Patent Publication Number: US-2022220017-A1

Title: Ferrate based water treatment

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     Not applicable. 
     STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT 
     Not applicable. 
     REFERENCE TO A MICROFICHE APPENDIX 
     Not applicable. 
     TECHNICAL FIELD 
     The present disclosure relates to a continuous process and system for treatment of water using ferrate. 
     BACKGROUND 
     Advanced oxidation processes (AOPs) are chemical-based water treatment procedures designed to remove organic and some inorganic material from water and wastewater by oxidation reactions. Common AOP technologies for waste water treatment include usage of ozone (O 3 ) with hydrogen peroxide (H 2 O 2 ) or ultraviolent (UV) light, hydrogen peroxide (H 2 O 2 ) with ultraviolent (UV) light, chlorine-containing compounds (sodium hypochlorite (NaClO), also known as bleach), or ferrous-based systems using iron ions (e.g., Fe 2+ , Fe 3+ ) in a solution of hydrogen peroxide (H 2 O 2 ). 
     Chemical-based AOP technologies for commercial scale wastewater treatment involve handling the chemicals in large volumes which are hazardous and even poisonous to humans, animals, and/or the environment. Additionally, the treatment cost and logistics requirement for common AOP technologies are challenging due to high quantity necessary to produce hydroxide radicals and oxidizing reagents when there&#39;s a high contaminant loading. As a result, synthesizing and supplying chemical reagents for the oxidation process, on a continuous basis, is not feasible in many situations. 
     SUMMARY 
     A process for treatment of a contaminated water stream, comprising: contacting the contaminated water with ferrate in a redox reactor to produce a redox water; removing particulate contaminants from the redox water in a clarifier to produce a clarified water; and filtering at least a portion of the clarified water in a two-stage filtration system to produce a treated water, wherein each step of the process is performed on a continuous basis. 
     A ferrate-based water treatment system comprising: a ferric compound solution preparation system configured to prepare ferric compound solution; an acidic oxidant solution preparation system configured to prepare an acidic oxidant solution; a flocculant-adsorbent solution preparation system configured to prepare a flocculant-adsorbent solution; a redox reactor fluidly coupled to the ferric compound solution preparation system and to the acidic oxidant solution preparation system and to the flocculant-adsorbent solution preparation system; a clarifier fluidly coupled to the redox reactor, to the ferric compound solution preparation system, and to the acidic oxidant solution preparation system; and a two-stage filtration system coupled to the clarifier. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       For a more complete understanding of the present disclosure and the advantages thereof, reference is now made to the following brief description, taken in connection with the accompanying drawings and detailed description, wherein like reference numerals represent like parts. 
         FIG. 1  illustrates a process flow diagram of the continuous water treatment process and system disclosed herein. 
         FIGS. 2A and 2B  illustrate process flow diagrams of embodiments of the pre-treatment system of  FIG. 1 . 
         FIGS. 3A to 3C  illustrates preparation system for the ferric compound solution, the acidic oxidant solution, and the flocculant-adsorbent solution. 
         FIG. 4  illustrates a process flow diagram of an embodiment of the sludge handling system of  FIG. 1 . 
         FIG. 5  illustrates a process flow diagram of the continuous water treatment process and system, with exemplary control instrumentation illustrated. 
     
    
    
     DETAILED DESCRIPTION 
     It should be understood at the outset that although illustrative implementations of one or more embodiments are illustrated below, the disclosed systems and methods may be implemented using any number of techniques, whether currently known or not yet in existence. The disclosure should in no way be limited to the illustrative implementations, drawings, and techniques illustrated below, but may be modified within the scope of the appended claims along with their full scope of equivalents. 
     The following brief definition of terms shall apply throughout the application: 
     The term “comprising” means including but not limited to, and should be interpreted in the manner it is typically used in the patent context; 
     The phrases “in one embodiment,” “according to one embodiment,” “in some embodiments,” and the like generally mean that the particular feature, structure, or characteristic following the phrase may be included in at least one embodiment of the present invention, and may be included in more than one embodiment of the present invention (importantly, such phrases do not necessarily refer to the same embodiment); 
     If the specification describes something as “exemplary” or an “example,” it should be understood that refers to a non-exclusive example; 
     The terms “about” or “approximately” or the like, when used with a number, may mean that specific number, or alternatively, a range in proximity to the specific number, as understood by persons of skill in the art field; and 
     If the specification states a component or feature “may,” “can,” “could,” “should,” “would,” “preferably,” “possibly,” “typically,” “optionally,” “for example,” “often,” or “might” (or other such language) be included or have a characteristic, that particular component or feature is not required to be included or to have the characteristic. Such component or feature may be optionally included in some embodiments, or it may be excluded. 
     The term “stream” as used herein can refer to the fluid described herein and/or the physical piping and/or conduit through which the fluids discussed herein flow. “Stream” can be used interchangeably with “pipe”, “piping”, and “conduit” in some instances. 
     Embodiments of the process and system are described with reference to equipment and process functionality. The process may be described using the system components and equipment, and it is to be understood that embodiments of the system can include any combination of the components and equipment disclosed herein and having functionality described herein to perform the process. 
     The system and process disclosed herein involve the treatment of water using a ferrate-based reduction-oxidation (redox) reactor, a clarifier, and a two-stage filtration system. Three treatment substrates can be used to treat water in the water treatment system, namely, a ferric compound(s), an acidic oxidant, and a flocculant-adsorbent. Contact of the ferric compound(s) (e.g., containing iron as Fe′) with acidic oxidant can form ferrate that has a high redox potential, functions to remove contaminants by oxidation and by disinfection, and is safer to humans and the environment (e.g., compared with the production of disinfection byproducts (e.g., trihalomethane and haloacetic acid) using chlorine-based technology or other hazardous or carcinogenic chemicals using ozone) for the treatment of contaminated water. The ferrate used in the disclosed process and system also produces ferric hydroxide in the form of Fe′, which is non-toxic and benign to the environment, while functioning as a coagulant. 
       FIG. 1  illustrates a process flow diagram of the continuous water treatment process and system  10  disclosed herein. The process and system can continuously produce a treated water in stream  141  from a continuously fed contaminated water in stream  102 , and can includes steps for ferrate-based reduction and oxidation reactions in redox reactor  110 , gravity separation or sedimentation in clarifier  120 , and/or mechanical filtration with catalytic precipitation, chemisorption and adsorption in a two-stage filtration system  150  that includes a first stage containing one or more zeolite-based advanced catalytic media (ACM) filter(s)  130  and a second stage containing one or more catalytic carbon (CC) filter(s)  140 , where the effluent of the first stage can be received by the second stage. The process and system  10  optionally include one or more of pre-treatment of raw source water received from stream  101  in pre-treatment system  100  to produce the contaminated water in stream  102 , sludge treatment in a sludge handling system  126 , and collection and treatment of dirty water in dirty backwash water sump  160  (e.g., when backwashing any of the filter(s)  130  and  140 ). 
     In more detail for the process and system  10 , contaminated water stream  102  (optionally received from pre-treatment system  100 ) can be fed to redox reactor  110 , along with a stream  111  of a ferric compound solution, a stream  112  of an acidic oxidant solution, and a stream  113  of a flocculant-adsorbent solution. The redox reactor  110  can be embodied as a vessel having one or more inlets and one or more outlets for the flow of components into and out of the vessel, as described herein; also, the redox reactor  110  can be embodied as two or more identical vessels each being fluidly connected to the streams  102 ,  111 ,  112 ,  113 ,  114 , and  115 . The ferric compounds can react with the acidic oxidant to form ferrate in the redox reactor  110 , and the ferrate can react with contaminants in the contaminated water to produce particulates that agglomerate and coagulate due to the flocculant-adsorbent. The reaction mixture in the redox reactor  110  can be kept under an inert gas blanket (e.g., nitrogen blanket), and gases can be vented from the redox reactor  110  in vent gas stream  114 . The redox water can flow from the redox reactor  110  in stream  115 . In optional embodiments, a portion  115   a  of the redox water in stream  115  can be recycled to the redox reactor  110  in recycle stream  116 , and the remaining portion  115   b  of the redox water in stream  115  can flow to the clarifier  120 . 
     The redox water in stream  115  can be fed to a clarifier  120 . In optional embodiments, a stream  123  of the ferric compound solution and a stream  124  of the acidic oxidant solution can be fed to the clarifier  120 . The clarifier  120  can be embodied as a vessel having one or more inlets and one or more outlets for the flow of components into and out of the vessel, as described herein; also, the clarifier  120  can be embodied as two or more identical vessels each being fluidly connected to streams  115 ,  121 , and  122  and optional streams  123  and  124 , and in parallel with one another. Clarified water can exit the clarifier  120  in stream  121 , and sludge can exit the clarifier in stream  122 . 
     In the clarifier  120 , solid particulates produced from the reaction of ferrate and the contaminants can settle to the bottom of the vessel, creating a layer of sludge. The sludge can be removed by any technique known in the art with the aid of this disclosure so as to flow in stream  122  to a sludge handling system  126 . Stream  127 , which contains a flocculant-adsorbent solution, can be connected to a sludge thickening vessel in the sludge handling system  126  and can be configured to dose the sludge with the flocculant-adsorbent solution so as to thicken the sludge. The sludge handling system  126  produces a “safe sludge” and is described in more detail below. 
     The clarified water in stream  121  can be fed to the first stage of the two-stage filtration system  150 . The first stage can be an advanced catalytic media filtration in one or more ACM filters  130  that are configured to produce a filtered water stream  131  containing filtered water. The filtered water stream  131  can then be fed to the second stage of two-stage filtration system  150 . The second stage can be a catalytic carbon filtration in one or more CC filters  140  that are configured to produce the treated water stream  141 . In embodiments, the treated water stream  141  can have a composition of water having less than 2 mg/L ammoniacal nitrogen, less than 2 mg/L iron, less than 0.1 mg/L phenol, less than 20 mg/L of organisms that have a biological oxygen demand, less than 100 mg/L of compounds that have a chemical oxygen demand, less than 0.1 mg/L H 2 S, less than 0.1 mg/L sulfur-containing compounds (other than H 2 S), less than 0.05 mg/L cyanide, 0 CFU/mL sulfate reducing bacteria, less than 75 mg/L of total organic carbon, and/or less than 0.01 mg/L heavy metal (e.g., Zinc, Arsenic, Aluminum, Copper, Cadmium, Manganese, or a combination thereof). 
     In some embodiments, a dirty backwash water sump  160  can be included to collect dirty water from the ACM filter  130  and/or the CC filter  140 , for example, during backwashing the ACM filter  130  or CC filter  140 . Stream  125  can be connected to the dirty backwash water sump  160  and to the clarified water stream  121  at a location that is upstream of the ACM filter  130 . Stream  132  can be connected to the dirty backwash water sump  160  and to the first filtered water stream  131  at a location that is upstream of the CC filter  140 . 
     In some embodiments, raw source water received from stream  101  can be pre-treated in pre-treatment system  100  to produce the contaminated water in stream  102 . The pre-treatment can include feeding/dosing the ferric compound solution to the pre-treatment system  100  via stream  103 , feeing the acidic oxidant solution to the pre-treatment system  100  via stream  104 , and feeding the flocculant-adsorbent solution to the pre-treatment system  100  via in stream  105 . 
     Water Pre-Treatment 
       FIGS. 2A and 2B  illustrate process flow diagrams of embodiments of the pre-treatment system  100  of  FIG. 1 .  FIG. 2A  illustrates the pre-treatment system  100  embodied as a buffer tank  201 . The buffer tank  201  can be configured to have a volume that accommodates for surges and dips in the flow of raw source water in stream  101  from the various sources (e.g., produced water from oil and gas recovery, water recovered from chemical processes, etc.), which may or may not provide a constant supply of contaminated water. Thus, the buffer tank  201  can be important for operation of the continuous process and system  10 , in that, the buffer tank  201  helps provide a continuous flow of contaminated water via stream  102  to the redox reactor  110  so that subsequent treatment steps in the process and system  10  can operate on a continuous flow basis. 
     In some embodiments of the pre-treatment system  100  of  FIG. 2A , a ferric compound solution can be fed/dosed to the buffer tank  201  via stream  103 , and an acidic oxidant solution can be fed to the buffer tank  201  via stream  104 . As will be described in more detail below, stream  103  can be generated by the ferric compound solution preparation system  300 , and stream  104  can be generated by the acidic oxidant preparation system  310 . 
       FIG. 2B  illustrates the pre-treatment system  100  embodied as the buffer tank  201  followed by a combined corrugated plate interceptor plus dissolved nitrogen flotation unit (CPI+DNF unit)  202 . Source water can flow from the buffer tank  201  to the CPI+DNF unit  202  via stream  203 . In some aspects, stream  203  can include a plug flow flocculator. In the CPI+DNF unit  202 , contaminants such as oil can be removed from the raw source water by flotation, and the floating contaminants can be removed from the CPI+DNF unit  202  via stream  204 , while the contaminated water is removed from the CPI+DNF unit  202  by stream  102 . The pre-treated water in stream  102  can then flow from the pre-treatment system  100  to the redox reactor  110 . 
     In some embodiments of the pre-treatment system  100  of  FIG. 2B , a ferric compound solution can be fed/dosed to the buffer tank  201  via stream  103 , and an acidic oxidant solution can be fed to the buffer tank  201  via stream  104 . Similar to the description above, stream  103  is generated by the ferric compound solution preparation system  300 , and stream  104  is generated by the acidic oxidant preparation system  310 . 
     Feed Components Preparation and Dosing 
     Aspects of the disclosed process and system  10  include preparation and dosing of the feed components.  FIGS. 3A-3C  illustrate process flow diagrams of the systems  300 ,  310 , and  320  for preparation and dosing of the ferric compound solution, the acidic oxidant solution, and the flocculant-adsorbent solution, respectively. 
     Ferric Compound Preparation and Dosing 
       FIG. 3A  illustrates an embodiment of a ferric compound solution preparation system  300  for the preparation and dosing of the ferric compound solution. As described above, the ferric compound solution can be fed to the redox reactor  110  and optionally to the clarifier  120 . The ferric compound solution can be contacted with the acidic oxidant solution in-situ of the redox reactor  110  and optionally in-situ of the clarifier  120  to generate ferrate. It is contemplated that ferrate can be made ex-situ of the redox reactor  110  and clarifier  120  in a separate vessel by mixing the ferric compounds and acidic oxidant with water, then feeding the resulting ferrate solution to the redox reactor  110  and optionally to the clarifier  120 . 
     The ferric compounds can be physically obtained as a solid in powder form or granular form, which may help to make it easy to handle, transport, and mix into the ferric compound solution. An example of the ferric compounds is a solid having a composition of 25 wt % iron(III), 5 wt % iron(II), 3 wt % sulfuric acid, 32 wt % H2O, and 35 wt % sulfate. The ferric compounds can be stored in containers or silos, shown in  FIG. 3A  as a container  301 , having a capacity to store an amount of solid powder suitable to operate the process for a desired time period. For example, the container  301  can store an amount of the ferric compound that will last at least one week in the continuous processes disclosed herein. 
     The ferric compounds can be mixed with water (e.g., potable water, local tap water provided by a municipality, etc.) from stream  303  to form a ferric compound solution containing 5% v/v ferric compounds. The solid powder can be transferred from the container  301  to a dilution tank  304  by any transport means available, such as conveyor or manual scoops, shown as stream  302 . The clean water can be added to the dilution tank  304  from the utility water supply via stream  303 . Once the dilution tank  304  is filled with the ferric compound solution, the ferric compound solution can be mixed with an agitator  305  such that the ferric compounds are well dispersed in the solution. 
     The volume of the dilution tank  304  can be sized to contain an amount of the ferric compound solution suitable for the process. For example, the amount of the ferric compound solution may be suitable to handle changes in flowrates within the system. As an example, the ferric compound solution may be stored in an amount that is used for one to three days in the process and system  10 . 
     A ferric compound solution outlet line  306  can be connected to the dilution tank  304  and to a dosing pump  307 . A flow rate of the ferric compound solution in the outlet line  306  can be in the range of 0 to 70 parts per million (by weight) at 5% v/v strength solution, and the disclosed systems and process allow for a controlled dosing of the ferric compound solution on a continuous basis while allowing for changing and/or controlling the dosage rate up or down depending on the flow rate of contaminated water in stream  102  to the redox reactor  110 . 
     In embodiments, the dosing pump  307  can have two or three discharge heads  307   a - c  such that a single pump  307  can provide the ferric compound solution to two or three locations in controlled amounts or doses. A first discharge head  307   a  can be fluidly connected to an inlet of the redox reactor  110  via stream  111 . A second discharge head  307   b  can be fluidly connected to an inlet of the clarifier  120  via stream  123 . An optional third discharge head  307   c  can be fluidly connected to an inlet of the contaminated water buffer tank of pre-treatment system  100  via stream  103  (which can be upstream of the redox reactor  110  and can be connected to stream  102  to supply the contaminated water to the redox reactor  110 ). Alternatively, it is contemplated that pump  307  can be embodied as three dosing pumps that can be used and be fluidly connected to the ferric compound solution outlet line  306 , with the first pump being fluidly connected to an inlet of the redox reactor  110  to provide a controlled amount or dose of the ferric compound solution to the redox reactor  110  via stream  111 , the second pump being fluidly connected to an inlet of the clarifier  120  to provide a controlled amount or dose of the ferric compound solution to the clarifier  120  via stream  123 , and the optional third pump being fluidly connected to the contaminated water buffer tank of pre-treatment system  100  to provide a controlled amount or dose of the ferric compound solution to the buffer tank  201  via stream  103 . 
     In embodiments having a two-headed dosing pump or two single-headed dosing pumps, the flow of ferric compound solution in the outlet line  306  can be divided, with approximately 60 vol. %-90 vol. %, or about 85 vol % to the redox reactor  110  via stream  111  and between about 10 vol. %-40 vol. %, or about 15 vol % going to the clarifier  120  via stream  124 , based on the total volumetric flow rate of the ferric compound solution in the outlet line  306 . Put another way, a volumetric ratio of a first portion of the ferric compound solution in stream  111  to a second portion of the ferric compound solution in stream  123  to a third portion of the ferric compound solution in stream  103  can be between about 3:2:0 to 9:1:0, or about 8.5:1.5:0. 
     In embodiments having a three-headed dosing pump or three single-headed dosing pumps, the flow of ferric compound solution in the outlet line  306  can be divided into about 70-vol. %-90 vol. %, or about 80 vol % to the redox reactor  110  via stream  111 , about 5 vol. % to about 20 vol. %, or about 10 vol % to the clarifier  120  via stream  123 , and about 5 vol. % to about 20 vol. %, or about 10 vol % to the buffer tank  201  via stream  103 , based on the total volumetric flow rate of the ferric compound solution in the outlet line. Put another way, a volume ratio of a first portion of the ferric compound solution in stream  111  to a second portion of the ferric compound solution in stream  123  to a third portion of the ferric compound solution in stream  103  can be between about 14:3:3 and 9:1:1, or about 8:1:1. 
     In embodiments, a volume ratio of a first portion of the ferric compound solution in stream  111  to a second portion of the ferric compound solution in stream  123  to a third portion of the ferric compound solution in stream  103  can be in the range of 8.5:1.5:0 to 8:1:1. 
     Acidic Oxidant Preparation and Dosing 
       FIG. 3B  illustrates an embodiment of an acidic oxidant solution preparation system  310  for the preparation and dosing of the acidic oxidant solution. As described above, the acidic oxidant solution can be fed to the redox reactor  110  and optionally to the clarifier  120 . The acidic oxidant solution can be contacted with the ferric compound solution in-situ of the redox reactor  110  and optionally in-situ of the clarifier  120  to generate ferrate. It is contemplated that ferrate can be made ex-situ of the redox reactor  110  and clarifier  120  in a separate vessel by mixing the ferric compounds and acidic oxidant with water, then feeding the resulting ferrate solution to the redox reactor  110  and optionally to the clarifier  120 . 
     The acidic oxidant can generally be obtained as a solid in powder form, which is easy to handle and transport. The solid can generally be an oxidizing compound used for water treatment and can be sulfate-based. A commercially available example of the acidic oxidant is FeOxy-S2. The acidic oxidant can be stored in containers or silos, shown in  FIG. 3B  as container  311 , having a capacity to store an amount of solid powder suitable for use for a desired time period in the continuous processes disclosed herein. 
     The acidic oxidant can be mixed with water (e.g., potable water, local tap water provided by a municipality, etc.) from stream  313  to form an acidic oxidant solution containing about 5% v/v acidic oxidant. The acidic oxidant solid powder can be transferred from the container  311  to a dilution tank  314  by any transport means available, such as conveyor or manual scoops, shown in  FIG. 3B  as stream  312 . The water can be added to the dilution tank  314  from the water supply. Once the dilution tank  314  is filled with the acidic oxidant solution, the acidic oxidant solution can be mixed with an agitator  315  such that the acidic oxidant is well dispersed in the solution. The volume of the dilution tank  314  can be sized to contain an amount of the acidic oxidant solution that is used for a suitable time period in the process. 
     An acidic oxidant solution outlet line  316  can be connected to the dilution tank  314  and to a dosing pump  317 . A flow rate of the acidic oxidant solution in the outlet line  316  can be in the range of 0 to 70 parts per million (by weight) at 5% v/v strength solution, and the disclosed systems and process allow for dosing of the acidic oxidant solution on a continuous basis while allowing for changing the dosage rate up or down depending on the flow of contaminated water in stream  102  to the redox reactor  110 . 
     In embodiments, the dosing pump  317  can have two or three discharge heads  317   a - c  such that a single pump can provide the acidic oxidant solution to two or three locations in controlled amounts or doses. A first discharge head  317   a  can be fluidly connected to an inlet of the redox reactor  110  via stream  112  and a second discharge head can be fluidly connected to an inlet of the clarifier  120  via stream  124 . An optional third discharge head  317   c  can be fluidly connected to an inlet of the contaminated water buffer tank  201  of pre-treatment system  100 , which is described above, via stream  104 . Alternatively, it is contemplated that the dosing pump  317  can be embodied as three dosing pumps that can be used and be fluidly connected to the acidic oxidant solution outlet line  316 , with the first pump being fluidly connected to an inlet of the redox reactor  110  via stream  112  to provide a controlled amount or dose of the acidic oxidant solution to the redox reactor  110 , the second pump being fluidly connected to an inlet of the clarifier  120  via stream  124  to provide a controlled amount or dose of the acidic oxidant solution to the clarifier  120 , and the optional third pump being fluidly connected to the contaminated water buffer tank of pre-treatment system  100  to provide a controlled amount or dose of the acidic oxidant solution to the buffer tank via stream  104 . 
     In embodiments having a two-headed dosing pump or two single-headed dosing pumps, the flow of acidic oxidant solution in the outlet line  316  can be divided, with approximately 60 vol. %-90 vol. %, or about 85 vol % to the redox reactor  110  via stream  112  and between about 10 vol. %-40 vol. %, or about 15 vol % to the clarifier  120  via stream  124 , based on the total volumetric flow rate of the acidic oxidant solution in the outlet line  316 . Put another way, a volume ratio of a first portion of the acidic oxidant solution in stream  112  to a second portion of the acidic oxidant solution in stream  124  to a third portion of the acidic oxidant solution in stream  104  can be between about 3:2:0 to 9:1:0, or about 8.5:1.5:0. 
     In embodiments having a three-headed dosing pump or three single-headed dosing pumps, the flow of acidic oxidant solution in the outlet line  316  can be divided into about 70-vol. %-90 vol. %, or about 80 vol % to the redox reactor  110  via stream  112 , about 5 vol. % to about 20 vol. %, or about 10 vol % to the clarifier  120  via stream  124 , and about 5 vol. % to about 20 vol. %, or about 10 vol % to the buffer tank  201  via stream  104 , based on the total volumetric flow rate of the acidic oxidant solution in the outlet line  316 . Put another way, a volume ratio of a first portion of the acidic oxidant solution in stream  112  to a second portion of the acidic oxidant solution in stream  124  to a third portion of the acidic oxidant solution in stream  104  can be between about 14:3:3 and 9:1:1, or about 8:1:1. 
     In embodiments, a volume ratio of a first portion of the acidic oxidant solution in stream  112  to a second portion of the acidic oxidant solution in stream  124  to a third portion of the acidic oxidant solution in stream  104  can be in the range of 8.5:1.5:0 to 8:1:1. 
     Flocculant-Adsorbent Preparation and Dosing 
       FIG. 3C  illustrates an embodiment of a flocculant-adsorbent solution preparation system  320  for the preparation and dosing of the flocculant-adsorbent solution. Flocculant-adsorbents are used to agglomerate and coagulate the particulates that are produced by the ferrate in the redox reactor  110 . The flocculant-adsorbent is generally obtained as a solid in powder form, which can be easy to handle and transport. The solid can generally be a compound used for water treatment. A commercially available example of the flocculant-adsorbent is FeOxy-S3. The flocculant-adsorbent can be stored in containers or silos, shown in  FIG. 3C  as container  321 , having a capacity to store an amount of solid powder that will last one week in the continuous processes disclosed herein. 
     The flocculant-adsorbent can be mixed with clean water to form a flocculant-adsorbent solution containing 5% v/v flocculant-adsorbent. The flocculant-adsorbent solid powder can be transferred from the container  321  to a dilution tank  324  by any transport means available, such as conveyor or manual scoops, shown in  FIG. 3C  as stream  322 . The clean water can be added to the dilution tank  324  from the utility water supply via stream  223 . Once the dilution tank  324  is filled with the flocculant-adsorbent solution, the flocculant-adsorbent solution can be mixed with an agitator  325  such that the flocculant-adsorbent is well dispersed in the solution. The volume of the dilution tank  324  is sized to contain an amount of the acidic oxidant solution that is used for two days. 
     A flocculant-adsorbent solution outlet line  326  can be connected to the dilution tank  324  and to a dosing pump  327 . A flow rate of the flocculant-adsorbent solution in the outlet line can be in the range of 0 to 70 parts per million (by weight) at 5% v/v strength solution, and the disclosed systems and process allow for dosing of the flocculant-adsorbent solution on a continuous basis while allowing for changing the dosage rate up or down depending on the flow of contaminated water to the redox reactor  110  via stream  102 . 
     In embodiments, the dosing pump  327  can have one, two, or three discharge heads  327   a - c  such that a single pump can provide the flocculant-adsorbent solution to one, two, or three locations in controlled amounts or doses. A first discharge head  327   a  can be fluidly connected to a second compartment of the redox reactor  110  via stream  113 . An optional second discharge head  327   b  can be fluidly connected to an inlet of the plug flow flocculator in stream  203  of the pre-treatment system  100  via stream  105 . An optional third discharge head  327   c  can be fluidly connected to the sludge handling system  126  via stream  127 . Alternatively, it is contemplated that one, two, or three separate dosing pumps can be used and be fluidly connected to the flocculant-adsorbent solution outlet line, with the first pump being fluidly connected to an inlet of the redox reactor  110  via stream  113  to provide a controlled amount or dose of the flocculant-adsorbent solution to the redox reactor, the optional second pump being fluidly connected to an inlet of the plug flow flocculator in stream  203  of the pretreatment system  100  via stream  105  to provide a controlled amount or dose of the flocculant-adsorbent solution to the water mixture in stream  203 , and the optional third pump being fluidly connected to the sludge handling system  126  via stream  127  to provide a controlled amount or dose of the flocculant-adsorbent solution to the sludge handling system  126 . 
     In embodiments having a single-headed dosing pump (a single dosing pump), the flow of flocculant-adsorbent solution in the outlet line  326  to the redox reactor  110  via stream  113  can be 100 vol % of the flow of the flocculant-adsorbent solution in the outlet line  326 . 
     In embodiments having a two-headed dosing pump or two single-headed dosing pumps, the flow of flocculant-adsorbent solution in the outlet line  326  can be divided with approximately 60 vol. %-90 vol. %, or about 85 vol % to the redox reactor  110  via stream  113  and between about 10 vol. %-40 vol. %, or about 15 vol % to the sludge handling system  126  via stream  127 , based on the total volumetric flow rate of the flocculant-adsorbent solution in the outlet line  326 . Put another way, a volume ratio of a first portion of the flocculant-adsorbent solution in stream  113  to a second portion of the flocculant-adsorbent solution in stream  127  to a third portion of the flocculant-adsorbent solution in stream  105  can be between about 3:2:0 to 9:1:0, or about 8.5:1.5:0. 
     In embodiments having a three-headed dosing pump or three single-headed dosing pumps, the flow of flocculant-adsorbent solution in the outlet line  326  can be divided into about 70-vol. %-90 vol. %, or about 80 vol % to the redox reactor  110  via stream  113 , about 5 vol. % to about 20 vol. %, or about 10 vol % to the sludge handling system  126  via stream  127 , and about 5 vol. % to about 20 vol. %, or about 10 vol % to the pre-treatment system  100  via stream  105 , based on the total volumetric flow rate of the flocculant-adsorbent solution in the outlet line  326 . Put another way, a volume ratio of a first portion of the flocculant-adsorbent solution in stream  113  to a second portion of the flocculant-adsorbent solution in stream  127  to a third portion of the flocculant-adsorbent solution in stream  105  can be 8:1:1. 
     In embodiments, a volume ratio of a first portion of the flocculant-adsorbent solution in stream  113  to a second portion of the flocculant-adsorbent solution in stream  127  to a third portion of the flocculant-adsorbent solution in stream  105  can be in the range of 8.5:1.5:0 to 8:1:1. 
     Redox Reactor 
     Referring again to  FIG. 1 , the redox reactor  110  can be configured for oxidation-reduction reactions to take place in order to remove contaminants in the contaminated water received via stream  102 . The redox reactor  110  can be manufactured of any material suitable for the functions described herein. In an embodiment, the redox reactor  110  can be formed from concrete and is below the ground. In some embodiments, the redox reactor  110  can be formed of a suitable metal, plastic, plastic coated metal, or the like and formed as a tank that can be placed above or below ground. The redox reactor  110  can have a volume suitable to treat water for a particular application on a continuous basis, e.g.,  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900 ,  1000 , or more m 3 /h of contaminated water. In embodiments, the redox reactor  110  can be embodied as multiple below-ground vessels connected in series with one another, connected in parallel relative to one another, or one or more vessels connected in series with one or more vessels connected in parallel. 
     In some aspects, the redox reactor  110  can have a first section or compartment  110   a  and a second section or compartment  110   b . The first section  110   a  and the second section  110   b  are separated by a partition or wall  117  having an underflow opening  118  for passage of material from the first section  110   a  to the second section  110   b . The first section  110   a  can be configured to receive contaminated water from stream  102 , receive the ferric compound solution from stream  111 , receive the acidic oxidant solution from stream  112 , mix the solutions to form a first amount of ferrate, and to contact the first amount of ferrate with the contaminated water for reaction with contaminants at a residence time of 0-60 minutes (e.g., 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 15, 20, 25, 30, 35, 40, 45, 50, 55, or 60 minutes). The steps in the first section  110   a  can happen simultaneously for the continuous process and system  10 . The second section  110   b  can be configured to receive the reacted water from the first section, receive the flocculant-adsorbent solution from stream  113 , mix the reaction mixture, allow for further ferrate reaction with contaminants to form larger particulate contaminants, and allow for flocculation and adsorption of particulate contaminants into flocs, at a residence time of 10-60 minutes (e.g., 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 30, 35, 40, 45, 50, 55, or 60 minutes). These steps in the second section  110   b  can happen simultaneously for the continuous process and system  10  to produce redox water. In some embodiments, the residence time in the first section of the redox reactor  110  is 10 minutes and the residence time in the second section of the redox reactor  110  is 20 minutes. 
     In embodiments, the redox reactor  110  can have at least one motorized flash agitator contained therein, configured to enhance mixing of the ferric compound solution and the acidic oxidant solution to form ferrate and to enhance contact of the ferrate with the contaminated water in the redox reactor  110 . 
     In embodiments of the redox reactor  110  having two sections, the first section  110   a  can have a motorized flash agitator as described above, and the second section  110   b  can have at least one motorized slow paddle agitator to enhance mixing of the flocculant-adsorbent with the reaction mixture, and to keep the flocs suspended in the fluid. 
     Ferrate anions (chemical formula (FeO 4 ) 2+ ) are negatively charged ions in which iron is in the +6 oxidation state. Ferrate anions as discussed herein can also be referred to as ferrate(VI), iron(VI), or Fe(VI). Ferrate anions are extremely powerful oxidizing agents compared to other AOP technologies. The redox potential for ferrate is higher than other chemicals available for water treatment as shown in the table below: 
     
       
         
           
               
               
               
             
               
                   
                   
               
               
                   
                 Compound 
                 Redox Potential (Volts) 
               
               
                   
                   
               
             
            
               
                   
                 Ferrate 
                 2.20 
               
               
                   
                 Ozone 
                 2.08 
               
               
                   
                 Hydrogen Peroxide 
                 1.78 
               
               
                   
                 Permanganate 
                 1.68 
               
               
                   
                 Hypochlorite 
                 1.48 
               
               
                   
                 Chlorine 
                 1.36 
               
               
                   
                 Dissolved oxygen 
                 1.23 
               
               
                   
                 Chlorine dioxide 
                 0.95 
               
               
                   
                   
               
            
           
         
       
     
     The process and system is configured herein such that the ferrate simultaneously functions as an oxidant, disinfectant, and coagulant. Ferrate is more powerful than other oxidants such as ozone and chlorine dioxide (as indicated above), and it can be used instead of additional coagulants such as ferric chloride, alum, and polymers for the removal of metals, non-metals and humic acids. Ferrate can outperform other disinfectants such as UV, hydrogen peroxide, and chlorine, and can kill many chlorine resistant organisms such as aerobic spore-formers and sulfite-reducing clostridia. 
     The purity of ferrate formed in-situ of the redox reactor  110  can be greater than 99% in the mixed form. A ferrate content monitor be coupled with the stream  115  and configured to measure the oxidation-reduction potential (ORP) of the reduced and oxidized water in stream  115 . The potential can be correlated with the purity (weight, mol, or volume basis) of ferrate formed in-situ of the redox reactor  110 . For example, a measured ORP of 2.20 V in the reduced and oxidized water in stream  115  can indicate that the purity of ferrate formed in-situ of the redox reactor  110  is 100% ferrate, and a measured ORP of 2.10 in the reduced and oxidized water in stream  115  can indicate that the purity of ferrate formed in-situ of the redox reactor  110  is 95.55% ferrate. Using the high purity ferrate, there is no need to dose poisonous and corrosive components like chlorine, hypochlorite, or ozone. These oxidants have deleterious side effects. Additionally, the handling of chlorine, hypochlorite, HOCl, chlorine dioxide or ozone are potential danger to workers due to their high toxicity. Moreover, a major disadvantage of chlorine and chlorine dioxide or any other chlorine-containing compound is that they produce, chloramines, chlorinated aromatics, chlorinated amines, or hydrocarbons. All these oxidants are potential mutagens or carcinogens. 
     Inter gas (e.g., nitrogen) for the inert gas blanket over the reaction mixture in the redox reactor  110  can be supplied by an inert gas source connected to the redox reactor  110 . 
     The reduced and oxidized water in stream  115  from the redox reactor  110  can contain a high amount (e.g., 1,000-1,500 mg/L) of non-abrasive and agglomerated contaminant flocs, as well as the water. In some embodiments, the redox water in stream  115  can also contain unreacted contaminants, for example, if the contaminant stream contained more contaminants than redox capacity of the redox reactor  110  (e.g., ferrate supply is exhausted for a given amount of water reacted for the set residence time), or if not all the contaminants were reacted within the residence time of the redox reactor  110 . 
     A pump (e.g., a low shear centrifugal pump) can be included in stream  115  to transfer the redox water from the redox reactor  110  to the clarifier  120 . 
     Vent gas can be vented via stream  114 . The vent gas stream  114  can contain a majority amount of nitrogen from the optional nitrogen blanket, and also water vapor. In some applications, such as for treatment of produced water from an oil and gas well, the vent gas stream  114  can also contain gases received from the contaminant stream  102 , such as light hydrocarbons (e.g., methane, ethane, propane, butane, pentane, or combinations thereof) and acid gases (e.g., carbon dioxide, hydrogen sulfide, or a combination thereof). 
     Clarifier 
     Referring again to  FIG. 1 , the clarifier  120  can be configured for bulk solids and particulate removal using gravity sedimentation. The clarifier  120  can be manufactured from any material suitable for the functions described herein. In an embodiment, the clarifier  120  can be formed of concrete and is an above-ground vessel. In some embodiments, the clarifier  120  can be formed from a metal, plastic, plastic coated metal, or other material. In some embodiments, the clarifier  120  can have a conical-shaped bottom portion  120   c , and the stream  122  can be connected to the center point of the conical-shaped bottom portion  120   c . The clarifier  120  can have a volume suitable to clarify water for a particular application on a continuous basis, e.g.,  100 ,  200 ,  300 ,  400 ,  500 ,  600 ,  700 ,  800 ,  900 ,  1000 , or more m 3 /h of contaminated water. In embodiments, the clarifier  120  can multiple vessels connected in series with one another, connected in parallel relative to one another, or one or more vessels connected in series with one or more vessels connected in parallel. 
     In embodiments, the residence time of the redox water in the clarifier  120  can be between about half an hour and three hours. For example, the residence time can be about 30-180 minutes, or between about 60-120 minutes, for example 60, 70, 80, 90, 100, 10, or 120 minutes. For example, the residence time in the clarifier  120  can be about 90 minutes. 
     In embodiments, the clarifier  120  can be configured to receive the ferric compound solution via stream  123  (e.g., dosed intermittently or continuously) and to receive the acidic oxidant solution via stream  124  (e.g., dosed intermittently or continuously), which will form additional ferrate in-situ of the clarifier  120 . The additionally formed ferrate can remove any unreacted contaminants that are received in the clarifier  120  from the redox reactor  110  via stream  115 . As such, the clarifier  120  can also be configured to be a redox-reactor while functioning as a clarifier, since ferrate is formed in the clarifier  120  and available for redox reaction with suitable contaminants. 
     The clarifier  120  can include a skimmer. Floatable solids (scum) including foams can be removed from the surface of the redox water in the clarifier  120  by the skimmer, while sludge (e.g., the contaminant flocs and other particulate contaminants that form the sludge) can be collected on the bottom of the clarifier  120 . 
     The clarifier  120  can include a motorized sludge rake configured to keep the sludge at the conical-shaped bottom portion  120   c  of the clarifier  120  in a flowable/movable form and to direct the sludge toward the center of conical-shaped bottom portion  120   c . The sludge at the bottom of the clarifier  120  can be intermittently routed to the sludge handling system  126  via a sludge transfer pump located in stream  122 . The sludge transfer pump can be progressive cavity type pump that is designed to intermittently deliver a constant flow of oxidation sludge to the sludge handling system  126  via stream  122 . A flow rate of the sludge in stream  122 , when the pump is on, can be between about 5 and about 35 m 3 /h, for example about 5, 10, 15, 20, 25, 30, or 35 m 3 /h. 
     The clarifier  120  can also include a main compartment  120   a  and a clarified water chamber  120   b . The main compartment  120   a  can include the conical-shaped bottom portion  120   c  for collecting the sludge, and the clarified water chamber  120   b  can be fluidly connected to the main compartment  120   a  at a location above the conical-shaped bottom portion  120   c  such that clarified water flows into the chamber  120   b . The main compartment  120   a  can be configured to i) receive at least a portion  115   b  of the redox water via stream  115 , the ferric compound solution via stream  123 , and the acidic oxidant solution via stream  124 , ii) mix the ferric compound solution and the acidic oxidant solution to form a second amount of ferrate (the second amount being less than the first amount formed in the redox reactor  110  since redox reaction is a secondary function of the clarifier  120 ), iii) contact the second amount of ferrate with the redox water for reaction with unreacted contaminants in the redox water, and iv) allow particulate contaminants and flocs to settle to a conical-shaped bottom portion  120   c  of the clarifier  120 . These steps in the main compartment  120   a  can happen simultaneously for the continuous process and system  10  to clarified water. The clarified water chamber  120   b  can be configured to receive clarified water from the main compartment  120   a . One or more centrifugal pumps can be included in stream  121  to pump the clarified water to the two-stage filtration system  150 . 
     Sludge Treatment System 
       FIG. 4  illustrates a process flow diagram of an embodiment of the sludge handling system  126 . The sludge handling system  126  can include a sludge thickener  401 , a decanter centrifuge  403 , and a sludge container  405 . 
     The sludge thickener  401  is a vessel that is connected to stream  122  and configured to receive sludge from the clarifier  120  via the stream  122 . The sludge thickener  401  can also be configured to connect with stream  127  so as to receive a dose of the flocculant-absorbent solution (e.g., 10-15 wt % of the flocculant-absorbent solution flowing in outlet  328 ) that promotes further flocculation and agglomeration of contaminants to thicken the sludge in the sludge thickener  401 . Another sludge transfer pump located in stream  402  can move thickened sludge from the sludge thickener  401  to the decanter centrifuge  403 , where the solids in the sludge can be separated from liquid by centrifugal forces and the solids are recovered in stream  404  and sent to sludge container  405 . The sludge container  405  can be embodied as any vessel in which an amount of sludge can be stored for disposal or use in another application. 
     The sludge recovered in container  405  can be considered a “safe sludge” in the sense that it can be used in other applications and is not simply an item for hazardous waste disposal. That is, in contrast to other APO techniques, the disclosed process and systems create a “safe sludge” that is relatively (compared to other sludges) more inert to the environment (e.g., has no chemical oxygen demand) and can be used, for example, as an additive for cement. 
     Filters 
     The clarified water from the clarifier  120  can be fed to a two-stage filtration system  150  via a filter feed pump in stream  121 . 
     First Filtration Stage 
     The first stage of media filtration can use an advanced catalytic media (ACM) filtration. The first stage of the system  150  can contain one or more ACM filters  130 . When more than one ACM filter is used, the ACM filters  130  can be fluidly connected in parallel relative to one another. Each ACM filter  130  can be configured to remove the fine particulates, organic materials (e.g., aliphatic organic compounds, aromatic organic compounds, or both aliphatic and aromatic organic compounds), and heavy metals (e.g., Zinc, Arsenic, Aluminum, Copper, Cadmium, Manganese, or a combination thereof) from the clarified water, and to reduce the turbidity of the clarified water. Each ACM filter  130  generally includes a filter media contained in a filter housing, where the housing has an inlet for the clarified water and an outlet for first filtered water. 
     In embodiments, the media of each ACM filter  130  can have a composition that includes clinoptilolite ((Ca,K 2 ,Na 2 ,Mg) 4 Al 8 Si 40 O 96 .24H 2 O), manganese dioxide (MnO 2 ), and/or calcium hydroxide (Ca(OH) 2 ). A commercially available ACM filter is the Katalox Light ACM filter manufactured by Watch Water GmbH, having &gt;85% w/w clinoptilolite, &gt;10% w/w MnO 2 , and &lt;5% w/w Ca(OH) 2 . 
     In embodiments, each ACM filter in the first stage is capable of processing 100-300 m3/h of clarified water; alternatively, 150-250 m3/h of clarified water; alternatively, 175-240 m3/h of clarified water; alternatively, 200-230 m3/h of clarified water; alternatively, 215-225 m3/h of clarified water; alternatively, about 220 m3/h of clarified water. 
     In some embodiments, the first stage includes three ACM filters  130  operated in 3×33% configuration during normal operation, and operated in 2×50% configuration when one of the three ACM filters  130  is offline for backwashing, maintenance, replacement, etc. 
     In some aspects, the ACM filter can have a catalytic coating on the surface of the filter media that contacts the clarified water. For example, the catalytic coating can be manganese dioxide (MnO 2 ) on a special adsorbent media. Having the catalytic coating on the filter media enables the ACM filter to function as a mechanical filter and catalytic filter. The concentration of MnO 2  on the surface of the ACM filter media can be between about 5 wt. % and about 20 wt. %, or about 10 wt. % based on a total weight of the filter media. The presence of the MnO 2  catalytic coating on the ACM filter media in such an amount increases the oxidation and co-precipitation of contaminants over filters having a lower concentration of catalytic coating. 
     The ACM filter can be lighter in weight, have a higher filtration surface, have longer service life, have more reliable performance, and provide filtration down to about 3 μm, which is an improvement over other existing granular filter media. 
     The inlet to each of the ACM filter can have a flow control valve (with respective flow transmitter) to ensure equal distribution of the flow across the filters. 
     The ACM filter  130  can be configured with appropriate piping and valves for backwashing on an intermittent basis, for example, every 24 hours of operation or triggered by a differential pressure across the filter that is higher than a setpoint pressure value. Treated water from a treated water tank can be pumped by one or more backwash pumps to backwash the ACM filter  130 . 
     Flow Control First Filtration Stage 
     In embodiments where the ACM filter  130  is embodied as multiple filters connected in parallel, stream  121  can be split into a portion for each ACM filter  130 . Each portion of the stream  121  can have a flow control valve and a flow transmitter placed therein and coupled to one another. The flow transmitter can be configured to send a flow signal which is compared by a controller against the flow controller setpoint to ensure a constant and equal inlet flowrate for through each portion of stream  121  to each ACM filter  130 . 
     Additionally, the flow controller can increase the % open of the flow control valves if the water level in the clarified water chamber  120   b  of the clarifier  120  rises above a threshold limit (as detected by a level transmitter connected to the clarified water chamber  120   b  and to the flow controller). Alternatively, the flow controller can decrease the % open of the flow control valves if the water level in the clarified water chamber  120   b  of the clarifier  120  falls below a threshold limit (as detected by the level transmitter). The flow rate of each portion of stream  121  can be maintained to be equal with one another to maintain equal flow through each of the ACM filters  130 . 
     In some embodiments, a total flowrate through the multiple ACM filters  130  can be calculated by the flow controller, and the level signal from the level transmitter of the clarifier can be using in combination with the total flow rate through the multiple ACM filters  130  to actuate valves and pumps associated with the clarified water level in the clarified water chamber  120   b  of the clarifier  120 . 
     In embodiments where the ACM filter  130  is embodied as N filters connected in parallel, the flow rate of each portion of stream  121  is the total flow rate in stream  121  divided N, where N is the number of ACM filters  130  that is online. 
     Second Filtration Stage 
     The first filtered water in stream  131  from the first stage filtration (e.g., the ACM filter)  130  can be filtered in the second stage filtration (e.g., the CC filter  140 ) of the two-stage filtration system  150 . 
     The second filtration stage of media filtration can use catalytic carbon (CC) filtration to remove biological organisms (e.g., bacteria that have biological oxygen demand) and other materials (e.g., humic substances, tannins and lignin, hydrogen sulfide (H 2 S), chloramines, phenols, or a combination thereof). The second stage can contain one or more CC filters  140  fluidly connected in parallel relative to one another. Each CC filter  140  can include a CC filter media contained in a filter housing, where the housing has an inlet for the first filtered water and an outlet for second filtered water (the treated water in stream  141 ). 
     In embodiments, the filter media of the CC filter  140  can include a composition of carbon and iron hydroxide (FeO(OH)). An examples of a commercially available CC filter is the Catalytic Carbon CC filter manufactured by Watch Water GmbH, having a composition of &gt;85% w/w carbon and &lt;15% w/w iron hydroxide. 
     In embodiments, the CC Filter  140  can have iron particles coated inside and outside the micro-pores of catalytic carbon media. The iron particle coating can eliminate the need of expensive ion-exchange and membrane processes. 
     In embodiments where the CC filter  140  includes at least two CC filters  140  connected in parallel, the inlet to each of the CC Filter  140  can include a flow control valve (with respective flow transmitter) to ensure equal distribution of the flow across the filters. 
     The CC filter  140  can be configured with appropriate piping and valves for backwashing on an intermittent basis, for example, every 24 hours of operation or triggered by a differential pressure across the filter that is higher than a setpoint pressure value. Treated water from a treated water tank can be pumped by one or more backwash pumps to backwash the CC filter  140 . 
     Flow Control Second Filtration Stage 
     In embodiments where the CC filter  140  is configured as multiple filters connected in parallel, stream  131  can be split into a portion for each CC filter  140 . Each portion of the stream  131  can have a flow control valve and a flow transmitter placed therein and coupled to one another. The flow transmitter can be configured to send a flow signal which is compared by a controller against the flow controller setpoint to ensure a constant and equal inlet flowrate for through each portion of stream  131  to each CC filter  140 . 
     Additionally, the flow controller can increase the % open of the flow control valves when the flow transmitter indicates that flow in the portion of stream  131  is decreasing, and the flow controller can decrease the % open of the flow control valves when the flow transmitter indicates that the flow in the portion of stream  131  is increasing. 
     In some embodiments, a total flowrate through the multiple CC filters  140  can be calculated by the flow controller, and the total flowrate can be used by the flow rate controller to calculate the flow ratio and proportions for each of the CC filters  140  that is online. 
     In embodiments where the CC filter  140  can be configured or embodied as N filters connected in parallel, the flow rate of each portion of stream  131  is the total flow rate in stream  131  divided N, where N is the number of CC filters  140  that is online. 
       FIG. 5  illustrates a process flow diagram of the continuous water treatment process and system  500 , with exemplary control instrumentation illustrated. Components that are the same as shown in  FIG. 1  are given the same reference numerals. 
     Pumps  605 ,  606 , and  607  can be seen added to streams  115 ,  122 , and  121 , respectively. The pumps  605 ,  606 , and  607  are configured to facilitate of the fluid through the respective streams. 
     A first water analyzer  601  is placed in stream  102  for online analysis of the contents of the contaminated water in stream  102 . Similarly, a second water analyzer  602  is placed in stream  141  for online analysis of the treated water in stream  141 . Generally, the concentration of any contaminant discussed herein is less in the treated water stream  141  than in the contaminated water stream  102 . The process, in these embodiments, can include analyzing the concentration of a contaminant in the contaminated water and analyzing the concentration of the same contaminant in the treated water. 
       FIG. 5  also shows piping for backwashing the filters  130  and  140 . The water used for backwashing the filters  130  and  140  is pumped from a treated water tank  142  (connected to the treated water stream  141  and configured to store treated water) by pump  603  to the filters  130  and  140 . The pump  602  can be placed in stream  604 , which is connected to the treated water tank  142 . Stream  604  can be configured to split into a first stream  604   a  and a second stream  604   b . Stream  604   a  can be connected to stream  131 , and stream  604   b  is connected to stream  141 . During backwash of the ACM filter(s)  130 , treated water flows through stream  604 , stream  604   a , stream  131 , filter(s)  130 , stream  121 , stream  125 , and then to the dirty backwash water sump  160 . During backwash of the CC filter(s)  140 , treated water flows through stream  604 , stream  604   b , stream  141 , filter(s)  140 , stream  131 , stream  132 , and then to the dirty backwash water sump  160 . 
     Various transmitters can be seen in  FIG. 5 , with flow transmitters FT, pressure transmitters PT, level transmitters LT indicated in various locations and configured to send a signal to a controller for actuation of valve that control the flow of fluid in the process and system  500 . 
     For example, a pressure transmitter can be included in the redox reactor  110  for actuation of a valve in the vent gas stream  114 , so as to control the flow of vent gas in vent gas stream  114  (e.g., allow flow upon pressure in the redox reactor  110  exceeding a setpoint pressure, disallow flow upon the pressure falling below the setpoint pressure). A level transmitter can be included in the redox reactor  110  for actuation of a valve in stream  115 , so as to control a level of redox water in the redox reactor  110  (e.g., allow flow upon a level exceeding a setpoint level, disallow flow upon the level falling below the setpoint level). A flow transmitter can be included in the redox water stream  115  for actuation of a valve in the recycle stream  116 , so as to control the flow of redox water to the clarifier  120  (e.g., allow recycle upon a flow rate exceeding a setpoint flow rate, disallow recycle upon the flow rate falling below the setpoint flow rate). 
     A level transmitter can be included in the clarified water chamber  120   b  of the clarifier  120  for actuation of a valve in the clarified water stream  121 , so as to control a level of clarified water in the chamber  120   b  (e.g., allow flow upon a level exceeding a setpoint level, disallow flow upon the level falling below the setpoint level). A level transmitter can be included in the conical-shaped bottom portion  120   c  of the clarifier  120  for actuation of a valve in stream  122 , so as to control a flow of sludge to the sludge handling system  126  (e.g., allow flow upon a level exceeding a setpoint level, disallow flow upon the level falling below the setpoint level). 
     A flow transmitter can be included in stream  121  upstream of the two-stage filtration system  150  (e.g., upstream of the first stage or ACM filter(s)  130 ) for actuation of a valve placed in stream  121  between the flow transmitter and the ACM filter(s)  130 ), so as to control a flow of clarified water to the two-stage filtration system or to control a flow of backwash water so that backwash water does not flow upstream in stream  121 , and instead flows via stream  125  to the dirty backwash water sump  160 . A flow transmitter can be included in stream  131  between the stages of the two-stage filtration system  150  (e.g., between the first stage or ACM filter(s)  130  and the second stage or CC filter(s)  140 ) for actuation of a valve placed in stream  131  between the flow transmitter and the CC filter(s)  140 ), so as to control a flow of filtered water to the CC filter(s)  140  or to control a flow of backwash water so that backwash water does not flow upstream in stream  131  to the ACM filter(s)  130 , and instead flows via stream  132  to the dirty backwash water sump  160 . 
     Applications of the disclosed process and system include, but are not limited to, municipal wastewater treatment, municipal drinking water treatment, industrial wastewater treatment, seepage water (from water storage caverns), and produced water (produced from an oil and gas well) treatment. In municipal wastewater treatment and industrial wastewater treatment, the disclosed process and system can be used for sulfide removal, ammonia reduction, degradable and non-degradable chemical oxygen demand (COD) removal, biological oxygen demand (BODS) removal, and heavy metals removal. In municipal drinking water treatment, the disclosed process and system can be used for TOC removal, trihalomethane (THM) reduction, and algae control. In produced water treatment, the disclosed process and system can be used for biocide for sulfur-reducing bacteria, TDS reduction, sulfides removal, and chemical oxygen demand (COD) reduction. 
     The disclosed continuous process and system can be scaled to any size for a particular application, since the treatment is continuous. Moreover, the system can be fabricated in process modules, and the modular design of the system allows easy transport to any location. Moreover, the discloses continuous process and system can be stand-alone or can be integrated with existing facilities (e.g., existing drinking water treatment facility, wastewater treatment facility, or industrial waste treatment facility). 
     The disclosed continuous process and system also produce treated water that can be reintroduced into sewage treatment, reinjected into an enhanced oil recovery (EOR) reservoir, or discharged into an open body of water (e.g., streams, lakes, seawater). This cannot be accomplished with other AOP technologies that use chlorine-based chemicals and/or that produce sodium hydroxide because, for example, bleach is hazardous and mostly banned disinfectant/oxidant in oil and gas facilities, caustic soda requires utmost care in handling, and ferric chloride compounds are unstable and gives the treated water an undesirable color if not fully reacted. 
     While various embodiments have been shown and described, modifications thereof can be made by one skilled in the art without departing from the spirit and teachings of the disclosure. The embodiments described herein are exemplary only, and are not intended to be limiting. Many variations and modifications of the subject matter disclosed herein are possible and are within the scope of the disclosure. Where numerical ranges or limitations are expressly stated, such express ranges or limitations should be understood to include iterative ranges or limitations of like magnitude falling within the expressly stated ranges or limitations (e.g., from about 1 to about 10 includes, 2, 3, 4, etc.; greater than 0.10 includes 0.11, 0.12, 0.13, etc.). For example, whenever a numerical range with a lower limit, R L  and an upper limit, R U  is disclosed, any number falling within the range is specifically disclosed. In particular, the following numbers within the range are specifically disclosed: R=R L +k*(R U −R L ), wherein k is a variable ranging from 1 percent to 100 percent with a 1 percent increment, i.e., k is 1 percent, 2 percent, 3 percent, 4 percent, 5 percent, . . . 50 percent, 51 percent, 52 percent, . . . , 95 percent, 96 percent, 97 percent, 98 percent, 99 percent, or 100 percent. Moreover, any numerical range defined by two R numbers as defined in the above is also specifically disclosed. Use of the term “optionally” with respect to any element of a claim is intended to mean that the subject element is required, or alternatively, is not required. Both alternatives are intended to be within the scope of the claim. Use of broader terms such as comprises, includes, having, etc. should be understood to provide support for narrower terms such as consisting of, consisting essentially of, comprised substantially of, etc. 
     Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as an embodiment of the present disclosure. Thus, the claims are a further description and are an addition to the embodiments of the present disclosure. The discussion of a reference is not an admission that it is prior art to the present disclosure, especially any reference that may have a publication date after the priority date of this application. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference, to the extent that they provide exemplary, procedural, or other details supplementary to those set forth herein. 
     The particular embodiments disclosed above are illustrative only, as the present disclosure may be modified and practiced in different but equivalent manners apparent to those skilled in the art having the benefit of the teachings herein. Furthermore, no limitations are intended to the details of construction or design herein shown, other than as described in the claims below. It is therefore evident that the particular illustrative embodiments disclosed above may be altered or modified and all such variations are considered within the scope and spirit of the present disclosure. Alternative embodiments that result from combining, integrating, and/or omitting features of the embodiment(s) are also within the scope of the disclosure. While compositions and methods are described in broader terms of “having”, “comprising,” “containing,” or “including” various components or steps, the compositions and methods can also “consist essentially of” or “consist of” the various components and steps. Use of the terms “optionally,” “may,” “might,” “possibly,” and the like with respect to any element of a claim means that the element is required, or alternatively, the element is not required, both alternatives being within the scope of the embodiments. Also, references to examples are merely provided for illustrative purposes, and are not intended to be exclusive. 
     Numbers and ranges disclosed above may vary by some amount. Whenever a numerical range with a lower limit and an upper limit is disclosed, any number and any included range falling within the range are specifically disclosed. In particular, every range of values (of the form, “from about a to about b,” or, equivalently, “from approximately a to b,” or, equivalently, “from approximately a-b”) disclosed herein is to be understood to set forth every number and range encompassed within the broader range of values. Also, the terms in the claims have their plain, ordinary meaning unless otherwise explicitly and clearly defined by the patentee. Moreover, the indefinite articles “a” or “an”, as used in the claims, are defined herein to mean one or more than one of the element that it introduces. If there is any conflict in the usages of a word or term in this specification and one or more patent or other documents, the definitions that are consistent with this specification should be adopted. 
     Additionally, the section headings used herein are provided for consistency with the suggestions under 37 C.F.R. 1.77 or to otherwise provide organizational cues. These headings shall not limit or characterize the invention(s) set out in any claims that may issue from this disclosure. Specifically and by way of example, although the headings might refer to a “Field,” the claims should not be limited by the language chosen under this heading to describe the so-called field. Further, a description of a technology in the “Background” is not to be construed as an admission that certain technology is prior art to any invention(s) in this disclosure. Neither is the “Summary” to be considered as a limiting characterization of the invention(s) set forth in issued claims. Furthermore, any reference in this disclosure to “invention” in the singular should not be used to argue that there is only a single point of novelty in this disclosure. Multiple inventions may be set forth according to the limitations of the multiple claims issuing from this disclosure, and such claims accordingly define the invention(s), and their equivalents, that are protected thereby. In all instances, the scope of the claims shall be considered on their own merits in light of this disclosure, but should not be constrained by the headings set forth herein. 
     Aspects disclosed herein include: 
     Aspect 1: A process for treatment of a contaminated water stream, comprising: contacting the contaminated water with ferrate in a redox reactor to produce a redox water; removing particulate contaminants from the redox water in a clarifier to produce a clarified water; and filtering at least a portion of the clarified water in a two-stage filtration system to produce a treated water, wherein each step of the process is performed on a continuous basis. 
     Aspect 2: The process of Aspect 1, further comprising: feeding a first portion of a ferric compound solution to the redox reactor; feeding a first portion of an acidic oxidant solution to the redox reactor; and contacting a ferric compound and an acidic oxidant to form the ferrate in-situ of the redox reactor. 
     Aspect 3: The process of Aspect 1 or 2, further comprising: feeding a second portion of the ferric compound solution to the clarifier; and feeding a second portion of the acidic oxidant solution to the clarifier. 
     Aspect 4: The process of Aspect 1, 2, or 3, further comprising: feeding a raw source water to a buffer tank; feeding a third portion of the ferric compound solution to the buffer tank; feeding a third portion of the acidic oxidant solution to the buffer tank; and removing the contaminated water from the buffer tank. 
     Aspect 5: The process of Aspect 4, wherein 1) a volume ratio of the first portion to the second portion to the third portion of the ferric compound solution is in the range of 3:2:0 to 8:1:1; 2) a volume ratio of the first portion to the second portion to the third portion of the acidic oxidant solution is 3:2:0 to 8:1:1; or both 1) and 2). 
     Aspect 6: The process of any of Aspects 1 to 5, further comprising feeding first portion of a flocculant-adsorbent solution to the redox reactor; optionally further comprising pumping a sludge from the clarifier to a sludge handling system, and feeding a second portion of the flocculant-adsorbent solution to a sludge thickener of the sludge handling system; optionally further comprising flowing a portion of the clarified water to a dirty backwash water sump, flowing a portion of a filtered water to the dirty backwash water sump, and feeding a third portion of the flocculant-adsorbent solution to the dirty backwash water sump; optionally, wherein a volume ratio of the first portion to the second portion to the third portion of the flocculant-adsorbent solution is 8:1:1. 
     Aspect 7: The process of any of Aspects 1 to 6, further comprising: analyzing a first concentration of a contaminant in the contaminated water; and analyzing a second concentration of the contaminant in the treated water, wherein the first concentration is greater than the second concentration. 
     Aspect 8: The process of any of Aspects 1 to 6, wherein filtering at least a portion of the clarified water in the two-stage filtration system comprises: filtering at least a portion of the clarified water in an advanced catalytic media filter to produce a filtered water, and filtering at least a portion of the filtered water in a catalytic carbon filter to produce the treated water. 
     Aspect 9: A ferrate-based water treatment system comprising: a ferric compound solution preparation system configured to prepare ferric compound solution; an acidic oxidant solution preparation system configured to prepare an acidic oxidant solution; a flocculant-adsorbent solution preparation system configured to prepare a flocculant-adsorbent solution; a redox reactor fluidly coupled to the ferric compound solution preparation system and to the acidic oxidant solution preparation system and to the flocculant-adsorbent solution preparation system; a clarifier fluidly coupled to the redox reactor, to the ferric compound solution preparation system, and to the acidic oxidant solution preparation system; and a two-stage filtration system coupled to the clarifier. 
     Aspect 10: The system of Aspect 9, wherein the redox reactor has a first section fluidly coupled with a second section; wherein the first section is configured to i) receive contaminated water, the ferric compound solution, and the acidic oxidant solution, ii) mix the ferric compound solution and the acidic oxidant solution to form a first amount of ferrate, and iii) contact the first amount of ferrate with the contaminated water for reaction with contaminants to produce a reacted water; and wherein the second section is configured to i) receive the reacted water from the first section, ii) receive the flocculant-adsorbent solution, iii) mix the reacted water and the flocculant-adsorbent solution to produce a reaction mixture, iv) allow for further ferrate reaction with contaminants to form larger particulate contaminants, and v) allow for flocculation and adsorption of particulate contaminants into flocs, and vi) produce a redox water. 
     Aspect 11: The system of Aspect 9 or 10, wherein the clarifier has a main compartment fluidly coupled with a clarified water chamber; wherein the main compartment is configured to i) receive the redox water, the ferric compound solution, and the acidic oxidant solution, ii) mix the ferric compound solution and the acidic oxidant solution to form a second amount of ferrate, iii) contact the second amount of ferrate with the redox water for reaction with unreacted contaminants in the redox water, iv) allow particulate contaminants and flocs to settle to a conical-shaped bottom portion of the clarifier; and wherein the clarified water chamber is configured to receive clarified water from the main compartment. 
     Aspect 12: The system of any of Aspects 9 to 11, wherein the two-stage filtration system comprises a first stage and a second stage, wherein an effluent of the first stage is received by the second stage. 
     Aspect 13: The system of Aspect 12, wherein 1) the first stage comprises one or more advanced catalytic media filters, 2) the second stage comprises one or more catalytic carbon filters, or 3) a combination of 1) and 2). 
     Aspect 14: The system of any of Aspects 12 to 13, further comprising: a dirty backwash water sump fluidly coupled to i) a clarified water stream that fluidly connects the clarifier to the first stage of the two-stage filtration system, ii) a first filtered water stream that fluidly connects the first stage to the second stage, and iii) to the flocculant-adsorbent solution preparation system. 
     Aspect 15: The system of any of Aspects 9 to 14, further comprising: a pre-treatment system fluidly coupled to the redox reactor, wherein the redox reactor is configured to receive contaminated water from the pre-treatment system, wherein a buffer tank of the pre-treatment system is fluidly coupled to the ferric compound solution preparation system and to the acidic oxidant solution preparation system; and a sludge handling system fluidly coupled to a conical-shaped bottom portion of the clarifier and to the flocculant-adsorbent solution preparation system. 
     While several embodiments have been provided in the present disclosure, it should be understood that the disclosed systems and methods may be embodied in many other specific forms without departing from the spirit or scope of the present disclosure. The embodiments and present examples are to be considered as illustrative and not restrictive, and the intention is not to be limited to the details given herein. Many variations and modifications of the invention disclosed herein are possible and are within the scope of the invention. For example, the various elements or components may be combined or integrated in another system or certain features may be omitted or not implemented. Also, techniques, systems, subsystems, and methods described and illustrated in the various embodiments as discrete or separate may be combined or integrated with other systems, modules, techniques, or methods without departing from the scope of the present disclosure. Other items shown or discussed as directly coupled or communicating with each other may be indirectly coupled or communicating through some interface, device, or intermediate component, whether electrically, mechanically, or otherwise. Other examples of changes, substitutions, and alterations are ascertainable by one skilled in the art and could be made without departing from the spirit and scope disclosed herein. 
     Numerous other modifications, equivalents, and alternatives, will become apparent to those skilled in the art once the above disclosure is fully appreciated. It is intended that the following claims be interpreted to embrace all such modifications, equivalents, and alternatives where applicable. Accordingly, the scope of protection is not limited by the description set out above but is only limited by the claims which follow, that scope including all equivalents of the subject matter of the claims. Each and every claim is incorporated into the specification as an embodiment of the present invention. Thus, the claims are a further description and are an addition to the detailed description of the present invention. The disclosures of all patents, patent applications, and publications cited herein are hereby incorporated by reference.