Patent Publication Number: US-2023133212-A1

Title: Electrocoagulation system

Description:
RELATED APPLICATIONS 
     This non-provisional patent application is a continuation-in-part of U.S. patent application Ser. No. 16/252,443 filed on Jan. 18, 2019, which is incorporated herein by reference. 
    
    
     TECHNICAL FIELD 
     This disclosure is related to the field of water treatment systems, and more particularly, to electrocoagulation (EC) systems. 
     BACKGROUND 
     Oil production industries and other industries are consistently forced to deal with water challenges that result from processes (i.e., drilling processes). During a drilling process, for example, an oil/water mixture is pumped from the ground, which is referred to as production water or wastewater. The wastewater coming from the ground could be 95% water and 5% oil by volume. The wastewater may also include traces of heavy metals and other contaminants. Before the wastewater can be safely disposed of or reused, the contaminants need to be removed. Thus, oil companies have the challenge of removing contaminants and safely disposing of the wastewater. Other companies in other industries face similar problems of having to safely dispose of wastewater. 
     One common way of treating wastewater is through a reverse osmosis filtering process. Unfortunately, the reverse osmosis filtering process is expensive and can be relatively slow especially when the contaminant content in the wastewater is high. Another common way of treating wastewater is through a distillation process, which again is expensive and time consuming. Yet another way of treating wastewater is through chemical processes, which are expensive and further processes are needed to return the wastewater to a safe level. 
     Thus, there is a need for improved filtering systems so that wastewater can be safely and reliably processed. 
     SUMMARY 
     Embodiments described herein set forth an electrocoagulation (EC) unit for cleaning wastewater or the like. In one embodiment, an EC unit includes a reaction tank formed from a non-conductive material, charge plates within the reaction tank that are spaced at a distance, intermediate plates disposed within the reaction tank between the charge plates, and plate conductors configured to electrically couple the charge plates to a power source. The bottom of the reaction tank tapers toward one or more ports on the bottom of the reaction tank. Due to the tapered bottom, the reaction tank may be completely emptied or drained of liquids when desired, whether it be wastewater, sludge, a cleansing solution, etc. 
     In an embodiment, a method of cleaning an EC unit is disclosed comprising a reaction tank formed from a non-conductive material, and charge plates and intermediate plates disposed within the reaction tank. The method comprises initiating a cleaning cycle for the EC unit by stopping a flow of wastewater into a flush bottom port from an inlet tank fluidly coupled to the flush bottom port, where the flush bottom port is disposed at a lowest portion of the reaction tank in a gravity flow direction. The method further comprises draining the wastewater from the reaction tank through the flush bottom port to the inlet tank. The method further comprises filling the reaction tank, through the flush bottom port with a cleansing solution from a cleansing tank fluidly coupled to the flush bottom port, to at least an uppermost plate level of the charge plates and the intermediate plates. The method further comprises containing the cleansing solution in the reaction tank for a threshold time, and draining the cleansing solution from the reaction tank through the flush bottom port to the cleansing tank after the threshold time. 
     In an embodiment, the cleansing solution comprises an acid, such as hydrochloric acid. 
     In an embodiment, the cleaning cycle is initiated periodically. 
     In an embodiment, the cleaning cycle is initiated in a time range of four to six hours after an operation cycle of the EC unit. 
     In an embodiment, the reaction tank further comprises an overflow port through a side wall of the reaction tank between a water level of the EC unit and the uppermost plate level. The method further comprises producing a flow of the cleansing solution through the reaction tank and out of the overflow port during the cleaning cycle. 
     In an embodiment, a system comprises an EC unit comprising a reaction tank formed from a non-conductive material, charge plates and intermediate plates disposed within the reaction tank, and a flush bottom port disposed at a lowest portion of the reaction tank in a gravity flow direction. The system further comprises an inlet tank containing a wastewater fluidly coupled to the flush bottom port, and a cleansing tank containing a cleansing solution fluidly coupled to the flush bottom port. The system further comprises a controller configured to initiate a cleaning cycle for the EC unit by stopping a flow of the wastewater into the flush bottom port from the inlet tank, draining the wastewater from the reaction tank through the flush bottom port to the inlet tank, filling the reaction tank, through the flush bottom port with the cleansing solution from the cleansing tank, to at least an uppermost plate level of the charge plates and the intermediate plates, containing the cleansing solution in the reaction tank for a threshold time, and draining the cleansing solution from the reaction tank through the flush bottom port to the cleansing tank after the threshold time. 
     In an embodiment, the cleansing solution comprises an acid, such as hydrochloric acid. 
     In an embodiment, the controller is configured to initiate the cleaning cycle periodically. 
     In an embodiment, the controller is configured to initiate the cleaning cycle in a time range of four to six hours after an operation cycle of the EC unit. 
     In an embodiment, the reaction tank further comprises an overflow port through a side wall of the reaction tank between a water level of the EC unit and the uppermost plate level. The controller is configured to produce a flow of the cleansing solution through the flush bottom port that flows out of the overflow port during the cleaning cycle. 
     In an embodiment, the flush bottom port disposed at the lowest portion of the reaction tank in the gravity flow direction comprises a first flush bottom port fluidly coupled to the inlet tank, and a second flush bottom port fluidly coupled to the cleansing tank. 
     In an embodiment, the reaction tank is cylindrical. 
     In an embodiment, a bottom section of the reaction tank, that includes the flush bottom port, is conical. 
     In an embodiment, a system comprises an EC unit comprising a reaction tank comprising an upper section and a lower section formed from a non-conductive material, and charge plates and intermediate plates disposed within the upper section of the reaction tank. The lower section is funnel-shaped with a flush bottom port disposed at a lowest portion of the reaction tank in a gravity flow direction. The system further comprises an inlet tank containing a wastewater fluidly coupled to the flush bottom port, and a cleansing tank containing a cleansing solution fluidly coupled to the flush bottom port. The system further comprises a controller configured to initiate a cleaning cycle for the EC unit by stopping a flow of the wastewater into the flush bottom port from the inlet tank, draining the wastewater from the reaction tank through the flush bottom port to the inlet tank, filling the reaction tank, through the flush bottom port with the cleansing solution from the cleansing tank, to at least an uppermost plate level of the charge plates and the intermediate plates, containing the cleansing solution in the reaction tank for a threshold time, and draining the cleansing solution from the reaction tank through the flush bottom port to the cleansing tank after the threshold time. 
     In an embodiment, the cleansing solution comprises an acid, such as hydrochloric acid. 
     In an embodiment, the controller is configured to initiate the cleaning cycle periodically. 
     In an embodiment, the lower section of the reaction tank is conical. 
     The above summary provides a basic understanding of some aspects of the specification. This summary is not an extensive overview of the specification. It is intended to neither identify key or critical elements of the specification nor delineate any scope of the particular embodiments of the specification, or any scope of the claims. Its sole purpose is to present some concepts of the specification in a simplified form as a prelude to the more detailed description that is presented later. 
    
    
     
       DESCRIPTION OF THE DRAWINGS 
       Some embodiments of the invention are now described, by way of example only, and with reference to the accompanying drawings. The same reference number represents the same element or the same type of element on all drawings. 
         FIG.  1    illustrates a water filtering system in an illustrative embodiment. 
         FIG.  2    is a perspective view of an EC unit in an illustrative embodiment. 
         FIG.  3    is a cross-sectional view of a reaction tank in an illustrative embodiment. 
         FIG.  4    is a top view of a reaction tank in an illustrative embodiment. 
         FIG.  5    is a perspective diagram of charge plates and intermediate plates in an illustrative embodiment. 
         FIGS.  6 - 7    illustrate an electrical connection for a charge plate in an illustrative embodiment. 
         FIG.  8    is a perspective view of a charge plate in an illustrative embodiment. 
         FIG.  9    is a cross-sectional view of a lower section of a reaction tank in an illustrative embodiment. 
         FIG.  10    is a cross-sectional view of a lower section of a reaction tank in another illustrative embodiment. 
         FIG.  11    is a perspective view of an EC unit with a cylindrical reaction tank in an illustrative embodiment. 
         FIG.  12    is a flow chart illustrating a method of processing wastewater in an illustrative embodiment. 
         FIG.  13    is a flow chart illustrating a clean cycle in an illustrative embodiment. 
         FIG.  14    is a cross-sectional view of a lower section of a reaction tank in an illustrative embodiment. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     The figures and the following description illustrate specific exemplary embodiments. It will thus be appreciated that those skilled in the art will be able to devise various arrangements that, although not explicitly described or shown herein, embody the principles of the embodiments and are included within the scope of the embodiments. Furthermore, any examples described herein are intended to aid in understanding the principles of the embodiments, and are to be construed as being without limitation to such specifically recited examples and conditions. As a result, the inventive concept(s) is not limited to the specific embodiments or examples described below, but by the claims and their equivalents. 
       FIG.  1    illustrates a water filtering system  100  in an illustrative embodiment. Water filtering system  100  may be used as one of multiple stages for filtering wastewater, which comprises water that includes one or more contaminants. Wastewater may also be referred to as grey water or production water. In one example, wastewater is produced during oil drilling processes. 
     Water filtering system  100  includes one or more inlet tanks  102 , one or more EC units  104 , one or more cleansing tanks  106 , and one or more settling tanks  108 . An inlet tank  102  is a receptacle or storage chamber that stores or contains wastewater to be filtered or purified. An EC unit  104  (also referred to as an EC cell or EC system) comprises a system that uses electrocoagulation to separate suspended particles from a liquid. A cleansing tank  106  comprises a receptacle or storage chamber that stores or contains a cleansing solution for EC unit  104 , such as an acid. A settling tank  108  (also referred to as a receiving tank or a clarifier) is a receptacle or storage chamber that stores or contains wastewater after electrocoagulation. The EC unit(s)  104  of water filtering system  100  are elevated in relation to inlet tank  102  and cleansing tank  106  so that fluids in the EC unit(s) may drain via gravity into inlet tank  102  or cleansing tank  106 . 
     In this embodiment, inlet tank  102  is supplied with wastewater  115  via a supply fluid path  110 . Inlet tank  102  is fluidly coupled to EC unit  104  via an inlet fluid path  120  (also referred to as a supply fluid path). Inlet fluid path  120  may include a pump  122 , valves  124 - 125 , supply piping  181 , and common piping  182  that fluidly connect inlet tank  102  with EC unit  104 . Pump  122  is configured to force wastewater  115  from inlet tank  102  to EC unit  104  via inlet fluid path  120  when valves  124 - 125  are open. Inlet tank  102  is also fluidly coupled to EC unit  104  via a drain fluid path  130 . Drain fluid path  130  may include valves  125 - 126 , common piping  182 , and drain piping  183  that fluidly connect EC unit  104  and inlet tank  102 . Wastewater  115  from EC unit  104  is configured to gravity drain into inlet tank  102  via drain fluid path  130  when valves  125 - 126  are open. 
     Cleansing tank  106  is fluidly coupled to EC unit  104  via an inlet fluid path  140  (also referred to as a supply fluid path). Inlet fluid path  140  may include a pump  142 , valves  134 - 135 , supply piping  184 , and common piping  182  that fluidly connect cleansing tank  106  with EC unit  104 . Pump  142  is configured to force a cleansing solution  117  from cleansing tank  106  to EC unit  104  via inlet fluid path  140  when valves  134 - 135  are open. A cleansing solution  117  comprises a liquid configured to clean EC unit  104 , or more particularly plates of EC unit  104 , such as an acid, hydrochloric acid, etc. Cleansing tank  106  is also fluidly coupled to EC unit  104  via a drain fluid path  150 . Drain fluid path  150  may include valves  135 - 136 , common piping  182 , and drain piping  185  that fluidly connect EC unit  104  and cleansing tank  106 . Cleansing tank  106  is also fluidly coupled to EC unit  104  via an overflow fluid path  158 . Overflow fluid path  158  may include a valve  156  and drain piping  186  that fluidly connects EC unit  104  and cleansing tank  106 . 
     The configuration for inlet fluid path  120 , drain fluid path  130 , inlet fluid path  140 , and drain fluid path  150  are examples, and other configurations as considered herein. For example, a tee pipe  188  is illustrated between common piping  182  and each of inlet fluid path  120  and drain fluid path  130 , and inlet fluid path  140  and drain fluid path  150 . However, other plumbing configurations are considered herein. 
     Settling tank  108  is disposed near an outlet of EC unit  104 , and is fluidly coupled to EC unit  104  via an outlet fluid path  160 . As described in more detail below, wastewater  115  may be gravity fed from the outlet at or near the top of EC unit  104  to settling tank  108  via outlet fluid path  160 . Clean or purified water may be released from settling tank  108  via outlet path  170 . 
     Water filtering system  100  may further include a controller  109  configured to provide automated and/or computerized control of water filtering system  100 . Controller  109  is configured to regulate the opening and closing of various valves  124 - 126 ,  134 - 136 , and  156  throughout water filtering system  100 , to control pumps  122  and  142 , to control power to various components, such as EC unit  104 , etc. Controller  109  may include one or more processors that are communicatively coupled to a memory. While the specific hardware implementation of controller  109  is subject to design choices to perform the functionality described herein, the processor may comprise any electronic circuits and/or optical circuits that are able to perform functions. The processor may include one or more Central Processing Units (CPU), microprocessors, Digital Signal Processors (DSPs), Application-specific Integrated Circuits (ASICs), Programmable Logic Devices (PLD), control circuitry, etc. Some examples of processors include INTEL® CORE™ processors, Advanced Reduced Instruction Set Computing (RISC) Machines (ARM®) processors, etc. The memory comprises any electronic circuits, and/or optical circuits, and/or magnetic circuits that are able to store data. The memory may include one or more volatile or non-volatile Dynamic Random-Access Memory (DRAM) devices, FLASH devices, volatile or non-volatile Static RAM devices, magnetic disk drives, Solid State Disks (SSDs), etc. Some examples of non-volatile DRAM and SRAM include battery-backed DRAM and battery-backed SRAM. 
       FIG.  2    is a perspective view of EC unit  104  in an illustrative embodiment. Electrocoagulation is a technique used to treat wastewater to remove contaminants, such as ion particles, colloidal particles, etc. Contaminants are particles in wastewater that are generally held in the solution by electrical charges. Electrostatic repulsion of the particles inhibits the particles from coagulating in the wastewater. Electrocoagulation is a process that reduces the surface charges of the particles to a point where the particles are destabilized and can form an agglomeration. As will be described in more detail below, EC unit  104  includes an electrocoagulation reactor having a positively-charged electrode (an anode) and a negatively-charged electrode (a cathode) connected to an external power source. As wastewater  115  flows through EC unit  104 , a potential is placed across the electrodes by the power source, which injects a current through the wastewater  115 . The positive side undergoes anodic reactions while the negative side undergoes cathodic reactions. Consumable metal plates, such as iron or aluminum, are usually used as sacrificial electrodes to continuously produce ions in the wastewater  115 . The released ions neutralize the charges on the particles in the wastewater  115  and thereby initiate coagulation. As a result, the reactive and excited state causes the contaminant particles to coagulate, and be released from the wastewater  115 . 
     EC unit  104  includes a reaction tank  210  or tub, which is a receptacle or storage chamber configured to contain wastewater  115  that is being processed. Reaction tank  210  includes an upper section  212  and a lower section  214  that are formed from a non-conductive material, such as Polyvinyl Chloride (PVC), polyethylene, polypropylene, or another type of plastic, fiberglass, etc. In this embodiment, upper section  212  is square or rectangular with side walls  221 - 224 . Further in this embodiment, side walls  221 - 224  may generally be twice as tall as they are wide. 
     Lower section  214  tapers from upper section  212  to one or more ports  228  on the bottom of reaction tank  210  to form a funnel or hopper shape. Lower section  214  has one or more sloped walls  229  that join along a top edge to upper section  212 , and converge at a bottom edge at or near port  228 . Lower section  214  may be conical, wedge, pyramidal, or a combination of these shapes. The funnel shape of lower section  214  acts to concentrate liquid materials at port  228  when discharged from reaction tank  210 . Port  228  is a mouth or opening disposed at the bottom (i.e., lowest portion) of reaction tank  210  in the gravity flow direction, which acts as an ingress and/or egress point for liquid materials. Thus, port  228  is an inlet port for liquid materials, and an outlet port. 
     When in operation, wastewater  115  flows upward through EC unit  104  from port  228  and out of the top of reaction tank  210 . Therefore, reaction tank  210  includes a trough  226  at its top. Trough  226  comprises an opening(s), channel, conduit, etc., at or near the top of reaction tank  210  that acts as an exit point for wastewater  115  to flow out of EC unit  104 . Trough  226  may have any desired structural design to convey wastewater  115  out of EC unit  104  and to settling tank  108  (see  FIG.  1   ). Because trough  226  is the exit point for wastewater  115 , the vertical position of trough  226  alongside wall  223  defines a water level  238  for EC unit  104 . Trough  226  is shown on side wall  223  in this embodiment, but may be on other side walls in other embodiments. Also, side wall  221  is shown with an overflow port  270  through side wall  221  that is situated below the water level  238 . 
     Although not visible in  FIG.  2   , EC unit  104  includes a series of plates (or blades) installed in the interior  250  of reaction tank  210  that are configured to conduct a current through wastewater  115  that flows through reaction tank  210 . The plates include a pair of charge plates that connect to a power source  260 . One of the charge plates is a positively-charged electrode, and the other charge plate is a negatively-charged electrode. A plate conductor  251  for one of the charge plates, and a plate conductor  252  for the other charge plate are visible extending out of reaction tank  210 . The plates also include one or more intermediate plates that are aligned between the charge plates within reaction tank  210 , as will be described in more detail below. The top of one or more of the charge plates and the intermediate plates define an uppermost plate level  239 , which is below water level  238 . Overflow port  270  is disposed between uppermost plate level  239  and water level  238 . 
     EC unit  104  may further include a lid  230  that covers the top of reaction tank  210 . During processing of wastewater  115 , noxious gasses may be emitted from EC unit  104 . Lid  230  acts to contain gas emissions from EC unit  104 . Lid  230  may include a vent  232  that guides gases from the interior  250  of EC unit  104  to a more distant location. Lid  230  may further include plate conductor openings  234  that act as passageways for plate conductors  251 - 252  and insulators that surround plate conductors  251 - 252 . Plate conductors  251 - 252  may therefore connect to a power source  260  outside of reaction tank  210 . The power connection may be housed in a sealed chamber for safety of the operator and to protect the power connection from corrosion. 
     The EC unit  104  may further include a support framework  240  configured to hold reaction tank  210  in an upright position. 
       FIG.  3    is a cross-sectional view of reaction tank  210  in an illustrative embodiment. The view in  FIG.  3    is across cut-plane  3 - 3  in  FIG.  2   , and shows an electrocoagulation reactor having charge plates  301 - 302  that are spaced at a distance. A charge plate is a sheet of metallic material, such as iron, aluminum, etc. Charge plates  301 - 302  are disposed at or near opposite side walls of reaction tank  210  within upper section  212 . Plate conductor  251  is configured to connect with one terminal of power source  260  (see  FIG.  2   ), and plate conductor  252  is configured to connect with the other terminal of power source  260 . An insulator  320  is disposed around plate conductors  251 - 252  from below water level  238  to above water level  238 . Insulator  320  comprises any sleeve, sheath, covering, casing, coating, etc., made from a non-conductive material that is configured to electrically isolate at least a length of a plate conductor  251 - 252 . Insulator  320  may extend from above water level  238  to an electrical coupling (e.g., a weld) between a charge plate  301 - 302  and a plate conductor  251 - 252 . 
     The electrocoagulation reactor further includes one or more intermediate plates  303  or neutral plates disposed between charge plates  301 - 302 . Intermediate plates  303  are not directly connected to power source  260 . Intermediate plates  303  are spaced between charge plates  301 - 302  to improve current flow through the wastewater  115  within reaction tank  210 . In one embodiment, charge plates  301 - 302  may be oriented vertically and parallel to one another. Intermediate plates  303  may also be oriented vertically, and parallel to one another and to charge plates  301 - 302 . Intermediate plates  303  are installed within reaction tank  210  so that there are gaps  310  between opposing faces of charge plates  301 - 302  and intermediate plates  303 . For example, the gap  310  may be in the range of ⅛ th  inch to ⅜ th  inch, such as 5/16 th  inch spacing between opposing faces. Gaps  310  form conduits for wastewater  115  to flow upward between plates  301 - 303 . It may be desirable for gap  310  to be substantially constant or uniform along the entire length and width of the plates to avoid physical contact between the plates. The tops of charge plates  301 - 302  and intermediate plates  303  may be co-planar, and the bottoms of charge plates  301 - 302  and intermediate plates  303  may be coplanar as shown in  FIG.  3   . The tops of charge plates  301 - 302  and intermediate plates  303  are positioned below water level  238  defined by trough  226 . It may be desirable for the space between water level  238  and the tops of charge plates  301 - 302 /intermediate plates  303  to be minimal to avoid a current path between charge plates  301 - 302  that traverses above intermediate plates  303 . At the same time, the space between water level  238  and the tops of charge plates  301 - 302 /intermediate plates  303  is large enough to accommodate overflow port  270 . 
     In other embodiments, charge plates  301 - 302  and intermediate plates  303  may be oriented at a slight angle relative to vertical, with a gap  310  between the plates. 
     In other embodiments, charge plates  301 - 302  and intermediate plates  303  may be staggered in the vertical direction so that the tops and bottoms of charge plates  301 - 302  and intermediate plates  303  are not coplanar. 
     Assume in an operational example that a potential is placed across plate conductors  251 - 252  by power source  260  with wastewater  115  in reaction tank  210 , where charge plate  301  acts as the anode (+) and charge plate  302  acts as the cathode (−). When this occurs, current is injected into plate conductor  251  and into charge plate  301 . The current passes through the wastewater  115  and intermediate plates  303 , into charge plate  302 , and along plate conductor  252 . The current is therefore dispersed through the wastewater  115  as the wastewater  115  traverses upward through reaction tank  210 , to neutralize charges on the particles in the wastewater. 
       FIG.  4    is a top or plan view of reaction tank  210  in an illustrative embodiment. In this figure, lid  230  is removed to expose the interior  250  of reaction tank  210 . Reaction tank  210  may include a mounting rack  402  disposed at or near side wall  221  of reaction tank  210 , and a mounting rack  403  disposed at or near side wall  223  of reaction tank  210 . Charge plate  301  is slid into mounting racks  402 - 403  proximate to side wall  224  of reaction tank  210 , and charge plate  302  is slid into mounting racks  402 - 403  proximate to side wall  222  of reaction tank  210 . Intermediate plates  303  are slid into mounting racks  402 - 403  between charge plates  301 - 302 . In this view, charge plates  301 - 302  and intermediate plates  303  are oriented substantially vertical within reaction tank  210 , with a gap  310  between the plates.  FIG.  4    also shows trough  226  projecting outward from side wall  223  of reaction tank  210 . 
       FIG.  5    is a perspective view of charge plates  301 - 302  and intermediate plates  303  in an illustrative embodiment. In this embodiment, charge plates  301 - 302  and intermediate plates  303  are rectangular in shape. Charge plate  301  has a length L 1  (or height) in the vertical direction, and a width W 1  in the horizontal direction. Charge plate  302  has a length L 2  in the vertical direction, and a width W 2  in the horizontal direction. Intermediate plates  303  have a length L 3  in the vertical direction, and a width W 3  in the horizontal direction. The shape and/or area charge plates  301 - 302  may be the same or substantially the same, and the shape and/or area of intermediate plates  303  may be the same or substantially the same as charge plates  301 - 302 . 
     In one embodiment, the length of the plates  301 - 303  may be at least twice the width of plates  301 - 303 . As the wastewater  115  flows upward through reaction tank  210 , plates  301 - 303  that are longer than they are wide allows for longer residence or contact time between the wastewater  115  and the electrical current. For example, the residence time may be about 90 seconds, which makes the electrocoagulation process more effective. Additionally or alternatively, charge plates  301 - 302  may be at least twice as thick as intermediate plates  303 . 
     In other embodiments, plates  301 - 303  may have shapes that are non-rectangular. Also, the length and width of the plates  301 - 303  may differ as desired. 
       FIGS.  6 - 7    illustrate an electrical connection for a charge plate  301 - 302  in an illustrative embodiment. Charge plate  301 / 302  connects to power source  260  through a plate conductor  251 / 252  (see also,  FIG.  2   ). Plate conductor  251 / 252  is a length of conductive material, such as a wire or rod (e.g., round or flat), that connects to charge plate  301 / 302  and extends out of reaction tank  210 . Plate conductor  251 / 252  may be formed from the same material as charge plate  301 / 302 . In  FIG.  6   , plate conductor  251 / 252  extends down along a side of charge plate  301 / 302 , and makes an electrical connection with charge plate  301 / 302  at or near the bottom of charge plate  301 / 302  denoted by electrical coupling  606 . Electrical coupling  606  represents a point where plate conductor  251 / 252  and charge plate  301 / 302  are joined. Electrical coupling  606  may comprise a weld or welded joint, a brazed joint, a fastened joint (e.g., bolts, screws, rivets, etc.), or another type of joint. 
     In the embodiments described herein, electrical coupling  606  is disposed a distance  609  from a top  608  of charge plate  301 / 302 . In one embodiment, distance  609  may be at least three inches below a top  608  of charge plate  301 / 302  or a top of an intermediate plate  303  in the vertical direction. By moving electrical coupling  606  down from the top  608  of charge plate  301 - 302 , current is injected toward the center or bottom of charge plate  301 / 302  and is not concentrated toward the top  608  of charge plate  301 / 302 . The area of charge plate  301 / 302  may be divided into a top region  611 , a middle region  612 , and a bottom region  613 . In the embodiment shown in  FIG.  6   , electrical coupling  606  of plate conductor  251 / 252  with charge plate  301 / 302  is located at bottom region  613 . In the embodiment shown in  FIG.  7   , electrical coupling  606  of plate conductor  251 / 252  with charge plate  301 / 302  is located at middle region  612  and bottom region  613 . In yet another embodiment, electrical coupling  606  of plate conductor  251 / 252  with charge plate  301 / 302  may be partially at top region  611 , middle region  612 , and/or bottom region  613 . 
     Plate conductor  251 / 252  is wrapped, covered, or encased by insulator  320  from above water level  238  of EC unit  104  to electrical coupling  606 . Insulator  320  may extend into or out of plate conductor openings  234  in lid  230  (see  FIG.  2   ). Insulator  320  electrically isolates plate conductor  251 / 252  from charge plate  301 / 302  except along electrical coupling  606 . Insulator  320  allows current to be injected into a charge plate  301 - 302  below the surface of the wastewater  115  in reaction tank  210 . Some benefits of injecting current below the surface of the wastewater  115  are to mitigate or eliminate current spread across the top of intermediate plates  303 , and to mitigate or eliminate deterioration of plate conductors  251 - 252  at the surface of the wastewater  115 . 
       FIG.  8    is a perspective view of a charge plate  301 - 302  in an illustrative embodiment. In this embodiment, a charge plate  301 - 302  and plate conductor  251 - 252  comprise a monolithic body formed, cast, stamped, etc., as a single piece. Charge plate  301 - 302  includes a recess  802  at the top  608  that extends downward. Plate conductor  251 - 252  projects out of top  608  of charge plate  301 / 302  from recess  802 . Insulator  320  surrounds plate conductor  251 - 252  from below the top  608  of charge plate  301 - 302  to above the water level  238 . 
       FIG.  9    is a cross-sectional view of lower section  214  of reaction tank  210  in an illustrative embodiment. As described above, side walls  229  of lower section  214  converge at port  228  to form a funnel shape. Side walls  229  have interior surfaces  902  that slope toward and abut port  228  at a bottom end  904 . In this embodiment, the bottom ends  904  of interior surfaces  902  are flush with port  228  to form a smooth transition between interior surfaces  902  and port  228 . Port  228  may therefore be referred to as a “flush” bottom port disposed at a lowest portion of reaction tank  210  (i.e., the inside of reaction tank  210 ) in a gravity flow direction (i.e., downward in  FIG.  9   ). The term “flush” refers to a generally continuous plane or generally unbroken surface. In other words, there is no lip or other protrusion between interior surfaces  902  and port  228 . This is beneficial in that liquid materials (e.g., wastewater, sludge, cleansing solution, etc.) are able to freely flow out of port  228  without obstruction so that reaction tank  210  can be completely or fully drained. 
     In an alternative embodiment, there may be more than one port  228  at the bottom of lower section  214 . For example, there may be one port  228  for wastewater  115 , and a separate port for the cleansing solution  117 .  FIG.  14    is a cross-sectional view of lower section  214  of reaction tank  210  in an illustrative embodiment. In this embodiment, port  228  includes a wastewater port  228 - 1  and a cleansing solution port  228 - 2 . Each of ports  228 - 1  and  228 - 2  are flush with interior surfaces  902  of side walls  229 . Wastewater port  228 - 1  may be fluidly coupled with inlet fluid path  120  and drain fluid path  130  as illustrated in  FIG.  1   . Likewise, cleansing solution port  228 - 2  may be fluidly coupled with inlet fluid path  140  and drain fluid path  150  as illustrated in  FIG.  1   . Thus, tee pipe  188  and common piping  182  as shown in  FIG.  1    would not be used. 
     In the embodiments shown above, reaction tank  210  has a single funnel structure that discharges at one or more ports  228 . In other embodiments, reaction tank  210  may have multiple funnel structures that discharge at one or more ports  228 .  FIG.  10    is a cross-sectional view of lower section  214  of reaction tank  210  in another illustrative embodiment. In this embodiment, lower section  214  includes two funnel structures. The side walls  229  of lower section  214  converge at two distinct ports  228  (e.g., wastewater port  228 - 1  and cleansing solution port  228 - 2 ). The embodiment in  FIG.  10    is just one example, and lower section  214  may have more than two funnel structures in other embodiments. 
     The shape of reaction tank  210  for EC unit  104  shown in the above embodiments is square or rectangular. However, the reaction tank may have other shapes in other embodiments.  FIG.  11    is a perspective view of an EC unit  104  with a cylindrical reaction tank in an illustrative embodiment. Reaction tank  1110  includes an upper section  1112  and a lower section  1114  that are formed from a non-conductive material. In this embodiment, upper section  1112  has a cylindrical side wall  1121 . Lower section  1114  tapers from upper section  1112  to one or more ports  1128  (e.g., flush bottom port) on the bottom of reaction tank  1110  to form a funnel shape. Lower section  1114  has a conical shape that joins along a top edge to upper section  1112 , and converges at a bottom edge at or near port  1128 . 
     When in operation, wastewater  115  flows upward through EC unit  104  from port  1128  and out of the top of reaction tank  1110 . Therefore, reaction tank  1110  includes a trough  1126  at its top. Trough  1126  may have any desired structural design to convey wastewater  115  out of EC unit  104  and to a settling tank  108  (see  FIG.  1   ). Although not visible in  FIG.  11   , EC unit  104  includes a pair of charge plates installed in the interior  1150  of reaction tank  1110  that connect to a power source, and one or more intermediate plates that are aligned between the charge plates within reaction tank  1110 . Trough  1126  is disposed above the top of the charge plates and the intermediate plates. Because trough  1126  is the exit point for wastewater, the vertical position of trough  1126  alongside wall  1121  defines a water level  238  for EC unit  104 . Also, side wall  1121  is shown with an overflow port  1170  that is situated below the water level  238 , and above the uppermost plate level  239 . 
     EC unit  104  may further include a lid  1130  that covers the top of reaction tank  1110 . Lid  1130  may include a vent  1132  that guides gases from the interior  1150  of EC unit  104  to a more distant location. Lid  1130  may further include plate conductor openings  1134  that act as passageways for plate conductors  251 - 252 , and insulators that surround plate conductors  251 - 252 . 
       FIG.  12    is a flow chart illustrating a method  1200  of processing wastewater  115  in an illustrative embodiment. The steps of method  1200  will be described with reference to water filtering system  100  in  FIG.  1    and EC unit  104  in  FIGS.  2 - 4   , but those skilled in the art will appreciate that method  1200  may be performed in other systems or devices. Also, the steps of the flow charts described herein are not all inclusive and may include other steps not shown, and the steps may be performed in an alternative order. 
     When in operation (i.e., in operation time or operation cycle), controller  109  produces a flow of wastewater  115  from inlet tank  102  to one or more EC units  104  (step  1202 ). There may be multiple EC units  104  operating in parallel based on the flow requirements of water filtering system  100 . Thus, controller  109  may select which of the EC units  104  are active at any point in time, and produce a flow of wastewater  115  to the selected EC unit(s)  104 . To supply wastewater  115  to an EC unit  104 , controller  109  opens valves  124 - 125  and activates pump  122  to produce a flow of wastewater  115  along inlet fluid path  120  to EC unit  104  through port  228 . Controller  109  controls power source  260  to apply a potential across charge plates  301 - 302  of EC unit  104  (step  1204 ). As EC unit  104  receives the flow of wastewater  115  from its bottom, the wastewater  115  flows upward within reaction tank  210  between the charge plates  301 - 302  and intermediate plates  303 . As the wastewater  115  flows between the charge plates  301 - 302  and intermediate plates  303 , the potential placed across the charge plates  301 - 302  injects a current through the wastewater  115 . The positive charge plate  301 / 302  undergoes anodic reactions while the negative charge plate  301 / 302  undergoes cathodic reactions, which continuously produces ions in the wastewater  115 . The released ions neutralize the charges on the particles in the wastewater  115  and thereby initiate coagulation. Controller  109  may control power source  260  to reverse polarity across charge plates  301 - 302  periodically (e.g., every 20 seconds) to avoid oxidation or scaling on one side of charge plates  301 - 302  and intermediate plates  303 . Controller  109  may also adjust the potential placed across charge plates  301 - 302  based on condition of the wastewater  115 , condition of plates  301 - 303 , or other factors. 
     The wastewater  115  flows out of trough  226  at the top of reaction tank  210 , and is gravity-fed into settling tank  108  along outlet fluid path  160  where the wastewater  115  is temporarily stored. As the wastewater  115  sits in settling tank  108 , the neutralized particles in the wastewater  115  separate from the wastewater  115  and fall to the bottom of settling tank  108 . The particles that are released from the wastewater  115  form a slurry of solids on the bottom of settling tank  108 , while the filtered water remains as a liquid on top of the slurry. The filtered water may be released from settling tank  108  via outlet path  170 . 
     Controller  109  determines whether to initiate a cleaning cycle for an EC unit  104  (step  1205 ). Charge plates  301 - 302  and intermediate plates  303  may become coated with a non-conducting oxide, which may cause the electrocoagulation process to fail through reduced efficiency and increased power consumption. Controller  109  may initiate or perform the cleaning cycle (step  1206 ) periodically (e.g., after a time range of about four to six hours of runtime of the operation cycle, after a time range of about six to twelve hours, or another time range) to remove the oxide or scaling that form on the plates  301 - 303  of the EC unit  104 . If multiple EC units  104  are running in parallel, controller  109  may select one or more EC units  104  for a cleaning cycle while other EC units  104  stay in operation. 
       FIG.  13    is a flow chart illustrating a clean cycle  1300  in an illustrative embodiment. When a cleaning cycle is initiated for an EC unit  104 , controller  109  stops the flow of wastewater  115  to the selected EC unit  104  through port  228  (step  1302 ). To do so, controller  109  may deactivate pump  122  and close valve  124  to stop the flow of wastewater  115  along inlet fluid path  120 . Controller  109  then drains the wastewater  115  (and any remaining sludge) from reaction tank  210  of EC unit  104  through port  228  (step  1304 ). To drain reaction tank  210 , controller  109  may open valve  126  and the liquid remaining in reaction tank  210  discharges along drain fluid path  130  to inlet tank  102  via gravity flow. The liquid remaining in reaction tank  210  is generally a slurry comprised of wastewater  115  and a sludge that forms in the lower section  214  of reaction tank  210 . Due to the funnel shape of lower section  214  of reaction tank  210 , the slurry is able to fully evacuate from reaction tank  210  along drain fluid path  130 , including any sludge that forms in reaction tank  210 . Thus, an operator does not need to remove lid  230  and scrape the sludge from reaction tank  210 . 
     With reaction tank  210  emptied of wastewater  115 , controller  109  may close valves  124 - 126 . Controller  109  then fills the reaction tank  210  of the EC unit  104  with a cleansing solution  117  from cleansing tank  106  through port  228  (step  1306 ). To do so, controller  109  may open valves  134 - 135 , and activate pump  142  to produce a flow of cleansing solution  117  along inlet fluid path  140  to EC unit  104 . As EC unit  104  receives the flow of cleansing solution  117  from its bottom, the cleansing solution  117  flows upward within reaction tank  210  between the charge plates  301 - 302  and intermediate plates  303 . In one embodiment, controller  109  may stop the flow of cleansing solution  117  at or above the uppermost plate level  239  (see  FIG.  2   ), or between the uppermost plate level  239  and the water level  238 . For example, controller  109  may stop pump  142  and close valve  134  when the cleansing solution  117  fills reaction tank  210  at least to the uppermost plate level  239 . It may be desirable for the plates  301 - 303  of the EC unit  104  to be fully submerged in the cleaning solution  117 . The cleansing solution  117  acts to remove oxide or scaling on charge plates  301 - 302  and intermediate plates  303 . Thus, controller  109  may wait for a configurable time period or threshold time, such as 30 seconds, 60 seconds, 90 seconds, etc., while reaction tank  210  contains the cleansing solution  117  with the plates  301 - 303  exposed or soaking in the cleaning solution  117  (step  1308 ). Thus, the cleaning cycle may be referred to as a soaking cycle. 
     In one embodiment, the cleansing solution  117  may flow through reaction tank  210  during the cleaning cycle. Thus, controller  109  may produce a flow of the cleansing solution  117  through reaction tank  210  and out of overflow port  270  during the cleaning cycle (optional step  1312 ). The flow of the cleansing solution  117  may be used during, after, or in place of a soaking cycle. 
     At the end of the cleaning cycle  1300 , controller  109  drains the cleansing solution  117  from reaction tank  210  through port  228  after the threshold time (step  1310 ). To do so, controller  109  may open valve  136  and the cleansing solution  117  in reaction tank  210  discharges along drain fluid path  150  back to cleansing tank  106  via gravity flow. After the cleaning cycle, controller  109  may close valves  135 - 136 , and put EC unit  104  back into operation (i.e., an operation cycle). 
     Controller  109  may also determine whether to initiate a service cycle for an EC unit  104  (step  1213 ). As stated above, charge plates  301 - 302  and intermediate plates  303  may be coated with a non-conducting oxide, which may cause the electrocoagulation process to fail through reduced efficiency and increased power consumption. Also, charge plates  301 - 302  and intermediate plates  303  are sacrificial and will corrode during the electrocoagulation process. The service cycle is performed to determine whether one or more of the charge plates  301 - 302  and intermediate plates  303  need to be serviced or replaced. If multiple EC units  104  are running in parallel, controller  109  may select one or more EC units  104  for a service cycle while other EC units  104  stay in operation. 
     When a service cycle is initiated for an EC unit  104 , controller  109  stops the flow of wastewater  115  to the selected EC unit  104  (step  1214 ). To do so, controller  109  may deactivate pump  122  and closes valve  124  to stop the flow of wastewater  115  along inlet fluid path  120 . Controller  109  then drains the wastewater  115  from reaction tank  210  of EC unit  104  through port  228  (step  1216 ). To drain reaction tank  210 , controller  109  may open valve  126  and the liquid remaining in reaction tank  210  discharges along drain fluid path  130  to inlet tank  102  via gravity flow. 
     With reaction tank  210  emptied, controller  109  may control a sensor (not shown) or another type of element to inspect charge plates  301 - 302  and intermediate plates  303  (step  1218 ). Alternatively, an operator may remove lid  230  to visually inspect charge plates  301 - 302  and intermediate plates  303 . One or more of charge plates  301 - 302  and intermediate plates  303  may be replaced (step  1220 ) as needed. After the service cycle, controller  109  may put EC unit  104  back into operation. 
     Although specific embodiments were described herein, the scope of the disclosure is not limited to those specific embodiments. The scope of the disclosure is defined by the following claims and any equivalents thereof.