US20120145634A1

US20120145634A1 - High Efficiency Water Purification System

Info

Publication number: US20120145634A1
Application number: US12/964,874
Authority: US
Inventors: Joseph Hooley; William E. Kovacs
Original assignee: Water Intellectual Properties Inc
Current assignee: Water Intellectual Properties Inc
Priority date: 2010-12-10
Filing date: 2010-12-10
Publication date: 2012-06-14
Also published as: KR20140115934A; AU2011338241A1; US8691095B2; US20120145636A1; EP2649013A4; WO2012078975A1; CN103459326A; CA2850565A1; EP2649013A1

Abstract

A high efficiency water purification system is provided incorporating a process to recover a portion of the concentrate wastewater associated with the reverse osmosis unit to reduce the overall volume of concentrate wastewater requiring discharge/disposal by reusing the purified concentrate of a concentrate recovery units as RO feed water. The initial municipal feedwater is pressurized and passed through an RO membrane, and separated into a permeate flow and a concentrate flow. After passing through the membrane, a portion of the higher pressure concentrate is then directed to an additional set of thin film composite membranes (concentrate recovery membranes). The concentrate is drawn from the primary RO unit upstream of a concentrate flow control valve where the pressure is typically 100-600 psig. The concentrate recovery membranes are arranged in an array such that the concentrate pressure is adequate to provide the force required to drive the concentrate through the recovery system membranes. The permeate produced by the concentrate recovery system is directed back to the feed of the primary RO unit; thereby, reducing the volume of raw feed water required for system operation. The instant abstract is neither intended to define the invention disclosed in this specification nor intended to limit the scope of the invention in any way.

Description

RELATED APPLICATIONS

None.

BACKGROUND OF THE INVENTION

1. Field of the Invention
The present invention relates generally to water purification systems for general industrial usage and, more particularly, to a reverse osmosis recovery systems that incorporate recoveries in excess of 85% or utilizing a secondary recovery on the concentrate.
2. Description of the Related Art
Virtually all large municipal water supply systems must treat their water in accordance with an extensive regime of global, federal and state agency regulations. Generally, water treatment occurs before the product reaches the consumer, and then again afterwards (when it is discharged). Water purification usually occurs close to the final delivery points to reduce pumping costs and the chances of the water becoming contaminated after treatment.
Traditional surface water treatment plants generally consists of three steps: clarification, filtration and disinfection. Clarification refers to the separation of particles (dirt, organic matter, etc.) from the water stream. Chemical addition (i.e. alum, ferric chloride) destabilizes the particle charges and prepares them for clarification either by settling or floating out of the water stream. Sand, anthracite or activated carbon filters refine the water stream, removing smaller particulate matter. While other methods of disinfection exist, the preferred method is via chlorine addition. Chlorine effectively kills bacteria and most viruses and maintains a residual to protect the water supply through the supply network.
Increasingly in recent years, water conservation has placed additional pressures on municipal water systems. The goals of water conservation efforts include: Sustainability; Energy Conservation; and Habitat Conservation. Sustainability is generally identified as limiting the withdrawal of fresh water from an ecosystem to a limit that does not exceed its natural replacement rate. Energy conservation is achieved through decreased need for water pumping, delivery, and wastewater treatment. In some regions of the world water purification and treatment consumes a significant amount of energy, (such as, for example, California, where over 15% of total electricity consumption is devoted to water management). Habitat conservation is achieved through minimizing human water use in order to help preserve fresh water habitats for local wildlife and migrating waterfowl.
While the goals of water conservation efforts at a macro level have justifiable economic benefits, in relation to a single municipal water system the result of water conservation efforts can often inevitably lead to increased per unit cost of production. The development and operation of fixed infrastructure over a small demand footprint can lead to, and has led to, significant increases in the cost of purified municipal water and the cost of wastewater sewer charges. While changes in such cost structures may not extremely effect individual residential users, industrial water users see significant effects to the operation of their facilities. Aside from just the cost of the commodity or services, which can double or triple in cost within a short period, limitations placed on an overall water balance within an aquifer can lead to limits on intake and discharge. While the residential user can merely forgo watering the lawn or washing the car, in such situations the industrial user can face production cuts, or limitations in industrial output. In such scenarios, the only way to increase output would be to increase efficiency of processing (or decrease of waste product).
Increased efficiency of water processing can result in a solution that may be effective to a specific process or process stream. Example include saltwater desalination, brine recovery in mine reclamation, or similar situations having specific product or process train requirements. However, such solutions tend to stay site specific and do not share a generally applicable benefit. Developing a general method for improving water purification efficience must taking into account that water can containing a variety of hardness compounds such as barium, calcium, magnesium, iron, silica, carbonate and bicarbonate, fluoride and sulfate. And, variations in hardness can be commonly found in surface water supplies such as lakes and rivers as well as underground water supplies such as water wells and aquifers and as aqueous industrial effluents and landfill leachates.
Such water is frequently purified by using water softeners in the form of “ion exchange resins”, chemical softeners using the cold lime or hot lime softening process, reverse osmosis and nanofiltration membranes and/or distillation. Most industrial users need purified water containing low to very low concentrations of hardness compounds and of soluble inorganic compounds in order to supply their cooling towers, low-pressure and high pressure boilers, heat exchangers and various process uses. The pharmaceutical and electronics industry users, as well as hospitals and laboratories, require high purity waters which are almost completely free from inorganic compounds. The water purification processes listed above involve transferring the soluble water impurities to a resin bed which must be regenerated and/or disposed of at high cost. Further, adding a large quantity of chemicals can generate a considerable volume of chemical waste in the case of lime softening. In the case of state-of-the-art RO and NF membrane processes, usage of reverse osmosis (RO) or nanofiltration (NF) membranes generates substantial volumes of concentrates which must be treated further or disposed of at a large cost. And, in the case of distillation, very high capital and/or operating costs exist.
Although membrane filtration processes such as reverse osmosis (RO) or nanofiltration (NF) have provided an effective and economically viable means for purifying water, these membrane processes in their current form are limited in the percentage of purified water produced, known as permeate or product recovery. Reverse Osmosis utilizes a thin film composite membrane to remove dissolved salts from a feed water source. Since most of the soluble compounds are separated and concentrated into a smaller volume, typically 25-50% (and sometimes as much as up to 75%) of the volume of the original water source becomes permeate. Water passes through the membrane, while most of the dissolved salts do not pass through the membrane. As such, the membrane concentrate volume is too large and costly to dispose of, except in seawater desalination where the concentrate stream (also known as the reject stream) is returned to sea and in some other applications where there are no regulatory limits on the quantity of the reject stream discharged or the concentration of inorganic compounds contained therein.
Additionally, the main reason why further recovery of purified water from RO or NF membranes is not possible is the tendency of scale to form on the surface of the membranes as the concentration of scale-forming compounds and sparingly soluble salts is increased beyond their saturation values. This deposition of scale frequently results in a loss of purified water production (also known as loss of permeate flux through the membrane) and the eventual need for costly replacement of the membranes.
Typically, Reverse Osmosis (RO) systems operate as a cross-flow filter were a portion of the feed water passes through the RO membrane (typically 75%) and a portion is discharged as a wastewater (25%). The feed water is pressurized (typically below the rating of standard pressure vessels, between 100-600 psig, depending on backpressure) (P-1) to provide the force required to drive the water through the RO membrane. The driving force required to produce a given volume of permeate is dependent upon the feed water salt concentration and water temperature. After passing through the membrane, permeate is typically at fairly low pressure 10-100 psig (P-3), while the concentrate remains at much higher pressure typically 100-600 psig (P-2). A control valve (V-1) is utilized to adjust the concentrate flow and also reduce the concentrate pressure suitable for discharge.
A disadvantage of the reverse osmosis process is the recovery is typically limited to 60-80% as calculated by Equation 1:
Percent Recovery=[(Feed water−Permeate)×100]/Feed water [Eq. 1]
As the cost of city water and wastewater disposal increases, minimizing the feed water and concentrate volume is of interest to many RO system operators. The use of chemical additives in the water supply such as acids to reduce the pH and inorganic or organic anti-scalant compounds is practiced in the water treatment and membrane industry in order to provide some improvement in the water recovery and prevent scale formation. However, such improvement is only of limited extent since no anti-scalant is effective for all the contaminants and therefore they do not provide economically viable options for treatment of the entire water stream.
A search of the prior art for a solution to the problem did not disclose any patents that read directly on the claims of the instant invention; however, the following references, considered related, were found.
As alluded to above, desalination processes in general provide an opportunity for process improvements that are not generally applicable to other areas. The energy required to desalinate seawater through RO membranes, in general, are nonanalogous to other applications in that they create a different economic balance for optimization that other types of process, such as boiler operation, food packaging, agricultural production, or other various and sundry application that may utilize municipal water sources. Examples of desalination process improvements are shown in U.S. Patent Application Publication No. 2007/0080113, filed in the name of Vuong, discloses what appears to be a standard, two pass reverse osmosis system for desalinating seawater into potable water. The permeate from the first RO membrane is fed as the feedstock for the second RO membrane since normal seawater has a high enough salt concentration that cannot be removed in a single pass. Specifically, the use of a charged nanofilter membrane is used to separate the scale forming, multi-valent ions from the single valent ions provides a buffering between stages to allow for operation of the second stage membrane at a lower pump pressure.
Further, U.S. Pat. No. 6,783,682, issued in the name of Awerbuch, discloses an improved desalination process to produce potable water in which an ion exchange membrane is used in conjunction with nanofiltration. Flash distillation is then used to remove salts, decrease the concentrate volume, and increase recovery of potable water.
Also, U.S. Pat. No. 6,508,936, issued in the name of Hassan, discloses a desalination process in which combining two or more substantially different water treatment processes in a unique manner to desalinate saline water, especially sea water, to produce a high yield of high quality fresh water, including potable water, at an energy consumption equivalent to or less than much less efficient prior art desalination processes. In this process a nanofiltration step is synergistically combined with at least one of sea water reverse osmosis, multistage flash distillation.
And finally, U.S. Pat. No. 6,187,200, issued in the name of Yamamura et al., discloses an apparatus and method for a multistage reverse osmosis separation which comprises reverse osmosis membrane module units arranged at multistage with a booster pump provided in the concentrate flow channel between reverse osmosis membrane module unit. By providing for interstage pumps, energy is shifted to lower stages by equalizing the pressures for each state. Again, the energy required to desalinate by any process makes the economics of adding the additional capital and energy in between stages provides an opportunity that is generally nonanalogous to other areas of water purification.
While desalination processes in general provide an opportunity for process improvements that are not generally applicable to other areas, the same is also the case for other solutions found that tend to stay site specific and do not share a generally applicable benefit. For example, U.S. Patent Application Publication No. 2010/0032375, filed in the name of Jagannathan et al., discloses a high-recovery integrated recycling process to treat water and waste water having high hardness, silica, and other contaminants to facilitate operation of a reverse osmosis (RO) membrane at very high overall recovery. The process utilizes chemical precipitation to remove hardness ions and other components such as silica, etc. While the RO membrane continuously operates in low or conservative recovery conditions, this is only under the conditions that the softening clarifier is controlled within a narrow operating range, effectively ‘changing’ the effective influent that the RO membrane sees. Precipitated chemicals are removed as solid sludge in hopes that the scale forming salts are reduced prior to filtration and reverse osmosis.
Also, U.S. Patent Application Publication No. 2006/0231491, filed in the name of Mukhopadhyay, discloses a high purity water produced by reverse osmosis that is extremely highly sight specific and uses a change in alkalinity, and the pH is raised to 8.5 or more to ionize solute species such as boron that are sparingly ionized when in neutral or near neutral pH aqueous solution. Calcium carbonate is converted to carbon dioxide in order to eliminate membrane fouling, and the ultrapure water resulting is suitable for industrial use. However, with a very high capital cost, lots of equipment, and the need for stringent system controls, such a system would appear to be a Rube Goldberg type of process having little or no commercial efficacy except in situations where an extremely high value exists for removed ions, i.e. gold mine recovery or the like.
Also still, U.S. Pat. No. 6,398,965 issued in the name of Arba et al., discloses a water treatment system and process for removing weakly ionized and/or organic materials from the water by intra-system pH adjustment. Weakly basic components in the water are converted to a more ionized state by chemical conversion. However, the need for a very narrow range of variability of feedstock that requires a two stage reverse osmosis purification prior to treatment narrows the range or number of scenarios where such an process would be applicable (such as, for example, pharmaceutical water production.
And finally, U.S. Pat. No. 5,501,798, issued in the name of Al-Samadi et al., discloses an improved method for extending the useful life of a reverse osmosis membrane having a high pressure side and a low pressure side, the membrane used for separating soluble and sparingly soluble inorganic materials from an aqueous solution, the process comprising introducing an aqueous solution containing the soluble and sparingly soluble inorganic materials to the high pressure side of a reverse osmosis membrane and pressurizing the aqueous solution on said high pressure side to produce liquid on the low pressure side substantially free of said inorganic materials. Solution containing concentrated inorganic materials is transformed from the high pressure side of the reverse osmosis membrane to a high pressure side of a microfiltration membrane, and soluble inorganic materials transferred to the high pressure side of the microfiltration membrane was precipitated to provide solution containing particles of the inorganic materials.
Other references were found that provide for increased RO recoveries through modifications to the membranes themselves. One such example is in U.S. Patent Application Publication No. 2005/0006295, filed in the name of Bharwada, in which the RO spacers of a spiral wound module are reduced in order create greater area and more turbulence within the same overall physical geometry. Another example is in U.S. Pat. No. 6,881,336, issued in the name of Johnson, which discloses an improved feed spacer for the spiral wound element. The feed spacer sheet is a net forming parallel filaments to form a plurality of parallelograms having an acute angle less than 70 degree. Again, a spacer of such a design in intended to increase Reynolds number and thereby optimize the action of the membrane itself.
Another such reference, U.S. Pat. No. 7,114,511, issued in the name of Lull et al., discloses a system improvement for achieving increased conversion through use of a flow controller to adjust the discharge based upon operating conditions. The use of actively controlling the waste stream narrows the variability that can result from changes in operational parameters across any RO membrane. While the use of active measurement to control an output does not appear to be entirely unique to the chemical processing industries, this reference appears to apply the concept to the discharge stream of a reverse osmosis process.
Of considerable relevance is U.S. Pat. No. 6,113,797, issued in the name of Al-Samadi, which discloses a two-stage high pressure high recovery process utilizing two reverse osmosis membrane systems intended to provide very high overall water recoveries from contaminated inorganic scale-containing water in an economical manner while preventing scale formation on the membrane and prolonging the useful life of the membrane. However, the benefits of increased recovery are not continuous. The use of an ion exchange softening resins to remove scaling ions need recovery, during which high periods of salty water are generated and discharged.
Consequently, a need has been felt for providing an apparatus and method of maintaining reverse osmosis recovery in excess of 70-80% on a continue basis and without the need for additional energy input (i.e. though additional pump-supplied or pressure) between various stages.

SUMMARY OF THE INVENTION

It is therefore an object of the present invention to provide an improved water purification systems for general industrial usage.
It is a feature of the present invention to allow for the processing of a convention municipal water feedstock with a reverse osmosis recovery systems that incorporate recoveries in excess of 80% by utilizing a secondary recovery on the concentrate.
Briefly described according to the present invention, a process to recover a portion of the concentrate wastewater associated with the reverse osmosis unit is provided that reduces the overall volume of concentrate wastewater requiring discharge/disposal by reusing the purified concentrate of a concentrate recovery units as RO feed water. The initial feed water inlet (anticipated as being from a municipal water source, industrial water source or tertiary water source) is pre-treated in an otherwise conventional manner as would be done for any RO operation (by filtering and otherwise removing materials known to be detrimental to RO membrane operation). The feed water inlet is then pressurized and passed through an RO membrane, and separated into a permeate flow and a concentrate flow. After passing through the membrane, the permeate is generally at a very lower pressure, while the concentrate remains at a much higher pressure. A portion of the higher pressure concentrate is then directed to an additional set of thin film composite membranes (concentrate recovery membranes). The concentrate is drawn from the primary RO unit upstream of a concentrate flow control valve where the pressure is typically 100-600 psig. The concentrate recovery membranes are arranged in an array such that the concentrate pressure is adequate to provide the force required to drive the concentrate through the recovery system membranes. The permeate produced by the concentrate recovery system is directed back to the feed of the primary RO unit; thereby, reducing the volume of raw feed water required for system operation. The concentrate flow rate is controlled by a second flow control valve and is discharged as a wastewater. The concentrate recovery system is operated at 30-60% recovery depending on the feed water characteristics. The recovery is limited by sparingly soluble salts which can foul the reverse osmosis membranes.
In accordance with a preferred embodiment, the concentrate recovery unit utilizes pressure that is available as part of the normal operating parameters of the primary RO unit. As such, additional energy is not required for the recovery process.
An advantage of the present invention is that such a concentrate recovery system can be retrofitted onto existing RO units, as well as incorporated on new RO installations.
While the preferred embodiment of the present invention ins disclosed in the context of high efficiency water purification systems in general industrial usage, those skilled in the art will appreciate that the principles of the present invention may be applied so as to provide alternate systems based on the principles described herein.

BRIEF DESCRIPTION OF THE DRAWINGS

The advantages and features of the present invention will become better understood with reference to the following more detailed description and claims taken in conjunction with the accompanying drawings, in which like elements are identified with like symbols, and in which:

FIG. 1 is process flow schematic of an exemplary concentrate recovery reverse osmosis system according to the preferred embodiment of the present invention;

FIG. 2 is a process flow schematic of an exemplary reverse osmosis unit 12 for use in conjunction with the preferred embodiment of the present invention;

FIG. 3 a is a process flow schematic of a concentrate recovery unit 14 for use in conjunction with the preferred embodiment of the present invention, and shown herein in a first alternate embodiment to that shown in FIG. 1 of the preferred invention;

FIG. 3 b is a detailed process flow diagram for the a first alternate embodiment of a concentrate recovery unit 14 for use in conjunction with the preferred embodiment shown in FIG. 1 of the preferred invention;

FIG. 4 is a piping and instrumentation diagram (P&ID) of a example utilizing the present invention and having a primary reverse osmosis with concentrate recovery;

FIG. 5 is a schematic representation of a typical thin film composite member 20 of a type currently available in the PRIOR ART and capable of being used in conjunction with the present invention;

FIG. 6A is a front elevational view of an exemplary configuration for a high efficiency water purification system reverse osmosis array incorporating the teachings, features and benefits of the preferred embodiment of the present invention;

FIG. 6B is a rear elevational view thereof;

FIG. 6C is a top plan view thereof;

FIG. 6D is a left side elevational view thereof; and

FIG. 6E is a right side elevational view thereof.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

Example systems, methods, processes, and so on are now described. In the following description, for purposes of explanation, numerous specific details are set forth in order to facilitate thoroughly understanding the methods, systems, processes, and so on. It may be evident, however, that the methods, systems and so on can be practiced without these specific details. In other instances, well-known structures and devices are shown in block diagram form in order to simplify description.
As used in this application, the term “semi-permeable membrane” or “polyamide membrane” refers to thin film composite membranes such as reverse osmosis (RO) or nanofiltration (NF) membranes used to purify water, the soluble inorganic ions such as sodium, potassium, calcium, magnesium, iron, chloride, fluoride, carbonate, bicarbonate, sulfate and silica are separated by the membrane while the water is allowed to permeate or pass through the membrane. These thin film composite membranes generally consist of three layers: a polyester support web; a microporous polysulfone inner layer; and an ultra thin polyamide barrier layer on the top surface. As used in this application, the invention does not rely exclusively on any specific type or brand of semi-permeable membrane, but rather broadly on the use of any such existing or newly developed reverse osmosis recovery systems that utilize a secondary recovery on the concentrate to achieve recoveries in excess of 80%. Membrane designs can be spirally-wound low pressure or “brackish water” RO membranes, spirally-wound “high pressure” or “seawater” RO membranes, or plate and frame or disc-type membranes. As should be obvious to a person having ordinary skill in the relevant art, with hindsight of the present teachings, to incorporate of newly developed membranes within such systems.
As used in this application, the term “hardness” of water indicates the presence of water soluble monovalent and multivalent ions in solution. Monovalent ion refers generally to ions having a valency of one and is used generally to refer to ions such as sodium, potassium, cesium, chloride, fluoride, nitrate and other monovalent cations of the periodic table. Multivalent ions refers generally to ions having a valency of two or more, and is used generally to refer to ions such as carbonate, phosphate, silicate, sulfate, aluminum, barium, calcium, magnesium, strontium, chromium, copper, lead, nickel, silver, tin, titanium, vanadium, zinc and other multivalent cations of the periodic table. The revoval of “hardness” form water is typically referred to as the separation of multivalent ions from the water, or the prevention of the passage of multivalent ions through a barrier, while allowing monovalent ions such as sodium, potassium, cesium, chloride, fluoride, nitrate and other monovalent ions to remain within the water or otherwise permeate through the barrier. Typically, the water solubility of these hardness ions, when combined with certain monovalent, divalent or multivalent anions such as fluoride, carbonate, hydroxide, phosphate and sulfate (i.e. calcium fluoride, calcium or magnesium carbonate, calcium or magnesium silicate, calcium sulfate) is rather low when compared to compounds of monovalent cations such as sodium chloride, sodium carbonate or sodium sulfate. These compounds of multivalent cations are therefore termed “sparingly soluble compounds” and such term will be used in the present invention.
The best mode for carrying out the invention is presented in terms of its preferred embodiment, herein depicted within the Figures.

1. DETAILED DESCRIPTION OF THE FIGURES

Referring to FIG. 1 is process flow diagram of an exemplary concentrate recovery reverse osmosis system, generally noted as 10, according to the preferred embodiment of the present invention. The system 10 includes a primary reverse osmosis unit 12 in fluid communication with at least one concentrate recovery unit 14.
While not a novel element of the present system, it is anticipated that any feed water inlet 16 could be of any municipal source, industrial source, or tertiary source that could be subject to pretreatment by any suitable means which will efficiently separate suspended solids and prevent premature fouling and “surface blinding” of the membranes downstream. As shown in conjunction with FIG. 2, an exemplary primary reverse osmosis unit 12 is used of any otherwise conventional type for use in water purification that utilizes a thin film composite membrane 20 to remove dissolved salts from the pretreated feed water source 16. For purposes of providing enablement of the preferred embodiment of the present invention sufficient to teach a person having ordinary skill in the relevant art how to practice the features and functions of the present invention, it is anticipated that a thin film composite membrane 20 similar to that provided by The Dow Chemical Company (“DOW®”) under the current brand name FILMTEC™ may be utilized as generally shown in FIG. 5, it will become equally aware to the person having ordinary skill in the relevant art that the use of reverse osmosis membrane sheet having such qualities and specifications would be a design choice capable of modification or replacement based upon equivalent functionality of alternate sources or suppliers, unique industrial performance requirements or conditions, newly available devices or technologies, or the like. Given the inclusion of broad functional equivalents, it is intended that water passes through the membrane 20, while most of the dissolved salts do not pass through the membrane. In an exemplary embodiment, the Reverse Osmosis (RO) systems 12 operate as a cross-flow filter were a portion of the feed water passes through the RO membrane 20, typically 75%, and a portion is discharged as a wastewater, typically 25%. It would be obvious to a person having ordinary skill in the relevant art, in hindsight light of the present teachings, to utilize any functionally equivalent system as a replacement therefore, with such a replacement being considered equivalent to the present innovation. The concentrate 22 contains the soluble salts that can not pass through the membrane 20. The permeate 24 passes through the membrane 20 and is relatively pure water.
The feed water 16 is pressurized to a level that is selected as a design criteria for overall operation of the systems 10 and membrane 20. While such a feedwater pressure P1 is typically between 100-600 psig, and preferably between 200-400 psig, the present invention is not dependant on any exact pressure range being used but merely utilizes a feedwater pressure P1 to provide the force required to drive the water through the RO membrane 20 with sufficient driving force to produce a given volume of permeate 24. It is anticipated that this pressure P1 is dependent, at least, upon the feed water salt concentration, water temperature, backpressure requirements, etc. However, at any pressure P1, after passing through the membrane 20 the permeate pressure P3 is typically fairly low, such as between approximately 20-40 psig, while the concentrate pressure P2 remains much higher, such as between approximately 100-600 psig, and preferably 200-300 psig, given this particular example. A control valve 26 is utilized to adjust the final concentrate flow 28 and also reduce the final concentrate pressure suitable for discharge.
The final concentrate flow 28 is discharged as a wastewater, but a final concentrate flow 28 is anticipated as being operated typically at 30-60% (and up to 80%) of the total concentrate 22, depending on the feed water characteristics. The recovery is limited by sparingly soluble salts which can foul the reverse osmosis membranes. The balance is diverted as recovered concentrate flow 30 and is directed as the inlet feedstock of the concentrate recovery unit 14, such as shown in conjunction with FIG. 3A in which a concentrate recovery unit is shown in which plurality of primary thin film recovery membranes 32, herein shown as three in parallel with each other, and together are in series with a reverse osmosis vessel 33. As shown in FIG. 3 a in a typical configuration, the recovered concentrate flow 30 is directed to an additional set of thin film composite membranes as concentrate recovery membranes 32. It is anticipated that a variable number of membranes 32 can be in fluid communication with the recovered concentrate flow 30 is a parallel fashion. To exemplify this, three such thin film recovery membranes 32 are shown in a parallel configuration as part of the concentrate recovery unit 14 of FIG. 3A. Similarly, as shown in FIG. 3B, an alternate, but equivalent configuration is shown in which a greater number of membranes 32 and reverse osmosis vessels 33 are utilized. As shown in each enablement, the permeate discharge from each recovery member 32 is collected in a common manifold and communicated to a reverse osmosis vessel 33 (with multiple reverse osmosis vessels 33 connected in parallel as shown in use as exemplified in FIG. 3B). Similarly, the concentrate discharge from each recovery member 32 is collected in a separate common manifold and communicated, with in common connection with the concentrate discharge of the reverse osmosis vessel 33, as a combined concentrate recovery permeate 34.
In any embodiment, the concentrate 30 is drawn from the primary RO unit upstream of the concentrate flow control valve 26 where the pressure is preferably between 100-600 psig, and typically between 200-300 psig. The concentrate recovery membranes 32 are arranged in an array such that the concentrate pressure P4 is adequate to provide the force required to drive the concentrate 30 through the recovery system membranes 32. The permeate 34 produced by the concentrate recovery system 14 is directed back to the feed of the primary RO unit 12; thereby, reducing the volume of raw feed water 16 required for system operation.
The concentrate recovery concentrate flow rate is controlled by a flow control valve 36 and is discharged as a wastewater 40. The concentrate recovery system is operated typically at 30-60%, and up to as much as 80% recovery depending on the feed water characteristics. The recovery is limited by sparingly soluble salts which can foul the reverse osmosis membranes. The percent recovery is established on a case by case basis depending on the feed water chemistry.

2. EXAMPLES OF OPERATION UTILIZING THE PRESENT INVENTION

In operation, the concentrate recovery unit utilizes pressure that is available as part of the normal operating parameters of the primary RO unit. No additional energy is required for the recovery process. The concentrate recovery system, as typically shown in FIG. 6A-6E, can be retrofitted onto existing RO units and incorporated on new RO installations. Further, as shown in conjunction with FIG. 4, a piping and instrumentation diagram (P&ID) of a example utilizing the present invention and having a primary reverse osmosis with concentrate recovery is shown in order to describe a nonlimiting example of a configuration that may be maintained and the performance that may be achieved from the teaching of the present invention.
The foregoing descriptions of specific embodiments of the present invention have been presented for purposes of illustration and description. They are not intended to be exhaustive or to limit the invention to the precise forms disclosed, and obviously many modifications and variations are possible in light of the above teaching. The embodiments were chosen and described in order to best explain the principles of the invention and its practical application, to thereby enable others skilled in the art to best utilize the invention and various embodiments with various modifications as are suited to the particular use contemplated. It is intended that the scope of the invention be defined by the Claims appended hereto and their equivalents. Therefore, the scope of the invention is to be limited only by the following claims.

Claims

1. A water purification systems comprising:

a feedwater source;

a primary reverse osmosis unit treating a first input and having a first permeate discharge and a first concentrate discharge;

at least one concentrate recovery unit in fluid communication with said first concentrate discharge in which at least a portion of said concentrate discharge is further separated into a second permeate discharge and a second concentrate recovery;

wherein both said second concentrate recovery and said feedwater source are in fluid communication with said first input; and

wherein the combination of said first permeate recovery and said second permeate recovery is capable of continuous recovery of at least 80% of said feedwater source.

2. The water purification system of claim 1, wherein said feedwater source is selected from the group consisting of: municipal water sources; industrial water sources; and tertiary water sources.

3. The water purification system of claim 2, wherein said primary reverse osmosis unit comprises at least one thin film recovery membrane.

4. The water purification system of claim 3, further comprising:

said concentrate recovery unit comprising a plurality of composite reverse osmosis membrane modules arranged in parallel, and

each said module having a permeate discharge in combination with each other and forming said second permeate discharge, and wherein each module further has a concentrate discharge in combination with each other and forming said second concentrate discharge;

wherein said first concentrate discharge is in driven in fluid communication with said concentrate recovery unit with the urging force of the concentrate pressure of said primary reverse osmosis unit and without the input of additional energy.

5. The water purification system of claim 3, wherein said concentrate recovery unit further comprises at least one additional reverse osmosis stage in series for separating the collected permeate form said plurality of composite reverse osmosis membrane modules arranged in parallel.

6. The water purification system of claim 5, wherein said additional reverse osmosis stage further comprises a plurality of additional reverse osmosis elements.

7. A water purification systems of claim 1, wherein said primary reverse osmosis unit is operated at a pressure in the range of 200-400 psig.

8. The water purification system of claim 7, wherein said concentrate recovery is operated at a pressure in the range of 200-300 psig.

9. The water purification system of claim 2, wherein said feedwater source is pre-treated by filtering and otherwise removing materials known to be detrimental to RO membrane operation.

10. The water purification system of claim 1, wherein said concentrate recovery system is adapted to be capable of retrofit onto existing RO installations.

11. A process to recover a portion of the concentrate wastewater associated with the reverse osmosis unit for reducing the overall volume of concentrate wastewater requiring discharge/disposal by reusing the purified concentrate of a concentrate recovery units as RO feed water, said process comprising:

a. obtaining an initial feed water inlet;

b. pressurizing said feedwater and passed said feedwater through a thin film composite reverse osmosis membrane to create a separate first permeate flow and a first concentrate flow;

c. directing said first concentrate flow to an additional set of thin film composite membranes (concentrate recovery membranes), wherein said concentrate recovery membranes are arranged in an array such that the concentrate pressure is adequate to provide the force required to drive the concentrate through the recovery system membranes; and

d. directing the permeate produced by the concentrate recovery system back to the feed of the primary RO unit;

thereby, reducing the volume of raw feed water required for system operation.

12. The process of claim 11, wherein said first concentrate is drawn from the primary RO unit upstream of a concentrate flow control valve at a pressure between 100-600 psig.

13. The process of claim 12, wherein a concentrate flow rate is controlled by a second flow control valve and is discharged as a wastewater.

14. The process of claim 13, wherein said concentrate recovery system is operated at between 30-60% recovery depending on the feed water characteristics as limited by sparingly soluble salts which can foul the reverse osmosis membranes.

15. The process of claim 14, wherein said concentrate recovery unit utilizes pressure that is available as part of the normal operating parameters of the primary RO unit such that additional energy is not required for the recovery process.

16. The process of claim 11, wherein said feedwater is selected from the group consisting of: a municipal water source; an industrial water source; and a tertiary water source.

17. The process of claim 16, wherein said feedwater is pre-treated by filtering and otherwise removing materials detrimental to RO membrane operation.

18. The process of claim 11, adapted to be retrofitted onto existing RO installations.