CN113697987B

CN113697987B - Method and system for industrial wastewater treatment

Info

Publication number: CN113697987B
Application number: CN202010439656.9A
Authority: CN
Inventors: 罗尼·班克; 耶尔·泽维·佩雷斯
Original assignee: P2W CY Ltd
Current assignee: P2W CY Ltd
Priority date: 2020-05-22
Filing date: 2020-05-22
Publication date: 2022-09-06
Anticipated expiration: 2040-05-22
Also published as: CN113697987A

Abstract

The present application provides methods and systems for industrial wastewater treatment that produce zero liquid discharge. The method comprises the following steps: the method comprises the steps of pretreating the provided industrial wastewater to remove heavy metals, ultrafiltering the pretreated wastewater to remove suspended and colloidal solids, nanofiltering the ultrafiltered wastewater to produce treated water (having monovalent ions) and a concentrate, treating the concentrate to remove divalent and trivalent elements and other compounds from the concentrate, and reducing the level of sulfate to a specific level above the sulfate solubility level to produce return water and sludge, mixing the return water with the provided industrial wastewater prior to or in a first treatment stage and/or with the pretreated wastewater prior to ultrafiltration, and removing residual water from the sludge to produce removed solids having zero liquid discharge. Advantageously, the disclosed methods and systems are more efficient, less expensive, and have greater sustainability than prior art systems.

Description

Method and system for industrial wastewater treatment

Technical Field

The present invention relates to the field of industrial wastewater treatment, and more particularly to the use of nanofiltration and water circulation to achieve affordable and sustainable industrial wastewater treatment.

Background

Prior art industrial wastewater treatment systems typically apply reverse osmosis and special treatment to achieve zero liquid discharge (ZLD, without removing any brine or concentrate from the plant), see, e.g., fig. 6A and 6B below, however, such systems are typically very expensive to build and operate and, in addition, are typically difficult to maintain.

Disclosure of Invention

The following is a simplified summary that provides a preliminary understanding of the invention. The summary does not necessarily identify key elements or limit the scope of the invention, but is merely used as an introduction to the following description.

One aspect of the present invention provides a method of wastewater treatment that produces Zero Liquid Discharge (ZLD), the method comprising: the method comprises the steps of pretreating the provided industrial wastewater to remove heavy metals and suspended and/or colloidal solids, providing pretreated wastewater, ultrafiltering the pretreated wastewater to remove suspended and colloidal solids, nanofiltering the ultrafiltered wastewater to produce treated water and a concentrate, wherein the treated water comprises monovalent ions, treating the concentrate to remove divalent and trivalent elements and other compounds from the concentrate, and reducing the level of sulfate to a specific level above the sulfate solubility level to produce return water and sludge, mixing the return water with the provided industrial wastewater prior to or in a first treatment stage and/or the pretreated wastewater prior to ultrafiltration, and removing residual water from the sludge to produce removed solids, having ZLD.

One aspect of the invention provides a system for wastewater treatment that produces a Zero Liquid Discharge (ZLD), the system comprising: a first treatment stage comprising: a first stage treatment unit configured to remove heavy metals and suspended and/or colloidal solids from provided industrial wastewater, and a filtration unit comprising: at least one ultrafiltration unit configured to remove suspended and colloidal solids from the pretreated wastewater, and at least one nanofiltration unit configured to nanofilter the ultrafiltered wastewater to produce treated water and a concentrate, wherein the treated water comprises monovalent ions; the second processing stage comprises: a second stage treatment unit configured to remove divalent and trivalent elements and other compounds from the concentrate and reduce the level of sulfate to a specific level above the solubility level of sulfate to produce return water and sludge, and a final device configured to remove residual water from the sludge to produce removed solids, with ZLD; and a piping system configured to mix the return water with the provided industrial wastewater at the first treatment stage before, at, and/or after the first stage treatment unit.

These, additional, and/or other aspects and/or advantages of the present invention will be set forth in the detailed description which follows; can be inferred from the detailed description; and/or may be learned by practice of the invention.

Drawings

For a better understanding of embodiments of the invention and to show how the same may be carried into effect, reference will now be made, by way of example only, to the accompanying drawings in which like reference numerals refer to corresponding elements or parts throughout.

In the drawings:

fig. 1A and 1B are high-level block diagrams (high-level block diagrams) of a system for wastewater treatment that produces Zero Liquid Discharge (ZLD) according to some embodiments of the present invention, schematically illustrating the main elements in the system 100, their functions and flows.

FIG. 2 is a high-level schematic block diagram of a system for ZLD wastewater treatment according to some embodiments of the present invention including the use of by-products from a second stage in a first stage.

Fig. 3 is a high-level schematic block diagram of a system for ZLD wastewater treatment showing contaminants and flows in the monitoring and control system, according to some embodiments of the present invention.

Fig. 4A-4C provide high-level schematic examples of embodiments of systems according to some embodiments of the invention.

Fig. 5A and 5B are high-level schematic diagrams of an FBR (fluidized bed reactor) according to some embodiments of the invention.

Fig. 6A and 6B are high level schematic diagrams of a prior art ZLD water treatment system.

FIG. 7 is a high-level flow diagram illustrating a wastewater treatment method that produces Zero Liquid Discharge (ZLD) according to some embodiments of the invention.

Detailed Description

In the following description, various aspects of the present invention are described. For purposes of explanation, specific configurations and details are set forth in order to provide a thorough understanding of the present invention. It will be apparent, however, to one skilled in the art that the present invention may be practiced without the specific details presented herein. In addition, well-known features may be omitted or simplified in order not to obscure the present invention. With specific reference to the drawings, it is stressed that the particulars shown are by way of example and for purposes of illustrative discussion of the present invention only, and are presented in the cause of providing what is believed to be the most useful and readily understood description of the principles and conceptual aspects of the invention. In this regard, no attempt is made to show structural details of the invention in more detail than is necessary for a fundamental understanding of the invention, the description taken with the drawings making apparent to those skilled in the art how the several forms of the invention may be embodied in practice.

Before explaining at least one embodiment of the invention in detail, it is to be understood that the invention is not limited in its application to the details of construction and the arrangement of the components set forth in the following description or illustrated in the drawings. The invention is applicable to other embodiments that can be practiced or carried out in various ways and in combinations with the disclosed embodiments. Also, it is to be understood that the phraseology and terminology employed herein is for the purpose of description and should not be regarded as limiting.

Embodiments of the present invention provide efficient and economical methods and mechanisms for treating industrial wastewater, thereby providing an improvement in the art of industrial wastewater treatment. Methods and systems for industrial wastewater treatment that produces Zero Liquid Discharge (ZLD) are provided. These include: the method comprises the steps of pretreating the provided industrial wastewater to remove heavy metals and suspended and/or colloidal solids, ultrafiltering the pretreated wastewater to remove suspended and colloidal solids, nanofiltering the ultrafiltered wastewater to produce treated water (which comprises monovalent ions) and a concentrate, treating the concentrate to remove divalent and trivalent elements and other compounds from the concentrate, and reducing the level of sulfate to a specific level above the sulfate solubility level to produce return water and sludge, mixing the return water with the provided industrial wastewater prior to or in the first treatment stage and/or with the pretreated wastewater prior to ultrafiltration, and removing residual water in the sludge to produce removed solids (without removing any brine or concentrate from the plant), having ZLD. Advantageously, the disclosed methods and systems are efficient, inexpensive, and more sustainable than prior art systems. In particular, the disclosed method and system are advantageous in terms of construction costs (CAPEX-capital expenditure) and maintenance costs (OPEX-operational expenditure) and, furthermore, make ZLD industrial wastewater treatment affordable and sustainable, relative to prior art ZLD systems based on multi-stage reverse osmosis and special treatment of the remaining residues.

Various embodiments are configured to treat various types of industrial wastewater, which may have a large number of contaminants in various concentrations. As explained below, the systems and methods disclosed below can be adjusted to treat industrial wastewater with these contamination ranges, thereby providing ZLD. For example, as disclosed below, metals and/or heavy metals may be removed from wastewaterFor example Ag (typically 0.1mg/l, ranging up to 100mg/l), Al (typically 0.5mg/l, ranging up to 1000mg/l), As (typically 0.8mg/l, ranging up to 100mg/l), Cd, Co, Cr, Mo, Ni (typically 0.5mg/l, ranging up to 100mg/l), Cu, Mn (typically 0.5mg/l, ranging up to 500mg/l), Fe (typically 1mg/l, ranging up to 500mg/l), Pb, Sb, Se, Sn, Ti, V (typically 0.5mg/l, ranging up to 5mg/l) and Zn, V (typically 0.5mg/l, ranging up to 1000mg/l), which are typical characteristics of industrial waste water in the metal and mining industries. The relevant alkaline earth metals Mg (typically 50Mg/l, in the range up to 1000Mg/l) and Ca (typically 120Mg/l, in the range up to 2000Mg/l), and Be and Ba (typically 0.5Mg/l, in the range up to 5Mg/l) can also Be removed. Other elements and compounds in metal-related and other industrial processes include silicon dioxide (SiO) ₂ Typical values 0.5mg/l, ranging up to 10mg/l), Sulfate (SO) ₄ A typical value of 500mg/l, a typical range of 500- ₄ Typical values of 1mg/l, typical ranges up to 5mg/l), cyanides (CN typical ranges up to 10mg/l) and Carbonates (CO) ₃ Typical values 10mg/l, typical ranges up to 100mg/l) and bicarbonate (HCO) ₃ Typical values 20mg/l, typical ranges up to 100mg/l) and Nitrate (NO) ₃ Typical values of 20mg/l, typical ranges up to 100mg/l) -all of the above can be removed in the ZLD methods and systems disclosed below. Other related elements and compounds include F (typically 0.5mg/l, typically ranging up to 5mg/l, also typical of metal-related industries), Cl (typically 250mg/l, typically ranging from 20 to 250mg/l), Nitrogen dioxide (NO) ₂ Typical values are 5mg/l, typical ranges up to 50mg/l), P (typical values 0.5mg/l, ranges up to 5mg/l), monovalent Na (typical values 150mg/l, ranges from 20 to 250mg/l) and K (typical values 15mg/l, ranges up to 100mg/l) and B (typical values 0.5mg/l, typical ranges up to 5 mg/l). Other characteristics of industrial wastewater that may be treated in the systems and methods disclosed below include conductivity (typically 2500. mu.s/cm, typically in the range of 1,000-U, Nephelometric Turbidity units (Nephelometric Turbidity units), typical values of 50NTU, typically ranging from 1 to 300NTU, and color (platinum-cobalt scale, typical value 30 typically ranging from 1 to 300). As disclosed below, the disclosed systems and methods may be configured and/or adjusted to manage these features according to a given specification. Obviously, since these ranges and compositions are very versatile, the adjustment of the disclosed system and method is shown below for only a few non-limiting examples that provide the principles for adjusting the disclosed system and method to treat any industrial wastewater composition that needs to be treated.

Fig. 1A and 1B are high-level block diagrams of a wastewater treatment system 100 for producing Zero Liquid Discharge (ZLD) according to some embodiments of the present invention, schematically illustrating the main units in the system 100, their functions and flows.

The system 100 includes a first processing stage 110 and a second processing stage 120. The first treatment stage 110 includes a first stage treatment unit 102 configured to remove metals and/or heavy metals and optionally suspended and/or colloidal solids (TDS and/or TSS, and possibly other contaminants, depending on wastewater quality) from the provided industrial wastewater 80; and a filtration unit 105 configured to filter the pre-treated wastewater to produce treated water that may include monovalent ions 107 (and possibly some low concentration of divalent and/or trivalent ions) and a concentrate 109. The second treatment stage 120 includes a second stage treatment unit 125 configured to treat the concentrated liquor 109 to primarily remove divalent ions and other compounds and elements not removed by the first stage treatment unit 102 (as specified), and in particular to reduce the level of sulfate to a specified level (e.g., 1500-. The second treatment stage 120 further includes a dewatering unit 103 (e.g., including a filter press or dewatering unit), the dewatering unit 103 configured to remove residual water from the sludge 128 to produce a removed solids 129 having ZLD. The residual water may be mixed back into the treated water at different stages (see below). The system 100 further includes a piping system that is configured to beConfigured to mix the return water 121 with the provided industrial wastewater 80 at the first treatment stage 110 before the first stage treatment unit 102, at the first stage treatment unit 102, or after the first stage treatment unit 102. It should be noted that although sulfate is used herein as an illustrative example, other compounds, such as other divalent and/or trivalent ions (e.g., Mg), may be removed according to similar principles ⁺⁺ )。

The second stage treatment unit 125 may be configured to use calcium, calcium compounds, and/or sodium hydroxide to reduce the level of sulfate to a specified sulfate level, which may be 2,000ppm to 5,000ppm, or 2,500ppm to 4,000ppm, or between similar ranges, depending on the specified desired sulfate level reduction and system configuration. In various embodiments, the second stage treatment unit 125 may be configured to reduce the sulfate level to any of approximately the sulfate level in the provided industrial wastewater 80, a slightly higher level (e.g., 110%, 120%, possibly up to 150%, or any intermediate value, as long as the concentration stabilizes after multiple iterations), or a lower level (e.g., about 80%, 60%, 40%, 20%, or any intermediate fraction thereof), depending on the initial concentration of the respective contaminant and the throughput of the respective portion of water (e.g., as derived from performance parameters of the filtration unit 105). In certain embodiments, the second stage treatment unit 125 may be configured to reduce the sulfate level to approximately half of the sulfate level in the provided industrial wastewater 80. The reduced level of sulfate in the second stage treatment unit 125 may be derived from the throughput of the concentrate 109 relative to the throughput of the wastewater 80 (see the illustrative example in table 1 below). In various embodiments, the second stage treatment unit 125 can be configured to use, for example, lime, Ca, CaO, Ca (OH) ₂ 、CaCO ₃ 、CaMg(CO ₃ ) ₂ Possibly NaOH or similar compounds to remove sulfate. In the second stage treatment unit 125, other divalent and/or trivalent ions may be removed using the corresponding chemistry. It should be noted that by filtration unit 105, and in particular by nanofiltration unit 105B (see below), the concentration of the compounds removed in concentrate 109 (e.g.,two to three times relative to the wastewater 80) can achieve effective contaminant removal without exceeding the solubility threshold.

For example, in certain embodiments, the first stage treatment unit 102 may be configured to remove any of Cd, Al, Fe, Mn, Zn, As, Pb, Cu, etc., possibly adjusting the pH, removing some SO ₄ And possibly Ca, Mg, CO ₃ 、SiO ₂ Etc. and their corresponding compounds, depending on the wastewater composition, contaminant concentration, and the particular design of the system. In certain embodiments, the second stage processing unit 125 may be configured to remove SO, for example ₄ 、SiO ₂ 、Ca、Mg、CO ₃ And their corresponding compounds, and any of suspended and colloidal solids, and further adjust water parameters, depending on the wastewater composition, contaminant concentration, and the particular design of the system.

Although piping is not explicitly shown, the disclosed flow is regulated using corresponding pipes, conduits, pumps, taps, flow controllers, vessels, and the like. Specifically, stream 111 relates to the feed wastewater 80 plus return water 121 stream, and stream 112 relates to the first stage pretreated water stream provided to the filtration unit 105. Corresponding piping and flow elements may be employed to regulate the disclosed flow.

Referring to FIG. 1B, the system 100 may be configured to remove at least heavy metals (and may also be SO) by the first stage processing unit 102 ₄ 、CO ₃ 、HCO ₃ Any of Mg, Ca, and other contaminants) by being configured to convert monovalent ions (e.g., Na) ⁺ 、Cl ^- ) And possibly some low concentration of divalent and/or trivalent ions, is passed with the treated water 107 through a filtration unit 105 to remove concentrate 109 from the pretreated wastewater 112, to reduce the level of sulphate (which may also be the level of any of Mg, Ca and any other divalent/trivalent ions and other contaminants), and to remove other contaminants through a second stage treatment unit 125, and to return residual dissolved sulphate in the return water to the first stage 110, for example to mix with the wastewater 80 to form stream 111, or possibly to mix at least partially with the pretreated water 112. Sulfate level (and equivalents)The levels of elements and compounds, such as divalent ions) to a level above its solubility threshold that is low enough that sulfate does not accumulate in the first stage and damage the membranes of the filtration unit 105, as disclosed below. If divalent ions remain in the treated water 107, their amount is at most a few percent of the amount in the waste water 80, e.g., 1-3% of the sulfate in the waste water 80 may remain in the treated water 107 as long as their level is below the corresponding standard requirement. Thus, at least 97-99% of the amount of sulfate in the wastewater 80 may be removed in the solids 129. Accordingly, with respect to monovalent ions, the system 100 may be configured to transfer 5-30% of its amount in the wastewater 80 into the treated water 107, avoiding the accumulation of monovalent ions throughout the entire cycle and operation of the system 100.

Table 1 provides an illustrative example showing the treatment of small amounts of contaminants by the system 100 at various stages of the process shown with reference to fig. 1A and 1B. This example is non-limiting as it relates to only a few contaminants (for simplicity), is schematic with respect to flow, and provides a range of contaminants after each stage. It should also be noted that as the flow and concentration are readjusted by the mixing of the return water, the concentration will generally increase gradually and then stabilize through the system. Table 1 provides a range of estimated steady states after the initialization phase of system 100. Assuming a plant feed of 100m ³ H, 95-97% of its total plant recovery, 55-65% of Nanofiltration (NF) recovery, Na and Cl ions permeate through the treated water and at concentrations similar to their concentrations in the feed water, and provide concentration ranges by simulation after running it over 10,000 cycles. The complete ZLD process removes heavy metals (Al, Fe, Mn, Cu, Zn, As, Cd, Mn, Cr, etc.) found in the industrial wastewater 80 As well As sulfates, magnesium, cyanides, calcium, etc.

Table 1: illustrative high-level illustrative examples of industrial wastewater treatment by the disclosed systems and methods.

It should be noted that after the removal of heavy metals and possibly other elements in the first stage treatment 102, most of the divalent ions and other compounds are removed from the concentrate 109 in the second stage treatment unit 125. However, these are removed to levels above their solubility levels (see, e.g., sulfate) using simple and rapid techniques, and the remaining contaminants are returned to the receiving stream of industrial wastewater 80 (or optionally to stream 112 after first stage treatment 102, as return water 121 is free of heavy metals). Since the concentration of the remaining contaminants is about their concentration in the provided industrial wastewater 80, they do not accumulate and their concentration does not rise to about the level allowed by the filter unit 105. The filtration unit 105 removes these contaminants into the concentrate 109 so that the treated water has a contaminant level (e.g., sulfate) below the solubility level without having to apply expensive prior art special treatment techniques 95 to reduce its level (see below). It is noted that the concentration of the various elements and compounds throughout the system 100 depends on the system configuration, such as the throughput and number of cycles (both in operation and in simulation) through which the system is run until steady state is reached.

In various embodiments, the first stage treatment unit 102 may be configured to provide mild pre-treatment, e.g., only adjust the pH of the water and remove heavy metals, or more important pre-treatment, e.g., also remove some sulfate and/or reduce any of TDS, TSS, turbidity, etc. In various embodiments, the first stage treatment unit 102 may be configured to provide a level of pretreatment that is dependent upon the quality of the received industrial wastewater 80 relative to the particular operational requirements of the filtration unit 105. For example, if the sulfate level in the wastewater 80 is about 3000ppm, no further reduction may be required in the first stage 110, but if the sulfate level in the wastewater 80 is about 10,000ppm, the first stage treatment 102 may be configured to reduce it to 3000-4000 ppm. It is noted that in any event, the second stage treatment unit 125 may be configured to remove a majority of sulfate and/or equivalent contaminants (from the concentrate 109) to achieve a sulfate level (forming stream 111) that may be returned 121 to the received water without increasing the sulfate concentration in the first stage 110.

Fig. 2 is a high-level schematic block diagram of a system 100 for ZLD wastewater treatment, including the use of byproducts 127 from a second stage 120 in a first stage 110, according to some embodiments of the invention.

In certain embodiments, filtration unit 105 may include an ultrafiltration unit 105A followed by a nanofiltration unit 105B configured to remove concentrate 109 from water while passing monovalent ions (and possibly some divalent and/or trivalent ions at low concentrations) along with treated water 107. For example, filtration unit 105 may include one or more Ultrafiltration (UF) units 105A to remove or reduce the levels of solids and colloids in water 112 and one or more Nanofiltration (NF) units 105B to selectively remove or reduce the levels of divalent ions and other compounds in water 113. The backwash 106 from the UF unit 105A may be reintroduced into the first stage treatment unit 102, while the concentrate 109 from the NF unit 105B may be treated in the second stage treatment unit 125.

It should be noted that UF membranes typically remove colloids and suspended solids from water flowing through them, whereas NF membranes typically block most or almost all of the divalent ions in water passing through them, while some monovalent ions pass through (unlike RO membranes that block most or all of the monovalent ions). UF membranes typically have pore sizes greater than 10nm (e.g., 10-50nm), and can be made of polymer (e.g., PVDF, polyvinylidene fluoride) hollow fibers for higher mechanical strength and chemical resistance, and removal of various particles. The NF, located between UF and RO, can be made of a membrane composite (e.g., polyamide), typically removes solutes down to the size of 1nm and blocks organic molecules with molecular weights greater than 200-400, such as dissolved organics, endotoxins/pyrogens, pesticides/pesticides, herbicides, antibiotics, nitrates, sugars, latex emulsions, metal ions, etc., and soluble salts, such as 20-80% for monovalent anions (e.g., sodium chloride or calcium chloride) and 90-98% for divalent anions (e.g., magnesium sulfate). Thus, the nanofiltration unit has a smaller pore size than the ultrafiltration unit, e.g. less than 10 nm. It should also be noted that the system configuration includes the extent to which water is circulated through the various membranes, thereby affecting the concentration of ions produced in the treated water. The more times a quantity of water is flowed through the device on the membrane, and/or the more membranes are used for a given throughput, the lower the resulting ion concentration in the treated water.

Thus, the treated water 107 may include low levels of other elements or compounds, particularly sulfate salts below the solubility threshold (e.g., < 1500-. It should be noted that prior art RO treatment produces very pure water and typically requires post-treatment addition of minerals for various purposes to allow residual low levels of elements and compounds to be achieved by the disclosed embodiments. In various embodiments, the NF unit 105B may pass most monovalent ions through to the treated water 107 while passing up to 1%, up to 3%, or possibly up to 5% or between 1-10% of one or more divalent or trivalent ions.

It should be noted that since the concentrate 109 (and possibly the backwash water 106 from the UF unit 105A) blocked by the NF unit 105B is free of heavy metals, at least some of the water may be returned to the first treatment stage 110 after the first stage treatment 102.

In certain embodiments, the sludge and/or solids 104 and/or any treatment product 127 from the second treatment stage 120 may be used in the pretreatment 102 of the first treatment stage 110, for example, to enhance coagulation and/or flocculation in the first stage treatment unit 102. For example, particles from the particle-based second stage treatment unit 125 may be delivered to the first stage treatment unit 102 as a treatment product 127.

For example, the second treatment stage 120 can include a fluidized bed reactor FBR 125C (see fig. 5A and 5B below) having solid particulate material fluidized by high velocity passing fluids, and the system 100 can be further configured to utilize used FBR substrate (e.g., coated particles 148 as a treatment byproduct 127) in the first stage treatment unit 102 for pre-treatment of the provided industrial wastewater 80.

Fig. 3 is a high-level schematic block diagram of a system 100 for ZLD wastewater treatment, showing the monitoring and control of contaminants and flows in the system 100, according to some embodiments of the present invention.

The system 100 may further include a monitoring unit 135 and one or more controllers 130 configured to monitor the flow throughout the system 100 and possibly the level of contaminants in the flow; and separately control these streams and thus the level of contaminants in the streams to maintain continuous operation of the system 100. The monitoring unit 135 is schematically shown in a non-limiting manner with respect to the plurality of

streams

80, 111, 112, 107, 109, 128 and 121 in the system 100; obviously, any internal flows (e.g. within the filtration unit 105, e.g. between the UF unit 105A and the NF unit 105B, see fig. 2) and additional flows may also be monitored according to their throughput and/or chemical composition. In certain embodiments, the treatment of the product 127, such as the sludge 104 and/or the coated particles 148, may also be monitored. The monitoring units 135 may be interconnected therebetween and may be interconnected with the controller 130 via various communication arrangements (e.g., wired and/or wireless communication, via a communication link or network, via a cloud service, etc.). The monitoring unit 135 may be configured to monitor the levels of ions or other compounds in the various monitored streams, and the data may be used by the controller 130 to adjust the process as needed.

The controller 130 may be configured to modify the flow in the system 100 and may modify the operating parameters of the units in the system 100 to maintain the concentration of contaminants within specified limits that allow the system 100 to run continuously and maintain the membranes in the filtration unit 105 in good service, thereby reducing maintenance costs. The controller 130 may be further configured to monitor the level of monovalent ions in the treated water 107. In certain embodiments, the controller 130 may be configured to determine the flow and circulation through the system 100 to meet standard requirements regarding the level of monovalent and/or divalent ions in the treated water 107, increasing the number of cycles for a given throughput to reduce the level of monovalent and/or divalent ions in the treated water 107.

In certain embodiments, the controller 130 may be operated relative to predetermined analog data that correlates contaminant levels to throughput, makes control of contaminant levels simpler, and allows the controller 130 to primarily modify the flow through the system 100. It should be noted that the concentration of the various elements and compounds throughout the system 100 depends on the system configuration, such as the throughput and number of cycles (both in operation and in simulation) through which the system is run until steady state is reached. The controller 130 may be configured to adjust these throughputs and cycles in real-time and adjust operating parameters to achieve desired specifications (e.g., thresholds for elements and compounds) related to parameters of the received wastewater and system components.

Fig. 4A-4C provide high-level schematic examples of embodiments of a system 100 according to some embodiments of the present invention. Elements from fig. 1A, 1B, 2, 3, and 4A-4C may be combined in any operable combination, and the illustration of some elements in some drawings, but not others, is for explanatory purposes only and is not limiting.

Fig. 4A schematically illustrates certain embodiments of the system 100, which include any of the following in a first processing stage 110. A coagulation mixer unit 102A and/or a flocculation unit 102B may be provided before the precipitation unit 102C in the first stage treatment unit 102 to improve pretreatment, and optionally remove dissolved and/or colloidal solids, for example by enhancing removal of heavy metals and/or silicates and/or other contaminants. Water from the precipitation unit 102C and/or water removed from the removed precipitate 108 by the filtration and/or dewatering unit 103 may be reintroduced into the wastewater 80.

In various embodiments, the sludge and/or solid material 104 from the precipitation unit 102C and/or the sludge/solid material 104 from the precipitation unit 125C may be recycled and used, for example, to enhance flocculation and precipitation (using the solid material 104 to produce high density sludge HDS). Sludge/solid material 104 from either of the first and second treatment stages 110, 120 may be used in the same or the other of the first and second treatment stages 110, 120, respectively, depending on the sludge composition and treatment needs.

At least one Ultrafiltration (UF) unit 105A may be used, for example, to remove dissolved and/or colloidal solids prior to at least one Nanofiltration (NF) unit 105B in filtration unit 105. The UF unit 105A may be configured to provide an initial filtrate 106, which may be returned and added to the wastewater 80 and/or to a location along the first stage treatment unit 102 (e.g., flocculation unit 102B).

Some embodiments of the system 100 may include any of the following in the second processing stage 120. A coagulation mixer unit 125A and/or a flocculation unit 125B may be provided before the precipitation unit 125C in the second stage treatment unit 125 to improve pretreatment, e.g., to remove sulfate (beyond its solubility threshold), e.g., using calcium (e.g., Ca, CaO, Ca (OH) ₂ Etc.) to produce gypsum, and remove other compounds, such as divalent ions and/or silicates or other contaminants (see the above list of common contaminants). Treated water 107A may be added to treated wastewater 80, in whole or in part, as return water 121 (first and third options shown in a non-limiting manner) before first stage treatment unit 102, at first stage treatment unit 102, or after first stage treatment unit 102. The exact details of mixing depend on the quality of wastewater 80, pre-treated wastewater 112, and treated water 107A, which can be controlled and adjusted during treatment (e.g., with respect to relative throughput). The return water 121 reduces the level of sulfate and other contaminants in the pretreated wastewater, thereby enabling a reduction in sulfate levels and enabling continuous operation and low maintenance costs of the membranes in the filtration unit 105 (e.g., preventing clogging and other damage to the membranes).

Water from the precipitation unit 125C and/or water removed from the sludge 128 by the filtration and/or dewatering unit 103 (e.g., a filter press or dewatering unit, similar or different from that used in the first stage 110) may be reintroduced into the concentrate 109 or return water 121 in the second stage 120, depending on the quality achieved.

Fig. 4B schematically illustrates that one or both of the first stage treatment unit 102 and/or the second stage treatment unit 125 may include any of the coagulation and/or sedimentation and/or

flocculation units

118A, 118B, 118C, respectively, depending on the type and level of contaminants that should be removed, depending on the respective flow throughput and depending on the particular treatment requirements. Lime and/or limestone may be added to either unit, for example to adjust the pH and remove sulfates, in one or both of the first stage treatment unit 102 and the second stage treatment unit 125.

As schematically shown in fig. 4B, in various embodiments, a Fluidized Bed Reactor (FBR)140 may be used in one or both of the first and second treatment stages 110, 120 to remove one or more contaminants from the respective treated water. FBR140 may be used in addition to, or in place of, coagulation and/or flocculation and/or

precipitation units

118A, 118B, 118C in either or both of first stage treatment unit 102 and/or second stage treatment unit 125.

For example, the FBR140 may be used in the second stage treatment unit 125 to produce rapid removal of sulfate using circulation through the fluidized bed rather than precipitation, which is a faster method (e.g., 10 to 50 times faster) to remove contaminants. In certain embodiments, FBR140 may be enhanced by the use of Ca or Ca compounds, such as CaO, Ca (OH) ₂ The sulfate is removed to reach a sulfate level below its solubility level. The byproducts 127 (e.g., coated particles 148, see below) from the FBR140 may be used in the first stage 110 and/or the second stage 120, respectively, e.g., in the flocculation and/or precipitation sub-units of the first stage treatment unit 102 and/or the second stage treatment unit 125, as described above. For example, coated particles 148 (see fig. 5A and 5B below) from FBR140 may be used in units 102 and/or 125 to remove solids, elements, and/or compounds as described above to recover materials and reduce the total solids used in system 100. For example, the coated particles 148 from the FBR140 may be used in the first stage treatment unit 102 to remove heavy metals.

FIG. 4C schematically illustrates non-limiting embodiments of the first stage processing unit 102 and the second stage processing unit 125 as several options to the extent schematically illustrated in FIG. 4B. For example, the condensing

units

102D, 125D of the

units

102, 125, respectively, may correspond to the condensing unit 118B of fig. 4B. The return water 121 may be introduced to any of a number of locations throughout the system 100, for example, to the coagulation unit 102A, flocculation unit 102B, pretreated wastewater 112, etc., and/or the throughput to various selectable locations may be adjusted by the controller 130 according to monitored flow parameters to stabilize the process and improve its efficiency. Backwash water 106 from ultrafiltration unit 105A may be introduced back into wastewater 80 and/or mixed within and/or after first stage treatment 102 because it is free of heavy metals to further dilute sulfate and corresponding contaminants. The discharged concentrate 126 from the second stage treatment unit 125 may be directly dewatered 103 (e.g., if the concentrate is substantially sludge 128), and/or the water produced thereby may be introduced to the coagulation unit 125A in the second stage 120 and/or to the coagulation unit 102A in the first stage 110, depending on the desired regulation of flow and contaminants through the system 100. Note that for simplicity, the illustration in fig. 4C only shows an optional mixing point for the return water 121 and the discharged concentrate 126, assuming the required piping is added accordingly.

Fig. 5A and 5B are high-level schematic diagrams of FBR140 according to some embodiments of the present invention. Fig. 5A is a schematic perspective view of a longitudinal section, and fig. 5B is a schematic longitudinal section with schematic examples of particles before and after being coated with

contaminants

142, 148, respectively. Fig. 5A and 5B show only one non-limiting example of an FBR structure, and equivalent structures may also be used. FBR140 uses fine solid particulate material 142 suspended in fast flowing treated water 109 and introduced chemicals 145 (e.g., lime, CaO, Ca (OH) ₂ 、CaCO ₃ Any of (a), optionally NaOH) to remove contaminants from the treated water to produce treated water 121. It should be noted that while prior art FBRs are primarily used to treat water hardness, the disclosed FBR140 may be used to remove sulfate and/or other divalent and/or trivalent ions in a rapid process, which may significantly simplify ZLD industrial water treatment while maintaining a consistent quality of serviceThe levels of these compounds are low and within the requirements of the disclosed systems and methods.

For example, as part of the second stage treatment unit 125, the fine silicate sand 142 may be used to remove sulfate and other contaminants from the concentrate 109. In certain embodiments, a fine solid particulate material 142, such as a Silicate (SiO) ₂ ) Or fine sand (e.g., silica sand or natural quartz No. 00, with a particle size of 0.3-0.6mm in non-limiting embodiments) may be coated with sulfate and other contaminants during the treatment process in the FBR140 and removed from the FBR140 after the process (148). The coated particulate material 148 may then be used as a substrate in the first stage treatment unit 102 and/or the second stage treatment unit 125. Advantageously, the coated particulate material 148 may comprise hydroxide (OH) ^- ) Which may be advantageously used in the first stage process 102 to remove heavy metals. In various embodiments, the FBR140 may be used in the first stage processing unit 102 and/or the second stage processing unit 125.

It should be noted that the FBR140 may be configured to introduce the chemical 145 through a conduit 146 that enters the FBR140 from its top or center portion and descends to the bottom of the FBR140 where the chemical 145 is released, unlike prior art FBRs. It should be noted that in a typical FBR, chemical 145 is introduced through a conduit that enters the FBR from its bottom and rises to release the chemical at its bottom portion. The inventors have found that the disclosed design change is more effective in the disclosed FBR140 because it reduces instances of plugging of the bottom of the FBR140 with particles 148 (typically there are some barriers in the bottom portion of the FBR140 to prevent interference with the introduction of the concentrate 109) and improves flow through the FBR 140.

Advantageously, the FBR140 rapidly removes large amounts of sulfate and other contaminants from the concentrate 109, such as when used in the second stage treatment unit 125. It should be noted that FBR does not reduce the level of sulfate below its solubility level in water because the remaining sulfate is left on the water (121) returned to the first stage treatment 110. For example, the FBR in the second stage treatment unit 125 can reduce the sulfate level in the concentrate 109 from, for example, about 10,000mg/l to about 4000 mg/l. In various embodiments, the FBR140 in the second stage treatment unit 125 may reduce the sulfate level in the concentrate 109 from, for example, a level of 5,000-. With respect to prior art processing of concentrate 89 (see fig. 6A below), FBR140 can remove sulfate more quickly (e.g., 5-10 times faster than several hours for prior art precipitation devices, which can be in minutes or tens of minutes) and, as with the prior art, achieve significantly higher throughput (e.g., 3-30 times greater) at the expense of not removing sulfate below its solubility level.

Fig. 6A and 6B are high level schematic diagrams of a prior art ZLD water treatment system 90.

The prior art system 90 includes a plurality of stages 91-93, each stage including a pretreatment unit 82 that removes sediment and heavy metals (as sludge or solid waste 97A) from the wastewater 80 and/or concentrate 89 received from a previous stage, then performs ultrafiltration in an RO (reverse osmosis) unit 85 that provides treated water 87, and removes all salts from the wastewater in the concentrate 89, which is treated in the next stage. It should be noted that in the prior art system 90, multiple stages 91-93 are required to reduce the volume of brine (concentrate 89) produced by each stage to achieve a small throughput, which must then be specially treated to achieve only solid residue.

For example, for 100m ³ Typically 60m in the first purification stage 91 ³ As treated 87, 40m remained ³ As the concentrate 89 of the first stage 91. The repeated stages 92, 93 remove additional treated water 87 (e.g., another 20m each) ³ And 10m ³ ) Leaving more and more concentrated concentrate 89 (e.g., 20m each) ³ And 10m ³ )。

For Zero Liquid Discharge (ZLD), the remaining concentrate 89 (e.g., the concentrate of stage 93) and possibly sludge 97A are subjected to special treatment 95, which is generally expensive in both equipment and energy used, and produces more treated water 87 and solid waste 97. Examples of prior art special treatments 95 include evaporation, freeze crystallization or other techniques, as well as chemical treatments discussed below, for example, the use of ettringite-producing aluminate gels.

However, prior art treatment of industrial wastewater, which may include large concentrations of waste (e.g., heavy metals and various salts), is particularly difficult, requires multiple treatment stages, causes damage by overloading the fragile RO membrane, rapidly disables it, and requires complex special treatments 95, such as distillation, freeze crystallization, or chemical treatments, to dispose of the remaining concentrate for ZLD. It should be noted that these prior art special treatment methods are often very expensive and sometimes increase the volume of the solid waste 97 during the process by adding chemicals (e.g., such as used in ion exchange technology).

One particular difficulty in treating industrial waste water is its high sulfate content. The prior art process reduces the level of sulfate below its solubility threshold (about 1,500-2,000ppm), which is below about 200-500ppm (depending on the particular regulations) to provide treated water 87. One particular problem is the high cost of chemicals (e.g., aluminum compounds) for binding sulfates below their solubility threshold.

The prior art system 90 typically has a high CAPEX (capital expenditure) and a high OPEX (operational expenditure). For example, process 500- ³ The typical cost of a/h system is between forty and fifty million dollars, with 60-70% of the CAPEX being used for special treatment 95 and the RO stage being 30-40%. In contrast, the cost of the system 100 of the present disclosure is expected to be only similar to the RO stage of the prior art system 90, e.g., about one-third of the cost of the prior art system 90. Additional savings include less power usage (estimated for the system 100 of the present disclosure)<1Kw/m ³ 2-3Kw/m of the feed and system 90 ³ Prior art cost comparison of the feed, mainly for special treatment 95, for 1m ³ Concentrates typically require 15-50Kw) and significantly lower cost of added chemicals. In addition, the prior art system 90 uses large amounts of chemicals to remove sulfate, e.g., large amounts of Ca and Al to form the compound ettringite (an aqueous calcium aluminum sulfate mineral) in the treatment system,the molecular formula is as follows: ca ₆ Al ₂ (SO ₄ ) ₃ (OH) ₁₂ ·26H ₂ O-requires CaO and Al (OH) ₃ To remove SO by conversion in complex chemical processes ₄ . It should be noted that Al (OH) is generally required in the prior art ₃ As amorphous gels which are expensive compounds.

In contrast, in the disclosed system 100, all SOs ₄ For example as CaSO ₄ Or the gypsum is removed. The stoichiometric balance is: for every 1 mole of SO removed ₄ A prior art ratio of 2mol Ca and 2/3mol Al is required for 1mol SO removed ₄ Is 1mol of Ca. Thus, the removed solids 129 also have a much smaller mass (possibly less than half) than the prior art solid waste 97, providing additional significant advantages.

In addition, ettringite is typically recovered in prior art system 90 to regenerate aluminum hydroxide gel using acid in an additional process, which further increases the CAPEX, OPEX and chemical waste produced by the prior art. Conversely, in certain embodiments, the removed solids 129 of the disclosed system 100 may primarily comprise gypsum (CaSO) of relatively high purity (e.g., greater than 95%, depending on the contaminants in the industrial wastewater 80) ₄ ). Gypsum sludge (128, e.g., having a water content of 30-50%, or 129, dry) can pass 500m ³ The/h system 100 is produced at about 5 tons of sludge per hour, yielding a total of about 1% of the process wastewater volume. Advantageously, the gypsum sludge 128 can be used as is in various industries (e.g., for cement, construction, or agriculture) without further treatment, and sold directly. Using the FBR140, the resulting coated particles 148 (see fig. 5B) may comprise gypsum-coated silica particles that may be effective in removing heavy metals from the first stage treatment unit 102, either directly or after activation, for example with ferric materials (e.g., ferric sulfate and/or chloride) and/or due to high levels of hydroxide.

Due to the high OPEX and required high maintenance of RO membranes, in practice, prior art industrial wastewater treatment facilities often become inoperable within the relatively short time of their establishment, especially in developing countries, due to high operating and maintenance costs.

Advantageously, the disclosed embodiments overcome the limitations of the prior art to provide an economical and efficient zero liquid discharge treatment of industrial wastewater. The disclosed embodiments manage and balance the levels of salts, particularly sulfates, throughout the treatment process and facility to achieve sustainable and economical treatment of heavily polluted industrial wastewater.

Specific contributing factors to the advantages provided by the disclosed system 100 include:

(i) in the first treatment stage 110, the RO membranes and modules are replaced by ultrafiltration and/or nanofiltration membranes and modules, which allow monovalent ions to enter the treated water 107. The disclosed system 100 monitors and controls the monovalent ion levels in the treated water 107 to ensure that they do not exceed a certain level. Reducing the purity level of the water 107 relative to the prior art treated water 87 maintains the acceptability of the water 107 and simplifies the processing of the concentrate 109 because the concentrate 109 eliminates the prior art need to precipitate monovalent ions in subsequent processing stages 92-94. Divalent ions (e.g., sulfate) remain in the concentrate 109. In particular, when treating hard industrial wastewater, the use of nanofiltration membranes is preferred over the use of RO membranes in terms of the expected lifetime of the membrane and maintenance costs.

(ii) The sulfate is removed from the concentrate 109 in the main process 125, which reduces the sulfate concentration, but not below the solubility threshold of the prior art. For example, the second treatment stage 120 may be configured to reduce the level of sulfate to 2,000-4,000 ppm. Advantageously, simpler sulphate removal methods may be used, for example using precipitation of calcium and/or being much cheaper than prior art methods (e.g. HDS-high density sludge treatment methods) which reduce the level of sulphate below its solubility threshold. The return water 121 may then be mixed in the first stage 110 with the received industrial wastewater 80, which typically has similar or higher levels of sulfate (e.g., 4,000-10,000ppm), so that the reduced sulfate level is feasibly maintained and does not accumulate in the system 100. Another advantage gained from the simpler sulfate removal process is that the disclosed system 100 and method 200 are less limited, or not limited at all, in the scale and throughput of the industrial wastewater 80.

(iii) The main process 125 can be modified relative to the prior art process 82 by using the FBR140, which can make the precipitation process faster (e.g., typically taking minutes instead of hours of the prior art method) and is sufficient to meet the relaxation requirements regarding sulfate level reduction. Sulfate removal and FBR140 may be used as alternatives, or both may be used for partial treatment 125.

(iv) Some of the process byproducts 127 from stage 120 may be used in the first stage processing unit 102 of stage 110 to further enhance pretreatment. For example, CaSO ₄ And/or used (coated) solid particulate material 148 from the FBR140 may be used as a coagulant in the first stage treatment unit 102.

The controller 130 provides the further advantage that the controller 130 can be configured to monitor and regulate the flow throughout the system 100 to maintain the levels of specific ions and compounds within specific ranges, such as sulfate, monovalent ions, silica, metal ions, calcium. In particular, controller 130 is configured to provide treated water 107 within specification, control the quality of return water 121 transferred from stage 120 into pretreatment 102 in stage 110, control the optional transfer of treated product 127 from stage 120 into pretreatment 102 in stage 110, and monitor the efficiency and maintenance of nanofiltration module 105.

FIG. 7 is a high-level flow diagram illustrating a wastewater treatment method 200 that produces Zero Liquid Discharge (ZLD) according to some embodiments of the invention. Method stages may be performed with respect to system 100 described above, which may optionally be configured to implement method 200. Method 200 may include the following stages regardless of their order.

Method 200 may include treating industrial wastewater treatment to produce ZLD (stage 210), removing heavy metals (and possibly other contaminants depending on the quality of the wastewater) by pretreating the provided industrial wastewater, removing suspended and/or colloidal solids (reducing TDS and/or TSS) and possibly divalent ions (e.g., sulfate) (stage 220), ultrafiltering the pretreated wastewater to remove suspended and colloidal solids (stage 225), nanofiltering the ultrafiltered wastewater to remove divalent ions (e.g., sulfate) and produce treated water (which may include monovalent ions and some divalent ions) and a concentrate (stage 230), treating the concentrate to remove divalent elements and trivalent elements and other compounds from the concentrate, and reducing the level of sulfate to a specific level above the solubility level of sulfate-to produce return water and sludge (stage 240), the return water is mixed with the provided industrial wastewater before or at the first treatment stage and/or with the pre-treated wastewater before ultrafiltration (stage 250), and the residual water in the sludge is removed to produce a removed solids with ZLD (stage 255). In certain embodiments, the method 200 may further include using the removed sludge for pre-treating the provided industrial wastewater and/or for treating the concentrate (stage 254)

In certain embodiments, the method 200 may further include controlling the level of the compound in the treated water to continuously repeat the steps of the method 200 (stage 260).

In certain embodiments, the method 200 may include the use of calcium and/or calcium compounds and/or sodium hydroxide (e.g., Ca, CaO, Ca (OH) ₂ 、CaCO ₃ Any of NaOH, etc.) to reduce sulfate levels (stage 246). For example, the method 200 may include: the prescribed sulfate level is maintained between 2,000 and 5,000ppm or between 2,500 and 4,000ppm and/or about half the sulfate level in the provided industrial wastewater based on the prescribed desired sulfate level reduction and system configuration (stage 248).

In certain embodiments, the method 200 may include treating the concentrate with a Fluidized Bed Reactor (FBR) (stage 242), and optionally pretreating the provided industrial wastewater with a used FBR substrate (stage 244). FBRs can be used to provide complete treatment of a concentrate or to provide partial treatment of a concentrate, with for example coagulation and/or flocculation treatments.

In certain embodiments, the method 200 may include monitoring the level of monovalent ions in the treated water (stage 270), and reducing the level thereof if necessary (stage 272).

It should be noted that the particular values may be modified and should be understood to include ± 10% of the respective value.

In the foregoing description, an embodiment is an example or implementation of the present invention. The various appearances of "one embodiment," "an embodiment," "certain embodiments," or "some embodiments" are not necessarily all referring to the same embodiments. While various features of the invention may be described in the context of a single embodiment, these features may also be provided separately or in any suitable combination. Conversely, although the invention may be described herein in the context of separate embodiments for clarity, the invention may also be implemented in a single embodiment. Certain embodiments of the invention may include features from different embodiments disclosed above, and certain embodiments may include elements from other embodiments disclosed above. In the context of particular embodiments, the disclosure of elements of the invention should not be taken to limit their use only in particular embodiments. Further, it is to be understood that the invention may be embodied or practiced in various ways, and that the invention may be practiced in certain embodiments other than those outlined in the description above.

The invention is not limited to those figures or to the corresponding description. For example, flow need not move through each illustrated box or state nor in exactly the same order as illustrated and described. Unless defined otherwise, the meanings of technical and scientific terms used herein are to be commonly understood by one of ordinary skill in the art to which this invention belongs. While the invention has been described with respect to a limited number of embodiments, these should not be construed as limitations on the scope of the invention, but rather as exemplifications of some of the preferred embodiments. Other possible variations, modifications, and applications are also within the scope of the invention. Accordingly, the scope of the present invention should not be limited by what has been described so far, but by the appended claims and their legal equivalents.

Claims

1. A method of wastewater treatment that produces zero liquid discharge, the method comprising:

pretreating the provided industrial wastewater to remove heavy metals and suspended and/or colloidal solids to provide pretreated wastewater,

subjecting the pretreated wastewater to ultrafiltration to remove suspended and colloidal solids,

subjecting the ultrafiltered wastewater to nanofiltration to produce treated water and a concentrate, wherein the treated water comprises monovalent ions,

treating the concentrate to remove divalent and trivalent elements and other compounds from the concentrate and reduce sulfate levels to specific levels above sulfate solubility levels to produce return water and sludge, the return water having sulfate levels above sulfate solubility levels,

mixing the return water with the provided industrial wastewater before or at the first treatment stage and/or with the pretreated wastewater before the ultrafiltration,

removing residual water from the sludge to produce removed solids having zero liquor drainage with no concentrate or brine drainage, an

Controlling the level of the compound in the treated water to continuously repeat the method.

2. The method of claim 1, wherein treating the concentrate comprises using calcium, calcium compounds, and/or sodium hydroxide to reduce sulfate levels.

3. The method of claim 2, further comprising treating the concentrate with a fluidized bed reactor.

4. The method of claim 3, further comprising pretreating the provided industrial wastewater with a used fluidized bed reactor substrate.

5. The method of claim 1 wherein the specified level of sulfate is 2,000-5,000 ppm.

6. The method of claim 1, wherein the specified level of sulfate is half of the level of sulfate in the provided industrial wastewater.

7. The method of claim 1, further comprising monitoring the level of monovalent ions in the treated water.

8. The method of claim 1, further comprising reducing the level of said monovalent ions.

9. A system for wastewater treatment producing zero liquid discharge, the system comprising:

a first processing stage comprising:

a first stage treatment unit configured to remove heavy metals and suspended and/or colloidal solids from the provided industrial wastewater to provide a pretreated wastewater, an

A filtration unit comprising:

at least one ultrafiltration unit configured to remove suspended and colloidal solids from the pretreated wastewater, an

At least one nanofiltration unit configured to nanofilter the ultrafiltration wastewater to produce treated water and a concentrate, wherein the treated water comprises monovalent ions;

a second processing stage comprising:

a second stage treatment unit configured to remove divalent and trivalent elements and other compounds from the concentrate and reduce the level of sulfate to a specific level above the solubility level of sulfate to produce return water and sludge, the return water having a sulfate level above the sulfate solubility level, and

a final device configured to remove residual water from the sludge to produce removed solids with zero liquid discharge, wherein no concentrate or brine is discharged from the system;

a controller configured to control the level of compounds in the treated water to maintain continuous operation of the system, an

A piping system configured to mix the return water with the provided industrial wastewater and/or the pretreated wastewater in the first treatment stage.

10. The system as claimed in claim 9, wherein the second stage treatment unit uses calcium, calcium compounds and/or sodium hydroxide to reduce the level of sulfate to the specified level of sulfate of between 2,000 and 5,000 ppm.

11. The system of claim 9, wherein the second stage treatment unit is configured to reduce sulfate levels to half of sulfate levels in the provided industrial wastewater.

12. The system of claim 9, wherein the second treatment stage comprises a fluidized bed reactor, and wherein the system is further configured to utilize used fluidized bed reactor substrate in the first stage treatment unit to pretreat the provided industrial wastewater.

13. The system of claim 9, wherein the controller is further configured to monitor a level of monovalent ions in the treated water.

14. The system of claim 13, wherein the system is further configured to reduce the level of monovalent ions.