INDUSTRIAL WASTEWATER

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority under 35USC§1 19(e) of US provisional patent application no. 61/944.219 filed on February 25, 2014, the specification of which is hereby incorporated by reference.

TECHNICAL FIELD

The technical field relates to a process and an apparatus for the treatment of a flow of liquids and, more particularly, relates to a process and an apparatus for electrocoagulation treatment of aqueous liquids, such as industrial wastewater.

BACKGROUND

Electrocoagulation is an effective process for removing suspended solids, emulsified oils or heavy metals from a liquid, and involves dissolution of a metal from an electrode while simultaneously forming hydroxyl ions and hydrogen gas at another electrode. In the simplest configuration, an electrocoagulation treatment device includes two electrodes spaced from one another, with a flow of liquid being treated in between. In more recent configurations, a large number of electrode plates are used in each electrocoagulation treatment device, so that larger volumes of water may be treated. However, using a large number of electrode plates can cause several issues. One of the issues is uneven current density in the electrode plates, thereby creating preferential zones in which the liquid to be treated will preferentially flow. This has a similar effect as reducing the effective contact surface between the liquid to be treated and the electrode plates, and also creates zones of turbulence within the reactor chamber and around the electrode plates. An existing solution to the uneven current density issue includes measuring the electrical conductivity of the liquid passing between the electrodes and controlling the current voltage applied to individual electrode portions so as to maintain a substantially constant current density over all of the electrode plates. However, this solution is costly and has other drawbacks such as requiring complex electrical connections to be made within the reaction chamber.

l Another issue arises because of the need to effectively precipitate or flocculate the impurities, to be able to separate them from the liquid stream. A known solution is to add a large quantity of polymeric flocculants in order to precipitate or flocculate the impurities more easily downstream of the electrocoagulation device. However, such polymeric flocculants are often costly and it is often difficult to properly mix them to the liquid stream.

Many challenges still exist in the field of electrocoagulation treatment of aqueous liquids. SUMMARY

According to a general aspect, there is provided an electrocoagulation treatment apparatus for treating a flow of liquid, the apparatus comprising: a housing comprising at least one side wall defining a reaction chamber with an inlet port in fluid communication with the reaction chamber and connectable to a liquid supply and an outlet port in fluid communication with the reaction chamber; a first set of electrode plates housed in the reaction chamber; a second set of electrode plates housed in the reaction chamber and interleaved with the first set of electrode plates and defining liquid flow channels inbetween; a first conductive bar having a first end, a second end, being electrically connected to the first set of electrode plates and a second conductive bar having a first end, a second end, being electrically connected to the second set of electrode plates; a first set of electrical connectors, each one of the electrical connectors of the first set being operatively connected to a respective one of the first and the second ends of the first conductive bar and extending outwardly of the housing; and a second set of electrical connectors, each one of the electrical connectors of the second set being operatively connected to a respective one of the first and the second ends of the second conductive bar and extending outwardly of the housing, the electrical connectors of the first and second sets being connectable to at least one power supply to provide current to the first and second conductive bars from the first and second ends thereof.

In some implementations, the first and second conductive bars extend through the reaction chamber.

In some implementations, the electrode plates of the first set are made of a different material than the electrode plates of the second set. In some implementations, the electrode plates of the first set are sacrificial electrode plates.

In some implementations, the sacrificial electrode plates comprise aluminum-based electrode plates or iron-based electrode plates. In some implementations, the electrode plates of the second set are inert electrode plates.

In some implementations, the inert electrode plates comprise graphite electrode plates, stainless steel electrode plates or boron doped diamond electrode plates.

In some implementations, the electrode plates of the first set have a width of about 1/16" to about 1/4".

In some implementations, the electrode plates of the second set have a width of about 1/16" to about 1/4".

In some implementations, the electrode plates of the first set and the second set have a substantially similar width. In some implementations, the width of each one of the liquid flow channels is between about 1/8" and about 1/4".

In some implementations, the width of each one of the liquid flow channels is about 3/16".

In some implementations, the first conductive bar comprises stainless steel, a titanium- based alloy or a combination thereof.

In some implementations, the second conductive bar comprises made of stainless steel, titanium-based alloy or a combination thereof.

In some implementations, the first conductive bar is mounted proximal to an outlet end of the housing, and the second conductive bar is mounted proximal to an inlet end of the housing. In some implementations, the first conductive bar comprises a first set of conductive contact elements for electrically connecting the electrode plates of the first set and the first conductive bar.

In some implementations, the conductive contact elements of the first set comprise stainless steel, a titanium-based alloy or a combination thereof.

In some implementations, the second conductive bar comprises a second set of conductive contact elements for electrically connecting the electrode plates of the second set and the second conductive bar.

In some implementations, the contact surfaces of the second set comprise stainless steel, a titanium-based alloy or a combination thereof.

In some implementations, the apparatus further comprises a structural mounting bar made of a non-conductive material, to mechanically connect together the electrode plates of at least one of the first and second sets.

In some implementations, the structural mounting bar is made of a non-conductive polymer.

In some implementations, the structural mounting bar extends between the first conductive bar and the second conductive bar.

In some implementations, the housing further comprises an outlet end cover with a first injection port in fluid communication with the reaction chamber and connectable to a polymer injector and/or an additive injector.

In some implementations, the housing further comprises an inlet end cover with a second injection port in fluid communication with the reaction chamber and connectable to an additive injector.

In some implementations, the housing comprises an outlet end cover and an inlet end cover defining a respective bottleneck shaped end section of the reaction chamber with the outlet end cover including the outlet port and the inlet end cover including the inlet port.

In some implementations, the housing comprises an inner non-conductive wall surface. According to another general aspect, there is provided a method for treating a liquid with electrocoagulation, the method comprising: Injecting a flow of the liquid containing contaminants through an inlet port of an electrocoagulation cell comprising two sets of electrode plates configured in an interleaved configuration, a first one of the sets of electrode plates being electrically connected to a first conductive bar having a first end and a second end and a second one of the sets of electrode plates being electrically connected to a second conductive bar having a first end and a second end; and supplying an electric current to the first conductive bar through the first and the second end thereof and to the second conductive bar through the first and the second end thereof.

In some implementations, the electric current is DC current.

In some implementations, the electric current supplied to the first conductive bar is a positive electric current and the electric current supplied to the second conductive bar is a negative electric current. In some implementations, the electric current has a voltage of about 3V to about 40V.

In some implementations, the electric current has an intensity of about 40A to about 500A.

In some implementations, the flow of the liquid is injected at a flow rate between about 2 gpm and about 10 gpm. In some implementations, the liquid has a residence time within the reaction chamber of about 5 seconds to about 2 minutes.

In some implementations, the residence time is of about 10 seconds to about 1 minute.

In some implementations, the residence time is of about 10 seconds to about 15 seconds. In some implementations, the electrode plates of the first set are made of a different material than the electrode plates of the second set. _s

In some implementations, the electrode plates of the first set are sacrificial electrode plates. In some implementations, the sacrificial electrode plates comprise aluminum-based electrode plates or iron-based electrode plates.

In some implementations, the electrode plates of the second set are inert electrode plates. In some implementations, the inert electrode plates comprise graphite electrode plates, stainless steel electrode plates or boron doped diamond electrode plates.

In some implementations, the method further comprises injecting a non-conductive polymer to the flow of liquid downstream of the two sets of electrode plates of the electrocoagulation cell to form electro coagulated contaminant floe in the liquid. In some implementations, the method further comprises injecting an oxidizing agent into the flow of liquid.

In some implementations, the oxidizing agent is injected proximate to the inlet port of the electrocoagulation cell.

In some implementations, the oxidizing agent is injected proximate to the outlet port of the electrocoagulation cell.

According to still another general aspect, there is provided an electrocoagulation treatment apparatus for treating a flow of liquid, the apparatus comprising: a housing comprising at least one side wall defining a reaction chamber with an inlet port in fluid communication with the reaction chamber and connectable to a liquid supply, an outlet port in fluid communication with the reaction chamber, and a polymer injection port; a first set of electrode plates housed in the reaction chamber; a second set of electrode plates housed in the reaction chamber and interleaved with the first set of electrode plates and defining liquid flow channels inbetween, the first and second sets of electrode plates being connectable to at least one power supply through respective conductive bars; and a polymer injector operatively connectable to the polymer injection port, the polymer injection port being defined in the housing, downstream of the first and second sets of electrode plates.

In some implementations, the housing further comprises at least one additive injection port downstream and/or upstream of the first and second sets of electrode plates and the apparatus further comprises an additive injector operatively connectable to the at least one additive injection port.

In some implementations, the polymer injection port and the at least one additive injection port located downstream of the first and second sets of electrode plates are two separate injection ports.

According to still a further general aspect, there is provided a method for treating a liquid with electrocoagulation, the method comprising the steps of: injecting a flow of the liquid containing contaminants through an inlet port of an electrocoagulation cell including two sets of electrode plates configured in an interleaved configuration; providing an electric current to the two sets of electrode plates; and injecting a non-conductive polymer to the flow of liquid downstream of the two sets of electrode plates of the electrocoagulation cell to form electro coagulated contaminant floe in the liquid.

In some implementations, the non-conductive polymer is directly injected into the flow of liquid as a solid. In some implementations, the non-conductive polymer is solubilized or suspended in an aqueous medium prior to injection in the liquid.

In some implementations, the non-conductive polymer is solubilized in an aqueous medium at a concentration of about 0.2 ml_/L to about 1 ml_/L

In some implementations, the non-conductive polymer is injected at an injection rate of about 5 ml_/L to about 20 ml_/L.

In some implementations, the injection rate is of about 8ml_/L to about 12 mL/L.

In some implementations, the method further comprises injecting an additive to the flow of liquid, downstream and/or upstream of the electrocoagulation cell.

In some implementations, the additive comprises an oxidizing agent. In some implementations, the oxidizing agent comprises sodium hypochlorite, a peroxide, a chlorate, oxygen, ozone, fluorine, chlorine, bromine, iodine, hexavalent chromium, a permanganate or a mixture thereof. In some implementations, the peroxide comprises hydrogen peroxide. BRIEF DESCRIPTION OF THE FIGURES

Figure 1 is a perspective view of an electrocoagulation treatment apparatus in accordance with an embodiment;

Figure 2 is a side elevation view of the electrocoagulation treatment apparatus of Figure

1 ;

Figure 3 is a top plan view of the electrocoagulation treatment apparatus of Figure 1 ;

Figure 4 is a cross-section view of the electrocoagulation treatment apparatus of Figure 1 , taken along cross-section lines 4-4 of Figure 3;

Figure 4A is an enlarged view of electrode plates and channels extending inbetween, in the electrocoagulation treatment apparatus shown in Figure 1.

Figure 4B is an enlarged view of a conductive bar provided with contact surfaces, in the electrocoagulation treatment apparatus shown in Figure 1.

Figure 5 is a perspective view of an electrocoagulation treatment apparatus including two electrocoagulation treatment devices of Figure 1 mounted in a series configuration;

Figure 6 is a side elevation view of the electrocoagulation treatment apparatus of Figure

5;

Figure 7 is a top plan view of the electrocoagulation treatment apparatus of Figure 5;

Figure 8 is a cross-section view of the electrocoagulation treatment apparatus of Figure 5 taken along cross-section lines 8-8 of Figure 7; and

Figure 9 is a perspective cross-section view, fragmented, of the electrocoagulation treatment apparatus of Figure 1 , taken along cross-section lines 4-4 Figure 3.

It will be noted that throughout the appended drawings, like features are identified by like reference numerals. DETAILED DESCRIPTION

Referring to Figures 1 to 4, there is shown an embodiment of an electrocoagulation treatment apparatus 10 for treating a flow of liquid. The flow of liquid to be treated is typically an aqueous solution, suspension or emulsion which may contain different types of contaminants such as solids, emulsified oils and/or heavy metals. For example, the flow of liquid may be from an industrial wastewater stream. The apparatus 10 includes a housing 12 including a side wall 14 and two end covers 15, provided at opposed ends of the side wall 14, and defining together a reaction chamber 16. An inlet port 18 is defined in a first one of the end covers 15 and is in fluid communication with the reaction chamber 16. The inlet port 18 is connectable to a liquid supply (not shown), directly or through a liquid supply conduit (not shown) securable to the first one of the end covers

15, in fluid communication with the inlet port 18. An outlet port 20 is defined in a second one of the end covers 15 and is also in fluid communication with the reaction chamber

16. In an embodiment, after exiting from the outlet port 20, the flow of liquid may be sent to a mixer, such as a static mixer, for further precipitation or flocculation of the impurities.

The flow of liquid may also be sent to a separation unit that may include a membrane filtration device and/or a lamella clarifier. Thus, the second one of the end covers 15 can be securable to a liquid outlet conduit connectable to a mixer or a separation unit, with the outlet port 20 (not shown) in fluid communication with the liquid outlet conduit. Referring now to Figure 4, in the embodiment shown, the reaction chamber 16 can be divided into three continuously extending sections. Each one of the end covers 15 defines a substantially bottleneck shaped reaction chamber end section. A first one 22 of the reaction chamber end sections is provided at an inlet end and a second one 24 of the reaction chamber end sections is provided at an outlet end. The reaction chamber end sections 22, 24 extend toward the respective inlet and outlet ports 18, 20 and are in fluid communication therewith. This configuration allows for the liquid entering the reaction chamber 16 from the inlet port 18 to reduce its speed and for the liquid exiting the reaction chamber 16 from the outlet port 20 to accelerate. A reaction chamber intermediate section 25 extends between the two reaction chamber end sections 22, 24 and is in fluid communication therewith. In the embodiment shown, the side wall 14 is cylindrical in shape and thus, the reaction chamber intermediate section 25 has also a substantially cylindrical shape. However, it is appreciated that the shape of the housing 12 and the shape of the reaction chamber can differ from the embodiment shown. For example, the housing may be of a substantially cylindrical shape and not include the bottleneck shaped end covers 15, or the housing may include several side walls of substantially rectangular shape or any other suitable polygonal shape. In some embodiments, the housing 12 may be made of a non-conductive material such as a non- conductive polymer. In a non-limitative embodiment, the polymer is PVC. In other embodiments, the housing 12 may be made of a conductive material and is provided with a non-conductive inner lining. The inner lining may be made of a non-conductive polymer. In a non-limitative embodiment, the inner lining is made of PVC.

Still referring to Figures 4, 4A and 4B, two sets of electrode plates 26a, 26b are housed in the reaction chamber 16. The first set of electrode plates is interleaved with the second set of electrode plates, thereby defining liquid flow channels 28 in between. In some embodiments, the electrode plates of the first set are made of a different material than the electrode plates of the second set. The electrode plates of the first set may be sacrificial electrode plates which are consumed over time. For instance, and without being limitative, the sacrificial electrode plates may include aluminum-based electrode plates, iron-based electrode plates, or a combination thereof. In some embodiments, the electrode plates of the second set are inert electrode plates. For example and without being limitative, the inert electrode plates may be graphite electrode plates, stainless steel plates or boron doped diamond electrode plates. In some embodiments, the electrode plates 26a, 26b may have different shapes and may also extend further into the reaction chamber end sections 22, 24 of the housing 12. In a non-limitative embodiment, the electrode plates 26a, 26b have a width of about 1/16" to about 1/4". Narrower electrode plates 26a, 26b allow for an increased number of electrode plates 26a, 26b in the reaction chamber 16. In the embodiment shown, the width of the channels 28, i.e. the distance between two consecutive electrode plates, is substantially the same between each adjacent ones of the electrode plates 26a, 26b. In a non-limitative embodiment, the distance between two consecutive electrode plates is between about 1/8" and about 1/4". For example, the distance between two consecutive electrode plates may be of about 3/16". In the embodiment shown, to increase the contact surface in a cylindrical shaped reaction chamber 16, the electrode plates 26a, 26b in the central portion of the electrode plate pack are wider than the electrode plates 26a, 26b close to the ends of the pack. Alternatively, if the reaction chamber is of a rectangular shape, all of the electrode plates provided therein may have the same width and general dimensions.

Still referring to Figures 4, 4A and 4B, the electrode plates 26a, 26b of each one of the sets are physically and electrically connected together by at least one conductive bar 30, 32 (at least one conductive bar for each one of the sets). In some embodiments, the first and second conductive bars 30, 32 extend through the reaction chamber 16. In the embodiment shown, the first conductive bar 30 is electrically connected to the first set 26a of electrode plates while being electrically isolated from the second set 26b of electrode plates. Similarly, the second conductive bar 32 is electrically connected to the second set 26b of electrode plates while being electrically isolated from the first set 26a of electrode plates. By electrically isolated, it is meant that: the first conductive bar 30 is not directly electrically connected to the electrodes 26b of the second set by physical connection, but current may still pass therebetween through the electrically charged liquid being treated in the reaction chamber 16; and that the second conductive bar 32 is not directly electrically connected to the electrodes 26a of the first set, but current may still pass therebetween, through the electrically charged liquid being treated in the reaction chamber 16. The conductive bars 30, 32 are made of a conductive material. For instance, and without being limitative, the conductive bars 30, 32 may be made of stainless steel, a titanium-based alloy or a combination thereof. In the embodiment shown, the conductive bar 30 is mounted close to an inlet end of the housing 12, including the inlet port 18, and the conductive bar 32 is mounted close to the outlet end of the housing 12, including the outlet port 20. It is appreciated that the configuration of the conductive bars 30, 32 can vary from the embodiment shown.

In some embodiments, the first and second conductive bars 30, 32 are provided with contact elements 33. In some embodiments, the contact elements 33 are conductive contact elements to ensure that the electrode plates 26a of the first set are electrically connected to the first conductive bar 30 and that the electrode plates 26b of the second set are electrically connected to the second conductive bar 32. In such case, the first conductive bar 30 is spaced apart from the electrode plates 26b of the second set while the second conductive bar 32 is spaced-apart from the electrode plates 26a of the first set. In a non-limiting embodiment, the conductive contact surfaces 33 are made of a metal or alloy resistant to corrosion such as stainless steel, a titanium-based alloy or a combination thereof.

Alternatively, the contact elements 33 can be non-conductive contact elements, such that the electrode plates 26a of the first set are electrically isolated from the second conductive bar 32; and the electrode plates 26b of the second set are electrically isolated from the first conductive bar 30. In such case, the electrode plates 26a of the first set are in direct contact with the first conductive bar 30, and the electrode plates 26b of the second set are in direct contact with the second conductive bar 32. This configuration ensures that the second conductive bar 32 is not directly electrically connected to the electrode plates 26a of the first set and that the first conductive bar 30 is not directly electrically connected to the electrode plates 26b of the second set. In a non-limiting embodiment, the non-conductive contact elements are made of non- conductive polymer such as PVC.

In some embodiments, the electrode plates 26a, 26b can be provided with recesses defined in a respective one of their ends to prevent physical contact between them and the one of the conductive bars 30, 32 from which they are not electrically connected.

Now referring to Figure 9, in the embodiment shown, each one of the electrode plates 26a, 26b comprises at least two apertures defined therein. A respective one of the conductive bars 30, 32 extends through a respective one of the apertures defined in the electrode plates 26a, 26b. For each electrode plates 26a, 26b, a first one of the apertures has a diameter greater than a second one of the apertures. Thus, the first conductive bar 30 is inserted through the smaller diameter apertures of the electrode plates 26a of the first set and through the larger diameter apertures of the electrode plates 26b of the second set. Thus, the first conductive bar 30 is spaced apart from the electrode plates 26b of the second set and in contact with the electrode plates 26a of the first set, directly and/or through the conductive contact elements 33. Similarly, the second conductive bar 32 is inserted through the smaller diameter apertures of the electrode plates 26b of the second set and through the larger diameter apertures of the electrode plates 26a of the first set. Thus, the second conductive bar 32 is spaced apart from the electrode plates 26a of the first set and in contact with the electrode plates 26b of the second set, directly and/or through the conductive contact elements 33. In the embodiment shown, each one of the conductive contact elements 33 is an annulus having an inner diameter substantially equal to the smaller diameter apertures of the electrode plates 26a, 26b, and an outer diameter smaller than the larger diameter apertures of the electrode plates 26a, 26b.

Two sets of electrical connectors 34, 36 are also provided. Each one of the electrical connectors of the first set 34 is operatively connected to a respective one of the ends of the first conductive bar 30, and each one of the electrical connectors of the second set 36 is operatively connected to a respective one of the ends of the second conductive bar 32. The electrical connectors 34, 36 extend outwardly of the housing 12 and are connectable to a power supply, in order to provide current to the first and second conductive bars 30, 32 from each end thereof. In a non-limiting embodiment, the electrical connectors 34, 36 are made of a metal or alloy resistant to corrosion such as stainless steel, a titanium-based allow or a combination thereof.

The electrical connectors 34, 36 can extend outwardly of the housing 12 through holes defined in the side wall 14. In such case, suitable seals are provided to prevent liquid leaks there between. In the embodiment shown, the electrical connectors 34, 36 extend outwardly of the housing 12 through a casing 38. Optionally, and to provide current to the conductive bars 30, 32 without leakage of the liquid inside of the reaction chamber 16, an O-ring (not shown) may be provided at the base of each of the casings 38. In a non-limitative embodiment, the casings 38 are made of a metal or alloy resistant to corrosion such as stainless steel.

As mentioned above, electric current is provided to the first and second conductive bars 30, 32 from each end thereof. The electric current is supplied from at least one power supply (not shown) to the first and second conductive bars. Alternatively, each one of the first and second conductive bars 30, 32 can be connected to its own power supply. In an embodiment, positive electric current is supplied to the first conductive bar 30 while negative electric current is provided to the second conductive bar 32, through their respective ends.

In an optional configuration, at least one structural mounting bar 40 may be provided to connect together the electrode plates 26a, 26b of at least one of the sets. The structural mounting bar 40 does not extend outwardly of the reaction chamber 16. In the embodiment shown, two structural mounting bars 40 are provided, spaced-apart from one another, and extending substantially parallel to the first and second conductive bars 30, 32, between the first and second conductive bars 30, 32. The structural mounting bar 40 is made of a non-conductive material. For instance and without being limitative, the structural bars may be made of a non-conductive polymer. In an embodiment, the non- conductive polymer may be an aliphatic polyamide such as Nylon™.

In the embodiment shown in Figures 1 to 4, the end cover 15 of the housing 12 including the outlet port 20 is further provided with a first injection port 44 in fluid communication with the reaction chamber 16, close to the outlet port 20. The first injection port 44 is connectable to a polymer injector (not shown) for injecting polymer flocculants in the reaction chamber 16, downstream the electrode plates 26a, 26b; and/or is connectable to an additive injector (not shown) for injecting reaction additives to assist in the electrochemical reactions. The reaction additives can include an oxidizing agent. Non- limitative examples of oxidizing agents include sodium hypochlorite, peroxides (e.g. hydrogen peroxide), chlorate, oxygen, ozone, fluorine, chlorine, bromine, iodine, hexavalent chromium, potassium permanganate or a mixture thereof.

Similarly, in the embodiment shown in Figures 1 to 4, the end cover 15 of the housing 12 including the inlet port 18 is further provided with a second injection port 45 in fluid communication with the reaction chamber 16, close to the inlet port 18. The second injection port 45 is connectable to an additive injector (not shown), for injecting reaction additives to assist in the electrochemical reactions. The reaction additives can be similar to the additives described above.

In the embodiment shown, and without being limitative, the first injection port 44 is located at the narrower end of the bottleneck defined by the outlet end of the housing 24, where the liquid flow exiting the reaction chamber 16 is loaded with charged particles and is picking up speed due to the narrowing of the housing 12. Similarly, in the embodiment shown, and without being limitative, the second injection port 45 is located at the narrower end of the bottleneck defined by the inlet end of the housing 24, where the liquid flow enters the reaction chamber 16 and is slowed down due to the enlarging of the housing 12. The polymer flocculants may be cationic, anionic or non-anionic polymers. For example and in a non-limitative embodiment, the polymer flocculants may include a polyacrylamide or derivatives thereof. The polyacrylamide derivatives include but are not limited to anionic polyacrylamides and cationic polyacrylamides. Anionic polyacrylamides may be prepared by copolymerisation of acrylic acid with acrylamide, or by partial hydrolysis of polyacrylamide. Cationic polyacrylamides may be prepared by copolymerisation of acrylamide with quaternary ammonium derivatives of acrylamide, the type of cationic material being variable depending on the application. The polymer flocculants may be injected into the liquid stream to be treated via the first injector port 44, as described above, or may alternatively be injected into the liquid stream downstream of the electrocoagulation apparatus 10 (i.e., downstream of the outlet port 20.

Now referring to Figures 5 to 8, two electrocoagulation treatment devices are connected in a series configuration to provide an electrocoagulation treatment apparatus 50. In an exemplary embodiment, the connection between the two electrocoagulation devices is made by removing the outlet end cover 15, including the outlet port 20, from the housing 12 of an upstream electrocoagulation apparatus 10; and by removing the inlet end covers 15, including the inlet port 18, from the housing 12 of a downstream electrocoagulation apparatus 10. The two truncated electrocoagulation treatment devices thereby obtained are connected in a series configuration to provide the electrocoagulation treatment apparatus 50. In an optional configuration not shown in the Figures, two electrocoagulation treatment devices may also be connected in a parallel configuration. It is appreciated that more than two electrocoagulation treatment devices can be mounted in a series and/or parallel configuration(s).

In another embodiment, there is provided a method for treating a liquid with electrocoagulation. A flow of the liquid containing contaminants is injected through the inlet port 18 of an electrocoagulation cell of Figures 1 to 4 or Figures 5 to 8 at a flow rate. In non-limitative embodiments, the flow rate may be of about 2 gpm (gallons per minute) to about 10 gpm for each electrocoagulation apparatus 10.

An electric current is supplied to the first and second conductive bars 30, 32. In an embodiment, the electric current is supplied to the first and second conductive bars 30, 32 from each end thereof. In an embodiment, the electric current is DC current, has a low voltage and a high intensity. For instance and without being limitative, the current supplied may have a voltage of about 3 V to about 40 V or of about 3V to about 10 V, and intensity of about 40 A to about 500 A.

The liquid is contacted with the electrode plates 26a, 26b within the reaction chamber 16. In non-limitative embodiments, the residence time of the liquid within the reaction chamber 16 may be of about 5 seconds to about 2 minutes, or of about 10 seconds to about 1 minute, or again of about 10 seconds to 15 seconds.

A non-conductive polymer may be injected to the flow of liquid downstream of the two sets of electrode plates 26a, 26b of the electrocoagulation cell to help with the formation of electrocoagulated contaminant floe in the liquid. The polymer may be injected to the flow of liquid directly as a solid or may be solubilized or suspended in an aqueous medium beforehand. For instance and in a non-limitative embodiment, the polymer flocculants are injected in the form of an aqueous solution. The polymer flocculants may therefore be diluted at a concentration of about 0.2 mL/L to about 1 mL/L or of about 0.5 ml_/L The resulting solution may then be injected at an injection rate of about 5 ml_/L to about 20 ml_/L, or of about 8 ml_/L to about 12 ml_/L, or again of about 10 ml_/L

It is appreciated that features of one of the above described embodiments can be combined with the other embodiments or alternative thereof.

Moreover, although the embodiments of the electrocoagulation treatment apparatus and corresponding parts thereof consist of certain geometrical configurations as explained and illustrated herein, not all of these components and geometries are essential and thus should not be taken in their restrictive sense. It is to be understood, as also apparent to a person skilled in the art, that other suitable components and cooperation thereinbetween, as well as other suitable geometrical configurations, may be used for the electrocoagulation treatment apparatus, as it will be briefly explained herein and as can be easily inferred herefrom by a person skilled in the art. Moreover, it will be appreciated that positional descriptions such as "above", "below", "left", "right" and the like should, unless otherwise indicated, be taken in the context of the figures and should not be considered limiting. Several alternative embodiments and examples have been described and illustrated herein. The embodiments of the invention described above are intended to be exemplary only. A person of ordinary skill in the art would appreciate the features of the individual embodiments, and the possible combinations and variations of the components. A person of ordinary skill in the art would further appreciate that any of the embodiments could be provided in any combination with the other embodiments disclosed herein. It is understood that the invention may be embodied in other specific forms without departing from the spirit or central characteristics thereof. The present examples and embodiments, therefore, are to be considered in all respects as illustrative and not restrictive, and the invention is not to be limited to the details given herein. Accordingly, while the specific embodiments have been illustrated and described, numerous modifications come to mind without significantly departing from the spirit of the invention. The scope of the invention is therefore intended to be limited solely by the scope of the appended claims.