CA2505011C - Apparatus and method for wastewater treatment by means of electroflotation and/or electrocoagulation - Google Patents

Abstract

The invention relates to a wastewater treatment method. The inventive method comprises the following steps: (a) a reactor is obtained, consisting of an inlet, an outlet, at least one set of electrodes comprising at least one anode and at least one cathode, and a means of circulating the water to be treated between the electrodes in an upward direction; and (b) the water to be treated is circulated between the electrodes of at least one set in an upward direction, such as to subject the water to an electric current and, thus, treat the water by means of electrocoagulation or electroflotation, thereby generating sludge containing at least one pollutant from the water to be treated and treated water. The sludge thus generated is subsequently separated from the treated water. The invention also relates to an apparatus which is used to perform said method. The method and the apparatus can be used effectively to treat wastewater with different compositions and which can contain a wide range of contaminants.

Description

WO 2004/05056

2 PCT / CA2003 / 001882 APPARATUS AND METHOD FOR TREATING WASTE WATER BY ELECTROFLOTATION AND / OR
electrocoagulation FIELD OF THE INVENTION
The present invention is related to the field of electrochemistry applied to the treatment of wastewater. In particular, the invention relates to a apparatus and method for treating wastewater.
PRIOR ART
Due to the relatively recent concerns of society concerning pollution; industries have had to develop ways innovators to comply with environmental regulations.
Electrocoagulation has therefore reappeared as a viable technology.
Coagulation is one of the most important physicochemical chemicals used in the treatment of water. This process is particularly in use to cause the destabilization and aggregation of small particles into more large particles. Water contaminants such as ions (heavy metals) and the colloids (organic and inorganic) are mainly retained in solution by electric charges. It has been shown that colloidal systems could destabilized by the addition of ions having a charge opposite to that of the colloid (Benefield LD, JF Judkins and Weand, BL 1982. Process Chemistry for Water and Wastewater Treatment. Prentice - Hall Inc., p. 212). Colloids so destabilized can be aggregated and subsequently removed by sedimentation and or filtration.
Coagulation can be by chemical or electrical means.
Chemical coagulation is nowadays less used because of the costs high associated with chemical treatments. The high costs are explained by (the use of chemicals needed for coagulation and also by the broad volume of sludge and hazardous waste of heavy metals such as hydroxides of metals that are thus generated. Chemical coagulation processes including coagulants such as alum, lime and / or polymers have been used during last few decades.
Electrocoagulation is a process based on principles scientists in which contaminants of water are subjected to strong fields thus causing oxidation and reduction reactions. This process is able to remove more than 99% cent of some heavy metal cations.
Of Moreover, the applied electric field allows under certain conditions to obtain a bactericidal effect. The method also makes it possible to precipitate colloids loaded and to remove significant amounts of other ions, colloids and emulsions.
Although the mechanism of electrocoagulation is very similar to that of chemical coagulation, the cationic species responsible for the neutralization of the surface of the charges and the characteristics of the waves electrocoagulants differ in each of these processes. An electrocoagulated flow tends to contain less bound water, it is more resistant to shear and more easily filterable. Electrocoagulation can often neutralize ions and charges of particles, allowing contaminants or pollutants to precipitate. he is so possible to reduce the contaminant content to lower concentrations those reachable via chemical precipitation processes. At the same time, it is sometimes possible to replace and / or reduce the use of agents chemical expensive such as polymers or metal salts.
The published US application number 2002/0040855 describes a process in which water is treated by electrocoagulation. By against, in this process, the sludge must be treated in a clarifier or sedimentation and this process sometimes requires the use of flocculants.
U.S. Patent No. 6,488,835 discloses a method of treating liquids by electrocoagulation. After this treatment, the liquid Electrolytic can go through a development chamber where the liquid can be treated by additives. Alternatively, the electrolytic liquid may be subjected to a treatment

3 secondary separation in order to proceed to solid liquid separation.
This separation can be done with purifiers, filters, separators centrifuges, or centrifuges. Each . of these devices can be in use separately or in combination.
The published US application numbered 2003/0070919 describes an electrocoagulation reactor comprising electrodes defining of the openings allowing liquid to pass from one zone to another in a stack electrode. Two types of electrodes are used, some with opening central and others each comprising a plurality of openings peripheral devices.
These two types of electrodes are alternated in the electrode stack. Such arrangement is chosen so as to create turbulent flow of the liquid which promotes self-cleaning of the electrodes. On the other hand, the treated water rests then in a development tank where flocs are generated. Static mixer or polymers are also used to increase floc formation and the 15. decantation.
SUMMARY OF THE INVENTION
The present invention aims to provide a method for treatment of wastewater while overcoming the drawbacks of the techniques high mentioned.
Another object of the invention is to provide a simple method in which the sludge generated from the treatment of wastewater by a covering electric could be easily separated from the treated water.
The present invention also aims to provide a device allowing the treatment of wastewater while mitigating the disadvantages of techniques mentioned above.

4 Another object of the invention is to provide a simple apparatus allowing to easily separate the sludge generated from the treated water without to have use of flocculating agents or complex mechanical means.
According to a first aspect, (invention relates to a treatment method wastewater characterized in that:
a) there is provided a reactor comprising an inlet, an outlet, at least one electrode block comprising at least one anode and at least one. a cathode, and means for the water to be treated to circulate between electrodes selen an ascending sense; and b) the water to be treated is passed between the electrodes of the at least one block in an upward direction so as to subject the water to a current electric and thus treat the water by electrocoagulation or electroflotation, generating so a mud containing at least one pollutant included in the water to be treated and a water treated and in that the generated sludge is separated from the treated water.
According to a second aspect, the invention relates to a ~ method of wastewater treatment characterized in that:
a) there is provided a reactor comprising an inlet, an outlet, at minus two electrode blocks each having at least one anode and at least one cathode, and means for the water to be treated to circulate between electrodes in an ascending sense;
b) the water to be treated is passed between the electrodes of a first block in an upward direction so as to subject the water to a current electric and thus treat the water by electrocoagulation or electroflotation, generating so a mud containing at least one pollutant included in the water to be treated and a first water treated; and c) the treated water obtained in step (b) is passed between the electrodes of a second block in an upward direction so as to submit water to an electric current and thus treat the water by electrocoagulation or electroflotation, thus generating a sludge containing at least one pollutant included in the water at treat and a second treated water, and in step (b) and / or (c), the generated sludge is separated from the water treated.
According to a third aspect, (invention relates to a

5 wastewater treatment including a reactor having an inlet for water to be treated and an outlet for treated skin, and comprising at least one block of electrodes, the block having at minus one anode and at least one cathode, the electrodes being arranged way substantially parallel and they are spaced apart. so to define between they a space allowing the passage of the water to be treated, thus generating, when the water treat is subjected to an electric current, a sludge comprising at least one pollutant contained in the water to be treated and treated water, the reactor comprising also a means allowing (water to flow between the electrodes in one direction ascending; and means for separating the generated sludge from the treated water.
The Applicant discovered unexpectedly and unpredictably that using the processes and apparatus mentioned above, it was possible to decontaminate wastewater by obtaining a satisfactory abatement rate of various contaminants.
The expression "circulating between the electrodes in an ascending direction"
as used by the Applicant means that the water circulates between electrodes, from bottom to top of these.
The sludge generated in the processes of the invention can be aspirated by 15 ~ a suction means to be separated from the treated water. Way to sucking is preferably a vacuum cleaner or a pump. Alternatively, the generated sludge can separated from the treated water by the action of a conveyor comprising a strap in movement, to which the mud adheres in order to be conveyed and separated from the water treated. The belt may be a water permeable membrane. Water to be treated can be passed several times between the electrodes of one or more blocks.

6 Without limitation, the methods of the invention may cause a abatement rate of at least 85% of the suspended solids contained in the water to be treated. The methods of the invention can also cause a rate of at least 85%, preferably at least 95% and more 5. Preferably at least 98% of the turbidity of the water to be treated. The processes of the invention may also cause an abatement rate of at least 85%, preferably at least 95% and even more preferably at least 98%, orthophosphates included in the water to be treated. The methods of the invention can also cause a rate of at least 85% and preferably at minus 95%, phosphorus included in the water to be treated. The processes of the invention can also cause an abatement rate of at least 85% and preferably at 95% of the total nitrogen I ~ jeldahl ~ of the water to be treated. The processes of the invention can also cause an abatement rate of at least 75% and preferably at 90%, of the biochemical oxygen demand (for 5 days), water to treat.
In the apparatus of the invention, the reactor preferably comprises means for allowing water to flow in order to limit turbulence. This medium can be at least a baffle consisting of at least two walls or a baffle network constituted ~ by several walls. The reactor can be connected preferably by a conduit, to a feed tank for contain a water to treat. The reactor may include a feed compartment connected to feed tank, preferably by a conduit. Water to be treated contained in the supply tank can be fed to the reactor, preferably at supply compartment, by means of a means of conveying the water from the supply tank to the reactor, preferably through a pump.
Alternatively, water can be conveyed from the supply tank to reactor by gravity.
In the methods and apparatus of the invention, water circulates preferably between the electrodes so as to minimize turbulence, encouraging

7 thus the flotation of the generated sludge. To obtain such a flotation where the contaminant particles are substantially all grouped together at the surface of treated water, greatly facilitates the step of separating the mud and treated water. Thus, it is possible to separate the mud formed from the water treated by a simple means of suction or a simple means of filtration without resorting to of the flocculants, additional sedimentation chambers or any other means complex mechanical liquid / solid separation. Without limitation, the debit average water in the reactor can be less than 8 liters per minute for a volume from about 7000 to about 11500 cm3 and preferably from about 8500 to approximately 10500 cm3, representing the total volume of spaces between electrodes (preferably between 18 and 26 electrodes) of a block (having the shape of a prism rectangular and preferably a substantially cubic shape).
preferably the flow rate is approximately 0.5 to 5 liters per minute and, more preferably 1 to 3 liters per minute. In the light of these non-limiting examples, the skilled man understand that it is possible to minimize water turbulence by using other values for water flow and other values for the surface total electrodes. The skilled man will also understand that minimizing the Turbulence of the water favors the flotation of the mud. The electrodes are preferably flat electrodes. The electrodes are preferably submerged in the water so as to allow better flotation of the mud. The electrodes may be solid, grid-shaped or comb-shaped.
The electrodes of the blocks are preferably connected to a current generator continuous, alternating or pulsed. Preferably all electrical connections are made individually for each electrode.
In the methods of the invention, one or more blocks of electrodes can be used to perform electrocoagulation or Electroflotation.
When a block is used to treat water by electrocoagulation, its electrodes preferably include (aluminum, calcium or iron.
Alternately, its electrodes may comprise at least one anode including a mixture oh comprising a source of Ca + ions, a carrier and water. When a block is in use to treat the water by electroflotation, its electrodes are preferably of the inert electrodes. Inert electrodes can be electrodes including platinum or electrodes comprising titanium coated with iridium. It will appear obvious to those skilled in the art that other known inert electrodes may also be used.
In the process according to the second aspect of the invention, water is preferably treated by electrocoagulation in step (b) and by electroflotation to step (c). The electrodes of the first block preferably include (aluminum, calcium or iron: alternatively, the electrodes of the first block may comprise at least one anode including a mixture comprising a source of Ca2 + ions, a carrier and water. The electrodes of the second block are preferably inert electrodes. Inert electrodes can be electrodes comprising platinum or electrodes comprising coated titanium iridium. Step (b) and / or (c) may be repeated several times.
In the apparatus of the invention, the electrodes may comprise aluminum, calcium or iron, or be inert electrodes.
Alternately, the electrodes may comprise at least one anode including a mixture comprising a source of Caa + ions, a carrier and water. One or more blocks) electrodes can be used to perform electrocoagulation or a Electroflotation. When a block is used to treat water by electrocoagulation its electrodes preferably include (aluminum, calcium or iron.
When a block is used to treat the water by electroflotation, its electrodes are preferably inert electrodes. Inert electrodes can be electrodes comprising platinum or electrodes comprising coated titanium iridium. Preferably, the reactor comprises two blocks, one having electrodes comprising aluminum, calcium or iron, and the other having electrodes inert. Inert electrodes may be electrodes comprising platinum or electrodes comprising titanium coated with iridium. The block intended for treat electroflotation water and having inert electrodes is preferably downstream of the block for treating water by electrocoagulation and having electrodes comprising aluminum, calcium or iron.
In the apparatus of the invention, the means for separating the sludge generated from treated water may be a sludge collector comprising a recovery tank for recovering the sludge and having a carcass provided with an upper orifice, a lower outlet for drain the mud and an inlet with a first duct connected to the reactor, the entrance being disposed at a height between (upper orifice and lower outlet;
- a means of suécion connected by a second conduit to (orifice, upper the recovery tank and allowing the reactor sludge to be recovery tank.
The sludge recovery tank preferably comprises a horizontal wall disposed at a predetermined height between (entrance and exit lower and defining an upper chamber and a lower chamber. The wall horizontal being perforated so as to allow the passage of the mud recovered from the superior room to the lower room.
In the apparatus of the invention, the reactor can include means for recycling treated water leaving the reactor outlet to the feed compartment for additional treatment. The entrance to reactor is preferably provided with a separating means preventing coarse particles contained in the water to be treated to penetrate the reactor. This means of separation may be a grid comprising meshes having predetermined dimensions. The reactor may also include a means allowing the water contained in the feed tank to be reactor.
This means can be a pump.
In the methods and apparatus of the invention, when an anode comprising a source, Ca2 + is used, Ca2 + ions can be present in the mixture in a proportion of about 2% to about 30% and preferably from about 5% to about 20% by weight, based on the total weight of the mixture.
The Ca 2+ ion source preferably comprises calcium carbonate (CaCO 3), lime (Ca (OH) a) or a mixture of these. Preferably, the source of Ca2 + is made of calcium carbonate. When the source of Ca2 + ions is the Calcium carbonate, the latter may be present in the mixture in a from about 10% to about 50% and preferably about 25% to about 40% by weight, based on the total weight of the mixture. Support can to be present in the mixture in a proportion of about 40% to about 0% and preferably from about 45% to about 65% by weight, based on weight total 10 of the mixture. The support can comprise as components a clay limoneus, a ceramic or a cement, in combination with a material driver. This conductive material may advantageously be a residue industrial.
The conductive material included in the support can be chosen from the group consisting of graphite, coke, carbon fibers, iron and a mix of these latter. Graphite is preferred. Water can be present in the mix in a proportion of about 2 to about 30% and preferably about 10% and about 20% by weight, based on the total weight of the mixture.
According to a first preferred embodiment of the apparatus for (Invention, the reactor comprises a single block of electrodes.
means allowing water to flow between the electrodes in one direction ascending comprises a substantially vertical first wall disposed upstream of the block electrodes, and defining a lower passage for receiving treat. The reactor can also include a feed compartment upstream of the first wall. This feed compartment is used to collect water at treat from the feed tank. Preferably, the reactor comprises also a means of allowing water to flow so as to minimize the turbulence. The means allowing water to flow in order to minimize the turbulence can allow the water to be treated from the reservoir power supply flow in order to minimize turbulence before reaching the first wall, and may include a second substantially vertical wall disposed between the reactor inlet and the first wall. The second wall defines a passage upper to receive the water to be treated. The second wall substantially vertically preferably allows to control the level of water in the reactor.
The reactor may also include a containment compartment of treated skin disposed downstream of the electrode block. The means by which water from flowing so as to minimize turbulence can also include a third substantially vertical wall disposed between the block of electrodes and retaining compartment and defining a lower passage for receiving Skin treated. This third wall allows treated water from the block electrodes flow in order to minimize turbulence before entering the compartment of detention.
The means allowing water to flow in order to minimize the turbulence can also include a fourth wall substantially vertical disposed upstream of the third wall. The third and fourth walls define between them another space allowing water to flow from way to minimize turbulence. The fourth wall defines a overpass available a predetermined height so as to prevent the mud from entering the other space.
Preferably, the electrode block is elevated in relation to the bottom of the reactor, so as to define an additional space communicating with (space between the electrodes and allowing the water to be treated to circulate under the electrodes. The electrode block is preferably mounted on a support resting removable way on the bottom of the reactor and allows the water to be treated to pass to through (additional space) Alternatively, the support can be fixed, so removable at no, at least one of the walls of the reactor and allows the water to treat of pass through (extra space.
According to a second preferred embodiment of the apparatus of (Invention, the reactor can comprise a single electrode block and comprises preferably a means to allow the water to flow so as to minimize the turbulence. The electrode block can be elevated relative to the bottom of the reactor in order to define an additional space communicating with (space between the electrodes and allowing the water to be treated to circulate under the electrodes. The way allowing water to flow between the electrodes in an upward direction can to understand a conduit connecting the entrance of the reactor with the space additional.
Preferably, the means for skin to peel off so as to minimize the turbulence comprises a transitional reservoir disposed downstream of the block electrode, and communicating with it, the transitional reservoir allows for collect the water having been treated by the electrode block. Preferably, the block electrode is mounted on a support resting removably on the bottom of the reactor and allowing the water to be treated to pass through (extra space.
Alternatively, the support can be fixed, removably or not, to less one of the walls of the reactor and allows the water to be treated to pass through (space additional. Preferably, the reactor further comprises a compartment feedstream upstream of the electrode block.
According to a third preferred embodiment of the apparatus of (Invention, the reactor may comprise a first electrode block and a second electrode block disposed downstream of the first electrode block. The way allowing to circulate between the electrodes in an upward direction can understand a first substantially vertical wall disposed upstream of the first block electrodes and defining a lower passage for receiving the water at treat. The reactor can also include a feed compartment upstream of the first wall. This feed compartment is used to collect water at treat from the feed tank. Preferably, the reactor comprises also a means to allow water to flow in order to minimize the turbulence. The means allowing water to flow in order to minimize the turbulence can allow. to the water to be treated from the reservoir power supply flow in order to minimize turbulence before reaching the first wall, and may include a second substantially vertical wall disposed between the reactor inlet and the first wall. The second wall defines a passage upper to receive the water to be treated.
The substantially vertical second wall preferably allows to control the level of the water in the reactor. The reactor can also include a treated skin containment compartment located downstream of the second block of electrodes. The means allowing water to flow so as to minimize the turbulence preferably comprises a third wall substantially vertical arranged between the second electrode block and the holding compartment and defining a lower passage for receiving treated water. The third wall allows treated water from the second electrode block to flow from way to minimize turbulence before entering the restraint compartment.
The means allowing water to flow in order to minimize the turbulence can also include a fourth wall substantially vertical disposed upstream of the third wall. The third and fourth walls define between them another space allowing water to flow from way to minimize turbulence. The fourth wall defines a overpass available a predetermined height so as to prevent the mud from entering the other space. Preferably, the electrode blocks are separated by a means allowing to flow from bottom to top between the electrodes of the second block. The way separating the electrode blocks and allowing water to flow from the bottom to the top between the electrodes of the second block may also include a fifth wall substantially vertical defining a lower passage intended for receive water processed from the first electrode block. Moreover, this means can understand a sixth wall disposed upstream of the fifth wall. The fifth and sixth wall define between them an additional space allowing the skin of flow to minimize turbulence. The sixth wall defining a passageway disposed at a predetermined height so as to prevent the mud to enter the additional space.

The electrode blocks are preferably elevated with respect to bottom of the reactor so that the electrode blocks each define a additional space communicating with (space between their electrodes and allowing the water to be treated to circulate under the electrodes. One of the blocks electrodes may be mounted on a support resting removably on the background of the reactor and allowing the water to be treated to pass through additional. Alternatively, the support can be fixed, removably at no, at least one of the walls of the reactor and allows the water to be treated to will pass through (extra space.
In the apparatus according to the first and third embodiments preferred embodiment of the invention, the electrodes are preferably arranged according to a plan and the global displacement of the water in the reactor from the inlet to the outlet perpendicular to this plane. The reactor can understand also another wall disposed downstream of the third wall, the other wall defining a overpass and to control the level of water in the reactor.
According to a fourth preferred embodiment of the apparatus for (Invention, the reactor may comprise a first electrode block and a second electrode block disposed downstream of the first electrode block.
Preferably, the reactor comprises means allowing water to flow so as to minimize the turbulence: The electrode blocks are preferably raised above basically of the reactor so as to define an additional space between each of the blocks and the background. The extra space communicates with (space between the electrodes and allows the water to be treated to circulate under the electrodes. The means by which Skin to flow between the electrodes in an upward direction may include a pipe connecting the reactor inlet with the extra space of the first block of electrodes. Each block of electrodes is preferably mounted on a support resting removably on the bottom of the reactor and allowing the water to treat of pass through (extra space.) Alternatively, the support can be fixed, detachably to the non, to at least one of the walls of the reactor and allows Skin to deal with getting through (extra space.
In the apparatus according to the fourth preferred embodiment of the invention, the means allowing water to flow so as to minimize the The turbulence may comprise a first transition reservoir disposed downstream of first electrode block, and communicating with the latter. The first tank Transition allows to collect water that has been treated by the first block electrode. In addition, this means may also include a second tank transition electrode disposed downstream of the second electrode block, and communicating with this 10 last. The second transitional tank is used to collect water having been treated by the second block of electrodes.
The means for separating the sludge generated from treated water can also include a conveyor having a portion disposed in the first tank of transition. The conveyor comprises a moving belt to which the The sludge adheres to be transported and separated from the treated water. The way allowing to separate the generated sludge from the treated water may also include a conveyor having a portion disposed in the second transition tank. The conveyor includes a moving belt to which the mud adheres in order to be transported and separated from the treated water. The belt can be a membrane permeable to water.
In the apparatus according to the fourth preferred embodiment of the invention, the conveyor is preferably in communication with a manifold of mud including a recovery tank for recovering the sludge and having a carcass provided with an inlet and an outlet for draining the sludge; and a suction means connected by a duct to the reservoir of recovery and to convey the mud from the entrance to the interior of the carcass.

,, iv. "~

The conveyor of the first or second block of electrodes is preferably provided with a filter. This filter is used to filter water from of first or second block of elecirodes before it enters the tank of corresponding transition. The means by which water circulates between electrodes in an upward direction may comprise a conduit connecting the first transition tank with the extra space of the second block electrode. This conduit may also include a diversion device for conveying the water treated from the first transitional reservoir to the space under the electrodes of the first block for further processing. The reactor can ~ also include a tank intended to receive the treated water, the tank communicating on the one hand with the second transitional reservoir through of one, duct and secondly with the outlet for treated water.
In the apparatus of the invention, the valves of the ducts, the generator current and the pump can be connected to a control system. This This system can be used to automatically control the input Skin to process and the output rate of treated water into the device, as well as the current applied to the electrodes. The apparatus could be raised from the ground and placed on a support where the ducts of the various tanks are connected. Electrodes can have a height of 15 to 100 cm, preferably between 20 and 50 cm.
The electrodes may have a width of 15 to 100 cm, preferably included between 20 and 50 cm. The thickness of these electrodes can be from 1.5 to ~ mm, preferably between 1.6 and 5 mm. An electrode block includes preferably between 14 'and 30 and more preferably between 1 ~ and 26 electrodes.
The space between two adjacent electrodes in the block can be 0.5 to 1.5 cm and preferably between 0.7 and 1.1 cm.
In the apparatus of the invention, the reactor may comprise a means allowing the polarity inversion of the electrodes and / or a means allowing a self-cleaning of the electrodes. The means for cleaning electrodes may consist of a device generating vibrations and preferably of the ultrasound. The feed tank may also be provided with a regulator of pH. The reactor may include an airtight lid with a chimney allowing evacuation of the gases produced in the reactor. The reactor comprises preferably a device for recovering the gases produced. The support electrodes may be made of a non-conductive material, such as a polymer nonconductive. The carcass of the apparatus may also consist of even material that supports. As an example of a non-conductive polymer, can mention polymethyl methacrylate. The reactor may include means.
to perform a quality control of the treated water. The means for perform quality control of treated water may include a reader infrared.
The apparatus and methods of the invention thus make it possible to efficient way of wastewater of various compositions and which may contain a wide range of contaminants. The apparatus and methods of the invention are therefore useful for the purpose of environmental protection or to enable a user to comply with environmental standards.
Electrocoagulation is based on the principle of soluble anodes. he is to generate, by imposing a direct current between the iron electrodes, of aluminum or any alloy, metal cations (A13 + or Fe3 +
) according to the reactions (1) or (2) which will act as coagulants for allow the destabilization by discharge of suspended particles and buildings colloid.
Al 'A13 + + 3rd (1) Fe ~ Fe3 + + 3e (2) The formation of iron or aluminum hydroxides and geometry Electrocautery reactors lead to flocculation. The flocs thus formed can be removed by flotation.
The electrochemical process in addition to coagulation phenomena flocculation involves redox reactions at the electrodes oxidation at the anodes and reductions at the cathodes according to the reactions (3) and (4). The Electrochemical reactions develop at the electrodes:
Anode 2H20 - 4th -. Oa +, 4H + (3) Al - Al3 + + 3e (1) Fe, Fe3 ++ 3e (2) Cathode 2Ha0 + 2e 'Ha + 20H- (4) When two metal electrodes between which is established a potential difference plunge into a solution, the ions present are subject to faction of the electric field, the negative ions are moving towards the anode then that positive ions are moving towards the cathode. The passage of the current through the solution is thus due to the transport of electric charges via anions and cations. The ions arriving at the electrodes are discharged and participate in of the reactions which together constitute the phenomenon of electrolysis.
In addition, the currents of ions and charged particles created by the electric field increase the probability of collision between ions and particles of opposite sign that migrate in opposite directions. This action brings together suspended matter in the form of a floc that is removed by micro-organisms bubbles produced at the electrodes.
During the water treatment, the electrolysis reactions to electrodes (3) and (4) make it possible to produce micro-bubbles of oxygen and hydrogen. These micro-bubbles, finely divided will result in their upward movement the flocs thus formed.
The dissolution of the metal ions of the anode increases considerably the roughness of the anodes. For this reason, (electrocoagulation does not can not produce tiny, uniform bubbles. The dimensions of bubbles produced by electrocoagulation are generally greater than 100 gym. Of more, the roughness of the surface of (anode increases the adhesion strength of bubbles this which decreases (effectiveness of treatment).
bubbles are small, the greater the separation efficiency of the flotation process is big.
When the treatment of waste water is done with electrodes inert, the process is called electroflotation. The interest of electroflotation is more to remove particles that have aggregated but not separated during of electrocoagulation process.
During an electroflotation, the inert electrodes used are smooth, and they standardize and reduce the size of microbubbles, minimizing the effects of their adhesion. Small sized bubbles allow a best flotation of particles suspended in (water .. Moreover, these electrodes do not are not soluble and does not degrade with use. They therefore have a duration of life much longer than soluble electrodes and therefore require less of talks. However, (absence of metal cations, necessary for to neutralize the electrical charges of the pollutants, reduces (efficiency of the cleanup of these waters. It can therefore be very advantageous to combine the electrocoagulation and electroflotation during the treatment of wastewater.
BR ~ VE DESCRIPTION OF THE FIGURES
Other features and advantages of the invention will become apparent more clearly to the reading of the following description of a mode of production preferred embodiment of the invention as illustrated by way of example in the drawings joints, in which Figure 1 is a schematic representation of an apparatus for wastewater treatment, according to a preferred embodiment of the invention;
Figure 2 is a perspective view of the reactor used in the apparatus illustrated in Figure 1, including the cover and a side wall vertical have been removed for illustrative purposes;

Figure 3 is a perspective view of a variant of the reactor used in the apparatus illustrated in Figure 1, including the cover and a wall vertical lateral were removed for illustrative purposes;
Figure 4 is a perspective view of the mud trap used 5. in the apparatus illustrated in Figure 1; and Figure 5 is a perspective view of a reactor for treatment wastewater, according to another preferred embodiment of the invention.
DETAILED DESCRIPTION OF THE INVENTION
Figure 1 schematically shows an apparatus for the wastewater treatment comprising a feed tank 10 for receive the water. to be treated, a reactor 12 or 12 'used to treat the waste water and one sludge collector 14 to recover sludge generated during the treatment of the water worn. The supply tank 10 is connected to a pump 16 via a conduit 18. The pump 16 is connected to (inlet 20 of reactor 12 or 12 'via a conduit 22.
. As illustrated in FIG. 2, the reactor 12 comprises a carcass 24, a bottom 26, a removable cover (not shown) and two electrode blocks 28 and 30, arranged inside the carcass 24. Each of these electrode blocks is mounted on a support 32. The supports 32 define respectively under the blocks 28 and 30, spaces 34 and 36 allowing the passage of ~ feau to treat. The block electrode 28 comprises electrodes 38 arranged in parallel fashion and the electrodes 38 are spaced so as to define between them spaces 40 allowing the passage of Skin. Of analogously, the block 30 comprises electrodes 42 arranged so parallel and the electrodes 42 are spaced apart so as to define between them spaces 44 allowing the passage of water. The electrode blocks 28 and 30 can include.
or not the same number of electrodes and the electrodes 38 and 42 can be made of the same material or not. The nature of the material (s) component the electrodes 38 and 42 can vary according to the composition of the water to be treated and according to contaminants contained in the latter. The electrode blocks 28 and 30 are separated by two walls 45 and 46 respectively having an upper passage 47 and a lower passage 48 and defining between them a space 49 allowing Skin of flow to minimize turbulence. The overpass 47 is available a height such as to prevent the sludge from entering (space 49. A wall 50 is disposed upstream of the electrode block 28, the wall 50 defining a passage lower 52 for receiving the water to be treated. A wall 53 defining a passage upper 55 is disposed downstream of the electrode block 30 and a wall 54 defining a lower passage 56 is disposed downstream of the wall 53. The walls 53 and define between them a space ~ 57 allowing the water to flow from way to minimize turbulence before entering a compartment, restraint 68 disposed downstream of the wall 54 and intended to receive treated water.
The reactor 12 also includes a feed compartment 58 disposed upstream of the wall 50. The compartment 58 is provided with walls 60 and 62 defining respectively upper passages 64 and 66 which allow the water to circulate in order to minimize turbulence. On the other hand, the compartment of retainer 68 comprises a wall 70 defining an upper passage 72 and a under-compartment 74 for collecting the water intended to be discharged from the reactor 12 by an outlet 76 and through a conduit 78.
As illustrated in FIG. 3, the reactor 12 'comprises a carcass 24, a bottom 26, a removable cover (not shown) and an electrode block 28 available (interior of the carcass 24. The electrode block 28 is mounted on a support 32. The support 32 defined under the electrode block 28 a space 34 allowing the passage of (water to be treated) The electrode block 28 comprises electrodes 38 arranged of parallel manner and the electrodes 38 are spaced to define between them of the spaces 40 allowing the passage of water. The nature of the material (s) component the electrodes may vary according to the composition of the water to be treated and according to the contaminants contained in the latter. A wall 50 is disposed upstream of electrode block 28, the wall 50 defining a lower passage 52 for at receive Skin to treat. A wall 53 defining an upper passage 55 is.
arranged downstream of the electrode block 28 and a wall 54 defining a passage lower 56 is disposed downstream of the wall 53. The walls 53 and 54 define between they have a space 57 allowing water to flow in order to minimize the turbulence before entering a holding compartment 68 disposed downstream of the wall 54 and intended to receive the treated water.
The reactor 12 'also includes a feed compartment 58 disposed upstream of the wall 50. The compartment 58 is provided with walls 60 and 62 defining respectively upper passages 64 and 66 which allow (flow of water so as to minimize turbulence.
retaining compartment 68 includes a wall 70 defining a passage 72 and a sub-compartment 74 for collecting the water intended for to be discharged from the reactor 12 'through an outlet 76 and through a conduit 78.
As illustrated in Figure 4, sludge collector 14 includes a recovery tank 80 connected to a vacuum cleaner 82 via a conduit 84.
tank 80 comprises a carcass 86 provided with an inlet 88, a lower outlet 90 and an upper orifice 92 connected to the conduit 84. A wall 94 provided with perforations 96 is disposed to (inside the carcass 86. The wall 94 defines a chamber upper 98 and a lower chamber 100. The input 88 is connected to a leads 102 whereby the generated sludge is sucked. The perforations 96 of the wall 94 allow the mud to pass from the upper chamber 98 to the lower chamber 100.
When (apparatus of Figure 1 is provided with the reactor 12, skin with to treat is homogenized in the tank 10 by means of homogenization (no illustrated), then it is conveyed through the pump 16 into the ducts 18 and 22 before reaching the entrance 20 of the reactor 12. The water to be treated arnve then in the compartment 58 of the reactor 12 where it flows along the walls 60 and 62 of way to minimize turbulence, and through the overpasses 64 and 66.
Then, the water flows between the walls 50 and 62, so as to minimize turbulence, before of pass through the lower passage 52 and move in (space 34 under the block electrode 28 resting on the support 32. The water then rises between the electrodes.
38, in the spaces 40, to be treated and a sludge is thus generated.
The electrodes are submerged in the water so as to allow better floatation mud. The water flows into the spaces 40 so as to minimize the turbulence and promote the flotation of mud. Micro-bubbles of oxygen and hydrogen are then formed during the electrolysis of water and they carry with them to the top the pollutant particles contained in the waste water, thus forming a sludge.
The buoy thus generated has a low density and is found in the form of foam because of the micro bubbles mentioned above. This low density allows in besides the mud to float on the surface of the water. The water thus treated a first time, passes through the passage 47 in order to reach (space 49 defined between the walls 45 and 46 where it flows in such a way as to minimize turbulence before passing through the passage lower 48. Then, water circulates in (space 36 under the block of electrodes 30 resting on the support felt 32. The water then rises between the electrodes 42, in the spaces 44, in order to be treated a second time and another mud is thus generated.
The treated water then flows into the spaces 44 so as to minimize the turbulence and promote the flotation of mud. Following this second treatment, Treated skin passes through the passage 55 to reach the space 57 defined between the walls 53 and 54 where it flows so as to minimize turbulence before will pass through the underpass 56 and reach the restraint compartment 68.
The treated water then runs along the wall 70 before passing through the overpass 72 and reach the subcompartment 74. Finally, the water treated is discharged from the reactor ~ 12 through the outlet 76 and through the conduit 78.
In the reactor 12, the walls 45, 46, 50, 53, 54, 60, 62 and 70 therefore constitute a network of baffles to minimize water turbulence. Similarly, in the reactor 12 'the walls 50, 53, 54, 60, 62 and 70 therefore constitute a network of chicanes.

When the apparatus of FIG. 1 is equipped with the reactor 12 ', the water circulates, in the reactor 12 ', in a manner similar to the manner previously mentioned for the reactor 12.
The sludge generated above the electrode blocks 28 and 30 of the reactor 12, or that generated above the electrode block 28 of the reactor 12 ', is recovered by the mud manifold 14 shown in Figure 4. The sludge is sucked by the leads 102 and then enters the upper chamber 98 of the tank 80 via the entrance 88.
This suction is generated by (vacuum cleaner 82 which is connected to the tank 80 by the 84. Then, the sludge passes through the perforations 96 of the wall 94 to to reach the lower chamber 100 where it is finally evacuated via the exit 90. The sludge that was in the form of a foam eventually loses its air bubbles as well as water and tends to become denser.
Figure 5 schematically shows an apparatus for the wastewater treatment including a reactor 112 comprising a carcass 111, a bottom 113, a feed compartment 110 for receiving the water to treat, a first electrode block 114, a first transition tank 116, a first separator mud 118, a second electrode block 120, a second reservoir of transition 122, and a reservoir for receiving treated water 124. Each of these electrode blocks is mounted on a support 126 fixed to the walls of the carcass 111.
The supports 126 define respectively under blocks 114 and 120, spaces 128 and 130 allowing the passage of the water to be treated. The electrode block 114 comprises electrodes 115 arranged in parallel and the electrodes 115 are spaced so as to define between them spaces 132 allowing the passage of Skin.
In a similar way, the block 120 comprises electrodes 121 arranged in such a way parallel and the electrodes 121 are spaced apart in order to define between them spaces 134 allowing the passage of water. The electrode blocks 114 and 120 can with or without the same number of electrodes and the electrodes 115 and 121 can be made of the same material or not. The nature of the materials constituting the electrodes 115 and 121 may vary according to the composition of water to treat and according to the contaminants contained in the latter.
The feed compartment 110 and the reactor 112 are connected by a conduit 136, one end of which is located under the block 114, in the space 5 to allow water to flow 'from the bottom to the top of the electrodes 115. The transition tank 116 is connected to the space 130 by a conduit 13 8. The tank Transition 122 is connected to the treated water reservoir 124 via a conduit 140. The sludge separator 118 comprises conveyors 141 and 142 each including rollers 144 and a belt 146, and a sludge collector 148 comprising a 10 recovery tank 150 for receiving the sludge, an inlet 152 and output . The conveyors 141 and 142 are actuated by a motor (not shown).
The motor drives the upper rollers by friction. The collector 148 comprises also an output 155 which is connected to a suction means ie a pump or a vacuum cleaner (not shown) and which allows to suck the mud at the entrance 152. The exit 154 15 is connected to a conduit 156 for discharging the sludge. The conveyor 142 is equipped with a filter 157 comprising grooves 158. In the reactor 112, the provision of the block 114 relative to the reservoir 116, the arrangement of ~ ce last by to block 120, and the disposition of the latter relative to the reservoir constitutes a network of baffles in which the water circulates so as to minimize the 20 turbulence.
The water to be treated is therefore first introduced into the compartment 110 and then it is routed through the conduit 136 into space 128 under the pad of electrodes 114. Then, the water rises in the spaces 132 between electrodes 115 where it is subjected to an electric current. Electrodes are 25 submerged in the water to allow better flotation of the mud.
Water circulates between the electrodes to minimize turbulence and promote Flotation of the mud. Micro-bubbles of oxygen and hydrogen are then formed during the electrolysis of the water and they carry with them upward the particles pollutants contained in the wastewater, thus forming a boûe. The mud as well generated has a low density and is found as a foam in reason microbubbles mentioned above. This low density also makes it possible to the mud float on the surface of the water. Water and mud, once returned to above block 114, are then routed to the inlet of the transition tank 116 where they will be separated from each other. The water passes through the belt 146 of, conveyor 141 to enter the reservoir 116 while the sludge adheres to the belt 146 of the conveyor 141 and is then conveyed to the entry 152 where it is sucked to the recovery tank 150. Then, the mud is evacuated by the conduit 156. A scraper wall (not shown) may be disposed of way adjacent to the inlet 152 so as to loosen the sludge from the belt and thus make drop the mud more easily in the entrance 152. The density of the mud increases when conveyed by the conveyor and when introduced into the tank 150. In fact, mud that was in the form of foam loses its air bubbles as well as water and tends to become denser.
Subsequently, the water having been substantially separated from the sludge by the belt, it leaves the reservoir 116 by flowing in the conduit 138 before to reach the space 130 under the electrode block 120 to be treated at new.
Just as when passing through the electrodes of block 114, the water mounts in spaces 134 between electrodes 121 of block 120 where it is subjected to an electric current. A mud in the form of foam is then generated as during the treatment with the block 114, then the water and the mud are then routed to the entrance of Transition Tank 122 where they will be separated one of the auire through the belt 146 of the conveyor 142 as he has summer previously described for the conveyor 141. The filter 157 prevents certain particles of pollutants to contaminate the treated water and collected in the tank 122.
Then, the treated water leaves the reservoir 122 to reach the reservoir 124 via 140. This duct is adjustable and can perform a rotation of way to control the flow of the water leaving the tank 124.

The apparatus of Figure 5 may include a feed tank connected to the supply compartment by a conduit. The water contained in the feed tank can be delivered to the compartment .d'alimentation through a pump with a filter. The wall between the compartment feed and the reactor can also include at least one other Entrance located above the duct 136. This entry consists of an orifice in this wall and the water contained in the compartment 110 flows along a front duct to reach space 128. The wall can also have other entrances similar according the desired input flow rate into the reactor. The conduit connecting the tank supply and the feed compartment and the ducts 136, 138, and 140 may be provided with valves or means to control the debit of water in the device. The tanks 110, 116, 122, 124 as well as the walls located under the spaces 128 and 130 may also include entities connected to of the ducts and to empty the tank. These conduits are preferably equipped with valves. Similarly, in Figures 2 and 3, the ducts 22 and 78 may be equipped with valves or means to control flow water in these devices. The compartment 58 and the tank 68 can also include outlets connected to ducts and to drain the tank. These ducts are preferably equipped with valves.
The apparatus according to FIG. 5, the reservoir 122 can also comprise a diversion device allowing, if necessary, to convey the water treated up to space 128 below the electrodes of block 114 to space 130 under the electrodes of the block 120 or in the supply compartment 110 for a additional treatment. This bypass device is a conduit provided with valve and the latter is open if the means of control of the quality of the water.
indicated that the treated water requires additional treatment. Similarly, in the apparatuses of FIGS. 2 and 3, the conduit 78 may be provided with such device variation permitting the water to be returned to the compartment 58 for a treatment additional.

Before being transported to the feed compartment, the water can be treated in order to adjust the pH and / or homogenized. PH can also be adjusted at the end of treatment, and preferably in the water tank processed in order to meet certain environmental standards. Dice readings can be at the level of the feed tanks and treated water and the feed compartment to determine the content, in the water to be treated and in treated water, various pollutants or contaminants.
EXAMPLES
Examples have been made using the apparatus as shown in FIG.
Figure 5. As a first step, wastewater from a refinery processed meat (Table 1) and in a second step, a wastewater from a dairy was processed (Table 2). During these treatments them two pads of electrodes were each provided with 22 electrodes constituted aluminum. The electrodes of the two blocks were identical. Electrodes had dimensions of 22.5 cm by 24 em and the spacing between electrodes was 0.8 cm. The total volume of all spaces (21 spaces) of a block was therefore 9072 cm3. During these tests, the content of various pollutants in the water at treat and treated water was measured to determine the rate of abatement got for each of these pollutants during treatment. When treating wastewater from a meat processing plant (Table 1) 200 liters of water have treated at an average current of 78.4 A and an average voltage of 4.6 V.
The treatment lasted 106 minutes and the average flow rate was 1.9 liters per minute.
During the treatment of wastewater from a dairy (Table 2) 240 liters of water have been treated at an average current of 57.8 A and a mean voltage of 6.5 V.
The treatment lasted 130 minutes and the average flow rate was 1.8 liters per minute.
In tests, the abatement rate was calculated as follows [(initial concentration - final concentration) / initial concentration] X

Table 1.
Parameter Units Before After Rate treatment treatment of abortion Conductivity ~, S / cm 4420 4290 -PH. - 10.25 9.96 -True color UCV 313 68 78.27 Turbidity UTN 240 37 84.58 Total nitrogen Kjeldahlmg N / L, 110 48 56.36 Orthophosphates mg P / L 16 0.23 98.56 Total phosphorusmg P / L 83 7 91.57 Dissolved solids mg / L 2862 2286 20.12 Biochemical application / L 1188 777 34.60 in soluble oxygen, days Biochemical application / L 1374 1028 25.18 in oxygen, 5 days Chemical applicationxng / L 2006 1094 45.46 in soluble oxygen Chemical application / L 2650 2160 18.49 in oxygen Oils and greasesmg / L 16.1 7.3 54.66 Total Table 2.
Parameter unit Before After Rate treatment treatment of abortion Conductivity ~, S / cm 1641 1307 PH - 7.36 9.72 -True color UCV 190 <5 97.37 Turbidity UTN 780 15.3 98.04 Matters in addition mg / L 766 92 87.99 ension Total nitrogen Kjeldahlm N / L 68 5.6 91.76 Orthophosphates mg P / L 98 0.46 99.53 Total phosphorusmg P / L 98 1.2 98.77 Dissolved solids m L 1388 1120 19.31 Biochemical application / L 542 264 51.29 in soluble oxygen, days Biochemical application / L 1599 363 77.30 in oxygen, 5 days bear Chemical application mg / L 963 511. 46.93 in oxy does not soluble Chemical demand mg / L 2614 590 77.42 in oxygen 5 The results presented in Tables 1 and 2 clearly demonstrate that the apparatus and method of the present invention are effective for treat wastewater from various sources including various pollutants. He has then summer demonstrated that the method and apparatus of the invention make it possible to water used in a simple way without resorting to various chemical additives such of the 10 flocculants, and without the use of sedimentation ponds, clarifier or complex mechanical means for separating the sludge from the treated water.
In the apparatus and methods of the invention, the mud is separated from the water treated so simple and efficient. This step is also facilitated by the fact that mud is recovered just above or near the electrodes.
Finally, the Treatment can be performed in a short period of time.
Although. the present invention has been described by means of preferred embodiment, it is understood that several variations and modifications can graft to these specific embodiments, and the present invention intended to cover such modifications, uses or adaptations of the present invention following in general, the principles of the invention and including any variation of the present description that will become known or conventional in the field activity in which the present invention is found, and which can apply to essential elements mentioned above, in accordance with the scope of the claims following.

Claims (92)

1. Wastewater treatment process characterized in that:

a) a reactor comprising an inlet, an outlet, at the at least one electrode block comprising at least one anode and at least one cathode, and a means allowing the water to be treated to circulate between said electrodes in an ascending direction; and b) the water to be treated is passed between the electrodes of said at least a block in an upward direction so as to subject said water to a current electricity and thus treat said water by electrocoagulation or electroflotation, thereby generating a sludge containing at least one pollutant included in the water at treat and treated water;
and in that the sludge generated is separated from said treated water just above of the electrodes or near them by means of a suction means. 2. Wastewater treatment process characterized in that:
a) a reactor comprising an inlet, an outlet, at the least two electrode blocks each having at least one anode and at least one cathode, and a means allowing the water to be treated to circulate between said electrodes in an ascending direction;

b) the water to be treated is passed between the electrodes of a first block in an upward direction so as to subject said water to a current electric and thereby treating said water by electrocoagulation, thereby generating a sludge container at least one pollutant included in the water to be treated and a first treated water;
and c) the treated water obtained in step (b) is passed between the electrodes of a second block in an upward direction so as to submit said water to an electric current and thus treat said water by electroflotation, generating thus a sludge containing at least one pollutant included in the water to be treated and a second treated water, in that at least one of steps (b) and (c), the generated sludge is separated from said treated water, in that the electrodes of said blocks are arranged in a plane and the shift overall water in said reactor from inlet to outlet takes place perpendicular to said plane, and in that the water circulates between the electrodes so as to minimize the turbulence, thus promoting the flotation of the generated sludge. 3. Method according to claim 2, characterized in that the sludge generated is sucked up by a suction means in order to be separated from said treated water. 4. Method according to claim 1 or 3, characterized in that the means suction is a vacuum cleaner or a pump. 5. Method according to claim 1 or 2, characterized in that the sludge generated is separated from said treated water by the action of at least one conveyor comprising a moving belt, to which the mud adheres in order to be conveyed and separated from said treated water. 6. Method according to claim 5, characterized in that the belt is a water-permeable membrane. 7. Method according to claim 2, characterized in that at least one of steps (b) and (c) is repeated several times. 8. Method according to claim 2, characterized in that the electrodes of the first block include aluminum, calcium or iron. 9. Method according to claim 1, characterized in that the electrodes include aluminum, calcium or iron. 10. Method according to claim 2 characterized in that the electrodes of the second block are inert electrodes. 11. Method according to claim 1, characterized in that the electrodes are inert electrodes. 12. Method according to claim 10 or 11, characterized in that the Inert electrodes are electrodes comprising platinum or electrodes comprising titanium coated with iridium. 13. Method according to claim 1, characterized in that the water circulates between the electrodes in such a way as to minimize turbulence, thus favoring the flotation mud generated. 14. Method according to claim 2, characterized in that the electrodes of the first block comprise at least one anode including a mixture comprising a source of Ca2+ ions, a support and water. 15. Method according to claim 1, characterized in that the electrodes comprise at least one anode including a mixture comprising a source of Ca2+ ions, a support and water. 16. Method according to claim 14 or 15, characterized in that the ions Ca2+ are present in the mixture in a proportion of about 2% to about % by weight, relative to the total weight of the mixture. 17. Method according to any one of claims 14 to 16, characterized in that the source of Ca2+ ions comprises calcium carbonate or lime. 18. Method according to any one of claims 14 to 17, characterized in that the carrier is present in the mixture in a proportion of approximately 40% to about 80% by weight, relative to the total weight of the mixture. 19. Method according to any one of claims 1 to 18, characterized in that the electrodes are planar in shape. 20. Method according to any one of claims 1 to 19, in which the water to be treated has turbidity, and characterized in that it causes a rate reduction turbidity of at least 85%. 21. Method according to claim 20, characterized in that it causes a turbidity reduction rate of at least 95%. 22. Method according to any one of claims 1 to 21, in which the water to be treated comprises orthophosphates, and characterized in that it causes a orthophosphate reduction rate of at least 85%. 23. Method according to claim 22, characterized in that it causes a orthophosphate reduction rate of at least 95%. 24. Method according to any one of claims 1 to 23, in which the water to be treated comprises phosphorus, and characterized in that it causes a rate phosphorus reduction of at least 85%. 25. Method according to claim 24, characterized in that it causes a phosphorus reduction rate of at least 95%. 26. A method according to any one of claims 1 to 25, wherein the water to be treated comprises suspended solids, and characterized in that that it causes a suspended solids reduction rate of at least 85%. 27. Wastewater treatment apparatus including:

- a reactor having an inlet for the water to be treated and an outlet for treated water, and comprising at least one block of electrodes, the block having to at least one anode and at least one cathode, the electrodes being arranged way substantially parallel and they are spaced, so as to define between they one space allowing the passage of the water to be treated, thus generating, when the water treat is subjected to an electric current, a sludge comprising at least one pollutant contained in the water to be treated and a treated water, the reactor comprising also a means allowing water to flow between the electrodes in one direction ascending; and - a means for separating the generated sludge from the water treated, said means being disposed just above the electrodes or at proximity to these and comprising at least one conveyor including a belt in movement to which the sludge adheres in order to be transported and separated from the treated water, Thus a suction means connected to a recovery tank intended to receive the mud. 28. Apparatus according to claim 27, characterized in that it allows the water to circulate between the electrodes so as to minimize turbulence, favoring thus the flotation of the generated sludge. 29. Apparatus according to claim 27 or 28, characterized in that the reactor comprises a single block of electrodes and in that said means allowing the water to circulate between the electrodes in an upward direction comprises a first substantially vertical wall disposed upstream of the block electrodes, and defining a lower passage intended to receive the water to be treated. 30. Apparatus according to claim 28, characterized in that said means allowing water to flow between the electrodes in an upward direction understand a substantially vertical first wall disposed upstream of said at less an electrode block, and defining a lower passageway for receiving water to to treat, and in that the reactor further comprises a compartment feeding upstream of said first wall, said supply compartment serving to collecting the water to be treated from a supply tank, and in this that the reactor includes a means for allowing water to flow so as to minimize the turbulence. 31. Apparatus according to claim 30, characterized in that the means allowing water to flow in a way that minimizes turbulence allows water to treat from said supply compartment to flow so as to minimize turbulence before reaching said first wall, and includes a substantially vertical second wall disposed between said inlet of the reactor and said first wall and defining an upper passage intended to receive water to treat. 32. Apparatus according to claim 31, characterized in that the second substantially vertical wall makes it possible to control the level of the water in the reactor. 33. Apparatus according to claim 31 or 32, characterized in that the reactor further comprises a compartment for retaining the treated water arranged in downstream of said at least one block of electrodes. 34. Apparatus according to claim 33, characterized in that said means allowing water to flow in a way that minimizes turbulence includes a substantially vertical third wall disposed between said at least one block of electrodes and said retaining compartment and defining a passage inferior intended to receive the treated water, said third wall allows the water processed from of said at least one block of electrodes to flow so as to minimize the turbulence before entering said holding compartment. 35. Apparatus according to claim 34, characterized in that said means allowing water to flow in a way that minimizes turbulence includes besides a substantially vertical fourth wall arranged upstream of said third wall, said third and fourth walls define between they one other space allowing water to flow so as to minimize the turbulence, said fourth wall defining an upper passage disposed at a height predetermined so as to prevent said mud from entering said other space and to allow the passage of the treated water. 36. Apparatus according to any one of claims 30 to 35, characterized in that said reactor has a bottom and in that said at least one block of electrodes is raised with respect to said bottom so as to define a space additional contacting the space between the electrodes and allowing the water to be treated to circulate under said electrodes. 37. Apparatus according to claim 36, characterized in that said at at least one electrode block is mounted on a removably resting support on the bottom of said reactor and allowing the water to be treated to pass through space additional. 38. Apparatus according to claim 27 or 28, characterized in that the reactor comprises a single block of electrodes, and in that it comprises a means allowing water to flow in a way that minimizes turbulence. 39. Apparatus according to claim 27, characterized in that it comprises a means for allowing water to flow so as to minimize turbulence and in this that said reactor has a bottom and in that said at least one block of electrodes is raised relative to said bottom so as to define an additional space communicating with the space between the electrodes and allowing water to deal with circulate under said electrodes. 40. Apparatus according to claim 39, characterized in that said means allowing water to flow between the electrodes in an upward direction understand a conduit connecting the inlet of the reactor with said additional space, and in that said means permitting water to flow so as to minimize turbulence comprises a transition tank disposed downstream of said at least one block of electrodes, and communicating with the latter, said transition tank allow to collect the water having been treated by said at least one block of electrodes. 41. Apparatus according to claim 39 or 40, characterized in that said at least one electrode block is mounted on a removably attached support Where not to at least one of the walls of said reactor and allowing the water to be treated exceed through the additional space, and in that the reactor further comprises a supply compartment upstream of said at least one block of electrodes. 42. Apparatus according to any one of claims 27 to 41, characterized in that the electrodes comprise aluminum, calcium or from iron. 43. Apparatus according to any one of claims 27 to 41, characterized in that the electrodes are inert electrodes. 44. Apparatus according to claim 43, characterized in that the electrodes inert are electrodes comprising platinum or electrodes comprising from iridium coated titanium. 45. Apparatus according to any one of claims 27 to 41, characterized in that the electrodes comprise at least one anode including a mixture comprising a source of Ca2+ ions, a support and water. 46. Wastewater treatment apparatus including:

- a reactor having an inlet for the water to be treated and an outlet for the treated water, and comprising at least two blocks of electrodes, a first block of electrodes making it possible to treat said water by electrocoagulation and a second block of electrodes making it possible to treat said water by electroflotation, each of said blocks having at least one anode and at least one cathode, the electrodes being arranged according to a plan and the overall movement of the water in the reactor of the entrance to the exit takes place perpendicular to this plane, the electrodes being arranged substantially parallel and spaced apart, in order to define between them a space allowing the passage of the water to be treated, thus generating, when the water to be treated is subjected to an electric current, a sludge including at minus one pollutant contained in the water to be treated and one treated water, the reactor also comprising a means allowing water to circulate between the electrodes in an ascending direction; and - a means for separating the generated sludge from the water processed, said apparatus allowing water to flow between the electrodes so as to minimize turbulence, thus favoring the flotation of the generated sludge. 47. Apparatus according to claim 46, characterized in that the reactor further comprises a supply compartment upstream of a first wall substantially vertical disposed upstream of said first block of electrodes and defining a lower passage intended to receive the water to be treated, said compartment supply for collecting water to be treated from a reservoir supply, and in that it comprises a means allowing the water to flow from way to minimize turbulence. 48. Apparatus according to claim 47, characterized in that the means allowing water to flow in a way that minimizes turbulence allows water to treat from said supply tank to flow so as to minimize the turbulence before reaching said first wall, and comprises a second wall substantially vertical disposed between said reactor inlet and said first wall and defining an upper passage intended to receive the water to be treated. 49. Apparatus according to claim 48, characterized in that the second substantially vertical wall makes it possible to control the level of the water in the reactor. 50. Apparatus according to claim 48 or 49, characterized in that the reactor further comprises a compartment for retaining the treated water arranged in downstream of said second block of electrodes. 51. Apparatus according to claim 50, characterized in that said means allowing water to flow in a way that minimizes turbulence includes a substantially vertical third wall disposed between said second block of electrodes and said retaining compartment and defining a passage inferior intended to receive the treated water, said third wall allows the water processed from of said second electrode block to flow so as to minimize turbulence before to enter said holding compartment. 52. Apparatus according to claim 51, characterized in that said means allowing water to flow in a way that minimizes turbulence includes besides a substantially vertical fourth wall arranged upstream of said third wall, said third and fourth walls define between they one other space allowing water to flow so as to minimize the turbulence, said fourth wall defining an upper passage disposed at a height predetermined so as to prevent said mud from entering said other space and to allow the passage of the treated water. 53. Apparatus according to claim 52, characterized in that said blocks of electrodes are separated by a means allowing water to circulate between them electrodes of the second block in an upward direction. 54. Apparatus according to claim 53, characterized in that said means separating said blocks of electrodes and allowing water to flow between them electrodes of the second block in an upward direction comprises a fifth wall substantially vertical defining an underpass for receive water processed from the first block of electrodes. 55. Apparatus according to claim 54, characterized in that said means separating said blocks of electrodes further comprises a sixth wall arranged in upstream of said fifth wall, said fifth and sixth walls define between them an additional space allowing water to flow so as to minimize turbulence, said sixth wall defining an upper passage arranged at a predetermined height so as to prevent said mud from enter in said additional space and to allow the passage of the treated water. 56. Apparatus according to any one of claims 46 to 55, characterized in that said reactor has a bottom and in that said blocks of electrodes are raised above said bottom so that said blocks of electrodes each define an additional space communicating with the space between their electrodes and allowing the water to be treated to circulate under said electrodes. 57. Apparatus according to claim 56, characterized in that each of the electrode blocks is mounted on a support resting removably on the bottom of said reactor and allowing the water to be treated to pass through the space additional. 58. Apparatus according to any one of claims 27 to 45, characterized in that the electrodes are arranged in a plane and the shift overall water in the reactor from inlet to outlet takes place perpendicular to this plane. 59. Apparatus according to claim 34 or 51, characterized in that said reactor further comprises another wall disposed downstream of said third wall, the other wall defining an upper passage and allowing control the water level in the reactor. 60. Apparatus according to claim 27, 28, or 46 characterized in that the reactor comprises a first block of electrodes and a second block of electrodes arranged downstream of said first block of electrodes, and in that it comprises a medium allowing water to flow in a way that minimizes turbulence. 61. Apparatus according to claim 60, characterized in that said reactor has a bottom and in that said blocks of electrodes are raised with respect to audit bottom so as to define an additional space between each of the blocks and the bottom, said additional space communicating with the space between the electrodes and allowing the water to be treated to circulate under said electrodes. 62. Apparatus according to claim 61, characterized in that said means allowing water to flow between the electrodes in an upward direction understand a duct connecting the inlet of the reactor with the additional space of the first block of electrodes. 63. Apparatus according to claim 61 or 62, characterized in that each block of electrodes is mounted on a support fixed, removably or not, to to at least one of the walls of said reactor and allowing the water to be treated to pass through the additional space, and in that the reactor further comprises a supply compartment upstream of said first block. 64. Apparatus according to any one of claims 60 to 63, characterized in that said means allowing water to flow so as to minimize turbulence includes a first transition tank disposed in downstream of the first block of electrodes, and communicating with the latter, said first transition tank collects water that has been treated by the first block of electrodes. 65. Apparatus according to claim 64, characterized in that said means allowing water to flow in a way that minimizes turbulence includes in addition to a second transition tank disposed downstream of said second block of electrodes, and communicating with the latter, said second reservoir of transition makes it possible to collect the water having been treated by the second block of electrodes. 66. Apparatus according to claim 64 or 65, characterized in that the means for separating generated sludge from treated water comprises a conveyor having a portion disposed in said first reservoir of transition, said conveyor comprising a moving belt to which the sludge adheres in order to to be transported and separated from the treated water. 67. Apparatus according to claim 66, characterized in that the means for separating generated sludge from treated water further comprises a conveyor having a portion disposed in said second reservoir of transition, said conveyor comprising a moving belt to which the mud adheres to be transported and separated from the treated water. 68. Apparatus according to claim 27, 66 or 67, characterized in that the belt is a water-permeable membrane. 69. Apparatus according to any one of claims 66 to 68, characterized in that the conveyor is in communication with a collector of mud including:
- a recovery tank for recovering the sludge and having a casing provided with an inlet and an outlet for draining mud; and - a suction means connected by a conduit to the reservoir of recovery and allowing the sludge to be conveyed from said inlet to inside of said carcass. 70. Apparatus according to any one of claims 66 to 69, characterized in that the conveyor is provided with a filter making it possible to filter the water coming from the second block of electrodes before it enters the second transition tank. 71. Apparatus according to any one of claims 66 to 70, characterized in that said means allowing water to circulate between the electrodes in an upward direction further comprises a duct connecting said first tank transition with the additional space of the second block of electrodes. 72. Apparatus according to claim 71, characterized in that the reactor further comprises a tank intended to receive the treated water, said tank communicating on the one hand with said second transition tank by the bias of a conduit and on the other hand with said outlet for the treated water. 73. Apparatus according to any one of claims 27 to 68, characterized in that said means for separating generated sludge from the water processed is a sludge collector comprising:
- a recovery tank for recovering the sludge and having a carcass provided with an upper orifice, with a lower outlet for drain the sludge and an inlet provided with a first conduit connected to the reactor, said entrance being disposed at a height between the upper orifice and the lower outlet; and - a suction means connected by a second conduit to the upper orifice of the recovery tank and making it possible to convey the sludge from the reactor to the recovery tank. 74. Apparatus according to claim 73, characterized in that the reservoir sludge collection further comprises a horizontal wall disposed at a predetermined height between the entrance and the lower exit and defining a upper chamber and a lower chamber, said horizontal wall being perforated in such a way as to allow the passage of the mud recovered from the chamber higher than the lower chamber. 75. Apparatus according to any one of claims 46 to 74, characterized in that the electrodes of at least one of said first and second blocks electrodes include aluminum, calcium or iron. 76. Apparatus according to any one of claims 46 to 74, characterized in that the electrodes of at least one of said first and second blocks of electrodes are inert electrodes. 77. Apparatus according to any one of claims 46 to 74, characterized in that the electrodes of one of said first and second blocks of electrodes comprise aluminium, calcium or iron, and in that the electrodes of the other of said first and second electrode blocks are electrodes inert. 78. Apparatus according to claim 76 or 77, characterized in that the Inert electrodes are electrodes comprising platinum or electrodes comprising titanium coated with iridium. 79. Apparatus according to any one of claims 27 to 74, characterized in that the electrodes comprise at least one anode including a mixture comprising a source of Ca2+ ions, a support and water. 80. Apparatus according to claim 79, characterized in that the Ca2+ ions are present in the mixture in a proportion of about 2% to about 30%
in weight, relative to the total weight of the mixture. 81. Apparatus according to claim 79 or 80, characterized in that the Ca2+ ion source includes calcium carbonate or lime. 82. Apparatus according to claim 81, characterized in that the support is present in the mixture in a proportion of about 40% to about 80% by weight, relative to the total weight of the mixture. 83. Apparatus according to any one of claims 27 to 82, characterized in that the electrodes are planar electrodes. 84. Apparatus according to any one of claims 27 to 83, characterized in that the electrodes are all individually connected to a direct current source. 85. Apparatus according to claim 30 or 47, characterized in that the reactor further comprises means for recycling the treated water leaving through the outlet from the reactor to said supply compartment for treatment additional. 86. Apparatus according to claim 30 or 47, further comprising a means for conveying said water contained in the tank feeding to the reactor. 87. Apparatus according to any one of claims 27 to 86, characterized in that the reactor comprises means allowing a self-cleaning electrodes. 88. Apparatus according to claim 87, characterized in that the means allowing self-cleaning of the electrodes consists of a device generating vibes. 89. Apparatus according to claim 88, characterized in that the vibrations are ultrasound. 90. Apparatus according to claim 41 or 63, characterized in that the feed compartment is connected to a feed tank, and characterized in that the apparatus further comprises means for conveying said water contained in the reactor feed tank. 91. Apparatus according to claim 86 or 90, characterized in that said means for conveying the water contained in the supply tank to reactor is a pump. 92. Apparatus according to claim 30 or 47, characterized in that the water contained in the supply tank is conveyed to the reactor by gravity.