WO2016187649A1

WO2016187649A1 - Sacrificial electrode with pulsed current supply

Info

Publication number: WO2016187649A1
Application number: PCT/AU2016/000181
Authority: WO
Inventors: James Dunstone Townsend
Original assignee: Micromet Pty Ltd
Priority date: 2015-05-25
Filing date: 2016-05-25
Publication date: 2016-12-01
Also published as: CN106186211A

Abstract

The present disclosure provides an electrode plate array suitable for use in a waste water treatment apparatus. The array comprises a plurality of electrodes at least one of which is a sacrificial electrode and a pulsed DC power source operably connected to at least the sacrificial electrode in the array.

Description

SACRIFICIAL ELECTRODE WITH PULSED CURRENT SUPPLY

PRIORITY DOCUMENTS

[0001 ] The present application claims priority from Australian Provisional Patent Application No. 2015901914 titled "SACRIFICIAL ELECTRODE WITH PULSED CURRENT SUPPLY" and filed on 25 May 2015, the content of which is hereby incorporated by reference in its entirety.

TECHNICAL FIELD

[0002] The present disclosure relates to electrolytic flocculation and water treatment systems.

BACKGROUND

[0003] Continuous flow, electrolytic flocculation and water treatment systems are known in the art. One example of such a system is disclosed in Australian patent application 201 1202095 "A Continuous Flow Electro-flocculation Water Treatment System".

[0004] In practice, it can be difficult to treat some effluents using the known systems. For example, when certain effluents are treated the electrolytic resistance of the treatment system can build up over time. This is particularly noticeable with aluminium electrode plates used in aluminium/stainless steel electrode systems that are commonly used. The build-up of resistance over time can lead to a reduction in treatment efficiency and an increase in costs.

[ 0005] There is a need to provide electrolytic waste water treatment apparatus and, in particular, effluent treatment apparatus that overcome one or more of the difficulties associated with known apparatus.

SUMMARY

[0006] According to a first aspect, there is provided an electrode plate array suitable for use in a waste water treatment apparatus, the array comprising a plurality of electrodes at least one of which is a sacrificial electrode and a pulsed DC power source operably connected to at least the sacrificial electrode in the array.

[0007] According to a second aspect, there is provided a waste water treatment electrode plate array comprising a plurality of electrodes at least one of which is a sacrificial electrode and a pulsed DC power source operably connected to at least the sacrificial electrode in the array. [0008] According to a third aspect, there is provided a waste water treatment apparatus comprising at least one sacrificial electrode water treatment chamber comprising the electrode plate array of the first or second aspect of the invention.

[0009] Advantageously, pulsed DC power source provides a pulsed current to at least the sacrificial electrode and this may reduce or prevent the development of electrolytic resistance in the electrode plate array.

[0010] In some embodiments, a power source is also used to reverse the polarity of the current to one or both of the electrode(s). Reversing the polarity of an electrode may prevent "plating out" of the electrodes and the build-up of electrolytic resistance.

[001 1 ] In some embodiments, the electrode plate array is an iron/iron electrode system. In other embodiments, the electrode plate array is an iron/stainless steel electrode system. In both of these embodiments, the sacrificial electrode contains iron. In still other embodiments, the electrode plate array is an aluminium/stainless steel electrode system. In these embodiments, the sacrificial electrode contains aluminium.

[0012] The sacrificial electrode water treatment chamber may reduce the amount of particulates in the water by electroflocculation.

[0013] According to a fourth aspect, there is provided a method for treating wastewater comprising passing wastewater to be treated though the apparatus of the third aspect of the invention.

BRIEF DESCRIPTION OF DRAWINGS

[0014] A preferred embodiment of the present invention will be discussed with reference to the accompanying drawings wherein:

[0015] Figure 1 is a schematic side view of an embodiment of a sacrificial electrode water treatment chamber;

[0016] Figure 2 is a schematic of an embodiment of a water treatment apparatus; and

[0017] Figure 3 is a schematic plan view of the sacrificial electrode water treatment chamber shown in Figure 1.

[ 0018] In the following description, like reference characters designate like or corresponding parts throughout the figures. DESCRIPTION OF EMBODIMENTS

[0019] Referring now to Figure 1 , there is shown a waste water treatment apparatus 10. The apparatus 10 comprises at least one sacrificial electrode water treatment chamber 12. The sacrificial electrode water treatment chamber 12 comprises an electrode plate array 14 comprising a plurality of electrodes 18, 20 at least one of which 18 is a sacrificial electrode and a pulsed DC power source 22 operably connected to at least the sacrificial electrode 1 in the array 14.

[0020] The at least one sacrificial electrode water treatment chamber 12 may be a stand-alone apparatus or it may be a component of a modular waste water treatment apparatus 10 comprising a plurality of water treatment chambers connected in series. Suitable apparatus are disclosed in Australian Patent Application No. 201 1202095 and the present Figure 2.

[0021 J An embodiment of the electrode plate array 14 is shown in Figures 1 and 2 but it is contemplated that the electrode plate array 14 may be any configuration. The electrode plate array 14 comprises at least two electrodes 18, 20 with each electrode in a pair of electrodes having opposite polarity. One of the electrodes 1 in each electrode pair is a sacrificial electrode. There may be any number of pairs of electrodes in the array 14. In the array 14 shown in Figure 1 , there are six pairs of electrodes 18, 20 in the array 14. There could also be one, two, three, four, five, seven, eight, nine or ten pairs of electrodes 1 8, 20 in the electrode plate array 14.

[0022] The electrode plate array 14 is supported in the chamber 12 in an appropriate way. For continuous flow water treatment systems the array 14 is preferably supported above the base of the chamber 12. This may be done by inserting one or more rods through the electrode plate array 14 and fixing ends of the rod(s) to the chamber 12. Alternatively, the electrode plate array 14 may be assembled in a housing which, in turn, is placed in the chamber 12 and may be spaced from the bottom of the chamber using spacers between the base of the chamber 12 and the base of the housing.

[0023] The configuration of the electrodes 18, 20 themselves is not particularly important and, for example, they may be in the form of plates, expanded mesh, cylinders, and the like. It is advantageous for the surface area of the electrodes 18, 20 to be as large as possible. In the illustrated embodiments, the electrodes 18, 20 are plates that are held substantially parallel and spaced from one another.

[0024] The sacrificial electrode 18, which is the anode, may contain iron or aluminium (e.g. may be an iron or aluminium electrode). The counter electrode 20, which is the cathode, may be any conductive material and, for example, could be stainless steel, iron, aluminium, and the like. In specific

embodiments, the sacrificial electrode 18 contains iron. When a voltage is applied across the electrodes 18, 20 metal ions from the sacrificial anode electrode 18 (e.g. Fe³⁺ or Al³⁺) are released into the water. The released metal ions act as a flocculant and bind to particulate matter in the water. Oxygen gas is also produced at the anode electrode 1 8 and hydrogen is produced at the cathode electrode 20 and the bubbles of these gases assist in bringing the flocculated material to the surface of the water.

[0025 J The sacrificial electrode 18 is electrically connected to the pulsed DC power source 22. In the illustrated embodiments, the power source 22 is electrically connected to all of the plates of the anode electrode 18 via anode connector 26. The connector 26 may be any conductive material. Methods and devices for electrically connecting the anode connector 26 to the anode electrode plates 18 and to the pulsed DC power source 22 are known in the art and these connections may take any form.

[0026] The pulsed DC power source 22 supplies a pulsed current to the anode electrode 18 by delivering a current with a single polarity and a variable voltage. The pulsed current can be produced using a half- wave or full-wave rectifier or a modulator that pulses the DC current by switching it on and off rapidly. The periods of time during which current is applied and the intervals between applications of current can be adjusted to facilitate the diffusion of ions from the anode electrode. This may be varied depending on the chemistiy and the nature of the water to be treated and the optimum pulsed current parameters may be determined empirically. This system of generating ions by DC pulses allows the amount of the ions to be generated and the ratio of the positive and negative ions produced in the chamber 12 to be controlled by adjusting the applied voltages and current, the time applied at constant voltage and the time intervals between applied voltages. In this way, it is possible to reduce static charging resulting from an imbalance in the generation of the positive and negative ions.

[0027] The DC current applied may have a pulse frequency of 20 to 200 kilohertz and the DC pulsing current can have a duty cycle of the range of from about 20 to about 80 %.

[0028] The pulsed DC power source 22 can have any suitable output voltage level, current level, duty cycle, or waveform. It may be programmable so that a number of variables can be changed. For example, the power source 22 may be programmed to pulse at a variety of frequencies, duty cycles, etc. The power source may also be programmed to reverse the polarity of the current to one or both of the electrode(s) 18, 20. Reversing the polarity of the electrodes 18, 20 may prevent "plating out" of an electrode and the build-up of electrolytic resistance. The DC power source 22 may be, for example, a Meanwell DC power supplies 75-100A/20VDC power source.

[0029] In some embodiments, a pulsed current is supplied to the anode 18 and a constant current is supplied to the cathode 20. In these embodiments, the pulsed DC power source 22 may provide the constant current to the cathodes 20. Alternatively, the cathodes 20 may be connected to a separate power source.

[0030] In alternative embodiments, a pulsed current is supplied to the anode 18 and the cathode 20. In the these embodiments, positive and negative DC voltages are alternately applied to respective electrodes 18 and 20 at prescribed intervals to generate positive and negative ions from the respective electrodes alternately. The pulsed current may be supplied to the anode 18 and cathode 20 by the pulsed DC power source 22. Alternatively, the pulsed DC power source 22 may supply the pulsed current to the anode 1 8 and a separate pulsed DC power source may supply the pulsed current to the cathode 20.

[003 1 ] The cathode 20 is operatively connected to a power source via cathode connector 28.

[ 0032] It will be appreciated by those skilled in the art that the invention is not restricted in its use to the particular application described. Neither is the present invention restricted in its preferred embodiment with regard to the particular elements and/or features described or depicted herein. It will be appreciated that the invention is not limited to the embodiment or embodiments disclosed, but is capable of numerous rearrangements, modifications and substitutions without departing from the scope of the invention.

[0033 ] Throughout the specification and the claims that follow, unless the context requires otherwise, the words "comprise" and "include" and variations such as "comprising" and "including" will be understood to imply the inclusion of a stated integer or group of integers, but not the exclusion of any other integer or group of integers.

[0034 ] The reference to any prior art in this specification is not, and should not be taken as, an acknowledgement of any form of suggestion that such prior art forms part of the common general knowledge.

Claims

1. An electrode plate array suitable for use in a waste water treatment apparatus, the array comprising a plurality of electrodes at least one of which is a sacrificial electrode and a pulsed DC power source operably connected to at least the sacrificial electrode in the array.

2. A waste water treatment electrode plate array comprising a plurality of electrodes at least one of which is a sacrificial electrode and a pulsed DC power source operably connected to at least the sacrificial electrode in the array.

3. The electrode plate array according to either claim 1 or claim 2, wherein the power source is programmable to reverse the polarity of the current to the electrode.

4. The electrode plate array according to any one of claims 1 to 3, wherein the sacrificial electrode contains iron and a counter electrode is a stainless steel electrode.

5. The electrode plate array according to any one of claims 1 to 3, wherein the sacrificial electrode contains iron and a counter electrode is an iron electrode.

6. The electrode plate array according to any one of claims 1 to 5, wherein the DC power source comprises a half-wave or full-wave rectifier to supply pulsed current to the sacrificial electrode in the array.

7. The electrode plate array according to any one of claims 1 to 5, wherein the DC power source comprises a modulator to supply pulsed current to the sacrificial electrode in the array, wherein said modulator pulses the DC current by switching it on and off rapidly.

8. A waste water treatment apparatus comprising at least one sacrificial electrode water treatment chamber comprising the electrode plate array of any one of claims 1 to 7.

9. A method for treating wastewater comprising passing wastewater to be treated though the apparatus of claim 8.