Patent Abstract:
An electrolytic system for treating wastewater by electrocoagulation, electroflotation or a combination of both is disclosed. The electrolytic system comprises a first electrolytic reactor adapted for receiving the wastewater to be treated, the first electrolytic reactor comprising at least one cathode and at least one anode to perform a first electrolytic treatment for eliminating organic matter and calcium present in the wastewater that impact on nucleation of struvite; and a second electrolytic reactor downwardly connected to the first electrolytic reactor, the second electrolytic reactor comprising at least one cathode and at least one magnesium anode to perform a second electrolytic treatment for producing Mg 2+  ions which react with NH 4   +  and orthophosphates from said wastewater to form a struvite precipitate. The electrolytic system allows eliminating simultaneously orthophosphate and ammonium from the wastewater while enabling the production of struvite.

Full Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     The present patent application is a continuation of U.S. patent application Ser. No. 13/555,359, entitled “Method for Simultaneous Elimination of Orthophosphate and Ammonium Using Electrolytic Process”, and filed at the U.S. Patent Office on Jul. 23, 2012, the content of which is incorporated herein by reference. 
    
    
     FIELD OF THE INVENTION 
     This invention relates to a system for the simultaneous elimination of orthophospate and ammonium (NH 4   + ) from a nitrogen-rich effluent using an electrolytic process and thereby electro-synthesis of struvite. 
     BACKGROUND OF THE INVENTION 
     Electrocoagulation was already proposed in the late 19 th  and early 20 th  century. The use of electrocoagulation with aluminum and iron was patented in 1909 in the United States (Robinson, Australian Water &amp; Wastewater Association, Joint NSW and Victoria State Conference in Wodonga, 22-24 Nov. 1999 (www.electropure.com.au/paper.htm); Vik et al. WaterResearch, volume 18, Issue 1, 1984, pages 1355-1360). 
     Coagulation is essentially to neutralize or to reduce the electric charge of colloids and hence promote the aggregation of colloidal particles. To destabilize a suspension it is necessary that the attractive forces between particles are greater than the repulsive forces thereof. Attractive forces are mainly Van Der Waals forces, which act at a short distance thereof. In general, the total energy that controls the stability of the energy dispersion comprises attractive Van Der Waals energy of repulsion at short distance, the electrostatic energy and energy due to the steric effect of molecules solvent. 
     Coagulation can be done by chemical or electrical means. Alun, lime and/or polymers have been used as chemical coagulants. Chemical coagulation is becoming less popular today because of high costs associated with the chemical treatments of a significant volume of sludge and hazardous heavy metals such as metal hydroxides generated thereof in addition to the cost of chemical products needed for coagulation itself. Chemical coagulation has been used for decades. 
     Although the electrocoagulation mechanism resembles chemical coagulation, although, some differences benefit electrocoagulation. Indeed, electrocoagulated flocs differ from those generated by chemical coagulation. Flocs created with the electrocoagulation process tend to contain less bound water, are more resistant to shearing and are more easily filterable. 
     Flocs are created during the electrocoagulation water treatment with oxydo-reduction reactions. Currents of ions and charged particles, created by the electric field, increase the probability of collisions between ions and particles of opposite signs that migrate in opposite directions. This phenomenon allows the aggregation of suspended solids to form flocs. 
     The electrolytic reactions that take place at the electrodes are accompanied by production of micro bubbles of hydrogen (at the cathode) and oxygen (at the anode). These micro bubbles heading up will result in an upward movement of the flocs formed thereof that are recovered at the surface (this mechanism is named flotation). 
     The complexity of the mechanisms involved in the process of electrocoagulation in the treatment of water is not well scientifically elucidated (Yousuf et al., Journal of Hazardous Material B84, 2001). There are various features of the mechanism of the process and the geometry, or design, of the reactor in the literature. The different physico-chemical treatment, the shape of the reactor and the shape and size of electrodes affect the performance of the treatment. The wide variety of processing parameters reported in the literature and the lack of scientific data for efficient model processing and optimal processing conditions translate into a lack of development in this field. At this time, electrocoagulation is still problematic and therefore not popular (Holt et al., Colloids and Surfaces A: Physicochem. Eng. Aspects 211 (2002); Holt et al., Chemosphere 59(2005) 355-367). 
     The existence of an electric current in a body of water implicitly requires Faraday reactions surrounding the electrodes. The formation of chemical gradients depends on the electrolytic magnitude. The consequences of chemical reactions become more pronounced and significant in the prolonged application of electrokinetic. The effects include electrolytic of water with the simultaneous development of pH gradients and the transfer of electrolytic dissolution of the anode producing metal ions (Fe 3+ , Al 3+ , Mg 2+ , etc.) or cations of the electrolyte from the anode to the cathode. Chemical reactions can, in ion exchange or precipitation, form new mineral phases for cleaning water for instance. 
     At the cathode, the main reaction is:
 
4H 2 O+4 e   − →2H 2 +4OH −   (Equation 1)
 
     The increase in hydroxyl ions can increase the precipitation of metal hydroxide. The pH of the cathode&#39;s region is basic. The following equations describe the chemical reactions at the anode:
 
2H 2 O→O2+4H + +4 e   −   (Equation 2)
 
     If the anode is made of magnesium:
 
Mg→Mg 2+ +2 e   −   (Equation 3)
 
     It is noted that twice as many water molecules are electrolysed at the cathode compared to the anode for the same quantity of electricity. 
     The struvite is a compound with a little solubility and used as a fertilizer in agricultural fields. This compound is of the formula NH 4 MgPO 4 , 6H 2 O and comprised PO 4   3−  and NH 4   +  ions, both essential to plants growth. Struvite is known as a fertilizer and have been proved potent in soils having a pH between 5.5 and 6.5. 
     Precipitation of struvite in a wastewater allows the elimination of the ortho-phosphate, NH 4   +  and magnesium present in the waste water. Currently, processes for precipitating struvite use fluidized beds, or contained tanks reactors. In Japan, the precipitation of struvite has been tested in a sludge treatment reactor. To obtain a good performance, it is essential to optimized both nucleation and precipitation by optimizing the treatment time in the reactor and the nature of the support particles for the precipitation. 
     Precipitation of struvite is controlled by the pH, the supersaturation, the temperature and the presence of impurities such as calcium and can occur when the concentration in magnesium, ammonium and phosphor ions exceed the solubility product of the complex as per the following expression:
 
Ksp=[Mg 2+ ][NH 4   + ][PO 4   3− ]pKs=13.26
 
     The presence of organic matter impact on the nucleation and growth of struvite crystals and reduce the precipitation rate. In a waste water to be treated, NH 4   +  and PO 4   3−  are among the components to be eliminated. While adding Mg 2+  in the solution with a basic pH, the precipitate is formed. Several conditions are required for the reaction to occur:
         a phosphorous concentration higher than 50 ppm;   a pH value between 7 and 11, preferably between 8 and 9.2;   a molar ratio Mg/P of 0.9 to 1.5;   a strong agitation;   a simultaneous increase in pH and temperature to reduce time of precipitation.
 
Mg 2+ +NH 4   + +PO 4   3− +6H 2 O→MgNH 4 PO 4 .6H 2 O
       

     Many patent applications have been filed for the synthesis of the struvite. WO 01/19735 discloses a process for the treatment of manure. WO 95/05347 discloses an electrolytic system using a series of electrodes. WO 2007/009749 discloses a reactor and a method for the production of struvite. U.S. Pat. No. 4,389,317 discloses the chemical reduction of phosphates in water. WO 00/56139 discloses a method for preventing the formation of struvite in fish cans. 
     WO 2009/102142 discloses a two-steps treatment of an effluent, wherein the effluent is first treatment in an anaerobic reactor followed by a second treatment producing the struvite. 
     Therefore, there exists a need in the art for an improved method, system and apparatus for optimizing the production of struvite by an electrolytic treatment of a waste effluent over the existing art. There is a need in the art for such a method, system and apparatus for treating an effluent that can be easily installed, economically manufactured and operated. And there is a very perceptible need for an improved method, system and apparatus for treating wastewater over the existing art. 
     SUMMARY OF THE INVENTION 
     The present invention alleviates one or more of the drawbacks of the background art by addressing one or more of the existing needs in the art. 
     Accordingly, the present invention provides for an electrolytic system for treating wastewater by electrocoagulation, electroflotation or a combination of both. The electrolytic system comprises a first electrolytic reactor adapted for receiving the wastewater to be treated. The first electrolytic reactor comprises at least one cathode and at least one anode to perform a first electrolytic treatment for eliminating organic matter and calcium present in the wastewater that impact on nucleation of struvite. The electrolytic system also comprises a second electrolytic reactor downwardly connected to the first electrolytic reactor. The second electrolytic reactor comprises at least one cathode and at least one magnesium anode to perform a second electrolytic treatment for producing Mg 2+  ions which react with NH 4   +  and orthophosphates from said wastewater to form a struvite precipitate. The electrolytic system allows eliminating simultaneously orthophosphate and ammonium from the wastewater while enabling the production of struvite. 
     The electrocoagulation system may further comprise a first decanter downwardly connected to the first electrolytic reactor for separating solid/liquid fractions, and/or a second decanter downwardly connected to the second electrolytic reactor for isolating the struvite precipitate from the wastewater. 
     The first electrolytic reactor may be made of an inert material, such as magnesium, aluminum, or iron. 
     The least one anode of the first and second electrolytic reactor may be tubular. At least one of the first and second electrolytic reactors may comprise nine tubular anodes disposed circularly and parallel to a central axis of the reactor. Alternatively, at least one of the first and second electrolytic reactors may comprise one cylindrical anode disposed along a central axis of the reactor. 
     The at least one cathode of the first and second electrolytic reactors may consist in a central cathode or a peripheral cathode. 
     The at least one of the first and second electrolytic reactors may comprise both a central and a peripheral cathode. 
     The cathodes of the electrolytic system may be made of stainless or galvanized steel. 
     The cathodes of the electrolytic system may be made of a material having a potential close to a potential of the material of anodes. 
     The cathodes of the electrolytic system may be made of the same material as the anodes provided that in the second electrolytic reactor, the cathodes and anodes are made of magnesium. 
     The electrolytic system may further comprises a conditioning tank upwardly connected to the first reactor for receiving wastewater to be treated, the conditioning tank comprising a level captor for measuring and controlling a level of fluid in the tank. The conditioning tank may further comprise sensors for measuring wastewater&#39;s conductivity, pH, initial concentrations in NH 4   + , calcium and orthophosphates as well as initial organic content. The electrolytic system may further comprise a prefilter upwardly connected to the conditioning tank for retaining particles and allowing colloidal fractions to access the conditioning tank. 
     The present invention also provides for an electrolytic system for treating wastewater by electrocoagulation, electroflotation or a combination of both. The electrolytic system comprises:
         a first electrolytic reactor adapted for receiving the wastewater to be treated, the first electrolytic reactor comprising at least one cathode and at least one anode to perform a first electrolytic treatment for eliminating organic matter and calcium present in the wastewater that impact on nucleation of struvite;   a first decanter downwardly connected to the first electrolytic reactor for separating solid/liquid fractions;   a second electrolytic reactor downwardly connected to the first electrolytic reactor, the second electrolytic reactor comprising at least one cathode and at least one magnesium anode to perform a second electrolytic treatment for producing Mg 2+  ions which react with NH 4   +  and orthophosphates from said wastewater to form a struvite precipitate; and   a second decanter downwardly connected to the second electrolytic reactor for isolating the struvite precipitate from the wastewater;
 
whereby, in use, the electrolytic system allows eliminating simultaneously orthophosphate and ammonium from the wastewater while enabling the production of struvite.
       

     The electrolytic system disclosed above may further comprise a conditioning tank upwardly connected to the first reactor for receiving wastewater to be treated, the conditioning tank comprising: a level captor for measuring and controlling a level of fluid in the tank; and sensors for measuring wastewater&#39;s conductivity, pH, initial concentrations in NH 4   + , calcium and/or orthophosphates as well as initial organic content. The electrolytic system may further comprise a prefilter upwardly connected to the conditioning tank for retaining particles and allowing colloidal fractions to access the conditioning tank. 
     The present invention allows for the treatment of nitrogen-rich effluent and production of struvite by introducing the effluent in the electrolytic system disclosed herein, thereby eliminating organic matter that impact on nucleation of struvite; and thereby injecting Mg ions which react with ammonium and orthophosphates from the effluent to form a struvite precipitate. 
     In one embodiment of the present invention, a conditioning step prior to the first electrolytic treatment is provided. The conditioning step allows adjusting the stoechiometric ratio of orthophosphate in the effluent and determining, based on initial concentration of NH 4   + , orthophosphate and calcium comprised in the effluent, the current intensity and treatment time needed to be applied. 
     In one embodiment of the present invention, a conditioning step prior to the second electrolytic treatment is provided. The conditioning step allows adjusting stoechiometric ratio of orthophosphate in the effluent and determining, based on initial concentration of NH 4   +  orthophosphate and calcium comprised in the effluent, the current intensity and treatment time needed to be applied. 
     In one embodiment of the present invention, at least one anode of at least one of the first and second electrolytic reactor is tubular. Preferably, at least one of the first and second electrolytic reactors comprise 9 tubular anodes disposed circularly and parallel to the central axis of the reactor. 
     In an alternative embodiment of the present invention, at least one of said first and second electrolytic reactors comprises one cylindrical anode disposed along the central axis of the reactor. 
     The present invention provides for a system wherein the at least one cathode of the first and second electrolytic reactors consists in a central cathode or a peripheral cathode. In one embodiment of the present invention, at least one of the first and second electrolytic reactors comprises both a central and a peripheral cathode. It is provided that the cathodes used in the present invention are made of a material selected from the group consisting of stainless, galvanized steel and a material having a potential close to the one of the material of anodes. It is also provided that the cathode can be of the same material as the anode provided that in the second electrolytic reactor the cathode and anode are made of magnesium. 
     The present invention provides for a system wherein the effluent is treated at a pH between 7.0 and 9.5, preferably between 8.0 and 9.5 and most preferably at a pH of 9.2. 
     In a preferred embodiment of the present invention, the amount of orthophosphate in the effluent is adjusted to be about five time the amount of NH 4   + . 
     In a preferred embodiment of the present invention, the concentration of orthophosphate in the effluent is adjusted to be between 50 and 300 ppm. 
     In a preferred embodiment of the present invention, the effluent is agitated while being treated in the electrolytic reactors. 
     In a preferred embodiment of the present invention, the second electrolytic treatment generates Mg 2+  ions in a quantity such to obtain a molar ratio Mg/P between 0.9 and 1.5. 
     In a preferred embodiment of the present invention, the electrical current intensity used in the electrolytic treatments is between 1 and 120 A. 
     The present invention is suitable for any nitrogen-rich effluent, but most particularly for wastewater from industrial source, wastewater from agricultural source and manure. 
     In the present invention, the electrolytic treatment used can be electrocoagulation, electrofloatation or a combination of both. 
     Other objects and further scope of applicability of the present invention will become apparent from the detailed description given hereinafter. However, it should be understood that the detailed description and specific examples, while indicating preferred embodiments of the invention, are given by way of illustration only, since various changes and modifications within the scope of the invention will become apparent to those skilled in the art from this detailed description. 
     Additional and/or alternative advantages and salient features of the invention will become apparent from the following detailed description, which, taken in conjunction with the annexed drawings, disclose preferred embodiments of the invention. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       Referring now to the drawings which form a part of this original disclosure: 
         FIG. 1  is a schematic illustration of the electrolytic system with at least one embodiment of the invention; and 
         FIG. 2  is a schematic illustration of a modular electrolytic apparatus in accordance with at least one embodiment of the invention. 
     
    
    
     DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS 
     A preferred embodiment of the present invention is described bellow with reference to the drawings. 
     The electrolytic system  10 , as illustrated in  FIG. 1 , comprises a prefilter  12  that retains particles and allows the colloidal fraction to access a conditioning tank  14 . In the conditioning tank  14 , there is a level captor  16  measuring and controlling the level of fluid in the tanks. Also, they are sensors (not shown in  FIG. 1 ) that allow for the measurement of conductivity, pH, initial concentrations in NH 4   + , calcium and orthophosphates as well as initial organic content. Those measured values allow the continuous evaluation of the conductivity of the affluent, its pH and allows the adjustment of the quantity of orthophosphate in solution with respect to the NH 4   +  concentration in order to respect the stoechiometry of the reaction desired. Conductivity and pH probes are well known in the art and are easily available. The measure of NH 4   +  can be made, for example, with an ISE WTW probe coupled with a VARION® PLUS 7001Q sensor. Phosphate analysis can be made using colorimetric devices such as PHOS200 and TOPHO. The organic charge can be evaluated using a CSS70 sensor. Also, UV sensors allow for the measurement of absorbance at 254 nm, which can be easily correlated with the chemical demand in oxygen. 
     The measurement of the NH 4   +  concentration in solution also allows for the determination of the Mg concentration needed to precipitate the struvite. The second law of Faraday is used to convert the Mg concentration into current intensity and treatment time in order to maximize the production of struvite. 
     Once conditioned, the effluent is pumped in a first electrolytic reactor  18  comprising a fixed electrocoagulation module  20 . For the purpose of the present invention, the electrocoagulation could be interchanged with an electrofloatation module. The first electrolytic treatment reduces of about 85% the organic charge of the effluent and the treated effluent is brought in a first decanter  22  to separate the solid-liquid fractions. An automatic dosing device (not shown in  FIG. 1 ) is placed between the exit of the first decanter  22  and the entry of a second electrolytic reactor  26 . This automatic dosing device allows the adjustment of the quantity of orthophosphate in the effluent needed to react with all the NH 4   +  in solution. After this second conditioning step, the effluent is introduced in a second electrolytic reactor  26 , which also comprises a fixed electrocoagulation module  20 . The second electrolytic reactor  26  comprises in its fixed electrocoagulation module  20  at least one soluble anode made of magnesium. The ions Mg 2+  generated while applying the electrical current react with the NH 4   +  and orthophosphate in solution and therefore produce a struvite precipitate. Both first and second electrolytic reactors  18  and  26  optionally comprise a motor  70  allowing the rotation of the electrocoagulation module  20 , providing for an additional agitation of the fluid in the reactors  18  and  26 . 
     After this second electrolytic treatment, the effluent is brought in a second decanter  28  for isolating the struvite precipitate. 
     An exemplary electrocoagulation module  20  is illustrated in  FIG. 2  with a section view allowing a better view of its construction. The electrocoagulation module  20  comprises an anode module  30  and a cathode module  32  adapted to interact in an electrolytic process producing electrocoagulation. The electrocoagulation module  20  of the present embodiment includes an inlet  34  and an outlet  36  configured to respectively receive and extract the fluid to and from the electrocoagulation module  20 . The fluid, once introduced in the electrocoagulation module  20 , follows a path or a fluidic circuit configured to put the fluid in communication with the electrolytic process that is produced in the electrocoagulation module  20 . In the present example, the fluid follows a path identified by a series of arrows  38  defined by internal walls  40 . A pump, which is not illustrated in  FIG. 1 , pushes the fluid through the electrocoagulation module  20 . An opening  42  disposed on a bottom portion  44  of the electrocoagulation module  20  is normally closed with a plug (not illustrated) to prevent the fluid to exit the electrocoagulation module  20 . The opening  42  can be opened to remove the fluid from the electrocoagulation module  20  to purge the electrocoagulation module  20  for maintenance purposes, for instance. The electrocoagulation module  20  can also be purged to remove particles and debris. A larger closure member  46  is used to close the bottom portion of the electrocoagulation module  20  lower body  48 . The closure member  46  can be optionally removed to provide a larger access in the electrocoagulation module  20 . The lower body  48  can threadedly engage the upper body  56  and be removed from the upper body  56 , if desirable. 
     Still referring to  FIG. 2 , the closure member  46  is located at the lower portion of the electrocoagulation module  20  to receive particles therein. The cathode module  32  is bottomless and allows the particles to drop in the closure member  46  acting as a particles-receiving member  46 . The removable particles-receiving member  46  is preferably disposed in the center of the cathode module  32  as illustrated in the present embodiment and is used for removing decanted particles from the cathode module  32 . The opening  42  in the closure member  46  can alternatively be used to inject gas, like air, or liquids for further conditioning the liquid in the electrocoagulation module  20  and/or influence the electrocoagulation process inside the cathode module  32 . 
     The electrocoagulation module  20  further includes body portions  48 ,  56  that can optionally include insulating material to prevent heat transfer with the environment. Conversely, the electrocoagulation module  20  might be equipped with heating/cooling elements  58  to keep the electrocoagulation apparatus  20  at a predetermined operating temperature. The upper body  56  of an embodiment can be made of an insulating material preventing heat transfer between the inside of the electrocoagulation module  20  and the outside of the electrocoagulation module  20 . The lower body  48  of the embodiment illustrated in  FIG. 2  is made of a material that is less insulating the electrocoagulation module  20 . Heating or cooling elements  58  are disposed, for example, in a spiral around the lower body  48  to either heat or cool the lower body  48 . The heating or cooling elements  58  can use a fluid circulating in a tubular system or electric elements in contact with, or nearby, the lower body  48 . Another embodiment is using the upper body  56  to transfer heat to/from the electrocoagulation module  20  in cooperation or not with the lower body  48 . 
     Still referring to the embodiment of  FIG. 2 , the anode module  30  is secured to the upper body  56  and extends above the upper body  56  to allow electrical connection  62  thereto. The cathode module  32  of the present embodiment is also secured to the upper body  56  and extends therefrom  60  to allow electrical connection thereto. A power supply (not illustrated) is connected to the cathode module  32  to provide negative power thereof. Electrical polarity reversal is provided when desired to avoid passivation of the anode module  30  and the anodes  68  secured thereon. Insulators may be placed between two adjacent electrodes to prevent short circuits thereof. The cathode  32  and the anodes  68  are subjected to DC current. One skilled in the art can also appreciate that the upper body  56  is made of an insulating material to prevent establishing an electrical connection between the cathode  32  and the anode module  30 . 
     The anode module  30  can be made of soluble or inert materials. The cathode module  32  can be made of steel, aluminum, stainless steel, galvanized steel, brass or other materials that can be of the same nature as the anode module  30  material or having an electrolytic potential close to the electrolytic potential of the anode  68 . The cathode module  32  of the present embodiment has a hollowed cylindrical shape, fabricated of sheet material, and can be equipped with an optional lower frustoconical portion (not illustrated in  FIG. 2 ). The inter electrode distance of an embodiment of the invention is about between 8-25 mm and preferably 10 mm for electro floatation and 20 mm for electrocoagulation. The interior of the cathode module  32  electrically interacts with the outside of the anode module  30 . The electrocoagulation module  20  internal wall includes non-conductive material, like polymer, in an embodiment of the invention. The cathode module  32  could alternatively serve as a reservoir, or reactor, at the same time thus holding the liquid to treat therein in other embodiments. The cathode module  32  can be made of a material different from the anode material  30  or can alternatively be made of the same material, like, for instance, magnesium. 
     The size and the available active surface area of the cathode module  32  can be adapted to various conditions without departing from the scope of the present invention. The surface ration of the cathode/anode can be identical or vary to about 1.5. The cathode module  32  of other embodiments can alternatively be oval or conical; its diameter expending upward or downward. The electrocoagulation module  20  can include therein an optional fluid agitator module  64  adapted to apply kinetic energy to the fluid contained in the electrocoagulation module  20  by moving or vibrating the fluid in the electrocoagulation module  20  as it is illustrated in the embodiment depicted in  FIG. 2 . 
     As mentioned above, the movement of the fluid increases the kinetic energy contained therein to destabilize the colloidal solution. This can be achieved by turbulently injecting the fluid in the electrolytic module (the speed and tangential injection of the fluid are possible ways to create turbulences in the fluid). The fluid agitator module  64  in this embodiment is a spiral shaped protrusion member  64  that is secured to the anode module  30 . The movement of the fluid between the anode module  30  and the cathode module  32  is intensified by the protrusion member  64 , which influences the electrolytic process. The anode module  30  of an alternate embodiment that is not illustrated in  FIG. 2  could be rotatably secured to the upper body  56  of the electrocoagulation module  20  and be rotated by an external motor to rotate the anode and the protrusion members secured thereon to apply additional kinetic energy to the fluid as it will be discussed below. As it is illustrated in  FIG. 2 , the anode module  30  is preferably centered inside the electrocoagulation module  20  and preferably located at equal distance from the cathode module  32 . 
     The electrocoagulation module  20  of  FIG. 2  further comprises a pair of electrocoagulation module connectors  66  adapted to operatively install the electrocoagulation module  20  in a larger fluid treatment process if desired. The electrocoagulation module  20  can removably be mounted in series, or in parallel, in the fluid treatment process. This way, the electrocoagulation module  20  can easily be added, maintained, replaced and/or removed from the fluid treatment process. 
     EXAMPLE 1 
     An effluent from the agri-food industry has been treated using the method and process of the present invention. This effluent was providing from a pork transformation plant and was charged in urine, feces and blood with a pH of 6.8. The effluent has been treated with the process of the present invention using a 2 reactor and decanter process, with a variable tension generator (0-30V) offering current between 1 and 120 A. The anodes of the reactors were in magnesium and the measures of the chemical oxygen demand, orthophosphate concentration, NH 4   +  concentration, calcium concentration and magnesium concentration made using HACH chemicals. 
     
       
         
               
               
             
               
               
               
               
               
             
           
               
                   
                 TABLE 1 
               
             
             
               
                   
                   
               
               
                   
                 Analysis 
               
             
          
           
               
                   
                 Brut 
                 Conditioned 
                 Treated 
                 Treated 
               
               
                 Sample 
                 effluent 
                 effluent 
                 sample 
                 sample 
               
               
                   
               
               
                 Time 
                 10:00 am 
                 11:00 am 
                 1:30 pm 
                 2:30 pm 
               
               
                 Temperature (C.) 
                 28 
                 28 
                 43 
                 43 
               
               
                 pH 
                 7.02 
                 1.02 
                 9.03 
                 8.85 
               
               
                 M.E.S (mg/l) 
                 1700 
                 1900 
                 0 
                 8.85 
               
               
                 Turbidity (NTU) 
                 817 
                 1100 
                 2 
                 9 
               
               
                 PO 4   3−  (mg/l) 
                 43 
                 135 
                 0.4 
                 0.4 
               
               
                 NH 4   +  (mg/l) 
                 55 
                 55 
                 26 
                 13 
               
               
                   
               
             
          
         
       
     
     It is shown in Table 1 that the brut effluent has an initial concentration of orthophosphate of 43 ppm and ammonium concentration of 55 ppm. To eliminate these two elements, the stoechiometric ratio has to be respected. An initial concentration in orthophosphates of 55×5=275 ppm should have been needed according to the initial data. However, the effluent has been conditioned to have an orthophosphate concentration of 135 ppm, which allowed a reduction in NH 4   +  of 135:5=27 ppm corresponding to the results obtained (26 ppm). This example shows the importance of respecting the stoechiometric ratio to allow an optimal reduction of NH 4   +  as well as maintaining a pH of about 9.2. 
     
       
         
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                   
                 TABLE 2 
               
               
                   
                   
               
               
                   
                 NH 4   +   
                 PO 4   3−   
                 PO 4   3−   
                 PO 4   3−   
                 PO 4   3−   
                   
                 NH 4   +   
               
               
                   
                 (mg/l) 
                 (mg/l) 
                 (mg/l) 
                 (mg/l) 
                 (mg/l) 
                 NH 4   +   
                 Elimination 
               
               
                   
                 Initial 1 
                 initial 2 
                 Theory 3 
                 added 4 
                 final 5 
                 Final 6 
                 (%) 
               
               
                   
                   
               
             
             
               
                   
               
             
          
           
               
                 9:00 am 
                 68 
                 57 
                 340 
                 0 
                 0 
                 55 
                 19 
               
               
                 12:30 pm  
                 70 
                 73 
                 350 
                 174 
                 0 
                 28 
                 60 
               
               
                 1:30 pm 
                 55 
                 43 
                 275 
                 152 
                 0.4 
                 26 
                 52 
               
               
                 2:30 pm 
                 55 
                 43 
                 275 
                 230 
                 0.4 
                 13 
                 77 
               
               
                 3:00 pm 
                 50 
                 51 
                 250 
                 235 
                 0 
                 7 
                 86 
               
               
                   
               
             
          
         
       
     
     Table 2 illustrates that the ions ortho phosphate are needed to eliminate NH4+ and that the closer the ratio orthophosphate/NH 4   +  is closer to 5:1, the better is the NH 4   +  elimination. 
     EXAMPLE 2 
     A lixiviat has been treated using the method and process of the present invention. The effluent has been treated with the process of the present invention using a 2 reactor and decanter process, with a variable tension generator (0-30V) offering current between 1 and 120 A. The anodes of the reactors were in magnesium and the measures of the chemical oxygen demand, orthophosphate concentration, NH 4   +  concentration, calcium concentration and magnesium concentration made using HACH chemicals. 
     The effluent was treated with a tension of 27.3V and a current of 100 A. 
     
       
         
               
               
             
               
               
               
               
             
               
               
               
               
             
           
               
                   
                 TABLE 3 
               
             
             
               
                   
                   
               
               
                   
                 Analysis 
               
             
          
           
               
                 Sample 
                 Brut lixiviat 
                 Conditioned lixiviat 
                 Treated lixiviat 
               
               
                   
               
             
          
           
               
                 Temperature 
                 0 
                 0 
                 27 
               
               
                 pH 
                 7.19 
                 3.75 
                 9.09 
               
               
                 M.E.S (mg/l) 
                 234 
                 352 
                 27 
               
               
                 Turbidity (NTU) 
                 276 
                 390 
                 45 
               
               
                 PO 4   3−  (mg/l) 
                 29 
                 225 
                 0.5 
               
               
                 NH 4   +  (mg/l) 
                 190 
                 190 
                 140 
               
               
                   
               
             
          
         
       
     
     In this example, it is demonstrated again that the reduction of the NH4+ is in accordance with the stoechiometric ratio. To eliminate the residual NH4+, an total amount of 950 ppm of orthophosphate should have been in the conditioned lixiviat. 
     EXAMPLE 3 
     A combined effluent from landfill sites has been treated using the method and process of the present invention. The effluent has been treated with the process of the present invention using a 2 reactor and decanter process, with a variable tension generator (0-30V) offering current between 1 and 120 A. The anodes of the reactors were in magnesium and the measures of the chemical oxygen demand, orthophosphate concentration, NH 4   +  concentration, calcium concentration and magnesium concentration made using HACH chemicals. Several batches (A-H) of the initial effluent have been treated and the results are shown in Table 4. 
     
       
         
               
               
               
               
               
               
               
               
             
               
               
               
               
               
               
               
               
             
           
               
                 TABLE 4 
               
               
                   
               
               
                 Sam- 
                   
                   
                   
                 Conductivity 
                 M.E.S 
                 PO 4   3−   
                 NH 4   +   
               
               
                 ple 
                 Time 
                 T (° C.) 
                 pH 
                 (mS/cm) 
                 (mg/l) 
                 (mg/l) 
                 (mg/l) 
               
               
                   
               
             
             
               
                   
               
             
          
           
               
                 initial 
                 0 min 
                 22 
                 7.84 
                 5.94 
                 1140 
                 90 
                 310 
               
               
                 A 
                 5 min 
                 42 
                 8.82 
                 3.90 
                 24 
                 6.2 
                 220 
               
               
                 B 
                 4 min 
                 42 
                 8.77 
                 3.98 
                 39 
                 7.4 
                 280 
               
               
                 C 
                 5 min 
                 43 
                 8.66 
                 3.74 
                 21 
                 4.3 
                 120 
               
               
                 D 
                 4 min 
                 42 
                 8.77 
                 3.98 
                 29 
                 6.2 
                 280 
               
               
                 E 
                 5 min 
                 43 
                 8.63 
                 3.75 
                 20 
                 5.4 
                 270 
               
               
                 F 
                 4 min 
                 42 
                 8.62 
                 3.95 
                 22 
                 4.8 
                 290 
               
               
                 G 
                 5 min 
                 43 
                 8.56 
                 3.60 
                 18 
                 8.6 
                 290 
               
               
                 H 
                 4 min 
                 41 
                 8.51 
                 3.72 
                 25 
                 10.6 
                 150 
               
               
                   
               
             
          
         
       
     
     The results shown in Table 4 demonstrate that both the stoechiometric ratio and the time of treatment need to be sufficient for allowing a satisfactory elimination of NH 4   + . If the stoechiometric ratio is not respected, the complete, or at least satisfactory, elimination of NH 4   +  is impossible. Also, the treatment needs to be performed for a time sufficient to allow the production of a minimal quantity of Mg 2+  ions; otherwise the reaction cannot be optimal. 
     While the invention has been described in connection with what is presently considered to be the most practical and preferred embodiments, it is to be understood that the invention is not to be limited to the disclosed embodiments and elements, but, to the contrary, is intended to cover various modifications, combinations of features, equivalent arrangements, and equivalent elements included within the spirit and scope of the appended claims. Furthermore, the dimensions of features of various components that may appear on the drawings are not meant to be limiting, and the size of the components therein can vary from the size that may be portrayed in the figures herein. Thus, it is intended that the present invention covers the modifications and variations of the invention, provided they come within the scope of the appended claims and their equivalents.

Technology Classification (CPC): 2