid phase PCB content by
extraction of soil with a water-hydrocarbon containing liquid fluid mixture.
To assess final soil cleanup, the 120 minute slurry sample was treated as follows:
• decant fluid hydrocarbon containing liquid and water phases from settled solids
• heat the fluid phase mixture to 90°C
• transfer to a separatory funnel and decant the aqueous (sink) phase
• transfer 500 g of soil solids (saturated) to the flotation test apparatus described in Example 5
• add aqueous phase from the water-hydrocarbon containing: liquid separation (approximately 1.75 L) to the cell to permit froth overflow
• condition (mix) for 2 minutes, then float for 30 minutes. (Solution pH 11.7 throughout test; initial froth quality
was poor, but it improved throughout the test)
• shut down flotation and decant remaining water
• record soil wet weight
• air dry soil overnight, record dry weight
• submit soil sample for PCB analyses
Cleaned soil parameters were as follows:
Wet Weight (from 500 g wet feed) 395 g (-80% recovery)
Dry Weight 335 g
Dry basis PCB content 48 mg/Kg
These results demonstrate the practicality of recovering >90% of soil PCB content in a single stage of water-hydrocarbon containing liquid extraction to produce
hydrocarbon containing liquid phase PCB contents in the 1750 . mg range. The PCB content of the cleaned soil was marginal with respect to applicable disposal criteria (maximum 50 ppm PCBs for secure landfill disposal vs. incineration or other PCB destruction technology required for waste >50 ppm PCB).
Thus a second counter-current stage of extraction with low PCB hydrocarbon containing liquid will be required with the water-; hydrocarbon containing liquid sonication.
Hydrocarbon containing liquid phase from the water- hydrocarbon containing liquid decantation was transferred to a laboratory (low intensity) mixing system, heated to 110-115°C and treated with incremental doses of granular (3 x 0.1 mm) sodium to investigate the efficiency of sodium PCB reaction
using the high PCB hydrocarbon containing liquid extract, with the following results:
Sample No. PCB (mg/L) Sodium Dose (g/L) Notes
1 1832 . 0 0 Concentration increase from 1747 due to evaporation
2 126 2.6 2.6 Apparent high sodium efficiency .
3 34 2.6 5.2 Efficiency loss at
low PCB A
These data indicate a significant improvement in sodium
efficiency compared to the results of Example 7. . For PCB reduction from 1832 to 126 mg/L (93% destruction) the sodium consumption was only 5 times the stoichiometric requirement, compared to 30 times to reach 45 mg/Kg in Example 7. For
reduction of PCB from 126 to 34 mg/L, the stoichiometric
excess sodium requirement increases to about 87 times, which clearly indicates the desirability (in terms of sodium efficiency) of high PCB content hydrocarbon containing liquid phase extract. However, the overall efficiency in this
example (from 1832 to 34 mg/L) is about 10X stoichiometric, which is a very significant improvement over the 3OX
stoichiometric requirement in Example 7.
Extraction and Destruction of PCBs from Electrical Ballasts
A sample of concentrated ballast tar was obtained from
Contech Ltd.Richmond, BC. Contech is a firm, which uses
proprietary technology (low temperature attrition scrubbing)
to recover metal components from scrap PCB ballasts. The
metal fraction, containing typically
to a copper recycling operation. The separated tarry (high,
PCB) fraction, with residual metallics, paper, and debris, is
shipped to licensed hazardous waste incinerator operators in
Alberta for destruction.
The ballast tar sample provided (11.1 Kg, approx. 18 L volume, i.e. low bulk density) was processed initially in ,the pilot system as follows:
• transfer 100 L of fresh kerosene and 11.1 Kg ballast tar to circulation tank and heat to 105°C while circulating with the pump .(2 h contact time at T > 60°C)
• start inert gas flow and sonic generator at 10 kW
• after 15 minutes of sonic extraction, take baseline sample for hydrocarbon containing liquid phase PCB and commence incremental sodium addition.
The initial phase of the test was shut down after 165
minutes of sonication for two reasons: high sodium demand and visual observation of relatively large undispersed tar particles. A review of literature on ballast components was undertaken and this revealed that the air-blown asphalt
component contains a high proportion of phenolic (effectively acidic) materials.
The test system was then re-started and 150 g each of'
coarse and fine quick lime (calcium oxide) was added to ,
neutralize acidic (sodium consuming) components of the
mixture. The sample was then treated for a further 270
minutes with sonication and incremental sodium addition.
Test data are summarized as follows:
Sample No. PCB Sodium Addition Notes
solids (mg/Kg) Hydrocarbon
mg/L Interval cumulative
Ballast Tar 1200 • • • ±20% due to
#1 • 112 0. 0
#2 • 112 125 125 ' "■
#3 • 105 0 125
#4 60 97 150 275
#5 43 92 0 275
Shutdown after 270 minutes Restart with 30 Kg/ton lime addition
1A • 106 0 275 Note
increased extraction in heat up
2A • 9 125 400 Apparent major
improvement in sodium efficiency
3A • 6 125 525
4A • 8 0 525 t
5A 4 7 0 525
These data confirm the practicality of treating ballast,
tar in kerosene by sonication and sodium PCB reduction, as
well as indicating a favourable effect of quicklime addition
in relation to sodium efficiency.
The time (270 minutes) of hot sonication required to achieve 43 ppm residue PCB content indicates the difficult (relative to soil) extraction behaviour of ballast tar.
However, this could be mitigated by comminution of the feed material, which was relatively coarse (~10% + 74) .
Confirmation Test -Sodium Efficiency Improved by Lime Addition
A further test was done according to the procedure of
Example 9 with the following adjustments:
■* '* ' " ^ - ^t
• A new ballast sample was used and tar content of the feed '
was increased to 29 Kg/100 L of kerosene
• Sonic mixing time before sodium addition was increased to 9 hours
• Lime (50 g/Kg of tar) was added to the tar-kerosene
slurry after 8 h of mixing (i.e. 1 h before the first
» Sodium was added incrementally in two 1.0 g/L (100 g/100 L hydrocarbon containing' liquid phase) doses, allowing 2 h of mixing time between sodium addition and subsequent sampling to ensure complete reaction
Analytical results are summarized as follows:
Sample No. PCB Sodium Dose(g/100 L) Notes
Solids (mg/L) Liquid (mg/L) Interval Cumulative
Ballast Tar 1760 - - +/- 20% due to
1, Liquid Extract - 510 0 ' 0
2, First Reduction - 180 100 100 Large increase in initial
3, Second reduction - 57 100 200 Equivalent- to Example 9 Samples 1A & 2A
The initial hydrocarbon extract PCB content in the test was higher than for Example 9 due to the higher ratio (29 Kg/100 L vs. 11.1 Kg in Example 9) and also to the higher PCB content (1760 mg/Kg) of the new sample.
The effect of the lime addition on the initial sodium efficiency in this test is1 illustrated by comparing the change
in hydrocarbon PCB content for Example 9 between Sample #1 and #5 (PCB reduced from 112 to 92 mg/L after addition of 275 g sodium/100 L of extract) with the 510 to 180 mg/L PCB reduction after addition of 100 g sodium/100 L in the currents-test with lime added before any sodium addition. The initial
sodium efficiency in this test is approximately 60 times greater than in Example 9 (before lime addition).
For the second sodium treatment in the current example, the reduction in PCB content (Sample 3 - 2; 150 - 57 = 123 mg/L for a 100 g/100 L sodium addition) compares favourably to the second phase of Example 9 (Sample 2A vs. 1A; 106 - 9 = 97 mg/L for •a
efficiency ratio between this example (samples 2 and 3) and
Example 9 (samples 1A and 2A) is only 1.6. Considering the
previously noted trend to lower sodium efficiency at lower PCB
concentrations, these results are considered to be equivalent.
Overall, results of this example confirm the favourable
effect of lime addition on sodium efficiency on treatment of
ballast tar by hydrocarbon PCB extraction/sodium PCB
Accordingly, while this invention has been described with reference to illustrative embodiments, this description is not intended to be construed in a limiting sense. Various modifications of the illustrative embodiments, as well as
other embodiments of the invention, will be apparent to
persons skilled in the art upon reference to this description. It is therefore contemplated that the appended claims will cover any such modifications or embodiments as fall within the scope of the invention.
1. A method for treating polychlorinated biphenyl (PCB)
contaminated media comprising the steps of:
a) combining said media with a fluid containing one or more liquid hydrocarbons to form a media/fluid mixture;
b) sonicating said mixture at audio frequency to extract PCB from the media into the fluid; and
c) treating said fluid with sodium-containing alkali metal.
2. The method of claim 1 including the additional steps of
.heating said slurry prior to and during said sonicating
3. The method of claim 1 wherein said media is soil.
4. The method of claim 1 wherein said media is ballast residue such as tar or pitch.
5. The method of claim 1 wherein said fluid contains a
mixture of water and one or more liquid hydrocarbons.
6. The method of claim 1 wherein said liquid hydrocarbons
7. The method of claim 1 including the additional step of
reducing the particle size of said media prior to said
combining step, said reducing step being one or more of
sieving, comminuting and pulverizing said media.
8. The method of claim 1 including the additional step of
air-dryihg said media prior to said combining step.
The method of claim 1 wherein said treatment step takes
place during said sonication step and said sonication
step occurs at a temperature sufficient to melt said ,
sodium-containing alkali metal.
The method of claim 9 wherein said sonication step occurs in a sealed vessel with a vent to release gas during sonication. ,
The method of claim 9 wherein said sonication step occurs in a vessel with one or more inlets and outlets able to transfer said media/fluid mixture between said vessel and; a pump-equipped reservoir.
The method of claim 11 wherein said sonication step further includes using inert gas to purge the head space of said reservoir and said sonication vessel.
The method of claim 11 further including the step of transferring said sonicated media/fluid mixture of from one of said sonication vessel and said reservoir to a settling tank to separate sonicated liquid and sonicated ' media.
The method of claim 13 including an additional step of sonicating said separated sonicated fluid in the presence of sodium containing alkali metal and at a temperature sufficient to melt sodium containing alkali metal.
The method of claim 13 including the additional step of .. treating said separated sonicated media with water in a flotation cell to dislodge residual PCB-containing
hydrocarbon liquid and froth from said separated sonicated media.
The method of claim'15 wherein said flotation cell
treated soil is recycled to the environment.
The method of claim 15 wherein said flotation water separated from froth, media and hydrocarbon containing
liquid is recycled to the environment after pH
The method of claim 15 wherein-said froth is recycled and
used as part of said fluid in said method.
The method.of claim 15 wherein said floatation cell includes a frothing agent.
The method of claim 15 wherein said floatation cell includes pH adjustment with sodium carbonate.
The method of claim 1 wherein said sonication step includes the addition of lime to said mixture.
The method of claim 21 wherein said sonication step is .
repeated using said lime-sonicated media and a sodium-
containing alkali metal at a temperature sufficient to
The method of claim 22 wherein said sonication steps occur in a sealed vessel able to be vented to release gas during sonication.
24. The method of claim 14 wherein said treated separated sonicated fluid is recycled for use as said fluid in said method.
25. The method of claim 1 wherein said sonicating step uses sonication equipment without grinding media.
26. The method of claim 1, wherein said sonicating step occurs in a temperature range of 100-120 °C.
27. The method of claim 5, wherein said sonicating step occurs in a temperature range of 80-98°C.
28. The method of claim 1, wherein said sonicating step uses a resonating probe contacting said fluid.
29. The method of claim 1, wherein said sonicating step takes place in one or more chambers mounted axially to a resonating member.
30. The method of claim 1, wherein said liquid hydrocarbons contain one or more hydrocarbon subcomponents which are not liquids at sonication temperature.
31. The method according to claim 4, wherein said sonicating step occurs at a minimum
temperature of 100°C.
32. The method according to claim 1, wherein said sodium- containing alkali metal is commercially
pure sodium metal.
Dated this 8th day of October, 2004.
HIRAL CHANDRAKANT JOSHI AGENT FOR
SONIC ENVIRONMENTAL SOLUTIONS INC.
|Indian Patent Application Number||566/MUMNP/2004|
|PG Journal Number||42/2008|
|Date of Filing||08-Oct-2004|
|Name of Patentee||SONIC ENVIRONMENTAL SOLUTIONS INC.|
|Applicant Address||SUITE 2100 OCEANIC PLAZA 1066, WEST HASTINGS STREET VANCOUVER, BRITISH COLUMBIA V6E 3X2,|
|PCT International Classification Number||B09C1/02|
|PCT International Application Number||PCT/CA03/00593|
|PCT International Filing date||2003-04-23|