Abstract:
Laundry, industrial or food processing wastewater is purified to the degree that it can be reused. Water quality is ensured through the final process of reverse osmosis (“RO”) which removes dissolved contaminants such as mineral hardness, soils and residual detergents. The process combines a ceramic tubular cross-flow membrane filter to remove the suspended solids, oils and greases ahead of the RO. The RO process employs high temperature, low fouling membranes. This enables the RO process to operate sustainably, i.e. without fouling, plugging or membrane degradation.

Description:
[0001]    This application claims the benefit of copending U.S. Provisional Patent Application Ser. No. 62/267,662 filed Dec. 15, 2015, entitled: MEMBRANE FILTRATION PROCESS FOR REUSE OF INDUSTRIAL WASTEWATER which is incorporated by reference herein in its entirety. 
     
    
     FIELD OF THE INVENTION 
       [0002]    This invention is in the field of filtration processes for industrial and commercial wastewater streams. 
       BACKGROUND OF THE INVENTION 
       [0003]    U.S. Pat. No. 6,413,425 is incorporated herein by reference hereto in its entirety. U.S. Pat. No. 6,177,011 is incorporated herein by reference hereto in its entirety. European patent EP 1885 664 is incorporated herein by reference hereto in its entirety. U.S. Pat. No. 4,610,792 is incorporated herein by reference hereto in its entirety. 
         [0004]    U.S. Pat. No. 6,413,425 states: “A reverse osmosis composite membrane comprises a sponge layer, and a separation layer formed on a surface of the sponge layer, wherein at least one substance selected from the group consisting of an electrically neutral organic substance and an electrically neutral polymer is present in the separation layer or a surface of the separation layer is coated with at least one substance selected from the group consisting of an electrically neutral organic substance and an electrically neutral polymer, and wherein the specific surface area of the layer in which the at least one substance is present or the separation layer before the surface coating is in the range of 2 to 1,000. The reverse osmosis composite membrane has a high salt rejection, a high water permeability, and a high fouling tolerance, and permits practical desalination at a relatively low pressure.” 
         [0005]    U.S. Pat. No. 6,177,011 states: “reverse osmosis composite membrane that has a high salt rejection, a high water permeability, and a high fouling tolerance, and permits practical desalination at a relatively low pressure is provided by coating the surface of a reverse osmosis membrane of aromatic polyamide with polyvinyl alcohol (PVA), for example, and controlling the surface zeta potential of the separation layer within ±10 mV at pH 6. This reverse osmosis composite membrane is electrically neutral and controls the electrical adsorption of membrane-fouling substances having a charge group present in water. Therefore, a high separation property can be maintained without fouling the membrane even if water containing a surfactant or a transition metal component is supplied as raw water.” 
         [0006]    European patent EP 1 885 664 B1 recites “Method for producing a wear-resistant reaction bound ceramic filtering membrane, wherein a porous metallic or non-metallic support is provided with a suspension for the production of a green body, wherein the suspension is obtained from a dispersing agent and a disperse phase, and wherein the disperse phase can be obtained from at least one ceramic raw material of the group of metal nitrides and optionally at least one further ceramic raw material, characterized in that the green body produced in this manner is baked at a temperature of 700° C. to 1250° C. under atmospheric pressure in oxidizing atmosphere for obtaining a phase change of at least the ceramic raw material.” 
         [0007]    U.S. Pat. No. 4,610,792 states “Wastewater is treated with activated carbon, lime, and filter aid, and subjected to membrane filtration to provide water free from suspended solids and having a TOC levels less than about 200 mg/L and total solids less than about 2000 mg/L.” 
       SUMMARY OF THE INVENTION 
       [0008]    A water filter is disclosed and claimed. The water to be filtered is used in industrial applications, laundry applications, and food processing applications. 
         [0009]    The water filter includes: a coarse prefiltration or screen in fluidic communication with a feed tank; a ceramic microfilter unit/module, said ceramic microfilter unit/module includes an inlet, an outlet, a reject outlet, and an abrasion-resistant ceramic membrane filter; said feed tank includes a discharge to a first pump, said first pump is connected to a second pump, said second pump is connected to said inlet of ceramic microfilter unit/module, said first and second pumps extract water from said feed tank and force it through said ceramic microfilter unit/module; said reject outlet of said ceramic microfilter connected to said second pump; a concentrate reject valve in communication with said reject outlet of said microfilter; a first control loop for rejecting concentrate through said concentrate reject valve, said first control loop includes a flow control device for controlling said concentrate reject valve; a feed and neutralization tank, said feed and neutralization tank includes an inlet and an outlet; a filtrate pipe extending from said outlet of said ceramic microfilter unit/module to said inlet of said feed and neutralization tank; a pH control loop in fluidic communication with said feed and neutralization tank, said pH control loop includes a pH sensor and a pump for injecting acid into said feed and neutralization tank; a reverse osmosis filter, said reverse osmosis filter includes an inlet, and outlet and a reject port, said reverse osmosis filter includes a low foul, high temperature membrane; said outlet of said feed and neutralization tank includes a discharge to a third pump, said third pump is connected to a fourth pump, said fourth pump is connected to said inlet of said reverse osmosis filter; said reject port of said reverse osmosis filter interconnected to said inlet of said fourth pump; a reject valve is interconnected with said reject port and is controlled based on the total dissolved solids in the water emanating from the reject port; and, said outlet of said reverse osmosis filter is connected to a permeate pipe which routes water for disposal or reuse. 
         [0010]    A water filter is disclosed and claimed wherein a ceramic microfiltration (CMF) system and a reverse osmosis (RO) filtration system are used. The ceramic microfiltration, CMF, system includes: a source of water; a CMF feed pump for pumping the water from the source of water and through a pretreatment element and into a CMF recirculation loop; and, means for adjusting the pH of the water before the water enters the CMF recirculation loop. The CMF recirculation loop includes a CMF recirculation pump, a CMF module, a return conduit carrying CMF concentrate back to the CMF recirculation pump, and a CMF concentrate reject conduit interconnected with the CMF return conduit for disposal of the CMF concentrate reject. The CMF concentrate reject conduit includes a CMF concentrate reject valve for controlling the amount of the CMF concentrate reject flow discharged. A CMF concentrate reject flow meter measures CMF concentrate reject flow in the CMF concentrate reject. The CMF module includes a ceramic element and the ceramic element includes ceramic filter membranes. The CMF recirculation pump supplies water to and through the ceramic filter membranes of the ceramic element. The CMF module includes a CMF concentrate reject port for communication of CMF concentrate reject to the CMF return conduit. 
         [0011]    A CMF filtrate conduit is in communication with the CMF module. The CMF module includes a filtrate port for communication of CMF filtrate in the CMF filtrate conduit to a RO feed tank. A CMF filtrate flow meter in the CMF filtrate conduit measures CMF filtrate flow. Means for selecting a desired CMF concentration factor and means for computing an actual CMF concentration factor based on the CMF filtrate flow and the CMF concentrate reject flow are employed. And, means for controlling the CMF concentrate reject valve based on the concentration factor are used. 
         [0012]    The reverse osmosis, RO, system includes the RO feed tank which stores and receives CMF filtrate water from the ceramic filtration system and is interconnected with a RO feed pump for pumping the CMF filtrate water through a pretreatment element and into an RO recirculation loop. The RO recirculation loop includes a RO recirculation pump, a RO membrane filter housing, a RO return conduit carrying RO concentrate back to the RO recirculation pump, a control valve in the RO return conduit, and a RO concentrate reject conduit interconnected with the RO return conduit for disposal of the RO concentrate reject. The RO concentrate reject conduit includes a RO concentrate reject valve for controlling the amount of the RO concentrate reject flow discharged. A RO concentrate reject flow meter in the concentrate reject conduit measuring RO concentrate reject flow is used. The RO recirculation pump supplies water to and through the first stage of the RO filtration. The RO filter housing includes a high temperature, low fouling RO membrane. The RO filter housing includes a RO concentrate reject port for communication of RO concentrate reject to the RO return conduit. A RO filtrate conduit is in communication with the RO filter housing. The RO filter housing includes a RO filtrate port for communication of RO filtrate for reuse. A RO filtrate flow meter is in the RO filtrate conduit for measuring RO filtrate flow. Means for selecting a desired RO concentration factor and means for computing an actual RO concentration factor based on the RO filtrate flow and the RO concentrate reject flow are used. Means for controlling the RO concentrate reject valve based on the concentration factor and means for computing the differential pressure across the RO filter housing are used. And, means for controlling the control valve in the RO conduit varying the flow of RO concentrate through the RO return conduit are also employed to maintain constant differential pressure across the RO housing. 
         [0013]    A process for filtering laundry wastewater, industrial wastewater or food processing wastewater is disclosed and claimed using the ceramic microfiltration system in combination with a high temperature, low fouling reverse osmosis filtration system. 
         [0014]    It is an object of the invention to use an abrasion resistant ceramic microfilter in combination with a high temperature, anti-fouling membrane in a reverse osmosis filter to clean laundry waste streams and/or industrial waste streams and/or oily waste streams. 
         [0015]    It is an object of the invention to use RO for laundry water treatment. 
         [0016]    It is an object of the invention to use high temperature and low fouling RO membranes. 
         [0017]    It is a further object of the invention to use CMF to prefilter the water and thus use an entire process consisting of CMF and RO. 
     
    
     
       DESCRIPTION OF DRAWINGS 
         [0018]      FIG. 1  is a schematic of a first embodiment of the overall process illustrating the ceramic filtration portion and the reverse osmosis portion. 
           [0019]      FIG. 1A  is the schematic sectional view of the ceramic filtration portion of the first embodiment of the process. 
           [0020]      FIG. 2  is a schematic of a second embodiment of the overall process illustrating the ceramic filtration portion and the reverse osmosis portion. 
           [0021]      FIG. 2A  is a generalized schematic of the second embodiment of the ceramic microfiltration system. 
           [0022]      FIG. 2B  is another schematic of the second embodiment of the ceramic microfiltration system. 
           [0023]      FIG. 2C  is a schematic of the prefilter portion of the second embodiment of the ceramic microfiltration system. 
           [0024]      FIG. 2D  is a schematic of the modules of the ceramic microfiltration system of the second embodiment. 
           [0025]      FIG. 2E  is a generalized schematic of the reverse osmosis filtration system of the second embodiment. 
           [0026]      FIG. 2F  is another schematic of the reverse osmosis system of the second embodiment. 
           [0027]      FIG. 2G  is a schematic of the prefilter portion of the second embodiment of the reverse osmosis filtration system. 
           [0028]      FIG. 2H  is a schematic of the recirculation pump, the flow control valve and the reject concentrate flow meter in the recirculation loop. 
           [0029]      FIGS. 2I and 2J  are schematics of banks of reverse osmosis housings in the recirculation loop. 
           [0030]      FIG. 3  illustrates the pH control of the ceramic microfiltration and reverse osmosis systems. 
           [0031]      FIG. 3A  illustrates the reject valve control of the ceramic microfiltration and reverse osmosis systems. 
           [0032]      FIG. 3B  illustrates the tank level control of the ceramic microfiltration and reverse osmosis systems. 
           [0033]      FIG. 3C  illustrates the recirculation valve control of the reverse osmosis system. 
       
    
    
     DESCRIPTION OF THE INVENTION 
       [0034]      FIG. 1  shows a first embodiment of the overall filtration process, along with attendant tanks and pumps.  FIG. 1A  is an illustration of the ceramic filter. 
         [0035]    The process and apparatus include a membrane filtration process for reuse of industrial laundry wastewater as well as a membrane filtration process for reuse of other waste streams. 
         [0036]    Wastewater is pre-filtered or screened for large solids  1  and then collected in the Collection/Feed Tank  2 . From there it is pumped to the ceramic filter unit/module  3 . A recirculation pump pumps the water to the Ceramic Membrane Filter Unit/module  3 ; from there the rejected solids and major portion of the bulk liquid volume exit the ceramic membrane filters  34  and return via port  32  to the recirculation pump. The rejected solids are discharged from the loop via a concentrate modulating and control valve  4 ; the clean, filtered water aka “filtrate” is discharged to the next step in the process  5 . 
         [0037]    The ceramic filter unit/module is illustrated in  FIG. 1A  and includes a wastewater inlet  31 , a wastewater outlet  32 , a filtrate outlet  33 , a plurality of ceramic membrane filters  34  and a tube sheet and seal plate  35 . 
         [0038]    The filtrate water is collected in a Feed and Neutralization Tank  6  wherein acid is injected in order to neutralize the alkalinity of the wastewater using an acid metering pump  10  which is controlled by a pH sensor  11 . The neutralized water is pumped to the recirculation pump which sends the water to the second step of filtration which is the Reverse Osmosis (“RO”) filtration step  7 . The water with rejected solids exits the RO filters and returns to the recirculation pump. The rejected solids are discharged from this loop via a reject modulating and control valve  9 ; the filtered water also known as “permeate” is discharged and collected  8 . This permeate is the product water which is of high quality—free of contaminants—and can be reused in the industrial process. 
       Performance of the Filtration System 
       [0039]    The process is successful in the removal of pollutants as shown in the table below. The dissolved solids (called “TDS” for Total Dissolved Solids) are significantly removed, mainly through the function of the RO membranes. This works in conjunction with the CMF, which removes the oils, greases, and Total Suspended Solids (“TSS”). The overall result is that the purified product water is of high quality, and can be reused in the industrial process. 
         [0040]    The following is a table of results of the invention. The performance of the invention as indicated in the table of results is quite remarkable. Use of a two step, two stage filtration process, namely the ceramic microfiltration process and the reverse osmosis process with the low fouling results in reusable water for industrial processes, including, but not limited to, industrial wastes such as fracking wastewater and laundry wastes. The invention employs an abrasion resistant filtration step (process) which removes the oil and grease from the waste stream. The removal of the oil and grease from the waste stream enables effective operation of the low fouling membrane of the reverse osmosis filtration step (process). 
         [0000]                                                                                INDUSTRIAL UNIFORM WASTEWATER TREATMENT RESULTS            Parameter   RAW*   CMF*   % Removal   RO*   % Removal                    Copper   0.4801   0.291   39.39   0.014   97.08       Cadmium   0.005   ND   100.00   ND   100.00       Chromium   0.031   ND   100.00   ND   100.00       Lead   0.091   0.06   34.07   ND   100.00       Nickel   0.03   0.023   23.33   ND   100.00       Iron   0.72   0.253   64.86   0.03   95.83       Zinc   1.32   0.825   37.50   0.035   97.35       Sodium   405   378   6.67   20.87   94.85       Oil &amp; Grease   305   19   93.77   1.98   99.35       TSS   208   18.3   91.20   1.25   99.40       TDS   2,537   1599   36.97   63.1   97.51       Chloride   164   157   4.27   4.68   97.15       Sulfate   142   53   62.68   10.9   92.32       Total Alkalinity   840   480   42.66   45.5   94.58       Magnesium   2.46   1.14   53.66   ND   100.00       Total Hardness   113   27.7   75.49   3.25   97.12       Color (units)   8,240   85   98.97   6   99.93       Total Organic Carbon   520           15   97.12       Odor (threshold odor number)   16           ND   100.00                    
Note: Results are given in milligram per liter unless stated otherwise.
 
       RO Membrane—High Temperature Capability 
       [0041]    Another unique aspect to this process is in the selection of the RO membrane. The RO membrane is constructed of special materials, using special adhesives and materials of construction, which make the membrane suitable for high temperature water. To date, RO membranes have been widely constructed of thin film composite materials which can only tolerate temperatures of 113 degrees, Fahrenheit. Laundry wastewaters however typically have elevated temperature and temperatures normally range from 120 to 140 degrees. 
         [0042]    The membranes used in the process described in this invention are of a special, high temperature, design. They can tolerate temperatures of 170 degrees, F. This is a benefit to the industrial end user, since hot water can be reused resulting in significant savings of heat energy—savings of natural gas energy. 
       RO Membrane—Low Fouling Characteristics 
       [0043]    Yet another beneficial feature of the RO system is the use of special, low fouling membranes. The membrane materials, while still constructed of thin film composites, are enhanced with a low fouling surface. This is accomplished with the use of a material that minimizes the membrane surface charge. In doing so, the membrane is less likely to attract waste constituents that could stick to the surface due to electrostatic charge attraction. The long term effect of this feature is reduced fouling, and ease of membrane cleaning and restoration. 
         [0044]      FIGS. 2-2J  illustrate the second embodiment of the invention, 
         [0045]    The invention includes the use of a CMF system equipped with tubular, ceramic filter elements in crossflow configuration. Microfiltration removes to a high degree suspended and colloidal particles, emulsified oils and greases from wastewater, thus reducing parameters such as BOD, COD, TSS, and turbidity significantly. Ceramic filters are designed to withstand aggressive conditions, high temperatures and acids, alkaline and corrosive components, typical for many industrial wastewaters. Ceramic membranes can be cleaned aggressively if wastewater contaminants generate hard-to-remove accumulations. CMF systems are employed to either recycle wastewater or to comply with discharge requirements by local, state and federal agencies. 
         [0046]      FIG. 2  is a schematic of a second embodiment of the overall process illustrating the ceramic filtration process and the reverse osmosis process. Wastewater flows through prescreen or prefilter  1 A and continues to feed tank  2 A. The wastewater is then processed in ceramic microfiltration systems, CMF System # 1  denoted by reference numeral  3 A and CMF System # 2  denoted by reference numeral  3 B. CMF # 1  and CMF # 2  are in parallel and the effluent (filtrate) of both system flows to the feed/neutralization tank  6 A. The wastewater is then further processed by the reverse osmosis system (RO System). 
         [0047]    No specific position of any two way valve or any three-way valve is illustrated in connection with any drawing figure. 
         [0048]      FIG. 2A  is a generalized schematic  200 A of the second embodiment of one of the ceramic microfiltration systems. The Ceramic Crossflow Microfiltration System (CMF) system can be regarded as a separation device, separating a wastewater feed stream into a filtered water stream  208  and a heavy concentrate stream  207 . The CMF system consists of the following major components: CMF Feed System  202 , CMF Clean-in-Place (CIP) System  203 , CMF Recirculation Assembly  205 , Filtrate Discharge  208 , and Concentrate Discharge Header  207 . 
         [0049]      FIG. 2B  is another schematic  200  B of the second embodiment of one of the ceramic microfiltration systems, CMF System # 1 . CMF system # 2  is not disclosed herein as it is structurally and operationally the same as CMF System # 1  except capacities are different. The example given herein in regard to the CMF Systems # 1  and # 2  is just one of many possible arrangements of CMF Systems. In some applications there may only be one CFM System and the structure of that system may be substantially different than the one illustrated and described herein. 
         [0050]    CMF System # 2 , for example, has a different number of modules containing the containing the ceramic membranes. Feed water is admitted to the CMF feed tank  211  as indicated in  FIG. 2B  by arrow  295 . From there, the CMF feed pump  218  pumps the wastewater through a bag-filter, prefilter module  220  into the CMF recirculation loop. Water is moved to feed pump  218  through conduit  215 C. Valve  215 C isolates feed tank  211  from the pump  218  during cleaning of the system. Feed pump  218  is driven by a variable frequency drive (VFD). 
         [0051]      FIG. 2C  is a schematic  200 C of the prefilter portion of the second embodiment of the ceramic microfiltration system.  FIG. 2C  illustrates the feed pump discharge conduit  218 C entering the prefilter  220  and, in particular, entering the housings  220 A,  220 B and exiting therefrom in conduit  223 C toward the recirculation pump  250 . The pressure differential across the prefilter  220  is obtained from pressure transmitters  219 P and  222  and this information is displayed to the operator at the control panel in regard to the need to clean the system. 
         [0052]    The fluid is recirculated inside the recirculation loop by the CMF recirculation pump  250 . The feed pump  218  and the recirculation pump  250  are both driven by variable frequency drives which can be operated at different speeds. Recirculated feed fluid passes through the CMF modules  285 ,  286  where microfiltration takes place. The CMF modules  285 ,  286  hold elements and the elements have channels therein. The channels have ceramic layers/membranes on the surfaces of the channels. 
         [0053]    Pressurized fluid is allowed to pass in two directions: through the ceramic microfilter membrane channels into the concentrate discharge header  281 C for collection or other appropriate treatment and disposal method, and through the ceramic microfilter membranes into the filtrate discharge header  260 C for reuse in the process, discharge to sewer or for collection and further treatment by reverse osmosis. See  FIG. 2B . 
         [0054]    The CMF system continuously separates a water stream into a clean filtrate  260  and a heavy concentrate flow  262 . The concentrate (or reject) flow is only a fraction of the feed flow but contains all of the rejected feed components. The feed flow rate is the sum of the filtrate rate plus the rejected concentrate flow rate. Filtrate flow is measured by meter  260 F and the rejected concentrate rate is measured by meter  280 F. The meters  260 F,  280 F are illustrated in  FIG. 2B  and they transmit and totalize flow therebetween and send this information to the PLC at the control panel. The ratio between the feed flow rate and the concentrate flow rate is referred to as the Concentration Factor: 
         [0000]    
       
         
           
             
               Conc 
               . 
               Fact 
               . 
             
             = 
             
               
                 Flow 
                 Feed 
               
               
                 Flow 
                 
                   Conc 
                   . 
                 
               
             
           
         
       
     
         [0055]    The concentration factor is typically adjusted to 10 fold (10×) but can vary depending on the application. The concentration factor is selectable within limits and is input into the control system electronically at the control panel. Simply put, the reject concentrate flow rate is a fraction of feed flow rate and the feed flow rate is much larger than the concentrate flow rate. 
         [0056]    A 10× concentration factor stands for 90% water recovery (the filtrate), while 10% of the original feed flow is removed as the concentrate. The concentrate is 10 times as “heavy” as the feed flow, containing almost all of the suspended and colloidal particles, emulsified oils and greases. The loop concentration will influence filtrate permeability through the membrane and CMF system efficiency will decline for concentration factor adjustments beyond a critical ratio. The programmable logic controller (PLC) continuously computes the concentration factor from flow meters  380 F,  260 F. The real time concentration factor is displayed on a Human Machine Interface CMF system status screen which is part of the CFM control module  209  illustrated in  FIG. 2A . 
         [0057]    Every wastewater is unique in its quality, concentration and composition and thus exhibits an individual diffusion rate through the microfiltration membrane, the so called flux rate. The total membrane surface area of a CMF system depends on the quantity of installed ceramic elements. Each CMF ceramic element has a specific number of channels; the microfiltration membrane being located on the surface of these channels. In practical terms, the flux rate can be expressed as the filtrate production for each ceramic element, measurement units are in gallons per square foot per day (GFD). The PLC computes flux rate from the filtrate flowmeter and divides it by the installed membrane surface area. 
         [0058]    The effective pressure drop over the ceramic layers/membranes, the Transmembrane pressure (TMP), is determined from the pressure difference between the pressures inside the ceramic tubular elements and the back pressure the filtrate experiences on the filtrate side. The TMP is calculated as: 
         [0000]    
       
         
           
             TMP 
             = 
             
               
                 
                   
                     p 
                     
                       
                         CMF 
                          
                         _ 
                          
                         Module 
                       
                        
                       
                         _ 
                          
                         IN 
                       
                     
                   
                   + 
                   
                     p 
                     
                       
                         CMF 
                          
                         _ 
                          
                         Modul 
                          
                         e 
                       
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                         _ 
                          
                         OUT 
                       
                     
                   
                 
                 2 
               
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                 p 
                 FILT 
               
             
           
         
       
     
         [0000]    Each of the modules  285 ,  286  has an inlet pressure and an outlet pressure. See  FIG. 2B , inlet pressure transmitter  252 P for module CMF A and inlet pressure transmitter for module CMF B. Outlet/discharge pressure transmitter  256 P for CMF A and outlet/discharge pressure transmitter  259 P for CMF B are shown in  FIG. 2B . Pressure transmitter  256 P is the intermediate pressure between CMF A and CMF B. The rejected concentrate of module CMF A, reference numeral  285 , is fed to the inlet of the second module CMF B module, reference numeral  286  in conduit  250 M. Inlet pressure  252 P and outlet pressure  256 P of module CMF A is measured and processed by the control module. Inlet pressure  256 P of module CMF B is the output pressure of the first module, CMF A, and the outlet pressure  259 P of module CMF B. Inlet and outlet pressures of the modules are dependent on system design and cannot be varied. Filtrate pressures  285 P,  286 P (and therefore the TMP) can be adjusted by the operator, using the filtrate globe valves  285 M,  286 M to obtain the filtrate flow  260 . 
         [0059]      FIG. 2D  is a schematic  200 D of the CMF modules  285 ,  286 . Fluid enters module  285  and inlet pressure is sensed and transmitted by pressure transmitter  252 P. Filtrate output pressure is sensed and transmitted by pressure transmitter  285 P. Filtrate is removed from module  285  and passes through automatic shutoff valve  287 V and manual globe valve  285 M. Intermediate pressure of concentrate is sensed in conduit  250 M which extends from module  285  to the inlet of module  286 . The intermediate pressure of the concentrate in conduit  250 M is the same as the inlet pressure to module  286 . Filtrate output pressure is sensed and transmitted by transmitter  286 P. Filtrate is removed from module  286  and passes through automatic shutoff valve  289 V and manual globe valve  286 M. Globe valves  285 M,  286 M can be adjusted to produce the desired flow through CMF System # 1 . Output pressure of module  286  is sensed and transmitted by pressure transmitter  259 P where it is discharged to the recirculation loop  250 R and returned to recirculation pump  250 . A portion of the concentrate as a function of the concentrate factor is removed from the recirculation loop by conduit  281 C. Flow control valve  261 V resides in conduit  281 C and controls flow therethrough. Flow through control valve  261 V is controlled by the PLC. Control valve  261 V is a modulated pneumatically operated valve. The flow therethrough is 10% of the sum of the filtrate flow and the concentrate flow using a concentration factor of 10. 
         [0060]    Incompatible, “sticky” components in the wastewater can lead to a fouling layer build up on the membrane and increase the TMP. Generally speaking, the higher the TMP, the more build up that has accumulated on the membranes. The TMP is therefore an important indicator for system performance. Membrane separation is historically plagued by membrane fouling, a contaminant-layer build up on the membrane surface, suppressing filtrate flux. The CMF systems of the instant invention use a cross flow configuration and pH adjustment to prevent fouling from occurring. pH adjustment is made by the PLC. See  FIG. 3  which is a schematic of the pH control system. The CMF membranes are tubular and therefore oriented in-line with the flow direction. Crossflow microfiltration allows filtrate to be removed perpendicularly to the flow while particles larger than the membrane pore diameter are retained within the recirculation loop  250 R. Particulates cannot easily build up on the membrane surfaces since it is continuously swept away and recirculated at high velocities through the ceramic microfiltration elements. The retained fluid inside the recirculation loop  250  is referred to as the concentrate. The concentrate becomes more and more concentrated with particles until its concentration reaches a state of equilibrium due to concentrate removal in conduit  281 C. 
         [0061]    For wastewater, the water pH (water acidity or basicity) plays a critical role in the overall system performance. Wastewater components can become “sticky” to the ceramic membrane if pH is not correctly adjusted to an “optimum working” pH. This “optimum working” pH value is typically in the range of pH 7-10 but is application dependent. The CMF system operation adjusts wastewater feed pH to optimize the microfiltration process. The pH control schematic is illustrated in  FIG. 3 . 
         [0062]    The wastewater system illustrated has multiple CMF skids and multiple CMF modules. The system set forth herein is by way of example only; fewer or more modules and skids may be used, as needed for the specific flow volume requirements of each installation. 
         [0063]    The wastewater system illustrated has two CMF modules, A and B. CMF System # 1 , reference numeral  3 A, illustrated in  FIGS. 2 and 2B  has two CMF modules, CMF A and CMF B. CMF System # 2  has four modules. The structure of the systems is the same except for the number of modules employed in each. 
         [0064]    The CMF System # 1  has several major components, described in detail below. The CMF feed tank  211  is flat-bottomed and constructed of 304 stainless steel, 7 feet in diameter with a height of 10 feet and a total volume of approximately 2,800 gallons. The feed tank is split into two halves. One half contains wastewater that has been processed by a shaker screen and the other half contains water that has subsequently been treated through hydrocyclones and is ready to be fed to module CMF A. 
         [0065]    The CMF CIP (Clean In Place) tank  270  provides a small volume tank to mix chemicals required for the CIP process. The CMF tank is 35 gallons, 16-inches in diameter and 42 inches tall constructed of Type  304  stainless steel. 
         [0066]    The CMF feed pump  218  pumps wastewater that has been previously in the feed tank  211  through the bag filters and into the recirculation loop. The pump has a stainless steel impeller and case. It is rated for 125 gpm at 105′ TDH with a 5 hp, 3600 rpm motor and is controlled with a VFD (Variable Frequency Drive). A prefilter  220  comprising a set of two bag filters and housings  220 A,  220 B is located downstream of the CMF feed pump and removes coarse contaminants from the feed wastewater to help protect and reduce fouling the CMF membranes. The typical filtration size is 200-400 μm. The housing  220 ,  220 B are constructed of stainless steel. The equipment specified is by way of example only. 
         [0067]    The CMF modules  285 ,  286  are constructed of stainless steel which holds the CMF elements vertically. CMF System # 1  has two modules CMF A  285  and CMF B  286 , which contain a number of ceramic microfiltration elements as needed to fulfill the flow requirements of the specific installation. The ceramic microfilters have a porous ceramic membrane layer with a nominal pore size of 0.05 micron. CMF System # 2  (not shown) has  4  modules (not shown) each of which contains multiple elements, also containing ceramic membrane layers with a nominal pore size of 0.05 micron. 
         [0068]    A recirculation pump  250  provides the movement of the fluid within the CMF recirculation loop. The recirculation loop is comprised of the recirculation pump  250 , conduit  250 C, CMF modules  285 ,  286 , conduit  250 M, and conduit  250 R. The recirculation loop provides the required cross flow velocity to minimize fouling of the ceramic microfiltration elements. The recirculation pump  250  is a close-coupled, industrial centrifugal pump manufactured with an open, clog resistant impeller and driven with VFDs controlled by the control module. The recirculation pump of CMF System # 1  is sized for 2,400 gpm at 80′ TDH with a 75 hp, 1775 rpm motor. 
         [0069]    The recirculation loop is in communication with a Clean In Place tank  270  which supplies chemicals to be used for cleaning the CMF filter modules  285 ,  286 . An immersion heater  268  applies energy to the cleaning fluid in conduit  264 C with Clean-In-Place tank  270 . An immersion heater  268  is used to increase temperature of the water (and cleaning fluid) to increase the efficacy of cleaning and treatment of the microfiltration elements in modules  285 ,  286 . The heater has a 5-inch flange with a temperature switch and is rated at 24 kW. 
         [0070]    The CMF control panel is a 60-inch by 60-inch panel that houses a disconnect, transformer, motor starters, variable frequency drives, a PLC, input and output modules (both analog and digital), an Ethernet switch and router, and Hand-Off-Auto switches, pressure transducers, an air conditioner, and miscellaneous circuit breakers, fuses and relays. The front of the panel contains control switches, display lights which indicate the current operating conditions and a display indicating the operating parameters and conditions of the entire CMF System #  1 . 
         [0071]    Pressure sensing transmitters  219 P,  222 P,  252 P,  256 P,  259 P,  285 P, and  286 P measure and electronically communicate pressures of various locations of the CMF system with the input modules mounted in the control panel. The discharge pressure of the feed pump  219 P, the module CMF A inlet pressure  252 P, the intermediate pressure  256 P between modules, CMF A and CMF B, the outlet pressure  259 P, and the filtrate pressures  285 P,  286 P are monitored and processed by the PLC controller located in the control panel. From these pressure transmitters the transmembrane pressures are determined. Pressure transducer  211 T is also used to measure level in the CMF feed tank and this pressures is used to control the VFD feed pump. 
         [0072]    Flow meters monitor concentrate  280 F and filtrate  260 F discharge flow rates. Magnetic-inductive flowmeters  260 F,  280 F produce and a signal voltage directly proportional to the volumetric flow. The filtrate flow meter  260 F has a measuring range of 0.1 to 250 gpm and the concentrate flow meter  280 F has a measuring range of 0.1 to 26.4 gpm. The flow meters also provide a totalizer function (integrated flow) which is used to determine the total amount of CMF filtrate and CMF reject concentrate which enables the determination of the concentration factor. The flow meters  260 F,  280 F provide 4-20 mA output signals to the PLC. 
         [0073]    Several isolation ball valves with pneumatic actuators  212 V,  213 V,  214 V,  215 V,  216 V,  265 V,  266 V,  270 V,  287 V,  289 V,  273 V,  291 V, provide 2-way (open/close) control of flow in the CMF system. The valves have solenoid pilot valves which control air to the valve actuators. The valves have manual overrides located near the CMF control panel. The feed tank is isolated by valve  215 V enabling use of the CIP feature for cleaning. The CIP tank is further isolated from the CMF filtrate by valve  273 V. Still further, the waste tank, is isolated from the recirculation loop by valve  291 V, the heater  268  is isolated by valve  265 V from the recirculation loop  250 R and waste tank  267  is isolated from the recirculation loop by valve  266 V. 
         [0074]    A ball valve  261 V with a modulating actuator is provided in the CMF# 1  system for control of CMF concentrate flow  262  from the recirculation loop  250 R to the concentrate collection tank  263 . Valve  261 V modulates to control the flow of concentrate in conduit  281 C out of the RECIRCULATION LOOP  250 R and into the concentrate collection tank  263 . The reject concentrate flow is controlled as set forth in  FIG. 3A . Note that reference numerals used in  FIG. 3A  are for the control of the reject flow control valve used in the reverse osmosis system The schematic, however, is also applicable to the control of the reject valve of the CMF system. 
         [0075]    A pH probe  298  is connected to the recirculation loop to measure the full pH range and is made of CPVC and HDPE. It has a flat-surface electrode and is self-cleaning. It provides a signal to the PLC for continuous monitoring of the system pH during normal operation of the system and during the CIP process/mode. pH control is illustrated in  FIG. 3 . 
         [0076]    The CMF system of the instant invention is designed to be cleaned at regular time intervals. These intervals can be varied depending on the application. CMF systems must be cleaned regularly to prevent hard-to-remove residue accumulation. Also, a CIP procedure will become necessary if membrane flux rate has decreased significantly, attributable to CMF incompatible wastewater components. Generally, a flux rate decrease is due to formation of a membrane “fouling” layer. The flux rate of each module CMFA and CMF B is monitored continuously according to the aforementioned Transmembrane pressure (TMP) calculation. A clean in place procedure is instituted and chemicals supplied to the CIP tank are used in the CMF System # 1  and the valves  215 V,  260 V isolate the feed tank  211  and the CMF filtrate output  260 . 
         [0077]    The foulant layer accumulated on the ceramic microfiltration elements can be removed using CIP chemicals such acids, bleach, caustic materials and appropriate cleaning solutions. 
         [0078]    Ceramic membranes are employed in harsh environments and where difficult-to-remove residues are to be expected. These membranes can withstand strong chemicals as well as high temperatures. Cleaning solutions contain alkaline, acidic and/or corrosive substances and handling of these chemicals must be performed with caution. 
         [0079]    A series of CIP protocols enable successful membrane cleaning of many different contaminants. A standard CIP will target the removal of an organic foulant layer, using a caustic/bleach solution under elevated temperatures, followed by an acidic removal of mineral scaling. 
         [0080]    Reverse osmosis system described in connection with the second embodiment,  FIGS. 2-21 . 
         [0081]      FIG. 2E  is a generalized schematic  200 E of the reverse osmosis filtration system of the second embodiment illustrating the RO feed system, RO subsystems, the RO CIP system, the RO circulation system, the RO permeate discharge assembly, the RO reject discharge assembly and the RO control system. 
         [0082]      FIG. 2F  is another schematic  200 F of the reverse osmosis system of the second embodiment. The filtrate (permeate) output of CMF System # 1  and CMF System #  2  is combined as indicated in  FIG. 2  and is sent  310  to the feed and neutralization tank  311 . 
         [0083]    Feed water for the RO system is supplied from the RO feed tank  311 . Feed water is routed through the RO feed tank isolation valve  314 V via conduit  314 C into the RO feed pump  317  suction, and pumped through a 10 micron bag prefilter  320  before entering the RO recirculation loop. The recirculation loop includes conduit  346 C, recirculation pump  325  driven by a variable frequency drive, conduit  328 C interconnecting the recirculation pump  325  and the first stage of the reverse osmosis filter banks B 1 , B 2  and B 3 , the first stage concentrate reject conduit  330 C interconnected with the second stage of the reverse osmosis filter banks B 4 , B 5  and B 6 , second stage concentrate reject output conduit  331 C, reject output conduit  332 C leading to and communicating with reject output conduit  341 C, modulating control valve  342 V and recirculation return conduit  245 C, and check valve  296  with return conduit  345  in communication with conduit  346 C. 
         [0084]    The first stage includes banks B 1 , B 2  and B 3 . Each of banks B 1  and B 2  includes 3 housings, and each housing includes four reverse osmosis membranes. B 3  includes a bank of 2 housings, and each housing includes four reverse osmosis membranes each. The second stage includes banks B 4 , B 5  and B 6 . Bank  4  includes  3  housings, and each of the housings includes four reverse osmosis membranes. Each of banks B 5  and B 6  include 2 housings, and each housing includes four reverse osmosis membranes. 
         [0085]    Water is recirculated inside the loop and brought to operating pressure by the recirculation pump  325 . When a minimum net driving pressure is achieved, water is forced through the membrane in a direction perpendicular to the recirculating flow. This water, called permeate (filtrate), is collected inside a common header  335 C and recycled to the plant for reuse or disposal  339 . The second stage banks, B 4 , B 5  and B 6  discharge filtrate to a common outlet conduit  333 C. The first stage banks B 1 , B 2  and B 3  discharge filtrate to a common outlet header  338 C which communicates with outlet conduit  337 C. Outlet conduits  333 C and  337 C join and communicate with common header  335 C. Common header  335 C interconnects with three way valve  335 V which is an automatic solenoid operated valve. Clean In Place (CIP) tank  340  communicates with three way valve  335 V. Three way valve  335 V directs flow of permeate (filtrate) out  339  or permits cleaning of the RO system while isolating the process downstream of RO Out  339 . 
         [0086]    The remaining water inside the recirculation loop is referred to as reject and/or concentrate and/or reject concentrate. A fraction of the reject concentrate is discarded via conduit  347 C which interconnects with conduit  345 C downstream from the pneumatically modulated control valve  342 V. Reject concentrate in conduit  347 C flows to either the reject concentrate tank  350  or a waste tank  351  for further treatment. New feed water (make-up water) from the feed pump  317  replaces the permeated and purged volumes as recirculation is continuous. 
         [0087]    The RO system of  FIG. 2F  of the instant invention is used as a secondary filtration system after the prior ceramic microfiltration (CMF) system. The RO system of the invention is equipped with spiral wound polymeric reverse osmosis membranes. RO is a moderate to high pressure-driven process for separating dissolved solids from water by means of a semi-permeable membrane. RO membranes will reject dissolved solids, including monovalent salts (e.g. sodium chloride). The systems are equipped with spiral wound, polymeric (thin film composite) membranes in cross-flow configuration. This arrangement forces water through a controlled path over the membrane surface at a high flow rate (velocity), thereby enhancing permeate recovery and reducing membrane fouling. The permeate flows axially in a perforated central tube in the center of the RO membrane assembly and the concentrate flows axially in an annular volume surrounding the perforated central tube. The membrane is formed by concentric membranes each separated by a spacer. 
         [0088]    Concentration Factor 
         [0089]    The RO system of the instant invention separates feed flow into a clean permeate  339  and a heavy concentrate flow in conduit  348 C continuously. The concentrate (or reject) flow is only a fraction of the feed flow but contains all of the rejected feed components. The ratio between the feed flow rate and the concentrate flow rate is referred to as the concentration factor (CF): 
         [0000]    
       
         
           
             CF 
             = 
             
               
                 Flow 
                 Feed 
               
               
                 Flow 
                 
                   Conc 
                   . 
                 
               
             
           
         
       
     
         [0090]    The concentration factor is typically adjusted to 5 fold (5×) but can vary depending on the application. A 5× concentration factor stands for an 80% reduction in volume (i.e. 80% recovery of water). In this case the reject stream in conduit  348 C is nearly five times as concentrated as the feed stream, containing all of the solids rejected by the membrane. The feed stream or feed flow includes the permeate flow  336 F plus the reject concentrate flow  348 F. 
         [0091]    The loop concentration will influence permeate transport through the membrane and the RO system efficiency will decline for concentration factor adjustments beyond a critical ratio. The programmable logic controller (PLC) computes the concentration factor from flow meter readings  336 F,  348 F continuously. Flow meter  336 F measures and integrates the permeate flow through the common header (conduit)  335 C. Flow meter  348 F measures and integrates the reject concentrate flow in conduit  348 C. 
         [0092]    The real time concentration factor is displayed on the RO system status Human Machine Interface (HMI) screen at the control panel. The concentration factor is selectable and input electronically into the control system and the control panel. 
         [0093]    Flux Rate 
         [0094]    Every wastewater is unique in its quality, concentration and composition and thus exhibits an individual diffusion rate through the Reverse Osmosis membrane, the so called flux rate. The total membrane surface area of a RO system depends on the size and quantity of installed RO elements. Every RO element has a spiral wound sandwich layer structure. In practical terms, the flux rate can be expressed as the permeate production for each RO element, measurement units are in gallons per square foot per day (GFD). The PLC computes flux rate from the integrated permeate flowmeter  336 F over a period of time and then dividing integrated flow by the installed membrane surface area. 
         [0095]    Process flux rates can vary during the operation and will often slowly decline over time. The operator monitors and logs system data throughout the operation and decide when membrane cleaning becomes necessary. 
         [0096]    Transmembrane Pressure 
         [0097]    The effective pressure drop over the membrane, the Transmembrane Pressure (TMP), is determined from the pressure difference between the pressures inside the RO elements and the back pressure the permeate experiences on the permeate side. The TMP is calculated as: 
         [0000]    
       
         
           
             TMP 
             = 
             
               
                 
                   
                     p 
                     
                       RO_Module 
                        
                       _IN 
                     
                   
                   + 
                   
                     p 
                     
                       RO_Module 
                        
                       _OUT 
                     
                   
                 
                 2 
               
                
               
                 
                   p 
                   PERM 
                 
                 . 
               
             
           
         
       
     
         [0098]    The value of the input pressure  326 P to the banks B 1 -B 6  of reverse osmosis elements and the value of the outlet pressure  393 P of the banks B 1 -B 6  of reverse osmosis elements are added together and then divided by two, then the value of the outlet pressure of the permeate  381 P is subtracted thereform. The calculation is made by the PLC at the control panel. This values identifies when the banks B 1 -B 6  of elements should be cleaned. 
         [0099]    Permeate backpressure  381 P cannot be adjusted since it is a pure function of hydraulic pressure drop in the permeate piping. The RO vessel inlet pressure  326 P can be adjusted by tuning the output of the variable frequency drive (VFD) controller, installed on both the RO feed pump and recirculation pump. Permeate production can thus be increased or decreased by modulating the feed pump speed (RPM) or the recirculation pump speed (RPM). 
         [0100]    Membrane Fouling Prevention 
         [0101]    Membrane separation is historically plagued by membrane fouling, the formation of a contaminant layer (cake) on the membrane surface, which leads to a rapid decline of permeate flux. Foulants can originate from a variety of sources, some of which are inorganic (e.g. silica), organic (e.g. cationic polymers), colloidal (e.g. silt) or biological (e.g. microbes) in nature. Although concentration polarization is inherent to all membrane processes, the RO system utilizes pretreatment and cross-flow configuration to help mitigate the fouling phenomenon. 
         [0102]    The two major processes used for pretreatment are pre-filtration and scale control. The RO system illustrated in  FIG. 2F  is installed downstream of the CMF system illustrated in  FIG. 2B , which removes a high percentage of colloidal and particulate matter that would otherwise foul or cause mechanical damage to the membranes of the elements of the RO system. 
         [0103]    As permeate (filtrate), water that is relatively low in dissolved solids, passes through the membrane, the remaining reject becomes increasingly concentrated in those same substances. At certain degrees of concentration, the saturation limit of a sparingly soluble salt is exceeded and precipitation occurs. This leads to the formation of scale on the membrane surface, which can severely reduce permeate flow and possibly cause irreversible damage. The RO system may operate under conditions of supersaturation if the addition of antiscalants or chelants is part of the pretreatment process. Reducing the recovery (i.e. lowering the concentration factor) is a simple way to avoid supersaturation conditions. However, this may be undesirable due to the fact that less water is recycled to the plant  339  and more water is discarded as reject  350 . 
         [0104]    Scale control is also accomplished through pH adjustment. pH, a measure of the acidity or basicity of a solution, plays a role in RO system performance. The RO system of the instant invention doses the feed water with acid  312  to convert ions that favor scale formation into forms that tend to stay soluble, thus making them unavailable for precipitation reactions. See  FIG. 2F  where acid  312  is injected through an unnumbered conduit by an acid metering pump  312  as dictated by the PLC controller. 
         [0105]    The cross-flow configuration allows permeate to flow in a direction perpendicular to that of the bulk (feed) solution. Particles larger than the membrane pore diameter are retained within the recirculation loop. Without intending to be limited by theory, RO membranes actually have no detectable pores and separation is thought to occur through solution-diffusion mechanisms. Particulates cannot easily accumulate on the membrane surface since they are swept away and recirculated continuously at high velocities. The retained liquid inside the recirculation loop is referred to as reject. At startup, the recirculation loop concentration is equal to that of the feed stream; the recirculation loop gradually increases in concentration until a steady balance of material is achieved between the concentrations of the incoming feed and the outgoing permeate and reject streams. 
         [0106]    RO System Components 
         [0107]    Referring to  FIGS. 2E and 2F , the RO feed tank  311  is a flat-bottomed tank constructed of 304 stainless steel and is 7 feet in diameter with a height of 10 feet and a total volume of approximately 2,600 gallons. The RO Feed pump  317  is a centrifugal pump used to transfer water from the RO feed tank  311  to the RO System. The feed pump  317  is a horizontal close coupled pump constructed of 316 stainless steel with a Silicon Carbide/SV/Viton mechanical seal. It is sized for 150 gpm. The pump  317  is powered by a 10 hp, 3450 rpm motor, and feeds water via the conduit  318 C to the prefilter  320 . The prefilter  320  includes two bag filters within respective housings  320 A,  320 B and the two housings are located downstream of the RO Feed pump  317 . See  FIG. 2G  wherein the prefilter  320  is illustrated and the two bag filter housings  320 A,  320 B are shown. The prefilter  320  protects the RO membranes wherein the bag filters in housings  320 A,  320 B remove coarse contaminants from the feed water. Typical filtration size is 10 μm. The inlet pressure to the prefilter  320  is sensed and transmitted by pressure transmitter  319 P to the control panel and the outlet pressure is sensed and transmitted by pressure transmitter  321 P to the control panel. The two pressures are used in calculating the TMP (transmembrance pressure) across the prefilter. Water exits the prefilter in conduit  320 C. See  FIG. 2G  which is a schematic of the prefilter portion  340 . The equipment and specifications stated herein are by way of example only. 
         [0108]      FIG. 2H  is a schematic  200 H of the recirculation pump  325 , the control valve  342 V, and the reject concentrate flow meter  348 F and concentrate recirculation flow meter  345 M in the recirculation loop.  FIGS. 21 and 2J  are schematics of banks B 1 -B 6  of reverse osmosis housings  383 A-O in the recirculation loop. The system set forth herein by way of example only, is a two stage system. More or fewer stages may be used and more or fewer reverse osmosis membranes are used. 
         [0109]      FIGS. 2I and 2J  are schematics  200 I,  200 J of banks of reverse osmosis housings in the recirculation loop. The first stage illustrated in  FIG. 2I  includes banks B 1 -B 3 . The first stage has eight housings  383 A-H containing four membranes each. Bank B 1  includes housings  383 A,  383 B and  383 C. Water from recirculation pump  325  is discharged into conduit  328 C which communicates water to banks B 1 , B 2  and B 3  as illustrated in  FIGS. 2F and 2I . 
         [0110]    Referring to  FIG. 2I , bank B 1  includes reverse osmosis housings  383 A,  383 B and  383 C. Inlet ports  384 A, B, C of bank B 1  housings  383 A, B, C admit water into the reverse osmosis membranes. Filtrate is discharged from housings  383 A, B, C through filtrate outlet ports  386 A, B, C to filtrate conduit  338 C. 
         [0111]    Still referring to  FIG. 2I , bank B 2  includes reverse osmosis housings  383 D,  383 E and  383 F. Inlet ports  384 D, E, F of bank B 2  housings  383 D, E, F admit water into the reverse osmosis membranes. Filtrate is discharged from housings  383 D, E, F through filtrate outlet ports  386 D, E, F to filtrate conduit  338 C. 
         [0112]    Still referring to  FIG. 2I , bank B 3  includes reverse osmosis housings  383 G and  383 H. Inlet ports  384 G, H of bank B 3  housings  383 G, H admit water into the reverse osmosis membranes. Filtrate is discharged from housings  383 G, H through filtrate outlet ports  386 G, H to filtrate conduit  338 C. 
         [0113]      FIG. 21  further illustrates filtrate conduit  338 C joining filtrate outlet conduit  333 C as filtrate outlet conduit  335 C. Filtrate outlet conduit  335 C communicates with three-way valve  335 V. Three-way valve  335 V (three port valve) directs fluid into filtrate (permeate) outlet  339  for reuse or other disposal. Alternatively three-way valve is repositioned to enable the clean-in-place (CIP) system to function. No specific position of the three-way valve  335 V or any two way valve is illustrated in connection with the drawing figures. 
         [0114]    Still referring to  FIG. 2I , concentrate from bank B 1  is discharged from concentrate outlet port  385 A of housing  383 A to concentrate conduit  330 C. Concentrate outlet port  385 C of housing  383 C communicates with an unnumbered concentrate inlet port of housing  383 B. Concentrate outlet port  385 B of housing  383 B communicates with an unnumbered concentrate inlet port of housing  383 A. 
         [0115]    Still referring to  FIG. 2I , concentrate from bank B 2  is discharged from concentrate outlet port  385 D of housing  383 D to concentrate conduit  330 C. Concentrate outlet port  385 F of housing  383 F communicates with an unnumbered concentrate inlet port of housing  383 E. Concentrate outlet port  385 E of housing  383 E communicates with an unnumbered concentrate inlet port of housing  383 D. 
         [0116]    Still referring to  FIG. 2I , concentrate from bank B 3  is discharged from concentrate outlet port  385 G of housing  383 G to concentrate conduit  330 C. Concentrate outlet port  385 H of housing  383 H communicates with an unnumbered concentrate inlet port of housing  383 G. 
         [0117]    The second stage illustrated in  FIG. 2J  includes banks B 4 -B 6 . The second stage has seven housings  383 I-O containing four membranes each. Bank B 4  includes housings  383 I,  383 J and  383 K. Water from concentrate conduit  330 C communicates water to banks B 4 , B 5  and B 6  as illustrated in  FIGS. 2J and 2F . 
         [0118]    Referring to  FIG. 2J , concentrate conduit  330 C communicates concentrate to concentrate Inlet ports  385 I (bank B 4 ),  385 L (bank B 5 ) and  385 N (bank B 6 ). Filtrate from each respective filtrate outlet port  386 I, J, K of bank B 4  housings  383 I, J, K is communicated to conduit  333 C. Filtrate from each respective filtrate outlet port  386 L, M for bank B 5  housings  383 L, M is communicated to conduit  333 C. Filtrate from each respective filtrate outlet port  386 N, O for bank B 6  housings  383 N, O is communicated to conduit  333 C. 
         [0119]    Concentrate is communicated from an unnumbered port on housing  383 I to concentrate inlet port  385 J of housing  383 J. Concentrate is communicated from an unnumbered port on housing  383 J to concentrate inlet port  385 K of housing  383 K. 
         [0120]    Still referring to  FIG. 2J , filtrate flows from housings  383 I-O to concentrate conduit  332 C. Filtrate flows from filtrate outlet ports  384 I (bank B 4 ),  384 L (bank B 5 ), and  384 N (bank B 6 ) to conduit  332 C for return of concentrate to the recirculation loop. 
         [0121]    Conduit  332 C branches into conduit  343 C for measurement and evaluation of concentrate in the recirulation loop by pH meter  344 . Conduit  332 C also branches into conduit  341 C where concentrate enters and is controlled by modulating control valve  342 V. 
         [0122]      FIG. 3C  illustrates  300 C the recirculation valve control  342 V of the reverse osmosis system.  FIGS. 3C and 2F  illustrate pressure transmitter  326 P measuring and transmitting the value of the inlet pressure of the concentrate flow to the first stage of the reverse osmosis housings B 1 -B  3  to the PLC located in the control panel. As stated above, the concentrate admitted to banks B 1 -B 3  which is not expelled as filtrate from outlet filtrate ports  386 A-H is forwarded from the first stage of reverse osmosis housings B 1 -B 3  via conduit  330 C to the second stage of the reverse osmosis housings B 4 -B 6 . Pressure transmitter  398 P measures and transmits the intermediate pressure between the first stage (banks B 1 -B 3 ) of the housings and the second stage (banks B 4 -B 6 ) of the housings. Pressure transmitter  393 P measures and transmits the concentrate outlet pressure of the discharge of the banks B 4 -B 6 . Concentrate outlet pressure  393 P is the inlet pressure to the recirculation control valve  343 V. Pressure transmitter  382 P measures and transmits the second stage output pressure of the filtrate to the PLC in the control panel. 
         [0123]    The difference in pressure measured by the inlet pressure  326 P and the outlet pressure  393 P is compared by comparator  391 . The ΔP  392  which is compared to the setpoint ΔP by the comparator  393 . A setpoint error signal e(t) is generated and is operated on by controller  394  which outputs a signal to positioner  395  which positions recirculation valve  342 V in response to the error of the differential pressure across banks B 1 -B 6  of the reverse osmosis system. The position of the recirculation valve dictates the amount of flow through the recirculation valve which, in turn, adjusts the flow and the differential pressure across banks B 1 -B 6  of the reverse osmosis system. Flow through the recirculation valve  342 V is returned via conduit  345 C where flow  4  is rejected along conduit  347 C. Flow  5  is added to make-up flow  6  as illustrated. Recirculation flow  1  is controlled by variable frequency drive control as illustrated in  FIG. 3B . The recirculation pump  325  produces a family of pump curves based on pump speed and input head. The recirculation valve  342 V functions to vary the system resistance curve which controls the ΔP across banks B 1 -B 6 . 
         [0124]      FIG. 3B  illustrates  300  B the tank level control of the ceramic microfiltration and reverse osmosis systems. Desired flow out of the tank is the setpoint. An error signal e(t) is generated by comparing the desired setpoint and comparing it to the rate of change, the derivative, of the level of the tank times the area, A, ((dL(t) times A)/dt). Error as a function of time, e(t), is operated upon by a proportional plus integral plus derivative controller  376  (PID) which outputs a control signal to the VFD recirculation pump drive which, in turn, outputs a speed command, s(t) to the pump which determines the flow out in pump discharge conduit  328 C, fo (t). Flow into the tank, fi(t) is determined by process conditions. 
         [0125]    A pH probe is mounted in the recirculation loop and measures the full pH range and is made of CPVC and HDPE. It has a flat-surface electrode and is self-cleaning. It provides a signal to the PLC for continuous monitoring of the system pH during normal operation and during CIP (Clean-In-Place) operation. 
         [0126]      FIG. 3  is a schematic  300  of the pH control of both the ceramic microfiltration and reverse osmosis systems. The desired setpoint of the pH is compared to the sample measurement  344  of the discharge conduit  332 C of the banks of housings. The error signal based on pH is operated on by a 3 point proportional control  377  which can be expanded to more than a 3 point proportional control. The output of the proportional control  377  is operated upon by a metering pump  378  which determines the amount of acid to be injected into the tank  311 . 
         [0127]      FIG. 3A  is a schematic  300 A of the reject valve control of both the ceramic microfiltration and reverse osmosis systems. The setpoint is adjustable and is a function of the total flow. The total flow is determined by filtrate flow in conduit  335 C as sensed and transmitted by flow meter  336 F of the filtrate (permeate) plus the concentrate flow in conduit  345 C as sensed and transmitted by flow meter  345 F. The reject concentrate flow is determined by flow meter  348 F in conduit  348 C. The concentration factor may be set be the user and it is the concentrate factor which determines the setpoint. The concentration factor equals the reject concentrate flow/total flow. In the example of  FIG. 3A , a concentration factor of 0.2 has been used and the setpoint varies as the total flow changes based on system conditions. 
         [0128]    Referring to  FIG. 3A , the error signal e(t) is operated on by a proportional plus integral plus derivative controller  356  which outputs a valve position signal  356 S. The valve position signal  356 S positions the reject valve,  349 V and thus controls the reject flow  348 F in conduit  348 C. The reject flow signal is divided by the total flow and this calculation, made by the PLC, is fed back to the comparator  357 . 
         [0129]    The second stage has seven housings with four membranes each. The vessels are constructed of fiberglass and these housings are rated for 300 psi and 190° F. There are 60 elements in this RO system. These elements are thin film composite membranes packed in a spiral-wound configuration. Each element is 8 inches in diameter and 40 inches long. These particular membranes are suited for a high temperature application. The recirculation pump  325  is a vertical pump used to boost the pressure and recirculate the water in the recirculation loop. The pump is 316 stainless steel. This pump is sized to pump 200 gpm and is powered by a 50 hp, 3450 rpm motor. 
         [0130]    The RO Control Panel houses a disconnect, transformer, motor starters, variable frequency drives, remote input and output modules (both analog and digital), Hand-Off-Auto switches, pressure transducers, an air conditioner, and miscellaneous circuit breakers, fuses and relays. The front of the panel contains control switches, display lights and displays which indicate the current operating conditions. 
         [0131]    Pressure transmitters are used to monitor the feed pump discharge pressure  319 P, the recirculation loop pressures,  326 P,  381 P,  398 P,  382 P,  393 P, and permeate pressure  381 P,  382 P and from these, the transmembrane pressure is determined. Pressure transducer is also used to measure level in the feed and neutralization tank. 
         [0132]    Four magnetic-inductive flow meters are used. Recirculation flow  345 F in the recirculation loop is measured. Reject concentrate flow  348 F rate is measured as is the RO filtrate out flow  336 F rate. Flow is also measured  334 F coming from the second stage of the RO housings and leading to the combined first and second stage output which is the RO filtrate output. As the wastewater flows through the meter, a signal voltage is created which is directly proportional to the volumetric flow. The flow meters have varying ranges based on application. These can also provide a totalizer function. The meters provides a 4-20 mA output signal to the PLC indicative of the flow therethrough. 
         [0133]    There are several pneumatically actuated ball valves  315 V,  352 V,  399 V in the RO System which serve to isolate, among other things, the RO CIP tank, the waste tank, and the reject concentration tank. The air actuated valves provide 2-way (open/close) and 3-way control of flow in the RO System. The valves have solenoid pilot valves which control air to the valve actuators. The valves have manual overrides located near the RO control panel. 
         [0134]    A convertible PVDF ORP sensor  343 S is provided for online monitoring of the oxidation-reduction potential for the RO. The sensor measures ORP from −2000 to +2000 mV and is constructed with corrosion-resistant materials. Polymeric membranes can be damaged by oxidizers (bleach, permanganate, ozone, bromine, iodine) present in feed water especially at neutral or slightly acidic pH. The RO feed oxidizing-reducing potential (ORP) must be monitored frequently. The RO system features an inline ORP sensor and values are continuously displayed on the System Status screen. ORP can be measured by the maintenance person with a handheld ORP meter. The RO system must not be operated if ORP levels are not below prescribed levels. 
         [0135]    Conductivity probes are mounted in the system to monitor performance downstream of the RO feed pump  319 C with a cell constant of 5, in the recirculation loop  343 C with a cell constant of 10, and in the RO filtrate output  335 K with a constant of 1. The sensors use a cell constant of 1, 5 or 10 (depending on location) and can measure conductivity ranging from 0 to 5,000 or 200,000 μS/cm. They provide an analog signal to the PLC for continuous monitoring. 
         [0136]    Three 1.5-inch long thermocouples are located in the RO system to monitor feed  323 T, ambient, and loop  343 T temperatures. The thermocouple measures temperature by producing a voltage due to the heating or cooling of the two dissimilar metals (iron and constantan). This voltage is correlated to a temperature by the PLC. 
         [0137]    The RO system is cleaned in regular time intervals. These intervals can be varied depending on the application; some installations require periodic cleanings. RO systems must be cleaned regularly to prevent hard-to-remove residue accumulation. Also, a CIP will become necessary if membrane flux rate has decreased significantly, attributable to formation of a membrane “fouling” layer. This foulant layer can be removed using CIP chemicals. 
         [0138]    Cleaning solutions contain alkaline, acidic and/or corrosive substances and handling of these chemicals must be performed with caution. 
         [0139]    A series of CIP protocols enables successful membrane cleaning from many different contaminants. A standard CIP will target the removal of an organic foulant layer, using a caustic/bleach solution under elevated temperatures, followed by an acidic removal of mineral scaling. 
       REFERENCE NUMERALS 
       [0000]    
       
         B 1 , B 2 —bank of 3 housings, each housing with four reverse osmosis membranes each, part of first stage reverse osmosis filtering 
         B 3 —bank of 2 housings, each housing with four reverse osmosis membranes each, part of first stage reverse osmosis filtering 
         B 4 —bank of 3 housings, each housing with four reverse osmosis membranes each, part of second stage reverse osmosis filtering 
         B 5 , B 6 —bank of 2 housings, each housing with four reverse osmosis membranes each, part of second stage reverse osmosis filtering 
           1 ,  1 A—coarse prefiltration or screen 
           2 ,  2 A—feed tanks 
           3 ,  3 A,  3 B—ceramic microfiltration system 
           4 —concentrate reject valve 
           5 —filtrate pipe 
           6 ,  6 A—feed and neutralization tank 
           7 ,  7 A—reverse osmosis filtration system 
           8 —permeate pipe 
           9 —reject valve 
           10 —acid metering pump 
           11 —pH control sensor 
           31 —inlet, wastewater 
           32 —outlet, wastewater 
           33 —filtrate outlet 
           34 —an abrasion-resistant ceramic membrane filter 
           35 —tube sheet and seal plate 
           100 —schematic of a first embodiment of the overall process illustrating the ceramic filtration portion and the reverse osmosis portion 
           100 A—schematic sectional view of the ceramic filtration portion of the first embodiment of the process 
           200 —schematic of a second embodiment of the overall process illustrating the ceramic filtration portion and the reverse osmosis portion 
           200 A—generalized schematic of the second embodiment of the ceramic microfiltration system 
           200 B—schematic of the second embodiment of the ceramic microfiltration system 
           200 C—schematic of the prefilter portion of the second embodiment of the ceramic microfiltration system 
           200 C—schematic of the modules of the ceramic microfiltration system of the second embodiment 
           200 D—generalized schematic of the reverse osmosis filtration system of the second embodiment 
           200 E—schematic of the reverse osmosis system of the second embodiment 
           200 F—schematic of the prefilter portion of the second embodiment of the reverse osmosis filtration system 
           200 G—schematic of banks of reverse osmosis membranes in the recirculation loop 
           200 H—schematic of the recirculation pump, the control valve and the reject concentrate flow meter in the recirculation loop. 
           200 I, J—schematics of banks of reverse osmosis housings in the recirculation loop. 
           300 —schematic of the pH control of the ceramic microfiltration and reverse osmosis systems. 
           300 A—schematic of the reject valve control of the ceramic microfiltration and reverse osmosis systems 
           300 B—schematic of the tank level control of the ceramic microfiltration and reverse osmosis systems 
           300 C—schematic of the recirculation valve control of the reverse osmosis system. 
           202 —CFM feed system 
           203 —CFM CIP system 
           204 —CFM sub systems 
           205 —CFM recirculation assembly 
           207 —CFM concentrate header 
           208 —CFM filtrate header 
           209 —CFM control module 
           211 —CFM feed tank 
           211 T—level transmitter of feed tank  211   
           212 C—bleach supply conduit to feed tank 
           212 V—pneumatically operated isolation valve in bleach supply conduit to feed tank 
           213 C—base supply conduit to feed tank 
           213 V—pneumatically operated isolation valve in base supply conduit to feed tank 
           214 C—acid supply conduit to feed tank 
           214 V—pneumatically operated isolation valve in acid supply conduit to feed tank 
           215 C—conduit from feed tank to feed pump  218   
           215 V—pneumatically operated isolation valve in conduit  215 C from feed tank to feed pump  218   
           216 —flush water 
           216 V—pneumatically operated isolation valve in conduit  216 C 
           217 —check valve for flush water supply 
           218 —feed pump driven by a variable frequency drive 
           218 C—conduit from feed pump  218  to prefilter  220   
           219 P—discharge pressure of feed pump  218   
           220 —prefilter 
           220 A—prefilter bag housing 
           220 B—prefilter bag housing 
           221 T—prefilter discharge temperature 
           222 P—prefilter discharge pressure 
           223 C—conduit from prefilter to the recirculation pump  250   
           250 —recirculation pump driven by a variable frequency drive 
           250 C—conduit from recirculation pump  250  to ceramic microfiltration housing A  285   
           250 M—conduit from ceramic microfiltration A  285  concentrate discharge to ceramic microfiltration housing B  286   
           250 R—recirculation loop conduit from concentrate discharge to the recirculation pump 
           251 T—recirculation discharge temperature 
           252 P—recirculation discharge pressure 
           254 S—ceramic microfiltration A  285  sample 
           256 P—discharge pressure of ceramic microfiltration A  285  concentrate 
           257 S—ceramic microfiltration A  286  sample 
           259 P—discharge pressure of ceramic microfiltration A  286  concentrate 
           260 —CFM System # 1  filtrate 
           260 C—conduit carrying filtrate  260  from CMF A and CMF module B 
           260 F—flow measurement of CFM System # 1  filtrate 
           260 V—pneumatically operated isolation valve for CMF System filtrate 
           261 V—modulating pneumatically actuated control valve for controlling concentrate flow to concentrate collection tank 
           262 —CMF concentrate 
           263 —CMF concentrate collection tank 
           264 C—conduit interconnecting the reject concentrate conduit  281 C and the heater  268  and the Clean In Place (CIP) tank 
           265 V—pneumatically operated isolation valve in conduit  264 C 
           266 V—pneumatically operated isolation valve in conduit  264 C to waste tank  267   
           267 —waste tank 
           268 —heater for CIP solutions 
           270 —acid injection tank controlled by pH control system 
           270 A—CIP tank in conduit  270 C 
           270 C—conduit interconnecting conduit  215 C and cleaning solutions in CIP tank  270 A 
           270 V—pneumatically operated isolation valve in conduit interconnection between the CIP tank  270  and the conduit  215 C 
           271 —interconnection to CIP tank  270   
           272 C—conduit interconnecting CIP tank and filtrate conduit  260 C 
           273 V—pneumatically operated isolation valve in conduit  272 C 
           275 C—conduit interconnecting the acid injection system with the recirculation pump input conduit  223 C 
           280 —flow meter measuring CMF concentrate flow 
           281 —reject concentrate conduit 
           285 —CMF A 
           285 P—CMF A output filtrate pressure transmitter 
           286 —CMF B 
           286 P—outlet pressure of CMF B 
           287 C—output filtrate conduit of CMF A interconnected with combined filtrate output  260 C 
           287 V—pneumatically controlled isolation valve in conduit  287 C 
           289 C—outlet filtration conduit of CMF B interconnected with combined filtrate output  260 C 
           289 V—pneumatically operated isolation valve in conduit  289 C 
           290 —waste tank 
           291 C—conduit interconnecting a waste tank  290  and the recirculation loop 
           291 V—pneumatically operated waste tank isolation valve in conduit  291 C 
           296 —check valve 
           298 —pH sensor and transmitter 
           298 C—sampling conduit for the pH sensor 
           301 —RO feed system 
           302 —RO subsystems 
           303 —RO CIP system 
           304 —RO recirculation assembly 
           305 —RO permeate discharge assembly 
           306 —RO reject discharge assembly 
           307 —RO control system 
           310 —flow from the ceramic microfiltration system 
           311 —feed and neutralization tank 
           311 P—feed tank pressure/level measurement 
           312 —acid metering pump which admits acid to the feed and neutralization tank  311  as necessary for the control of pH 
           313 —CIP tank 
           314 C—conduit from feed and neutralization tank which supplies fluid to the feed pump  317  driven by a variable frequency drive 
           314 V—feed and neutralization pneumatically operated isolation valve 
           315 —CIP tank 
           315 V—pneumatically operated isolation valve for CIP tank 
           317 —feed pump driven by a variable frequency drive 
           318 C—conduit from the feed pump  317  to the prefilter  320   
           319 C—conductivity measurement measured before the prefilter  320   
           320 —prefilter with bag housing which filters the water/fluid prior to entering the reverse osmosis membranes 
           320 C—conduit from the prefilter  320  to the recirculation pump  325  which is driven by a variable frequency drive 
           321 P—pressure after the prefilter  320  in the conduit  320 C, this is the inlet pressure to recirculation pump  325   
           322 S—sampling station after the prefilter in the conduit 
           323 T—temperature measurement after the prefilter  320  in the conduit  320 C 
           325 —recirculation pump driven by a variable frequency drive 
           326 P—discharge pressure of recirculation pump  325 , this is the inlet pressure to the first stage of reverse osmosis filtering, the first stage comprises banks B 1 , B 2  and B 3   
           327 S—sample at discharge of recirculation pump  325   
           328 C—conduit from the recirculation pump  325  to the first stage of reverse osmosis filtering 
           329 C—branch conduit feeding liquid to be filtered to banks B 1 , B 2  and B 3  of housings having reverse osmosis filters therein 
           330 C—branch conduit feeding concentrate to be filtered to banks B 4 , B 5  and B 6  of housings having reverse osmosis filters therein 
           331 C—branch conduit for concentrate return to the recirculation loop via conduit  332 C, control valve  342 V, conduit  345 C, and check valve  346   
           332 C—conduit for return of concentrate to the recirculation loop 
           333 C—conduit for permeate (filtrate) flow from banks B 4 , B 5  and B 6  of housings 
           334 F—flow meter for measurement of flow in conduit  333 C from banks B 4 , B 5  and B 6  of housings 
           335 C—conduit for permeate from first and second stages of reverse osmosis filtering 
           335 V—three way valve controlling permeate flow to the process for reuse or permeating the reverse osmosis system to be cleaned in place 
           336 F—flow meter for measuring permeate flow in conduit  335 C 
           337 C—first stage flow conduit 
           338 C—first stage filtrate flow conduit 
           339 —RO output 
           340 —CIP tank 
           341 C—conduit for carrying concentrate to the modulating control valve  342 V for return 
           342 V—modulating pneumatic control valve for concentrate in the recirculation loop  341 C 
           343 —conduit to pH senor  344   
           343 S—ORP sensor 
           343 T—temperature of concentrate in recirculation loop 
           344 —pH sensor 
           345 C—recirculation conduit 
           345 F—flow meter measuring concentrate recirculation 
           347 C—concentrate reject from recirculation conduit  345 C 
           348 C—concentrate reject conduit to reject concentrate tank  350   
           348 F—flow meter measuring reject concentrate flow to the reject concentrate tank  350   
           349 V-modulating valve controlling flow in the concentrate reject conduit to reject concentrate tank  350   
           350 —reject concentrate tank 
           351 —waste tank 
           352 C—conduit for reject concentrate to waste tank  351   
           352 V—pneumatically operated isolation valve in conduit  352 C 
           353 C—conduit for reject concentrate to CIP tank  313   
           353 V—pneumatically operated isolation valve in conduit  353 C 
           356 —proportional plus integral controller (PID) 
           356 F—division of the reject flow  348 F by the total flow  356 F 
           356 S—valve position 
           357 —comparator 
           376 —proportional plus integral controller (PID) 
           376 C—comparator 
           377 —3 point proportional control 
           378 —metering pump 
           381 P—first stage permeate output pressure transmitter 
           382 P—second stage permeate output pressure transmitter 
           383 A-H housings, each housing includes four reverse osmosis membranes therein 
           384 A, B, C—inlet ports for bank B 1  housings  383 A, B, C 
           384 D, E, F—inlet ports for bank B 2  housings  383 D, E, F 
           384 G, H—inlet ports for bank B 3  housings  383 G, H 
           384 I, J, K—concentrate outlet ports for bank B 4  housings  383 I, J, K 
           384 L, M—concentrate outlet ports for bank B 2  housings  383 L, M 
           384 N, O—concentrate outlet ports for bank B 3  housings  383  N, O 
           385 A, B, C—concentrate outlet ports for bank B 1  housings  383 A, B, C 
           385 D, E, F—concentrate outlet ports for bank B 2  housings  383 D, E, F 
           385 G, H—concentrate outlet ports for bank B 3  housings  383 G, H 
           385 I, J, K—concentrate inlet ports for bank B 4  housings  383 I, J, K 
           385 L, M—concentrate inlet ports for bank B 5  housings  383 L, M 
           385 N, O—concentrate inlet ports for bank B 6  housings  383 N, O 
           386 A, B, C—filtrate outlet ports for bank B 1  housings  383 A, B, C communicating with conduit  338 C 
           386 D, E, F—filtrate outlet ports for bank B 2  housings  383 D, E, F communicating with conduit  338 C 
           386 G, H—filtrate outlet ports for bank B 3  housings  383 G, H communicating with conduit  338 C 
           386 I, J, K—filtrate outlet ports for bank B 4  housings  383 I, J, K communicating with conduit  333 C 
           386 L, M—filtrate outlet ports for bank B 5  housings  383 L, M communicating with conduit  333 C 
           386 N, O—filtrate outlet ports for bank B 6  housings  383 N, O communicating with conduit  333 C 
           385 M—manual globe valve 
           386 M—manual globe valve 
           398 P—intermediate pressure transmitted between first and second stages of the reverse osmosis system 
           391 —comparator 
           392 —delta P 
           392 S—delta P setpoint 
           393 —comparator 
           394 —controller 
           395 —positioner 
           399 V—isolation valve in conduit  348 C which carries the reject concentrate to the reject concentrate tank 
       
     
         [0350]    The invention has been set forth by way of example only. Various equipment specification set forth herein are by way of example only and those skilled will readily recognize that changes in the number of components used, changes in types of components used, and other changes may be made to examples provided herein without departing from the spirit and scope of the invention as set forth in the claims.