METHOD OF TREATING A LIQUID INCLUDING AN ORGANOFLUORINE

Abstract

The present invention relates to a method of treating a liquid including an organofluorine. The method includes electrochemically treating the liquid to produce a foam and an electrochemically treated liquid, wherein the foam includes the organofluorine and/or degradation products thereof; and separating the foam from the electrochemically treated liquid. This method may alleviate some of the problems associated with the presently available techniques for removing organofluorines from liquids.

Claims

1. A method of treating a liquid including an organofluorine, the method comprising: electrochemically treating the liquid to thereby produce foam and an electrochemically treated liquid, wherein the foam includes the organofluorine and/or degradation products thereof; and separating the foam from the electrochemically treated liquid.

2. The method of claim 1, wherein at least 60% of the carbon atoms in the organofluorine are substituted by a fluorine atom.

3. The method of claim 1, wherein the organofluorine is of the formula (I):
R—Y   Formula I wherein R is a fluoroalkyl group, and Y is an ionic group.

4. The method of claim 1, wherein the liquid is a groundwater, a landfill leachate or an industrial waste.

5. The method of claim 1, wherein the method includes the step of removing or depleting ammonia or ammonium from the liquid prior to the electrochemical treatment.

6. The method of claim 5, wherein the step of removing or depleting ammonia or ammonium from the liquid prior to the electrochemical treatment includes adding a magnesium salt and a phosphate salt to the liquid to form a precipitate.

7. The method of claim 1, wherein the method includes the step of filtering the liquid prior to the electrochemical treatment.

8. The method of claim 1, wherein the method further includes the step of adding a treatment agent to the liquid.

9. The method of claim 8, wherein the treatment agent is an alkaline earth metal.

10. The method of claim 1, wherein the step of electrochemically treating the liquid is performed using an electrochemical treatment apparatus, wherein the electrochemical treatment apparatus includes a treatment chamber including at least one inlet for entry of a liquid to be treated, and at least one outlet for exit of electrochemically treated liquid, and a plurality of electrodes positioned within the treatment chamber for electrochemical treatment of the liquid.

11. The method of claim 10, wherein at least one of the plurality of electrodes positioned within the treatment chamber include iron.

12. The method of claim 10, wherein there is substantially laminar flow of liquid between the electrodes during electrochemical treatment.

13. The method of claim 10, wherein the method includes the step of collecting the separated foam using a foam collector located in fluid connection with the at least one outlet for exit of electrochemically treated liquid; wherein the foam collector includes a mesh filter and a suction source.

14. The method of claim 1, wherein the method includes the step of treating the separated foam.

15. The method of claim 14, wherein the step of treating the separated foam includes degassing the foam or incinerating the foam.

16. The method of claim 15, wherein degassing the foam includes placing the foam under reduced pressure, or by spraying liquid onto the foam.

Description

BRIEF DESCRIPTION OF DRAWINGS

[0175] Various embodiments of the invention will be described with reference to the following drawings, in which:

[0176] FIG. 1 is a top view of the layout of a trailer including an exemplary water treatment system including an electrochemical liquid treatment apparatus (HEC20016);

[0177] FIG. 2 is a top view of the electrochemical liquid treatment apparatus in the system of FIG. 1;

[0178] FIG. 3 is a side view of the electrochemical liquid treatment apparatus of FIG. 2;

[0179] FIG. 4 is a perspective view of the electrochemical liquid treatment apparatus of FIG. 2;

[0180] FIG. 5 is a perspective view of an example electrode holder;

[0181] FIG. 6 is an exploded perspective view of the electrode holder of FIG. 5;

[0182] FIG. 7 is a perspective view of a first example electrochemical liquid treatment apparatus;

[0183] FIG. 8 is cross sectional view of the apparatus of FIG. 7, through the liquid entry point and defoaming chamber outlet;

[0184] FIG. 9 is a cross sectional view of the apparatus of FIG. 7, through the treatment chamber;

[0185] FIG. 10 is a perspective view of the electrode holder in the apparatus of FIG. 7;

[0186] FIG. 11 is a bottom perspective view of the electrode holder of FIG. 10;

[0187] FIG. 12 is a cross sectional view through the electrode holder of FIG. 10;

[0188] FIG. 13 is a top perspective view of the treatment chamber and defoaming chamber in the apparatus of FIG. 7;

[0189] FIG. 14 is a perspective view of the treatment chamber and defoaming chamber of FIG. 13;

[0190] FIG. 15 is a cross sectional view through the treatment chamber of FIG. 13;

[0191] FIG. 16 is a perspective view of the apparatus of FIG. 13 with the electrode holder partly removed; and

[0192] FIG. 17 is a cross sectional view through the treatment chamber and electrode holder of FIG. 13 with the electrode holder partly removed;

[0193] FIG. 18 is a perspective view of a second example electrochemical liquid treatment apparatus;

[0194] FIG. 19 is a cross sectional view of the apparatus of FIG. 18;

[0195] FIG. 20 is an exploded perspective view of the apparatus of FIG. 18;

[0196] FIG. 21 is a side cross sectional view of the apparatus of FIG. 18 with a foam collector;

[0197] FIG. 22 is a top view of the apparatus of FIG. 21; and

[0198] FIG. 23 is a side view of an exemplary foam mover.

[0199] Preferred features, embodiments and variations of the invention may be discerned from the following Examples which provides sufficient information for those skilled in the art to perform the invention. The following Examples are not to be regarded as limiting the scope of the preceding Summary of the Invention in any way.

EXAMPLES

Exemplary Electrochemical Apparatuses

[0200] Embodiments of the invention will now be described with reference to FIGS. 1 to 23 and the following section describing the methods. In the figures, like reference numerals refer to like features.

[0201] FIGS. 1 to 4 describe a water treatment system 200 and components thereof in the form of a trailer. FIGS. 1 to 4 illustrate a water treatment system 200 including an electrochemical liquid treatment apparatus 201. In FIG. 1, the treatment chamber 210 and defoaming chamber 250 are provided within the component labelled HEC20016 (this component is illustrated, for example, in FIGS. 2-4 and 18-22).

[0202] As shown in FIG. 1, raw water 300 external to the trailer is supplied to a balance tank 302 using a centrifugal pump. At least one treatment agent (stored in a dosing tank 304) may be added to the water flowing to the balance tank 302 using a positive displacement pump.

[0203] The water then flows to the treatment chamber 210 where electrochemical treatment occurs. The pH of the liquid during the electrochemical treatment may be controlled by the introduction of an acid from acid tank 305. The electrochemically treated water then flows to the defoaming chamber 250, and the foam to a foam separation vessel. The electrochemical process may be controlled via a system for regulating the electrochemical treatment (which includes a controller (PLC) 307). Electrochemically treated water then flows to clarifiers 306 (which have a level switch).

[0204] Clarified water (and floc) may exit the clarifiers 306 before passing through a positive displacement pump to a drain connection. Alternatively, the clarified water (and floc) from the clarifiers 306 may pass to a screw press 308 having a float valve. Pressed or substantially dewatered floc exits the screw press to a waste bin. Liquid exiting the screw press 306 passes to centrifugal pump, and then passes back to clarifiers 306.

[0205] Clarified water may be passed from clarifiers 306 to a drop tank 310. Fluid exiting drop tank 310 passes through a centrifugal pump and then to sand filters 312 (for separation of floc from the water) or optionally back through clarifiers 306. After sand filtration the water may be passed to a storage tank 314 (where is it optionally treated by a treatment agent (stored in a dosing tank 304, in which the treatment agent may be pumped into the storage tank 314 by way of a positive displacement pump)). From storage tank 314 the treated water may be released. Alternatively, water from the storage tank 314 may pass to: (i) further components of a filtration and/or polishing system, such as a carbon filter or similar fluorocarbon adsorbant material, nanofilter or ion exchange resin, and/or reverse osmosis system; (ii) screw press 308; or (iii) treatment chamber 210 and defoaming chamber 250. The filtered water may pass to a storage tank before re-electrochemical treatment or disposal. In FIG. 1, the electrochemical liquid treatment apparatus 201 includes balance tank 302, acid tank 305, dosing tank 304, treatment chamber 210, defoaming chamber 250, and clarifiers 306. As illustrated in FIGS. 1 to 4, there are various pumps 324 and valves associated with the system 200 and apparatus 201.

[0206] Two example treatment chambers 210, electrode holders 280, and defoaming chambers 250 are illustrated in FIGS. 5 to 22; a first at FIGS. 7-17, and a second at FIGS. 5, 6 and 18-22. The treatment chamber 210 illustrated in FIGS. 7-9 and 13-17 is capable of only accommodating one electrode holder 280. The treatment chamber 210 illustrated in FIGS. 18-22 is capable of accommodating 16 electrode holders 280. The electrode holders 280 illustrated in FIGS. 18-22 is capable of holding 10 electrodes 240 (as shown in FIGS. 5 and 6), whereas the electrode holder 280 illustrated in FIGS. 7-12, 16 and 17 is capable of holding 13 electrodes 240. The treatment chamber 210, defoaming chamber 250 and electrode holders 280 in the treatment system 200 illustrated in FIGS. 1-4 is of similar design to those in FIGS. 5-22. However, in the treatment system 200 of FIGS. 1-4, the treatment chamber 210 is capable of accommodating 400 electrodes (which equates to between 30 and 40 electrode holders 280) or the treatment chamber 210 is capable of accommodating 160 electrodes (equating to 16 electrode holders 280). In one embodiment, the treatment chamber 210, defoaming chamber 250 and electrode holders 280 in the treatment system 200 illustrated in FIGS. 1-4 is the treatment chamber 210, defoaming chamber 250 and electrode holders 280 illustrated in FIGS. 18-22.

[0207] The treatment chamber 210 in the apparatus 201 of FIGS. 1-4 and 18-22 is about 500 L, and can accept a liquid flow rate of about 14 L/second. The residence time of the liquid in the treatment chamber 210 in the apparatus 201 of FIGS. 1-4 and 18-22 is typically about 30 s.

[0208] The treatment chamber 210 in FIGS. 7-9 and 14-17 is about 1 L, and can accept a liquid flow rate of about 2 L/minute. The residence time of the liquid in the treatment chamber 210 of FIGS. 7-9 and 13-17 is typically about 30 s.

[0209] The apparatuses 201 illustrated in FIGS. 1-17 are configured to operate at atmospheric temperature and pressure. The apparatus 201 illustrated in FIGS. 18-22 may be configured to operate at atmospheric temperature and pressure, or at reduced or elevated pressures (by applying suction or pressure at ports 218 and 258).

[0210] In the examples of FIGS. 1-22, the apparatus 201 is configured so that the liquid rises (or ascends) as it passes through the treatment chamber 210. As illustrated in FIGS. 7-9 and 13-22, the treatment chamber 210 includes a base 212 (or first wall), and four side walls 216.

[0211] In FIGS. 7-9 and 13-17 the treatment chamber does not include a second wall (or lid), although a lid may be formed by the handle(s) of the electrode holders 280 (see FIGS. 7 and 8 for example). However, in FIGS. 18-22 the treatment chamber 210 and defoaming chamber 250 include a lid 219, 259. The lids 219, 259 include ports 218, 258 as discussed above. The ports 218, 258 may be for extracting gas.

[0212] The treatment chambers 210 in FIGS. 7-22 are generally of substantially rectangular (or square) cross section. Each side wall 216 is planar. However, the bases 212 include a trough or channel and are substantially V-shaped.

[0213] The treatment chambers 210 include a disperser 222, and the disperser 222 includes a tube with one liquid entry point 224 and a plurality of inlets 220. The disperser 222 illustrated in the apparatuses 201 of FIGS. 7-22 is a tube perforated along its length to provide a plurality of inlets 220 into the treatment chamber 210 (see FIGS. 8 and 20 in particular). The disperser 222 is positioned within the trough or channel in the base 212.

[0214] The apparatuses 201 further include a flow aligner 290. The flow aligner 290 is connected to the electrode holders 280 (see FIGS. 5, 6, 10-12, 19 and 20). The flow aligner 290 is in the form of a wall or partition defining a plurality of apertures for passage of the liquid. In use, liquid flows (or is pumped) through the inlets 220 into the lower portion of the treatment chamber 210. The rate at which the liquid flows through the inlets 220 is set so that the liquid pressure on the side of the flow aligner 290 proximate to the at least one inlet is greater than the liquid pressure on the side of the flow aligner 290 proximate to the electrodes 240. The inventors have advantageously found that the combination of the pressure differential across the flow aligner 290 and the consistently spaced and sized apertures across the flow aligner 290 provides an even flow of liquid between the electrodes 240, minimising so-called “dead spots” in between the electrodes 240 and thereby improving the service life of the electrodes, particularly sacrificial anodes and hence downtime associated with having to change electrodes.

[0215] The flow aligner 290 in the apparatuses 201 of FIGS. 1-6 and 18-20 is segmented (with one segment per electrode holder 280). When the electrode holders 280 are in position in the treatment chamber 210, each flow aligner 290 segment is in close proximity with the adjoining segment, so that the electrode holders 280 collectively form the flow aligner 290.

[0216] The flow aligner 290 in FIGS. 5, 6 and 18-20 have polygonal (hexagonal) apertures, and the flow aligner 290 in FIGS. 7 to 12, 16 and 17 have ovoid apertures.

[0217] The apparatus 201 may be configured to electrochemically treat the liquid in the presence of at least one treatment enhancer or at least one treatment agent. The at least one treatment enhancer is capable of penetrating a solid wall of the treatment chamber, and consequently the at least one treatment enhancer (such as ultraviolet radiation, microwave radiation or ultrasonic waves) may be applied to a side wall 216 of the treatment chamber 210. The at least one treatment agent may enter the treatment chamber 210 through at least one treatment inlet, such as through a gas inlet. The gas inlets may be part of a gas disperser, which may be integral with the base of the treatment chamber 210. The types and function of such gases may be as previously described. Alternatively, the at least one treatment inlet may be mixed with the liquid to be treated before the liquid enters the treatment chamber 210. As illustrated and discussed with reference to FIG. 1, in the illustrated system 200 the dosing tank 304 may include a treatment agent which is mixed with the liquid in balance tank 302 before the liquid enters the treatment chamber. Also, at least one treatment agent may be added to the liquid entering the storage tank 314 after electrochemical treatment from dosing tank 304. Furthermore, in FIG. 1 at least one treatment agent (in the form of a pH modifier (an acid)) may be added to the treatment chamber 210 during the electrochemical treatment from acid tank 305.

[0218] The treatment chamber 210 also includes at least one outlet 230 for exit of electrochemically treated liquid. In the apparatuses 201 of FIGS. 7-9 and 13-22 the at least one outlet 230 is one outlet. As shown in FIGS. 8 and 19, in these apparatuses 201 the outlet 230 is positioned so that the electrodes 240 are configured to be positioned intermediate the at least one inlet 220, and the at least one outlet 230, and the at least one inlet 220 is positioned in a lower portion of the treatment chamber 210 and the at least one outlet 230 is positioned in an upper portion of the treatment chamber 230.

[0219] In the apparatuses 201 of FIGS. 7-9 and 13-22 the at least one outlet 230 is in the form of a weir or spillway. The outlet 230 is positioned at the intended height of liquid in the treatment chamber 210. In the apparatuses 201 of FIGS. 7-9 and 13-22, after exiting the treatment chamber 210 at outlet 230, the liquid passes to a defoaming chamber 250.

[0220] In the apparatus 201 of FIGS. 7-9 and 27-30, after flowing through outlet 230, the liquid descends through defoaming chamber 250 and then through an outlet 254 at the base of the chamber 250.

[0221] In the apparatus 201 of FIGS. 18-22, the defoaming chamber 250 includes a first flow diverter 234 and a second flow diverter 236. The first flow diverter 234 provides a weir inside the defoaming chamber 250. The second flow diverter 236 provides an underflow weir (under which fluid passes when flowing through the defoaming chamber 250). The bottom of the second flow diverter 236 extends below than the top of the first flow diverter 234. Both the first and second flow diverters 234, 236 are substantially vertical and are in the form of a wall or plate. In the arrangement illustrated in FIG. 19, electrochemically treated fluid exits the treatment chamber 210 through outlet 230. As shown in FIGS. 21 and 22, the apparatus of FIGS. 18-22 is fitted with a foam collector 400 (foam collector not shown in FIGS. 18-20). The foam collector 400 includes a filter 420. The filter 420 may be in the form of a mesh, especially so-called ‘20 mesh’ stainless steel mesh (where the mesh contains 20 apertures to each lineal inch (25.4 mm)). The filter 420 of the foam collector 400 is in register with the outlet 230. The filter 420 forms part of vacuum nozzle 440, which extends to a hose 460, which is then connected to a partial vacuum source (such as a pump). The upper wall of the nozzle 440 does not extend as far as the outlet 230 to assist in drawing the foam into the foam collector 400. The vacuum source sucks collected foam to an intermediate vessel for settling. Preferably, the vessel is at a negative pressure to assist defoaming. In use, foam generated in the electrochemical treatment forms on top of the liquid in the treatment chamber 210. The foam is driven towards the outlet 230 and foam collector 400 by virtue of the flow rate of liquid through the apparatus 201. Once the foam and liquid reach the outlet 230, the foam does not pass through the filter 420, and instead moves across the filter into nozzle 440 and then into hose 460. The treated liquid (with entrained, but not yet fully formed floc) passes through the filter 440 and then into defoaming chamber 250. The fluid falls into the space between the second flow diverter 236 and the outlet 230, and in use fluid fills this space to at least the height of the first flow diverter 234. As any foam passing through the filter floats, the foam is trapped in this space, and the fluid falling into this space from outlet 230 penetrates the foam to thereby release trapped gas. Meanwhile, defoamed fluid passes beneath the second flow diverter 236 and then over the first flow diverter 234 before exiting the defoaming chamber 250 through outlet 254.

[0222] In FIG. 1, after exiting the defoaming chamber 250 the liquid flows to a vessel for separation of the floc from the liquid (clarifier 306).

[0223] A foam mover 80 (as illustrated in FIG. 23) may be used with the vessel (or clarifier 306) to assist in separating the foam, for example. The foam mover 80 may be positioned at the surface of the liquid above the electrodes in the treatment chamber 210. The foam mover may especially in the form of a foam skimmer for moving foam, especially on the surface of the liquid in the treatment chamber 210. The foam mover 80 may be configured to advantageously move the foam towards filter 400 (as shown in FIGS. 21 and 22), and may assist in providing a horizontal flow for the liquid at the top of the treatment chamber 210, especially on the surface of the liquid in the treatment chamber 210. The foam mover 80 may be positioned substantially above or below the surface of the liquid in the treatment chamber 210, especially at or near the surface of the liquid. The exemplary foam mover 80 illustrated in FIG. 23 includes a plurality of floc paddles or drivers 82 mounted to a belt, strap, chain or cable 84, which is turned by wheels 86. As the wheels 86 turn, floc rising to the surface of the liquid is skimmed and moved towards the filter 400.

[0224] In the apparatuses of FIGS. 1-22, the electrodes 240 are added or removed from the treatment chamber 210 via electrode holders 280. In the apparatus 201 of FIGS. 18-22 no such grooves 270 are present. In the apparatuses 201 of FIGS. 7-9 and 13-22 the treatment chamber 210 also includes a shelf 276 upon which the electrode holders 280 rest when in position.

[0225] Within each electrode holder 280 only two or three electrodes 240 may be connected to power (and thereby become anodes and cathodes). The remaining electrodes may all be electrical conductors. In each electrode holder 280 each electrode 240 is substantially planar and is of solid construction. The electrodes 240 may have a tapered lower edge, as previously described. The apparatuses 201 of FIGS. 1-22 are configured so that the electrodes 240 are positionable below the level of the liquid in the treatment chamber 210. The apparatuses 201 of FIGS. 1-22 are configured so that the electrodes 240 are positioned substantially vertically (substantially in a plane perpendicular to the first wall 212) within the treatment chamber 210 (although it may also be advantageous to position the electrodes 240 (or a portion of the electrodes) at an angle as previously described).

[0226] As illustrated in FIGS. 5, 6, 10-25 and 20, the electrode holder 280 includes a frame 281, and the frame 281 includes a handle 282 and two side walls 284. The frame 281 is substantially “U” shaped. The frame also includes a flow aligner 290 (or a segment thereof).

[0227] The treatment chamber 210 of FIGS. 2-4, 7-9, and 16-22 further includes at least one power connector 272 for connecting power to an electrode holder 280 or to at least one electrode 240 held by the electrode holder 280. In FIGS. 7-9 and 13-17, the treatment chamber 210 is configured to supply power longitudinally along the working face of at least one electrode 240. In this example, the power connector 272 is adapted to contact the working face of at least one electrode 240. The power connector 272 includes a partially flexible, corrugated metallic (for example stainless steel or titanium alloy) strip held under tension against the external two electrodes in the electrode holder. In this example, the power connector 272 also traverses the wall of the treatment chamber 210 to provide a tab 274 for connection to a power source. A similar arrangement may be used with a plurality of electrode holders 280 (such as in the treatment chamber 210 of FIGS. 1-4), as in this case each power connector 272 may be positioned intermediate to the working face of a terminal electrode 240 held by two electrode holders 280. The crests (and troughs) of the power connector 272 may be positioned so that the crests of the power connector 272 are held under sufficient tension to contact one terminal electrode 240, and the troughs of the power connector 272 contact the other terminal electrode 240.

[0228] A similar mechanism for connecting power to the electrodes 240 is illustrated in the treatment chamber 210 of FIGS. 18-22. In FIGS. 18-22 the treatment chamber 210 is also configured to supply power longitudinally along the working face of at least one electrode 240. However, while the power connector 272 illustrated in FIGS. 7-9 and 14-17 includes one corrugated metallic spring strip per electrode 240, in FIGS. 18-22 the power connector 272 includes two corrugated metallic spring strips per electrode 240 (see FIG. 20). The treatment chamber 210 in the apparatus 201 of FIGS. 18-22 includes four power connectors 272, and each power connector provides power to only one electrode 240.

[0229] In FIGS. 5, 6, 7-12 and 16-20, the electrodes 240 are, on average, 3 mm thick and 3 mm apart. However, alternative thicknesses and distances may also be used in the apparatus 201.

[0230] In the apparatus 201 of FIGS. 20-22 and 26-30 two of the 13 electrodes 240 (or about 15% of the electrodes 240) are connected to power. The remaining nine electrodes 240 are all electrical conductors.

[0231] In the apparatus 201 of FIGS. 18-22, four of the 160 electrodes 240 (or about 2.5% of the electrodes 240) are connected to power. The remaining 156 electrodes 240 are all electrical conductors.

[0232] The treatment chamber 210 in FIGS. 18-22 also includes a divider wall (or plate) 217 positionable between the electrode holders 280. The electrode holders 280 in FIGS. 18 and 20 also include an electrode holder remover 283 (in the form of a cable loop or chemically resistant rope) to assist in removing the electrode holder 280 from the treatment chamber 210.

[0233] As illustrated in FIGS. 2-4, the apparatus 201 may further include a liquid pump 324 for pumping liquid to be treated through the at least one inlet for entry of a liquid to be treated, and a further pump 324 for pumping liquid from the defoaming chamber 250 (see FIG. 2). In FIG. 2, 326 is a treated water outlet (DN80), 328 is a fresh water inlet (DN25), 330 is a clean-in-place connection (DN25), 332 is a drain outlet (DN25) and 334 is a raw water inlet (DN80). The power supply to the apparatus 201 of FIGS. 2-4 is 415 V, 50 Hz and 150 A.

[0234] The apparatus 201 of FIGS. 1-4 further includes sensors for sensing the level of liquid in the treatment chamber 210, and a variable speed pump 324 to control the flow rate of liquid exiting the treatment chamber 210. The sensors and variable speed pump 324 may form part of a system for regulating the electrochemical treatment, which may be controlled by controller (PLC) 307. The controller 307 may control the polarity of the current and its reversal to thereby switch the electrodes 240 between anodes and cathodes. The controller 307 may also control the sinewave ramping angles during the electrochemical treatment, and/or modify the rate of current application to the electrodes 240 during the electrochemical treatment. Similar components may be used in the apparatuses 201 discussed in FIGS. 7-22.

[0235] Any suitable current may be applied to the electrodes 240 during the electrochemical treatment, however the voltage applied to each electrode holder 280 in the treatment chamber 210 is typically from 1.1 to 3 V per cell, especially at least 1.1 V per cell.

[0236] In use, liquid is pumped into the treatment chamber 210 via the at least one inlet 220, and liquid pressure builds beneath flow aligner 290. Liquid passes through the flow aligner 290 and between the electrodes 240 where the liquid is electrochemically treated and floc and foam is generated. The foam floats on the surface of the electrochemically treated liquid, and the floc typically remains entrained in the liquid (in view of the residence time). The floc, foam and electrochemically treated liquid then pass through the at least one outlet 230 and into the foam collector 400, where the foam passes into hose 460, and floc and liquid pass through the filter 420 into defoaming chamber 250. The floc and liquid pass over/around flow diverter(s) 232 and optionally past defoamers 252. This process leads to defoaming of the floc/electrochemically treated liquid. The floc/electrochemically treated liquid then flows out the outlet 254 in the defoaming chamber 250 and then to a vessel for separation of the floc (e.g. clarifier 306).

Electrochemical Treatments

[0237] In examples 1 and 2 landfill leachate from Minnesota, USA was treated. In both examples, the ammonia was first significantly removed or depleted from the leachate. This step was taken as otherwise organofluoro sulfonic amides can form if excess ammonia is present. Such sulfonic amides may not pass into the foam during the electrochemical treatment as readily as other organofluorine substances.

[0238] Ammonia was depleted or removed from the leachate in one of two ways. A first way was to add magnesium chloride and sodium phosphate to the leachate. With stirring, substantially water insoluble struvite (comprising predominantly magnesium ammonium phosphate) forms from the ammonia. The struvite may then be either settled or filtered.

[0239] A second way is to air and/or air entrained steam strip the ammonia from the leachate. For example, the pH was raised to about 11.5 (so that ammonia is more likely to be present in the form of ammonia (NH.sub.3) gas than the more stable ammonium ion (NH.sub.4.sup.+)). Then the leachate is heated to about 150° F. (about 65° C.) to deplete the ammonia. An exemplary heating mechanism is to utilize the latent heat of partially condensing steam in air, blown through the liquid. The pH of the resultant, substantially ammonia free liquid was then reduced to about 7.5 by acidulation.

[0240] In Example 1 below, the struvite precipitation method was used. In Example 2 below, the air stripping method was used.

Example 1

[0241] The ammonia depleted leachate was subjected to electrochemical treatment using the apparatus of FIGS. 7-17, which has 13 electrode plates to provide 12 active cells. The electrochemical treatment was performed with a cell residence time of 45 seconds, a flow rate of 0.7 litres per minute, using mild carbon steel electrodes. The distance between electrodes was 3 mm, and the voltage applied was 1.1 volts per cell (one cell is the space between two adjoining electrodes). Electrode polarity was reversed every 30 seconds to avoid cathode passivation. The temperature of the liquid being treated was near ambient temperature (around 25-30° C.). No gases or other treatment agents were used during the electrochemical treatment.

[0242] Foam was produced during the electrochemical treatment. Without wishing to be bound by theory, it is believed that foam production was enhanced by the production of hydrogen gas at the sacrificial electrodes during the electrochemical treatment. After production, the hydrogen gas becomes entrained with the organofluorines, producing foam. The foam settled on the surface of the liquid in the treatment chamber 210. The foam was collected using a syringe and then allowed to de-gas in a separate vessel for collection.

[0243] The treated water was collected. Given the residence time and flow rate of the electrochemical treatment, floc did not settle on the base of the treatment chamber 210, and there was insufficient time for significant quantities of floc to settle on the surface of the liquid in the treatment chamber 210. Consequently, the treated water included floc. Polymer was added to separate the floc (Flopam AN 905 SH (an anionic polyacrylamide), produced by SNF, USA). A sample of the treated liquid (supernatant treated water) was collected.

[0244] Samples of the raw leachate, the foam, and the treated liquid were analysed by ALS, Kelso, Wash. Each sample was homogenized prior to assessment by LC MS MS MS. The results are provided in Tables 1-6.

TABLE-US-00001 TABLE 1 Organofluorine Acronyms Carbon Analyte chain Acronym Chemical Name Formula Length PFBS Perfluorobutane sulfonate C.sub.4F.sub.9SO.sub.3.sup.− 4 PFHxS Perfluorohexane sulfonate C.sub.6F.sub.13SO.sub.3.sup.− 6 PFOS Perfluorooctane sulfonate C.sub.8F.sub.17SO.sub.3.sup.− 8 PFBA Perfluorobutanoate F.sub.3F.sub.7CO.sub.2.sup.− 4 PFPeA Perfluoropentanoate C.sub.4F.sub.9CO.sub.2.sup.− 5 PFHxA Perfluorohexanoate C.sub.5F.sub.11CO.sub.2.sup.− 6 PFHpA Perfluoroheptanoate C.sub.6F.sub.13CO.sub.2.sup.− 7 PFOA Perfluorooctanoate C.sub.7F.sub.15CO.sub.2.sup.− 8 PFNA Perfluorononanoate C.sub.8F.sub.17CO.sub.2.sup.− 9 PFDA Perfluorodecanoate C.sub.9F.sub.19CO.sub.2.sup.− 10 PFUnDA Perfluoroundecanoate C.sub.10F.sub.21CO.sub.2.sup.− 11 PFDoDA Perfluorododecanoate F.sub.11F.sub.23CO.sub.2.sup.− 12 PFTrDA Perfluorotridecanoate C.sub.12F.sub.25CO.sub.2.sup.− 13 FOSA Perfluorooctane sulfonamide C.sub.8F.sub.17SO.sub.2NH.sub.2 8 62FTS 1H,1H,2H,2H- C.sub.6F.sub.13CH.sub.2CH.sub.2SO.sub.3.sup.− 8 Perfluorooctanesulfonic acid 82FTS 1H,1H,2H,2H- C.sub.8F.sub.17CH.sub.2CH.sub.2SO.sub.3.sup.− 10 Perfluorodecanesulfonic acid

TABLE-US-00002 TABLE 2 Analysis results for Organofluorine Concentrations Before and After Treatment - Full Data Supernatant Supernatant removal treated Ratio of Foam/ Removal vs foam Raw water water Foam foam conc. Supernatant Removal Removal efficiency enhanced Analyte (ng/L) (ng/L) (ng/L) to raw conc. ratio ng/L fraction (%) removal PFBS 1,400.0 1,000.0 2,300.0 1.64 2.30 400.0 0.286 28.6% 0.31 PFHxS 400.0 130.0 2,800.0 7.00 21.54 270.0 0.675 67.5% 0.10 PFOS 330.0 120.0 620.0 1.88 5.17 210.0 0.636 63.6% 0.42 PFBA 1,300.0 990.0 1,800.0 1.38 1.82 310.0 0.238 23.8% 0.38 PFPeA 1,400.0 930.0 1,800.0 1.29 1.94 470.0 0.336 33.6% 0.54 PFHxA 3,700.0 2,500.0 6,700.0 1.81 2.68 1,200.0 0.324 32.4% 0.29 PFHpA 640.0 260.0 3,400.0 5.31 13.08 380.0 0.594 59.4% 0.12 PFOA 970.0 210.0 8,400.0 8.66 40.00 760.0 0.784 78.4% 0.09 PENA 42.0 4.6 340.0 8.10 73.91 37.4 0.890 89.0% 0.11 PFDA 10.0 2.3 54.0 5.40 23.48 7.7 0.770 77.0% 0.15 PFUnDA 2.3 1.2 4.2 1.83 3.50 1.1 0.478 47.8% 0.37 PFDoDA 2.1 0.7 2.0 0.95 2.70 1.4 0.648 64.8% 1.08 PFTrDA 2.7 0.9 2.0 0.74 2.30 1.8 0.678 67.8% 1.62 FOSA 7.5 0.7 57.0 7.60 81.43 6.8 0.907 90.7% 0.12 62FTS 370.0 110.0 2,100.0 5.68 19.09 260.0 0.703 70.3% 0.13 82FTS 14.0 1.1 82.0 5.86 74.55 12.9 0.921 92.1% 0.16

TABLE-US-00003 TABLE 3 Analysis results for Organofluorine Concentrations Before and After Treatment - sorted by carbon chain length Raw water Foam concen- concen- Ratio of Removal # Carbon tration tration foam conc. efficiency Analyte Atoms (ng/L) (ng/L) to raw conc. % PFBS 4 1,400 2,300 1.64 28.6% PFBA 4 1,300 1,800 1.38 23.8% PFPeA 5 1,400 1,800 1.29 33.6% PFHxS 6 400 2,800 7.0 67.5% PFHxA 6 3,700 6,700 1.81 32.4% PFHpA 7 640 3,400 5.31 59.4% PFOS 8 330 620 1.88 63.6% PFOA 8 970 8,400 8.66 78.4% FOSA 8 8 57 7.6 90.7% 62FTS 8 370 2,100 5.68 70.3% PFNA 9 42 340 8.1 89.0% PFDA 10 10 54 5.4 77.0% 82FTS 10 14 82 5.86 92.1% PFUnDA 11 2.3 4.2 1.83 47.8% PFDoDA 12 2.1 2.0 0.95 64.8% PFTrDA 13 2.7 2.0 0.74 67.8%

TABLE-US-00004 TABLE 4 Analysis results for Organofluorine Concentrations Before and After Treatment - sorted by foam concentration (data <620 ng/L omitted) Raw water Foam Concen- concen- Ratio of Removal PFC # Carbon tration tration foam conc. efficiency name atoms (ng/L) (ng/L) to raw conc. % PFOA 8 970 8,400 8.65 78.4% PFHxA 6 3,700 6,700 1.8 32.4% PFHpA 7 640 3,400 5.3 59.4% PFHxS 6 400 2,800 7.0 67.5% PFBS 4 1,400 2,300 1.64 28.6% 62FTS 8 370 2,100 5.67 70.3% PFPeA 5 1,400 1,800 1.28 33.6% PFBA 4 1,300 1,800 1.38 23.8% PFOS 8 330 620 1.88 63.6%

TABLE-US-00005 TABLE 5 Analysis results for Organofluorine Concentrations Before and After Treatment - sorted by absolute removal (data less than 210 ng/L omitted) Absolute Raw water Foam removal Concen- concen- from Removal PFC tration tration effluent # Carbon efficiency name (ng/L) (ng/L) (ng/L) atoms % PFHxA 3,700 6,700 1,200 6 32.4% PFOA 970 8,400 760 8 78.4% PFPeA 1,400 1,800 470 5 33.6% PFBS 1,400 2,300 400 4 28.6% PFHpA 640 3,400 380 7 59.4% PFBA 1,300 1,800 310 4 23.8% PFHxS 400 2,800 270 6 67.5% 62FTS 370 2,100 260 8 70.3% PFOS 330 620 210 8 63.6%

TABLE-US-00006 TABLE 6 Analysis results for Organofluorine Concentrations Before and After Treatment - sorted by ratio of foam concentration to raw concentration (data less than 1.9:1 omitted) Raw water Foam Concen- concen- Ratio of Removal tration tration foam conc. efficiency Analyte (ng/L) (ng/L) to raw conc. % PFOA 970 8,400 8.7 78% PFNA 42 340 8.1 89% FOSA 7.5 57 7.6 90% PFHxS 400 2,800 7.0 67.5%.sup.  82FTS 14 82 5.9 92% 62FTS 370 2,100 5.7 70.2%.sup.  PFDA 10 54 5.4 77% PFHpA 640 3,400 5.3 59% PFOS 330 620 1.9 63%

Example 2

[0245] The ammonia depleted leachate was subjected to electrochemical treatment using the apparatus of FIGS. 18-22, which has 160 electrode plates. The electrochemical treatment was performed with a cell residence time of 45 seconds, a flow rate of 11.09 kL per hour (3.08 L per second), using mild carbon steel electrodes. The distance between electrodes was 3 mm, and the voltage applied was 1.1 volts per cell (one cell is the space between two adjoining electrodes). The target current was 9 amps. Electrode polarity was controlled externally to avoid cathode passivation. The temperature of the liquid being treated was near ambient temperature (around 30-32° C.). No gases or other treatment agents were used during the electrochemical treatment.

[0246] Foam was produced during the electrochemical treatment. Without wishing to be bound by theory, it is believed that foam production was enhanced by the production of hydrogen gas at the sacrificial electrodes during the electrochemical treatment. After production, the gas became entrained with the organofluorines, producing foam. The foam settled on the surface of the liquid in the treatment chamber 210. The foam was collected using foam collector 400 and then allowed to de-gas in a separate vessel for collection.

[0247] The treated water was collected. Given the residence time and flow rate of the electrochemical treatment, floc did not settle on the base of the treatment chamber 210, and there was insufficient time for significant quantities of floc to settle on the surface of the liquid in the treatment chamber 210. Consequently, the treated water included floc. A sample of the treated liquid was collected, immediately after it filtered through the foam collector 400 (i.e. most floc would not have time to settle out).

[0248] Samples of the raw leachate, the foam, and the treated liquid were analysed by ALS, Kelso, Wash. Each sample was homogenized prior to assessment by LC MS MS MS. The results are provided in Table 7.

TABLE-US-00007 TABLE 7 Analysis results for Organofluorine Concentrations Before and After Treatment - Full Data Treated water (ng/L) immediately Ratio of Removal Raw water Foam after foam conc. Removal efficiency Analyte (ng/L) (ng/L) filtering to raw conc. (ng/L) % PFBS 1,600 2,000 1,600 1.25 0 0.00% PFHxS 700 15,000 630 21.42 70 10.00% PFOS 290 15,000 88 51.72 202 69.66% PFBA 1,100 1,500 1,400 1.36 −300 −27.27% PFPeA 1,700 2,700 1,800 1.59 −100 −5.88% PFHxA 3,800 11,000 5,000 2.89 −1,200 −31.58% PFHpA 880 8,800 1,000 10.0 −120 −13.64% PFOA 1,600 51,000 930 31.88 670 41.88% PFNA 140 11,000 56 78.57 84 60.00% PFDA 48 4,400 16 91.67 32 66.67% PFUnDA 16 270 16.88 16 100.00% PFDoDA 34 0 PFTrDA 0 FOSA 330 1,400 −1,400 62FTS 710 21,000 1,400 29.58 −690 −97.18% 82FTS 66 17,000 160 257.58 −94 −142.42%

[0249] In this example, the treated water still contained floc which had not settled. Without wishing to be bound by theory, it is believed that some of the larger long chain organofluorines degraded to a smaller short chain organofluorine. The smaller organofluorine then either remained in the supernatant liquid, or adsorbed to form part of the floc.

[0250] In the present specification and claims (if any), the word ‘comprising’ and its derivatives including ‘comprises’ and ‘comprise’ include each of the stated integers but does not exclude the inclusion of one or more further integers.

[0251] Reference throughout this specification to ‘one embodiment’ or ‘an embodiment’ means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases ‘in one embodiment’ or ‘in an embodiment’ in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.

[0252] In compliance with the statute, the invention has been described in language more or less specific to structural or methodical features. It is to be understood that the invention is not limited to specific features shown or described since the means herein described comprises preferred forms of putting the invention into effect. The invention is, therefore, claimed in any of its forms or modifications within the proper scope of the appended claims (if any) appropriately interpreted by those skilled in the art.

Advantages

[0253] Advantages of a preferred embodiment of the present invention may include: [0254] The electrochemical process is engineered to rely on relatively low cost and freely available anode compositions compared to the examples in the scientific literature; [0255] The process is fast and scalable to commercial treatment rates unlike batch processes requiring 2-10 hours of treatment time; [0256] The treated effluent from the process is then directed (as required) to a sorptive process if needed for final polishing; [0257] The process is engineered so that the surfactant form of the PFC, PFOA and PFOS decay products is regenerated in the cell so that the surfactant segregates to the liquid-gas interface; [0258] The electrochemical process is engineered to also produce quantities of reductant, inert, or oxidative gases to facilitate the phase separation of PFCs and resulting PFOA and PFOS degradation products to the foam with the surfactant then separated by foam fractionation; [0259] The foam, selectively enhanced to carry the bulk of the PFC, PFOA and PFOS is collected by either a dissolved air flotation (DAF) type skimmer following adsorption onto sacrificial anode (cell generated) ferrous or ferric hydroxide sludge for either encapsulation, disposal or secure landfill; [0260] The foam, carrying the bulk of the PFC, PFOA and PFOS is collected by suction producing a concentrated liquid phase requiring disposal; [0261] Since cell residence times as low as 60 seconds (1 minute) can achieve the phase change required to separate the organofluorines and degradation products from the water columns, this enables much more cost effective adsorption onto a filtering media suitable for environmentally sensitive disposal; and [0262] A fast and efficient water treatment process typically of less than 60-120 seconds residence time to avoid 2-10 hour (120-600 minute) cell residence times required of many competing technologies.