Apparatus and method for electrodisinfection

Abstract

An electrolytic assembly and a method for the bacterial disinfection of water or wastewater is disclosed. Water circulating in cooling towers such as those that discharge heat from air conditioning; ships' ballast water; or wastewater with a dryness varying from 0.01 to 3%; can be treated. The assembly comprises one or more electrolytic units comprising at least one Dimensionnally Stable Anode commonly known as DSA, or a Boron Doped Diamond anode, also named BDD anode. The electrolytic treatment at least partially kill the bacteria present in the water. It has been shown that the electrolytic treatment breaks the cell membrane of bacteria present in the water. The treatment is particularly adapted for eliminating Legionella and others microorganisms, such as E. coli.

Claims

1. An electrolytic apparatus assembly for the electro-disinfection of water from a cooling tower, the apparatus comprising: at least one vertical electrolytic unit, each unit comprising: a vertical tubular reactor having a bottom section and a top section, an inlet adjacent to the bottom section of the reactor for injecting water to be treated into the reactor, an outlet adjacent to the top section of the reactor for extracting the water from the reactor, a plurality of anodes being rods extending longitudinally from the top section of the reactor inside the reactor; at least one cathode located inside the reactor; the plurality of anodes and the at least one cathode being configured to be operatively connected to an electric power supply providing a continuous current to the anodes and the at least one cathode to electrolyze the water flowing inside the reactor for at least partially kill bacteria present in the water; wherein each anode is a Dimensionnally Stable Anode (DSA); and a pump unit operatively connected to the inlet for injecting the water to be treated into the reactor, wherein the pump unit is fluidly connected to the cooling tower in order to extract and treat water that have previously circulated within the cooling tower; the outlet of the reactor being fluidly connected to the same cooling tower for re-injecting the water into the cooling tower after treatment, the electrolytic apparatus assembly and the cooling tower forming a treatment loop.

2. The electrolytic apparatus assembly of claim 1, wherein each DSA anode comprises a titanium metallic base covered by a conducting layer of iridium dioxide.

3. The electrolytic apparatus assembly of claim 1, wherein: the vertical electrolytic reactor defines an electrolysation chamber extending from the top of the reactor and containing the anodes and the at least one cathode substantially parallel to a flow of the water created from the bottom to the top of the reactor when the water is injected into the reactor; and a flow dispersion chamber located below the electrocoagulation chamber and in fluid communication with the inlet.

4. The electrolytic apparatus assembly of claim 1, wherein the vertical tubular reactor is configured to form the at least one cathode, or the at least one cathode extends from an inner wall of the vertical tubular reactor.

5. The electrolytic apparatus assembly of claim 1, comprising a number M of said plurality of anodes being rods, with M being 3, 6, 9, 12 or 15, the rods surrounding a central cathode.

6. The electrolytic apparatus assembly of claim 5, wherein the rods and the central cathode are operatively connected to a top crown member to form an electrode cartridge, the crown member being configured to be operatively connected to the power supply and to seal the top section of the vertical tubular reactor once the electrode cartridge is inserted into the reactor, the electrode cartridge being removable from the reactor for the maintenance of the anodes and cathode.

7. The electrolytic apparatus assembly of claim 6, wherein the cartridge also comprises a bottom crown member configured to maintain the anodes and the central cathode that extend therefrom, the bottom crown member being configured to be inserted inside the vertical reactor.

8. The electrolytic apparatus assembly of claim 1, wherein the power supply provides a current with an amperage between 10 A and 80 A, corresponding to 6V and 40V respectively, in order to reduce a treatment time of the water.

9. The electrolytic apparatus assembly of claim 1, comprising a number N of electrolytic vertical units with N≥2, and disposed in a parallel configuration to form a modular unit of N reactors, the outlet of the (N−1).sup.th electrolytic unit being fluidly connected to the inlet of the N.sup.th electrolytic unit, the number N being selected in accordance with a volume of water to be treated.

10. The electrolytic apparatus assembly of claim 1, wherein the water contains Legionella and/or E. coli bacteria.

11. The electrolytic apparatus assembly of claim 1, further comprising a flow control module for maintaining a transition or turbulent flow regime in the reactor.

12. The electrolytic apparatus assembly of claim 11, wherein the flow control module is configured to control the flow regime in the treatment loop and through the at least one vertical electrolytic unit in order to optimize the water treatment, and to maintain an optimal flow rate when performing electrolysis in the reactor.

13. The electrolytic apparatus assembly of claim 1, wherein the pump unit is configured to be modified in size in order to adjust a flow rate in the treatment loop, and through an automatically controlled and modulating valve operatively connected to the inlet.

14. The electrolytic apparatus assembly of claim 1, further comprising a unit of automated ON/OFF valves for directing the water in the treatment loop so that the water effectively passes multiple times through the at least one vertical electrolytic unit, until the treatment is completed.

15. A method for the electro-disinfection of water extracted from a cooling tower containing bacteria, the method comprising the steps of: a) injecting the water to be treated into the electrolytic apparatus assembly as defined in claim 1, the water having previously circulated in the cooling tower prior to be injected into the electrolytic apparatus assembly; b) performing an electrolytic treatment of the water circulating into the electrolytic unit assembly for at least partially kill the bacteria; and c) optionally, re-injecting the water once treated into the cooling tower.

16. The method of claim 15, wherein the bacteria are Legionella and/or E. coli.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The above and other objects, features and advantages of the invention will become more readily apparent from the following description, reference being made to the accompanying drawings in which:

(2) FIG. 1 is a schematic illustration of a modular unit of electrolysis reactors in accordance with at least one embodiment of the invention;

(3) FIGS. 2A and 2B are pictures showing the system for treating water from a cooling tower in accordance with a preferred embodiment of the invention.

(4) FIG. 3 is a front view of the exterior view of an electrodisinfection reactor in accordance with at least one embodiment of the invention;

(5) FIG. 4 is a perspective view of the electrodisinfection reactor illustrated on FIG. 2;

(6) FIG. 5 is a schematic illustration of the interior view of an electrodisinfection reactor in accordance with at least one embodiment of the invention; and

(7) FIG. 6 are schematic illustrations of the typical concentric arrangement of anodes and cathodes in an electrolysis reactor in accordance with at least one embodiment of the invention; and

(8) FIG. 7 are schematic illustrations of the typical concentric arrangement of anodes and cathodes in an electrolysis reactor in accordance with at least one embodiment of the invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

(9) In the present embodiment, now referring to FIGS. 1 and 2, a system 100 comprising a plurality of electrodisinfection reactors 110-116 is shown. In these embodiments, the reactors are arranged in a modular arrangement or configuration to make up an electrolysis unit 120. In the embodiment illustrated in FIG. 1, four electrolysis reactors are arranged in a single unit 120. In FIG. 2, two electrolysis reactors are arranged in a single unit 120. It has to be understood that the number of reactors required for treatment of fluid, will be a function of the dosage that must be applied to the concentration of microorganisms to be destroyed. Moreover, the design may be optimized with respect to other process steps and with respect to the working conditions that are being used.

(10) In another embodiment, a unit could potentially comprise 1, 2, 3, 4, 5, or even more reactors. Likewise, it is possible to have more than one unit depending on the extent of the treatment required by the fluid. Accordingly, multiple reactors and/or multiple units could be installed to achieve the objectives of disinfection. The actual configuration of the reactors in each unit may also vary and is typically left to the discretion of the client, depending on specifications and constraints such as the available footprint.

(11) Each reactor of the unit 120 are electrically powered with a power supply system 130 providing a continuous current 134. The power supply system may be controlled by a control panel 130, including a Programmable Logic Controller (PLC) and a Human Machine Interface (HMI).

(12) As illustrated on FIG. 1, the first reactor 110 is fed with the influent 122 to be treated via an inlet 124 located at the bottom of the reactor. The influent exits the reactor via an outlet 126 located at the top of the reactor 110 before entering via the inlet 124 of the second reactor 112. As shown on FIG. 2B, the reactors 110-112 are connected with flexible tubes 125. The same influent connections repeat with the third and fourth reactors (114, 116) before exiting the fourth reactor 116 via the outlet 126. A valve 128 at the exit of the unit 120 can be turned off if necessary. Each reactor has a valve 118 connected to the inlet 124 to purge the reactor when needed.

(13) Now referring to FIGS. 2, 3 and 4, the exterior of an electrolysis reactor is shown. Internal conceptions of the reactors are as those presented in the Applicants' patent application published as US 2014/0027271 A1 or US2015/0251932 A1, the content of these applications being incorporated herein by reference.

(14) According to an embodiment to the present invention, the system may also comprise two high temperature switches 140, one at the top and one at the bottom of the reactor, generally used to prevent overheating of the electrolysis reactors 110 in no-flow or in low-flow conditions. The high temperature switches are generally connected to a security relay installed in the control panel 130. In the event that one of the high temperature switches is activated due to a rise in temperature in the reactor beyond a pre-defined temperature setting, the security relay shall turn off the system and the corresponding DC power supply in order to prevent the overheating of the reactor.

(15) Still referring to FIGS. 3 and 4, the reactor is fed from an inlet 124 preferably located at the bottom of the reactor. The effluent 129 may exit the reactor 110 via an outlet 126 preferably located at the top of the reactor. As illustrated on FIG. 5, the reactor may be adapted to provide turbulent or transition type of flow rate in order to ensure a continuous cleaning of the anode(s) and cathode(s) (see also US2015/0251932 A1 cited above for more details). When quick-loading electrode cartridges are used, the reactor 110 further comprises quick-tightening bolts 170 to secure the loading top of the reactor.

(16) Now referring to FIG. 5, the interior of an electrolysis reactor 110 according to another preferred embodiment is shown. Above the inlet port 124 at the bottom of the reactor 110 is generally a flow dispersion chamber 115 that helps distributing the rising flow in an evenly fashion throughout the cross-sectional area 117 between the anode(s) 119 and the cathode(s) 121-123. The external cathode 123 can extend from the external wall of the reactor 125 or being the wall itself. Such a configuration is desired to make sure the fluid is forced through the reactive areas. As such, the only way for the fluid to make its way out of the reactor is by passing through the reactive zone of the reactor, also named electrolytic chamber 127, thereby being subjected to the electrolysis reaction. In such a configuration, no bypass is possible. Consequently, this configuration ensures that all the fluid is exposed to the electrolysis treatment.

(17) Now referring to FIG. 6, a cartridge 600 of six DAS or BOD anode rods 610 is illustrated. The rods 610 are generally inserted between an inner cathode 620 and an outer cathode 125 extending from the vertical tubular housing of the reactor (see FIG. 5). The gap 630 between anodes and cathodes where the fluid is allowed to pass and where it serves as a conductor between the two types of electrodes, allows for the electrolysis treatment to occur. This concentric arrangement between anodes and cathodes is typical of this electrolysis method.

(18) The DAS or BDD rods 610 extends from a top and bottom crown members 640-650. The crown members and rods form the cartridge 600. A nonconductive material 660 can be inserted between the rods for the sake of security.

(19) Now referring to FIG. 7, it is shown quick-loading electrode replacement cartridges that can be typically inserted into the body of the reactor having nine (9) rods (A, B and C) or fifteen (15) rods (D), and in each case a central cathode 720. Anodes and cathode extend from the crown members 740 or 750. FIG. 7 (C) shows a crown member 740 having 9 rods extending therefrom separated by an isolating member 741, whereas FIG. 6 (D) shows a crown member 750 having 15 rods extending therefrom separated by an isolating member 751.

(20) Moreover, electrical connections for the DC power supply to the electrical distribution rings (one for the cathodes and one for the anodes) are generally made at the top or the reactor, through a pair of circular holes that are drilled into the water-tight crown (see US 2015/0251932A1 for details). Various instruments may be installed in the system in order to monitor or control process parameters, such as pH, temperature, conductivity, and turbidity.

(21) According to an embodiment of the present invention, the design of the reactor may perform efficiently for treating solutions characterized by a relatively wide range of conductivity values. Design optimization of the reactor, such as the use of more than one cathode, the use of a larger useful anode area, or the use of a tighter inter-electrodes gap can gear the reactor for treatment in a lower conductivity fluid. The method according to the present invention is therefore flexible enough to be suited for disinfection in fresh water, brackish water, salt water environment or any kind of water susceptible to transport bacteria, germs, microalgae or any kind of potentially lethal microorganisms.

(22) According to one preferred embodiment of the invention, the apparatus comprises anodes which are commonly named Dimensionnally Stable Anode (or DSA). DSA are generally made of a metal support (here titanium) on which a conducting coating of iridium dioxide is applied. Titanium is generally selected for its excellent corrosion resistance related to chlorides allowing water disinfection treatment without any material risk of contamination or any substantial loss in overall product quality.

(23) The method of electrolysis according to the present invention could be performed in a single pass or through multiple passes through the unit of reactors. A unit of automated ON/OFF valves may be used to direct the fluid in a loop so that it effectively passes multiple times through the unit of reactors until the treatment is completed. The flow rate in the treatment loop and through the reactors may be controlled to optimize the treatment, and to maintain the optimal flow rate when performing electrolysis in the reactor. The flow rate in the treatment loop may also be adjusted by sizing the feed pump accordingly and through the use of an automatically controlled and modulating valve and the inlet of the feed line. Once the electrolysis treatment is completed, this modulating valve, as well as the other ON/OFF valves can be controlled to stop the treatment.

(24) According to an embodiment to the present invention, the method generally uses a flow control module in order to ensure that a transition or turbulent flow regime is maintained in the reactor throughout the treatment process. In addition, the type of flow regime will impact the collision rate in the fluid. The turbulent flow regime will generally promote the collision rate between different particles thereby increasing the kinetic energy of the fluid during electrolysis, while allowing cleaning up the surface of the anode(s) and cathode(s) on a continuous basis.

(25) According to one embodiment, the apparatus for disinfection may also comprise a feed tank equipped with level sensors and control instruments, a flow meter and an automated and modulating valve on the feed line, a modular unit of electrolysis reactors fed from the bottom and each loaded with a quick replacement electrodes cartridge, if needed.

(26) Table 1 shows the results of domestic water treatment with ECOTHOR™, with DSA anodes. While Table 2 shows the results with ANO2M anodes. Table 3 is obtained after water treatment in a cooling tower with ECOTHOR, with DSA anodes. Table 4 is the continuity of Table 3 showing additional results obtained after 30 Sep. 2015 using a pilot installed in a hospital.

(27) TABLE-US-00001 TABLE 1 results of domestic water treatment with ECOTHOR ™, with DSA anodes: DSA Raw Treated E. Coli (UFC/100 ml) (UFC/100 ml) 15 Sep. 2015 20000 <10 7 Oct. 2015 >60000 27

(28) TABLE-US-00002 TABLE 2 the results with ANO2M anodes ANO2M Raw Treated E. Coli (UFC/100 ml) (UFC/100 ml) 27 Jul. 2012 53000 <10 4 Sep. 2012 4700000 <10

(29) TABLE-US-00003 TABLE 3 Results obtained after water treatment in a cooling tower with ECOTHOR, with DSA anodes: DSA Raw Treated Treated Treated 14-08-15 4 sept. 15 15 sept. 15 30 sept. 15 (UFC/1 L) (UFC/1 L) (UFC/1 L) (UFC/1 L) Legionella spp. 10000 <3000 <3000 <3000 Legionella <3000 <3000 <3000 pneumophila serogroupe 1 Legionella <3000 <3000 <3000 pneumophila serogroupe 2-15 *Detection limit of the method: 3000 UFC/L

(30) TABLE-US-00004 TABLE 3 Results obtained after water treatment in a cooling tower with ECOTHOR, with DSA anodes: Results Legionella pneumophila Standard Legionella spp. Date (UFC/L) (UFC/L) (UFC/L) 2015 Oct. 4 <3000 10000 <3000 2015 Oct. 14 <3000 10000 <3000 2015 Oct. 21 <3000 10000 <3000 2015 Oct. 29 <3000 10000 <3000 2015 Nov. 3 <3000 10000 <3000 2015 Nov. 10 <3000 10000 <3000 2015 Nov. 16 <3000 10000 <3000 2015 Nov. 26 <3000 10000 <3000 2015 Nov. 30 <3000 10000 <3000 2015 Dec. 8 <3000 10000 <3000 2015 Dec. 15 <3000 10000 <3000 2016 Jan. 4 <3000 10000 <3000 2016 Jan. 12 <3000 10000 3000 2016 Jan. 19 <3000 10000 <3000 2016 Jan. 25 <3000 10000 <3000 2016 Feb. 1 <3000 10000 <3000 2016 Feb. 10 <3000 10000 <3000 2016 Feb. 16 <3000 10000 3000 2016 Feb. 23 <3000 10000 <3000 2016 Feb. 29 <3000 10000 <3000 2016 Mar. 9 <3000 10000 <3000 2016 Mar. 15 <3000 10000 <3000

(31) Disinfection of Wastewater or Muds

(32) The present invention is further directed to a system and a method for the bacterial disinfection of wastewater, such as wastewater having a dryness of from 0.01 to 3%. The system is the same as illustrated in the Figures used for the disinfection of water from a cooling tower.

(33) Wastewater, such as water from industrial, commercial, agricultural or merely domestic sources contains solid particles. Dryness content (or “siccité” in French) of a mud is the weight ratio between the weight of solid matter (Ms) contained in the mud and the total weight, ad expressed in percentage (%):

(34) $\frac{\mathrm{Ms}}{\mathrm{Mw}+\mathrm{Ms}}*100$

(35) Watewater having a dryness content from up to 10% is defined as a liquid mud. The present invention is particularly adapted for disinfecting wastewater having a dryness content up to 3%.

(36) The method comprises at least the steps of: a) injecting the wastewater into an electrolytic unit comprising at least one Dimensionnally Stable Anode or DSA; and b) performing an electrolytic treatment of the wastewater circulating into the electrolytic unit for at least partially kill bacteria present in the water.

(37) The invention is also directed to the use of an electrolytic unit as disclosed herein or the use of a Dimensionnally Stable Anode or DSA for disinfecting an influent of wastewater or mud, the dryness of which being up to 10%, preferably up to 5%, more preferably up to 3%, much more preferably from 0.01 to 3%.

(38) While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments and elements, but, to the contrary, is intended to cover various modifications, combinations of features, equivalent arrangements, and equivalent elements included within the scope of the appended claims.

(39) Furthermore, the dimensions of features of various components that may appear on the drawings are not meant to be limiting, and the size of the components therein can vary from the size that may be portrayed in the figures herein. Thus, it is intended that the present invention covers the modifications and variations of the invention, provided they come within the scope of the appended claims and their equivalents.