Patent Abstract:
A system comprising method and apparatus for separating biologically-digestible materials from an influent sewage stream. The system may comprise a primary clarification tank to capture sixty percent or more of the total solids from an influent stream; a sludge classifying press (SCP) to isolate and concentrate biologically digestible materials from sludge formed in the primary clarification tank, releasing valuable organics, such as are found in corn kernels, by fracturing the protective casings; a grit capture mechanism in a chamber within the primary clarification tank and isolated from the bulk of the sludge containing biologically-degradable materials; a grit trap to remove grit from the sludge prior to classifying the sludge with the SCP; apparatus for adding thickener to the sludge after classification and prior to digestion; and automation of one or more elements of the process for separating and digesting the biologically digestible materials in an influent stream.

Full Description:
TECHNICAL FIELD 
     The present invention relates to systems for processing sewage; more particularly, to such systems for handling biologically digestible materials in sewage; and most particularly to methods and apparatus for separating biologically-digestible materials from an influent sewage stream. 
     BACKGROUND OF THE INVENTION 
     The primary historical objective of waste water treatment operations has been to neutralize and otherwise render sewage effluence in compliance with regulatory limits based on environmental and health standards. An important and growing objective of modern waste water treatments is the generation of energy from biologically-digestible organic materials present in the waste water. To achieve this objective, during the treatment of waste water influent streams containing biologically-digestible materials, as part of selectively classifying and separating grits, solids, hair and fibers, particulates, and solvated materials, it is particularly desirable to separate the digestible materials in the influent stream from non-digestible materials such that digestion of the digestible materials can be optimized. For systems that produce sludge in processes downstream from primary clarification (i.e., secondary sludge), it is desirable to extract the remaining biologically-digestible materials present in that sludge. Optimization can include increasing and capturing the bio-gas producing materials; production of energy bearing bio-gasses such as methane, produced by the decomposition of the digestible materials; reducing the frequency with which digesters used to digest the digestible materials need to be taken off line and cleaned; automation of the process for separating the digestible materials in the influent stream for digestion to reduce operating costs; reducing energy consumption-related operating costs; reducing the particle size of organic materials to allow rapid biodegradation and to capture organics prior to conversion to carbon-dioxide and biomass; and reducing the capital costs to build a treatment facility to separate and digest biologically-digestible materials in an influent stream. 
     In the prior art, the separation of grit from waste water influent is a long standing problem. Grit adversely impacts equipment reliability and lifespan, and increases operating costs of downstream treatment processes. Consequently, grit separators traditionally are used to remove grit from the influent stream as early in the treatment sequence as possible, preferably prior to primary clarification, or in cases where no primary clarification exists, then prior to secondary treatment. In practice, these devices often perform poorly because they are designed for a specific flow range which often is based on peak flows based on projected increases in population or a specific maximum flow based on storm events or future expansion of flows from new industries, etc. The projected flow range frequently is not reached for a number of reasons, such as unanticipated changes in population; changes in economic conditions of a region causing industries to leave or never develop; increased inflow and infiltration (“I and I”) of water into the treatment system from deteriorating collection systems; and the increase in storm intensities. 
     In many treatment plants, in an attempt to provide flow equalization at the head of the plant, variable frequency drives have been added to control the pumps delivering influent to the treatment plants from wet wells used as buffers. The variable frequency drives enable operation of the pumps over a range of pump speeds rather than a single speed with the only control option being to turn them off and on. In practice, these variable frequency drives create large fluctuations in influent velocity that can hinder the performance of the highly velocity-sensitive hydrocyclone grit separators. Due to their poor performance, these velocity sensitive grit separators often fail and/or are left in disrepair, requiring grit to be removed from the influent stream as a component of the sludge formed during the primary-treatment process. Typically, the grit slowly fills the secondary treatment process tanks, contributing to reduced energy content of the primary sludge, increasing the frequency with which digesters and secondary process tanks must be cleaned, and causing wear and tear on the plant equipment. 
     Current typical waste water plants capture only thirty to thirty-five percent of the biologically-digestible materials during primary clarification. The remainder of the biologically-digestible materials are typically digested during secondary treatment in an activated sludge process that permits the greenhouse gas (CO 2 ) to escape into the atmosphere. 
     SUMMARY OF THE INVENTION 
     Briefly described, a system in accordance with the present application comprises a method and apparatus for separating biologically digestible materials from an influent sewage stream. 
     In one aspect of the present application, a primary clarification tank is used to capture sixty percent or more of the total solids from an influent stream. 
     In another aspect of the present application, a sludge classifying press (SCP) is used to isolate and concentrate biologically-digestible materials from sludge formed in a primary clarification tank, releasing valuable organics, such as are found in corn kernels, by fracturing the protective casings. 
     In another aspect of the present application, grit is captured in a chamber within the primary clarification tank and isolated from the bulk of the sludge-containing biologically-degradable materials. 
     In another aspect of the present application, a grit trap or hydrocyclone is used to remove grit from the sludge prior to classifying the sludge with the SCP. 
     In another aspect of the present application, the sludge is thickened after classification and prior to digestion. 
     In another aspect of the present application, one or more elements of the process for separating and digesting the biologically-digestible materials in an influent stream is automated. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
       The present invention will now be described, by way of example, with reference to the accompanying drawings, in which: 
         FIG. 1  is a schematic drawing of an embodiment of a water treatment plant in accordance with the present application; 
         FIG. 2  is a schematic drawing and elevational side view of an Influent Feed System (IFS) used in the embodiment shown in  FIG. 1 ; 
         FIG. 3  is a detailed plan view of one IFS shown in  FIG. 1 ; 
         FIG. 4  is a schematic drawing of a prior art primary treatment system suitable for use as a first stage in the present application to collect suspended and solvated BOD; 
         FIG. 5  is a schematic drawing and elevational end view of one embodiment of a clarification tank and IFS in fluid communication with apparatus to treat grit and sludge settled in the clarification tank and IFS in accordance with the present application; 
         FIG. 6  is a schematic elevational drawing of a grit separator in accordance with the present application; 
         FIG. 7  is a schematic drawing and plan view of an alternative embodiment of a clarification tank and IFS in fluid communication with apparatus to treat grit and sludge settled in the clarification tank and IFS in accordance with the present application; 
         FIG. 8  is a schematic drawing and plan view of another alternative embodiment of a clarification tank and IFS in fluid communication with apparatus to treat grit and sludge settled in the clarification tank and IFS in accordance with the present application; 
         FIG. 9  is a schematic drawing and plan view of another alternative embodiment of a clarification tank and IFS in fluid communication with apparatus to treat grit and sludge settled in the clarification tank and IFS in accordance with the present application; 
         FIG. 10  is an alternative embodiment of an IFS with separate discharge pipes for removing materials from the IFS troughs and grit box; 
         FIG. 11  is a schematic drawing and side elevational view of an IFS arranged to discharge grit and sludge in accordance with the present application; and 
         FIG. 12  is a schematic drawing and plan view of an adapative system for treatment of sludge and grit in accordance with the present application. 
     
    
    
     Corresponding reference characters indicate corresponding parts throughout the several views. The exemplifications set out herein illustrate currently preferred embodiments of the invention, and such exemplifications are not to be construed as limiting the scope of the invention in any manner. 
     DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     U.S. Pat. No. 7,972,505, PRIMARY EQUALIZATION SETTLING TANK, to Wright; U.S. Pat. No. 8,225,942 to Wright, SELF-CLEANING INFLUENT FEED SYSTEM FOR A WASTEWATER TREATMENT PLANT; U.S. Pat. No. 8,398,864 SCREENED DECANTER ASSEMBLY FOR A SETTLING TANK to Wright; co-pending U.S. patent application Ser. No. 14/142,197 METHOD AND APPARATUS FOR A VERTICAL LIFT DECANTER SYSTEM IN A WATER TREATMENT SYSTEM by Wright; co-pending U.S. patent application Ser. No. 14/142,099 FLOATABLES AND SCUM REMOVAL APPARATUS FOR A WASTE WATER TREATMENT SYSTEM by Wright, and co-pending U.S. patent application Ser. No. 14/325,421 IFS AND GRIT BOX FOR WATER CLARIFICATION SYSTEMS by Wright (the &#39;421 application), all of which are incorporated by reference in their entirety for all purposes, disclose systems and processes for primary clarification that remove substantially all grit, solids, and particulates larger than 50 microns during primary clarification. 
     Separation of Biologically Digestible Materials from the Influent Stream 
       FIG. 1  shows a block diagram of one exemplary embodiment of a clarification system  1  configured to separate biologically-digestible materials from an influent stream. In one embodiment, the influent enters the clarification system  1  via pipes  11  where it is stored in wet well  12 . A settling tank  30  is in fluid communication with eight IFS&#39;s,  100 - 107 . Pump  13  pumps influent from wet well  12  to IFS&#39;s  100 - 107  at a substantially constant flow rate via piping  14 ,  15  and  15 ′. In one embodiment, pump  13  operates under the control of a supervisory control and data acquisition system (SCADA)  900  in communication with pump  13  via communication channel  901 . In one embodiment, the SCADA  900  turns pump  13  in response to an indication of wet well  12  fluid level reaching an upper limit, the indication provided by sensor  18  in communication with SCADA  900  via communication channel  907 . In one embodiment, SCADA  900  turns pump  13  off in response to an indication of wet well  12  fluid level reaching a lower limit, the indication provided by sensor  19  in communication with SCADA  900  via communication channel  908 . In an alternative embodiment, SCADA  900  turns pump  13  off after a pre-determined period of time. In an alternate embodiment, SCADA  900  turns pump  13  off after a predetermined volume of fluid has been pumped as indicated by measuring the flow via signals provided by flow meter  25  in communication with SCADA  900  via communication channel  909 . Flow meters and sensors to measure fluid level are well known in the art. 
     As is well known in the art, pipes  14 ,  15  and  15 ′ are configured to deliver substantially the same flow rate of influent to each IFS  100 - 107 . Flow balancing valves and/or flow splitting may be used. The influent enters the IFS&#39;s  100 - 107  where grits, solids, and optionally solvated materials, are selectively classified and separated from the influent via settling and optionally flocculation. Materials settled in the IFS&#39;s  100 - 107  are removed via discharge pipes  570 - 577  as described in more detail with reference to  FIG. 5 . The influent traverses IFS&#39;s  100 - 107  to enter clarification settling tank  30 . As described in the &#39;505 and &#39;864 patents and &#39;197 application, solids remaining in the influent traversing to the clarification settling tank  30  are further classified and separated from the influent via settling. Upon completion of the separation of the solids from the influent, the influent is discharged from the settling tank  30  using screen box assemblies (SBX&#39;s)  50 - 54  as described in the &#39;197 application. 
     In the embodiment of  FIG. 1 , flocculents are optionally added to the influent stream by flocculent delivery systems  40 ,  41 . The use of flocculents, for the removal of solids and solvated materials in the treatment of waste water and designs to add flocculents to an influent waste water stream, is well known in the art. 
       FIG. 2  shows a side view of an exemplary IFS  100  with IFS troughs and grit box  500  and  FIG. 3  shows a top view of the IFS of  FIG. 2 , as further described and disclosed in the &#39;421 application. As described in more detail in the &#39;421 application, a mixing zone  504  is created within a grit box  500  at the location where deposition of the floc is desired. With reference to  FIG. 2  and  FIG. 3 , IFS  100  is configured with a grit box  500  and two IFS troughs  201 ,  202  having trough walls  207 ,  208 . IFS troughs  201 ,  202  are in fluid communication with the grit box  500 . Influent is delivered to IFS  100  via pipe  501  and is split into two streams which enter grit box  500  via pipes  502 ,  503 . The streams exit opposing pipes  502 ,  503  and collide under pressure to create turbulent mixing zone  504 . A deflector plate  505  is positioned above mixing zone  504  to confine the volume of the mixing zone and return the upward velocities of the streams existing pipes  502 ,  503  back into mixing zone  504 . Grit, dense solids, and flocs are deposited in grit box hopper  506 . 
     To limit disturbance of solids settling in the lower portion of IFS troughs  201 ,  202  in proximity to the grit box  500 , the length of pipes  502 ,  503  is arranged to position mixing zone  504  below the lowest portion of IFS troughs  201 ,  202  in proximity to and in fluid communication with grit box  500 . Mixing zone  504  and grit box hopper  506  are positioned below the lowest portion  150 ,  150 ′ of IFS troughs  201 ,  202  in proximity to and in fluid communication with grit box  500 . Solids with a lower settling rate than the designed influent rise velocity in the grit box hopper  506  move into IFS troughs  201 ,  202 . Additionally, prior to entering IFS troughs  201 , 202 , solids moving upward under the influence of the rising influent undergo a 90 degree change in direction, turning from vertical to horizontal thus losing inertia and lessening the fluid forces on the suspended grits, solids, and flocs. In one embodiment, as explained in more detail below, grits settle preferentially in grit box  500 . 
     Materials that settle in grit box  500  and clarification, tank  30  may be removed as part of periodic scouring of grit box  500  and clarification tank  30  or as part of the ongoing operation of clarification system  1  to selectively classify and separate grits, solids, particulates, and solvated materials from an influent stream. 
     Other methods may be used to separate and capture large quantities of biologically digestible material from an influent stream. By way of example and not limitation, with reference to  FIG. 4 , large quantities of solids, suspended materials, and solvated materials can be rapidly settled from an influent stream by a prior art system such as CLARI-FLOCCULATOR packaged sewage treatment  1100  for primary treatment manufactured by Waterneer, a company with offices in Lidkoping Sweden. In the Waterneer primary treatment system, inlet feed pump  1102  is in fluid communication with influent stream  1101  and mixing chamber  1103 . Flocculent source  1106  is in fluid communication with mixing chamber  1103 . Mixing chamber  1103  is in fluid communication with turbulence redirection apparatus  1104  which is in fluid communication with sedimentation chamber  1105 . Sedimentation chamber  1105  further comprises a sludge discharge pipe  1111 , a sensor  1108  in communication with programmable controller  1107 , and valve  1109  under control of and in communication with programmable controller  1107 . Valve  1109  is positioned in sludge discharge pipe to control fluid communication of materials from sedimentation chamber  1109  through sludge discharge pipe  1111 . 
     In the Waterneer primary treatment system, inlet feed pump  1102  pumps water from influent stream  1101  into a mixing chamber  1103  where it is mixed with flocculents added to the influent stream by flocculent source  1106 . The influent and flocculent mix is delivered to turbulence redirection apparatus  1104  to slow the velocity of the fluid after which it is delivered to sedimentation chamber  1105  where flocs, grits and other materials settle. Effluent  1110 , free of the settled materials, is evacuated from primary treatment system  1100 . Programmable controller  1106  opens and closes valve  1109  responsive to signals from sensor  1108  indicating that the thickness of the sludge settled in sedimentation chamber  1105  has exceeded a predetermined threshold. Sludge from sedimentation chamber  1105  is evacuated via discharge pipe  1111 . 
     Treatment of Materials Separated from the Influent Stream to Concentrate Biologically-Digestible Materials 
     With reference to  FIGS. 2 and 5 , grit box  500  of IFS  100  is in fluid communication with discharge pipe  570 . Fluid communication via discharge pipe  570  is controlled by valve  580 . Valve  580  may be a manually-operated valve. In an alternate embodiment, valve  580  is electronically controlled by a supervisory control and data acquisition SCADA system  900  which provides a signal via communication channel  919  to open and close valve  580 . SCADA systems and electronically controlled valves are well known in the art. 
     With reference to  FIG. 5  in one embodiment, IFS  100 , 104  discharge pipes  570 ,  574  and clarification tank  30  discharge pipe  70  are in fluid communication with sludge and grit intake pipe  20  which is in fluid communication with sludge pump  50 . Sludge pump  50  is in fluid communication with grit separator  51  via pipe  20   a . Grit separator  51  is in fluid communication with sludge classification press  52  via pipe  20   b.  Sludge classification press  52  is in fluid communication with optional sludge thickener  53  via pipe  20   c . Sludge thickener  53  is in fluid communication with pipe  20   d . Optionally, a flocculent source  55   a  is arranged to communicate flocculents to sludge prior to treatment by sludge classification press  52 . Optionally, a flocculent source  55   b  is arranged to communicate flocculents to the sludge discharged by sludge classification press  52 . In one embodiment, sludge pump  50  is in communication with and controlled by SCADA  900  via communication channel  926 . In one embodiment, classification press  52  is in communication with and controlled by SCADA  900  via communication channel  927 . In one embodiment, flocculent sources  55   a ,  55   b  are in communication with and controlled by SCADA  900  via communication channels  929   a ,  929   b . In one embodiment, sludge thickener  53  is in communication with and controlled by SCADA  900  via communication channel  928 . 
     In one embodiment, one or more optional flowmeters are incorporated in the system: flow meter  5701  to measure the flow in discharge pipe  570 ; flow meter  5741  to measure the flow in discharge pipe  574 ; flow meter  7001  to measure the flow in discharge pipe  70 ; flow meter  2001  to measure the flow in pipe  20   a;  flow meter  2003  to measure the flow in discharge pipe  20   b;  flow meter  2005  to measure the flow in pipe  20   c;  and flow meter  2007  to measure the flow in pipe  20   d.    
     In one embodiment, flow meter  5701  is in communication with SCADA  900  via communication channel  917 . In one embodiment, flow meter  5741  is in communication with SCADA  900  via communication channel  920 . In one embodiment flow meter  7001  is in communication with SCADA  900  via communication channel  923 . In one embodiment, flow meter  2001  is in communication with SCADA  900  via communication channel  936 . In one embodiment, flow meter  2003  is in communication with SCADA  900  via communication channel  938 . In one embodiment, flow meter  2005  is in communication with SCADA  900  via communication channel  940 . In one embodiment, flow meter  2007  is in communication with SCADA  900  via communication channel  942 . 
     In one embodiment, one or more optional sensors are incorporated in the system: sensor  5702  to measure the characteristics of materials in discharge pipe  570 ; sensor  5742  to measure the characteristics of materials in discharge pipe  574 ; sensor  7002  to measure the characteristics of materials in discharge pipe  70 ; sensor  2002  to measure the characteristics of materials in discharge pipe  20   a;  sensor  2004  to measure the characteristics of materials in discharge pipe  20   b;  sensor  2006  to measure the characteristics of materials in discharge pipe  20   c;  and, sensor  2008  to measure the characteristics of materials in discharge pipe  20   d . The optional sensors are in communication with SCADA  900 : sensor  5702  via communication channel  918 ; sensor  5742  via communication channel  921 ; sensor  7002  via communication channel  924 ; sensor  2002  via communication channel  937 ; sensor  2004  via communication channel  939 ; sensor  2006  via communication channel  941 ; and sensor  2008  via communication channel  943 . 
     Sensors  5702   5742 , 7002 ,  2004 ,  2006 , and  2008  may be a UVAS sensor, turbidity sensor, pH sensor, or any other type of sensor consistent with measuring the physical and/or chemical characteristics of sludge and grits undergoing treatment. 
     With reference to  FIG. 5 , sludge  1000  settled in grit box  500  of IFS  100  can be removed via discharge pipe  70 . With reference to the exemplary embodiment of  FIG. 2 , in one embodiment valve  580  is opened and fluid is pumped or gravity fed through pipes  410 ,  415  to scour the IFS troughs and grit box. In an alternative method for evacuating and scouring the IFS, valve  580  is opened and IFS troughs  201 ,  202  are scoured with liquid to evacuate solids from the entirety of the IFS. In one embodiment, as part of the ongoing operation of the clarification system  1  of  FIG. 1 , to selectively classify and separate grits, solids, particulates, and solvated materials from an influent stream, valve  580  is opened to remove the settled materials without concurrent scouring of the IFS. 
     With reference to  FIG. 5 , sludge  1000  settled in grit box  500  may have viscosity low enough to flow from the grit box under the influence of gravity. The solids content of the sludge is dependent on the type of solids, the depth of the tank, the methodology of extraction, and how long the sludge is resident in the tank prior to extraction. A representative range for the solids content of materials  1010  is from less than one-tenth of a percent to five percent or more. The head pressure from the influent in IFS  100  may be used to assist in moving sludge  1000  in grit box  500  through discharge pipe  570 . In one embodiment, sludge pump  50  is used to assist in the evacuation of materials  1000  settled in grit box  500 . In one embodiment, sludge pump  50  is electronically controlled by a supervisory control and data acquisition system SCADA  900  which provides a signal via communication channel  926  to start and stop pumping. 
     With reference to  FIG. 5 , sludge  1010  settled in clarification tank  30  can be removed via discharge pipe  70  in liquid communication with the clarification tank  30 . Fluid communication via discharge pipe  70  is controlled by valve  80 . Sludge  1010  settled in clarification tank  30  can be removed by scouring and cleaning with a fluid as described for example in the &#39;864 patent. In one embodiment, as part of the ongoing operation of clarification system  1  of  FIG. 1 , to selectively classify and separate grits, solids, particulates, and solvated materials from an influent stream, valve  80  is opened to remove the settled materials. 
     Sludge  1010 , settled in clarification tank  30  may have viscosity low enough to flow from clarification tank  30  under the influence of gravity. The solids content of the sludge is dependent on the type of solids, the depth of the tank, the methodology of extraction, and how long the sludge is resident in the tank prior to extraction. A representative range for the solids content of materials  1010  is from less than one-tenth of a percent to five percent or more. The head pressure from the influent in clarification tank  30  may be used to assist in moving sludge  1010  in the clarification tank  30  through discharge pipe  70 . In one embodiment, a sludge pump  50  is used to assist in the evacuation of sludge  1010  settled in clarification tank  30 . 
     Sludge from IFS  100 ,  104  and clarification tank  30  enters grit separator  51  which separates and removes coarse, dense solids, referred to herein as “grit” or “grits”, that are not biologically digestible from the sludge. Grit separator  51  may be a gravity separator as shown with reference to  FIG. 6  or a hydro-cyclone as is well known in the art. The removal of grits from the sludge removed from clarification tank  30  and IFS&#39;  100 - 107  rather than from the influent stream prior to primary clarification provides for improved operation of the grit separator and overall plant reliability. 
     With reference to  FIG. 6 , there is shown one embodiment of a grit separator  51  that is a gravity separator  1200  in accordance with the current invention. Gravity separator  1200  has an influent pipe  1201  in fluid communication with a gravity separation chamber  1202 . Gravity separation chamber  1202  is in fluid communication with grit discharge pipe  1203  and sludge discharge pipe  1204 . Valve  1205  is positioned on grit discharge pipe  1203  and controls fluid communication through pipe  1203 . Influent pipe  1201  is arranged to have dimensions perpendicular to the flow of influent sludge substantially larger than the dimensions perpendicular to the flow of influent sludge of pipes providing a source of sludge to be treated for removal of grit. Influent pipe  1201  is arranged to provide a downward direction to the flow of fluids and materials as they enter gravity separation chamber  1202  giving dense solids inertia downward to gently agitate settled solids and to re-suspend any low density organic materials. The bottom of gravity separation chamber  1202  is designed to slope down to grit discharge pipe  1203  to facilitate discharge of grit under the influence of gravity. 
     In operation, sludge enters gravity separator  1200  from a source such as clarification tank  30  of  FIG. 5  via pipe  20   a  as shown with respect to  FIG. 5 . The substantially larger dimensions of influent pipe  1201  relative to source pipe  20   a  in the direction perpendicular to the direction of sludge flow results in a rapid and substantial decrease in sludge flow velocity. The dimensions of gravity chamber  1202  are arranged to provide time for grit to settle in the gravity chamber prior to discharge of the sludge. Periodically valve  1205  is opened to remove accumulated grit from gravity separation chamber  1202 . Preferably, valve  1205  is a pinch valve to avoid fouling and failure associated with grit becoming lodged in a valve seat. 
     With reference to  FIG. 5 , sludge substantially free from grit exits the grit separator and is fluidly communicated to sludge classification press via pipe  20   b . The sludge classification press  52  may be a rotary screw press such as the Strainpress® Sludgecleaner SP manufactured by Huber Technology. In one embodiment, sludge classification press  52  removes all solids larger than 1.6 mm from the sludge. In alternate embodiments, the sludge classification press  52  removes solids with dimensions that range from 0.15 mm to 10 mm. In one embodiment the compression and sheering of the sludge by the sludge classification press  51  releases biologically-digestible material from items such as corn kernels while removing the indigestible or less rapidly digestible materials such as the outer layer of a corn kernel. 
     After treatment with sludge classification press  52 , the solids content of the sludge consists primarily of biologically-digestible materials that can be digested in a digester to produce energy-rich bio-gases such as methane. The removal of materials that are not biologically digestible increases the rate of digestion of the remaining materials, enabling greater throughput and processing of sludge by a digester. The removal of non-digestible materials reduces the frequency with which digesters need to be taken off line and cleaned. 
     In some applications, it may be desirable to increase the concentration of biologically-digestible material in the sludge after treatment by the sludge classification press  52  and prior to digestion to improve the efficiency of digestion, maintain a low hydraulic retention rate (HRT), and increase the volume of production of bio-gases, such as, by way of example and not limitation, methane. Optionally, a flocculent may be added to the sludge via flocculent source  55  after treatment of the sludge by sludge classification press  52 . The flocculent is added to the sludge to create flocs from dissolved and suspended biologically-digestible materials, thereby increasing the concentration of biologically-digestible materials to improve performance of the digesters that digest the resultant sludge. By way of example, in a municipal waste water treatment plant a representative range for the total solids content the sludge after treatment by sludge classification press  52  is between two and three percent, whereas a digester may operate more efficiently with a total solids content of five to seven percent, and some as much as ten percent or more, depending upon the type of digester. Current systems use total solids as a surrogate measure for the concentration of biologically-digestible organic material in sludge. Gas production comes from volatile solids (VS) which are approximately 70-80% percent of the total solids. In one embodiment of the system, the treated sludge from the sludge classification press is fluidly communicated to solids concentrator  53  via pipe  20   c . Devices to increase solids content of sludge are well known in the art. By way of example and not limitation, solids concentrator  53  may comprise a gravity deck thickener, rotary drum thickener, or a rotary screw press. Sludge thickener  53  increases the solids content of the sludge treated by sludge classification press  52 . 
     With reference to  FIG. 7 , in one embodiment IFS  100 - 107  discharge pipes  570 - 577  and clarification tank  30  discharge pipe  70  are in fluid communication with sludge and grit intake pipe  20  which is in fluid communication with sludge pump  50 . Sludge Pump  50  is in fluid communication with grit separator  51  via pipe  20   a . Grit separator  51  is in fluid communication with sludge classification press  52  via pipe  20   b . In one embodiment, sludge classification press  52  is in fluid communication with optional sludge thickener  53  via pipe  20   c . Optionally, a flocculent source  55  is arranged to communicate flocculents to sludge traversing pipe  20   c . Optional sludge thickener  53  is in fluid communication with digester  54  via pipe  20   d  and wet well  12  of  FIG. 1  via pipe  22 . In one embodiment, sludge pump  50  is in communication with and controlled by SCADA  900  via communication channel  926 . In one embodiment, sludge pump  52  is in communication with and controlled by SCADA  900  via communication channel  926 . In one embodiment, flocculent source  55  is in communication with and controlled by SCADA  900  via communication channel  929 . In one embodiment, sludge thickener  53  is in communication with and controlled by SCADA  55  via communication channel  928 . 
     In one embodiment, sludge classification press (SCP)  52  is in fluid communication with digester  54  via pipe  20   c.    
     In one embodiment, digester  54  is an anaerobic digester. Sensor  64  is arranged to measure aspects of the operation of digester  54 . Sensor  64  is in communication with SCADA  900  via communication channel  944 . Sensor  64  may be one or more of temperature sensors, carbon-dioxide sensors, oxygen sensor, pH sensor, methane sensor, or any other sensor suitable for measuring the physical condition and characteristics, and chemical properties of the materials undergoing digestion. 
     To optimize overall operations of the system and to detect indications of existing or imminent component or system failure, in one embodiment the characteristics of the sludge are measured by sensor  64  as the sludge is treated. Bacteria in an anaerobic digester thrive best when supplied with food at constant concentration and flow rate. If the rate of organics of solid being supplied to the digester  54  goes outside of the desired ranges as measured by one or more sensors  60 ,  61 ,  62 , SCADA  900  adjusts the throughput of the sludge classification press  52  as needed. If the organics/solids ratios are too low, as measured by one or more sensors  60 ,  61 ,  62 , SCADA  900  increases the dosage supplied by flocculent source  55 . If the organics/solids ratios are too high, as measured by one or more sensors  60 ,  61 ,  62 , SCADA  900  decreases or stops the dosage supplied by flocculent source  55 . In one embodiment, as single sampling well and set of sensors are used to minimize cost associated with sensors and simplify issues of cross-sensor calibration and correlation across multiple sensors deployed throughout the system. 
     Sampling pump  56  is in fluid communication with pipes  20   a - 20   d  via pipe  21 . Sampling pump  56  is preferably a positive displacement pump such as a diaphragm pump or progressive cavity pump in order to prevent fouling. Valves  7   a - 7   d  control fluid communication between pipes  20   a - 20   d  and pipe  21 . In one embodiment, valves  20   a - 20   d  are manually operated. In one embodiment, valves  20   a - 20   d  are controlled by and in communication with SCADA  900  via communication channels  935   a - 935   d . In one embodiment, sampling pump  56  is controlled by and in communication with SCADA via communication channel  931 . Sampling pump  56  is in fluid communication with sampling well  57  via pipe  21 . One or more sensors  60 , 61 , 62  are arranged in sampling well  57  to measure various characteristics of materials in sampling well  57 . The one or more sensors are controlled by and in communication with SCADA  900  via communication channels  932 ,  933 ,  934 . Sampling well  23  is in fluid communication with wet well  12  of  FIG. 1  via pipe  23 . 
     Sludge from IFS  100 - 107  and clarification tank  30  is treated in a substantially similar manner by sludge pump  50 , sludge classification press  52 , solids concentrator  53 , and flocculent source  55  as described hereinabove with respect to  FIG. 5 . Upon final treatment of the sludge by sludge classification press  52 , or optional sludge thickener  53 , as applicable, the sludge is fluidly communicated to digester  54 . 
     Sludge removed from IFS  100 - 107  and clarification tank  30  is sampled as it is discharged from sludge pump  50  via pipe  20   a . In one embodiment, SCADA  900  closes valves  7   b ,  7   c ,  7   d,  opens valve  7   a  and turns sampling pump  56  on to withdraw sludge via pipe  21 . Sludge is pumped via sampling pump  21  to sampling well  57  where one or more sludge characteristics are measured via one or more sensor  60 ,  61 ,  62 . Upon completion of the measurements, the sludge sample is discharged via discharge pipe  23 . In a similar manner, one or more characteristics of grit-free sludge are sampled as the sludge is discharged from grit separator  51  via pipe  20   b . In one embodiment, SCADA  900  closes valves  7   a ,  7   c ,  7   d , opens valve  7   b , and turns sampling pump  56  on to withdraw sludge via pipe  21 . Sludge is pumped via sampling pump  21  to sampling well  57  where sludge characteristics are measured via one or more sensors  60 , 61 , 62 . Upon completion of the measurements, the sludge sample is discharged via discharge pipe  23 . One or more characteristics of classified sludge are measured as the sludge is discharged from sludge classification press  52  via pipe  20   c . In one embodiment, SCADA  900  closes valves  7   a , 7   b , 7   d , opens valve  7   c  and turns sampling pump  56  on to withdraw sludge via pipe  21 . Sludge is pumped via sampling pump  21  to sampling well  57  where one or more sludge characteristics are measured via one or more sensors  60 , 61 , 62 . Upon completion of the measurements, the sludge sample is discharged via discharge pipe  23 . One or more characteristics of concentrated sludge are measured as the sludge is discharged from solids concentrator  53  via pipe  20   d . In one embodiment SCADA  900  closes valves  7   a , 7   b , 7   c , opens valve  7   d , and turns sampling pump  56  on to withdraw sludge via pipe  21 . Sludge is pumped via sampling pump  21  to sampling well  57  where one or more sludge characteristics are measured via one or more sensor  60 ,  61 ,  62 . Upon completion of the measurements, the sludge sample is discharged via discharge pipe  23 . 
     In an alternate embodiment, and with reference to  FIG. 8 , only the sludge from IFS&#39;  100 - 107  is treated by a grit separator as the sludge in clarification tank  30  is substantially free of grits and other dense solids. IFS  100 - 107  discharge pipes  570 - 577  are in fluid communication with sludge processing intake pipe  20 ′ and sludge pump  50 ′. Sludge pump  50 ′ is in fluid communication with grit separator  51  via pipe  20   f.  Grit separator  51  is in fluid communication with sludge classification press  52  via pipe  20   g . Clarification tank  30  discharge pipe  70  is in fluid communication with sludge pump  50 . Sludge pump  50  is in fluid communication with grit separator  51  via pipe  20   e.    
     In an alternate embodiment and with reference to  FIG. 9 , the content of biologically-digestible materials in sludge from the IFS&#39;  100 - 107  is insignificant relative to the cost of extraction from the sludge. IFS  100 - 107  discharge pipes  570 - 577  are in fluid communication with sludge processing intake pipe  20 ′ and sludge pump  50 ′. Sludge pump  50 ′ is in fluid communication with grit separator  51  via pipe  20   f . Grit separator  51  separates the grits and particulates from the liquid. Liquid and non-particulate, non-grit sludge extracted from the sludge by grit separator  51  are returned to wet well  12  of  FIG. 1  via discharge pipe  26 , and grit is disposed of in a landfill or by other means. 
     In another alternate embodiment, and with reference to  FIG. 10  where substantive biologically-degradable material settles in IFS  100  IFS troughs  201 , 202 , but not in IFS  100  grit box  500 , IFS trough  201 , 202  discharge pipes  271 , 272  may be arranged to be in fluid communication with sludge process intake pipe  20  in communication with sludge pump  50  while grit box discharge pipe  570  is arrange to be in fluid communication with sludge processing intake pipe  20 ′ in fluid communication with sludge pump  51 ′ for further treatment, as shown by way of example and not limitation in  FIG. 8  and  FIG. 9 . 
     In a waste water treatment plant, the composition of the sludge settled in the IFS troughs, grit box, and clarification tank can change over time as a result of variations in the composition of the influent, changes in plant operating conditions, and other factors such as temperature and relative humidity. With reference to  FIG. 11 , to provide flexibility in the treatment of sludge from clarification tank  30 , if the sludge has substantially no grit, discharge pipe  70  may be placed in fluid communication with sludge pump  50  by opening valve  36  and closing valve  35 , resulting in the sludge bypassing grit separator  51 . Check valve  47  prevents the sludge in discharge pipe  70  from entering sludge and grit intake pipe  20 ′ via pipe  20   i . Alternatively, if there is a need to separate grit from sludge in clarification tank  30 , discharge pipe  70  is placed in fluid communication with sludge pump  50 ′ by opening valve  35  and closing valve  36 . Check valve  49  prevents sludge from clarification tank  30  flowing into IFS&#39;  100 - 107  via sludge and grit intake pipe  20 ′. Similarly, to provide flexibility in the treatment of sludge from IFS&#39;  100 - 107 , if the sludge has substantially no grit, sludge and grit intake pipe  20 ′ may be placed in fluid communication with sludge pump  50  by opening valve  37  and closing valve  38 , resulting in the sludge bypassing grit separator  51 . Check valve  46  prevents the sludge from IFS′  100 - 107  flowing back into clarification tank  30  via discharge pipe  70 . Alternatively, if there is a need to separate grit from sludge in the IFS&#39;  100 - 107 , sludge and intake pipe  20 ′ is placed in fluid communication with sludge pump  50 ′ by opening valve  38  and closing valve  37 . Check valve  48  prevents sludge from IFS&#39;  100 - 107  flowing into clarification tank  30  via discharge pipe  70 . 
     Similarly, in a waste water treatment plant the amount of biologically-degradable material associated with sludge processed by grit separator  51  may change over time as a result of variations in the composition of the influent, changes in plant operating conditions and other factors such as flows from precipitation, snow melt, industrial discharges, and significant public events such as a surge in the use of toilets during Super Bowl halftime. 
     With reference to  FIG. 9 , IFS  100 - 107  discharge pipes  570 - 577  are in fluid communication with sludge and sludge intake pipe  20 ′ which is in fluid communication with sludge pump  50 ′. IFS  100 - 107  discharge pipes  570 - 577  are in fluid communication sludge pump  50  via sludge and intake pipe  20 ′ which is in fluid communication with pipe  20   i  which is in fluid communication with clarification tank  30  discharge pipe  70  which is in direct fluid communication with sludge pump  50 . Valve  38  is positioned in pipe  20 ′ to control the flow of materials from discharge pipes  570 - 577  to sludge pump  50 ′ and not to affect the fluid communication of materials between discharge pipes  570 - 577  and sludge pump  50  and between clarification tank  30  discharge pipe  70  and sludge pump  50  as described hereinbelow. Valve  37  is positioned in pipe  20   i  to control the flow of materials from IFS  100 - 107  discharge pipes  570 - 577  to sludge pump  50 . Valve  37  and pipe  20   i  are arrange to have no effect on the fluid communication between clarification tank  30 ′ discharge pipe  70  and sludge pump  50  and between clarification tank  30  discharge pipe  70  and sludge pump  50 ′. 
     Valve  36  is positioned to control the flow of materials in discharge pipe  70  to sludge pump  50  and to have no effect on the fluid communication of materials between pipe  20 ′ and sludge pump  50 ′ or on the fluid communication of materials between discharge pipe  70  and sludge pump  50 . 
     Clarification tank  30  discharge pipe  70  is in fluid communication with sludge pump  50 . Clarification tank  30  discharge pipe  70  is in fluid communication with sludge pump  50 ′ via pipe  20   h  which is communication with pipe  20 ′. Valve  36  is positioned in discharge pipe  70  to control the fluid communication of materials in discharge pipe  70  with sludge pump  50  and to have no effect on the fluid communication between materials in discharge pipe  70  and sludge pump  50 ′ and to have no effect on fluid communication of materials in discharge pipes  570 - 577  and sludge pump  50 . Valve  35  is positioned in pipe  20   h  to control the fluid communication of materials in discharge pipe  70  to sludge pump  50 ′ and to have no effect on the fluid communication of materials between discharge pipe  70  and sludge pump  50 . Valve  35  and pipe  20   h  are positioned so as to have no effect on the fluid communication between materials in discharge pipes  570 - 577  and sludge pump  50 ′ via pipe  20 ′. 
     Flap valve  46  is positioned in discharge pipe  70  between clarification tank and valves  35 ,  36  to prevent the reverse flow of materials in discharge pipe  70  when valves  35  or  36  are opened, preventing the fluid communication of materials between clarification tank  30  and IFS  100 - 107 . Flap valve  47  is positioned in pipe  20   i  to prevent the reverse flow of materials through pipe  20   i  when valve  37  is opened, preventing the fluid communication of materials from clarification  30  discharge pipe  70  with sludge pump  50 ′ and IFS troughs  100 - 107  via pipe  20   i.  Flap valve  48  is positioned in pipe  20   h  to prevent the reverse flow of materials through pipe  20   h  when valve  35  is opened, preventing the fluid communication of materials from IFS troughs  100 - 107  with clarification tank  30  and sludge pump  50  via pipe  20   h . Flap valve  49  is positioned in grit and sludge intake valve  20 ′ to prevent the reverse flow of materials in sludge and intake pipe  20 ′, preventing fluid communication of materials from clarification tank  30  and IFS troughs  100 - 107 . 
     Sludge pump  50  is in fluid communication with sludge classification press  52  via pipe  20   e . Sludge pump  50 ′ is in communication with grit separator  51  via pipe  20   f . Grit separator  51  discharges grit-free sludge via pipe  20   g  and is in communication with sludge classification press  52  via pipe  20   g.  Alternatively grit separator  51  discharges grit-free pipe via pipe  26  and is in fluid communication with wet well  12  of  FIG. 1  via pipe  26 . Grit Separator  51  discharges grit via discharge pipe  24 . Valve  39  is positioned on pipe  20   g  to control fluid communication between grit separator  51  and sludge classification press  52 . Valve  43  is positioned on pipe  26  to control fluid communication between grit separator  51  and wet well  12  of  FIG. 1 . 
     Sludge classification press  52  is in fluid communication with optional sludge thickener  53  via pipe  20   c . Optional solids concentrator  53  is in fluid communication with digester  54  via pipe  20   d . In one embodiment, sludge thickener is in direct fluid communication with digester  54  via pipe  20   c . 
     Valves  35 - 39  may be manually operated valves. In one embodiment, valves  35 - 39  are electronically-controlled valves under control of and in communication with SCADA  900  via communication channels  945 - 949  respectively. Valves  43  may be a manually operated valve. In one embodiment, valve  43  is an electronically-controlled valve under control of and in communication with SCADA  900  via communication channel  950 . 
     With reference to FIG. 11 , to provide flexibility in the treatment of sludge processed by grit separator  51 , if the sludge has substantially no biologically-degradable materials, valve  39  providing fluid communication between grit separator  51  and sludge classification press  52  remains closed. Valve  43  is opened and liquid and non-particulate, non-grit sludge extracted from the sludge by the grit separator  51  is returned to wet well  12  of  FIG. 1  via discharge pipe  26  and grit is disposed of in a landfill or by other means. If the sludge has substantive biologically-degradable materials, valve  39  providing fluid communication between grit separator  51  and sludge classification press  52  is opened and valve  43  is closed. Liquid and non-particulate, non-grit sludge extracted from the sludge by the grit separator  51  is then treated by sludge classification press  52  and grit is disposed of in a landfill or by other means. 
     In one embodiment of the current application, sludge and grit that has not otherwise been separated into components by a primary treatment system is treated to remove grits and other undesirable materials and to separate and concentrate biologically digestible materials. With reference to  FIG. 4 , discharge pipe  1111  of primary treatment system  1100  is in fluid communication with sludge and grit intake pipe  20  of  FIG. 12 . In one embodiment, a sludge pump  50  is used to assist in the evacuation of the primary treatment system  1100  sludge. In one embodiment, sludge pump  50  is electronically controlled by a supervisory control and data acquisition system SCADA  900  which provides a signal via communication channel  926  to start and stop pumping. 
     A sludge treatment system may receive sludge with varying characteristics during its operation. In a waste water treatment system, the characteristics of the sludge may vary due to seasonal and diurnal variations in the characteristics of the influent as well as from periodic and/or isolated events. A storm may result in flushing of grit and particulates from a sewer system connected to the waste water treatment system. An industrial emitter may periodically discharge low grit materials rich in biologically-digestible materials into a sanitary sewer system connected to a waste water treatment plant. Clarification systems such as the prior art CLARI-FLOCCULATOR® system of  FIG. 4  may be used to treat sites containing waste water that are remote or otherwise not directly connected to a waste water treatment system. In these circumstances, the sludge produced by treatment of the waste water may need to be transported to a sludge treatment system. It may be desirable to regularly or periodically treat secondary sludge to remove biologically-digestible materials as well as primary sludge. A waste treatment plant may accept food and other wastes with an exceptionally high proportion of biologically-digestible material trucked or otherwise transported directly to the plant. For these and other reasons, it is desirable to have an adaptive, configurable sludge treatment system. 
     With reference to  FIG. 12 , in one embodiment of the current application, sludge enters grit intake pipe  20  which is in fluid communication with sludge pump  50 . Sludge pump  50  is in fluid communication with grit separator  51  via pipe  20   a.  Valve  66  is arranged in line with pipe  20   a  to control fluid communication to grit separator  51 . Grit separator  51  is in fluid communication with sludge classification press  52  via pipe  20   b . Valve  84  is arranged in line with pipe  20   b  to control fluid communication to sludge classification press  52 . Sludge classification press  52  is in fluid communication with sludge thickener  53  via pipe  20   c . Valve  86  is arranged in line with pipe  20   c  to control fluid communication to sludge thickener  53 . Sludge thickener  53  is in fluid communication with digester  54  via pipe  20   d . A flocculent source  55  is arranged to communicate flocculents to sludge prior to being treated by sludge classification press  52  via pipe  27   a  or alternatively to sludge discharged from sludge classification press  52  via pipe  27   b . In one embodiment, sludge pump  50  is in communication with and controlled by SCADA  900  via communication channel  926 . In one embodiment, sludge classification press  52  is in communication with and controlled by SCADA  900  via communication channel  927 . In one embodiment, flocculent source  55  is in communication with and controlled by SCADA  900  via communication channel  929 . In one embodiment, sludge thickener  53  is in communication with and controlled by SCADA  900  via communication channel  928 . 
     In one embodiment, one or more optional flowmeters are incorporated in the system: flow meter  2009  to measure the flow in discharge pipe  20 ; flow meter  2001  to measure the flow in pipe  20   a , flow meter  2003  to measure the flow in discharge pipe  20   b;  flow meter  2005  to measure the flow in pipe  20   c;  and flow meter  2007  to measure the flow in pipe  20   d . In one embodiment, flow meter  2009  is in communication with SCADA  900  via communication channel  951 . In one embodiment, flow meter  2001  is in communication with SCADA  900  via communication channel  936 . In one embodiment, flow meter  2003  is in communication with SCADA  900  via communication channel  938 . In one embodiment, flow meter  2005  is in communication with SCADA  900  via communication channel  940 . In one embodiment, flow meter  2007  is in communication with SCADA  900  via communication channel  942 . 
     In one embodiment, one or more optional sensors are incorporated in the system: sensor  2010  to measure the characteristics of materials in sludge and grit intake pipe  20 ; sensor  2002  to measure the characteristics of materials in discharge pipe  20   a;  sensor  2004  to measure the characteristics of materials in discharge pipe  20   b;  sensor  2006  to measure the characteristics of materials in discharge pipe  20   c;  and, sensor  2008  to measure the characteristics of materials in discharge pipe  20   d . The optional sensors are in communication with SCADA  900 : sensor  2010  via communication channel  952 ; sensor  2002  via communication channel  937 ; sensor  2004  via communication channel  939 ; sensor  2006  via communication channel  941 ; and sensor  2008  via communication channel  943 . 
     Sensors  2010 ,  2004 ,  2006 , and  2008  may be a UVAS sensor, turbidity sensor, pH sensor or solids sensor or any other sensor consistent with measuring the physical and/or chemical characteristics of sludge and grits undergoing treatment. 
     Pipe  20   a  is in direct fluid communication with pipes  20   a ,  20   b ,  20   c , and pipe  20   d  via pipe  20   j . Valve  64  controls fluid communication between pipe  20   a  and pipe  20   j . Valve  65  controls fluid communication between pipe  20   j  and pipe  20   b.  Valve  85  controls fluid communication between pipe  20   j  and pipe  20   c . Valve  87  controls fluid communication between pipe  20   j  and pipe  20   d . Valve  69  controls the communication of grit discharged through grit separator  51  grit discharge pipe  24 . In one embodiment, valves  64 ,  65 ,  66 ,  69 ,  84 ,  85 ,  86 ,  87  are manually controlled. In one embodiment, valves  64 , 65 , 66 , 69 , 84 ,  85 , 86 , 87  are under the control of and in communication with SCADA  900 : valve  64  via communication channel  953 , valve  65  via communication channel  955 ; valve  66  via communication channel  954 ; valve  69  via communication channel  957 ; valve  84  via communication channel  958 ; valve  85  via communication channel  959 ; valve  86  via communication channel  960 ; and, valve  87  via communication channel  961 . 
     Check valve  68  is arranged in line with pipe  20   b  to permit flow of fluid from grit separator  51  to sludge classification press  52  and to pipe  20   j  where pipe  20   j  is in fluid communication with pipe  20   b  and while preventing the reverse flow of fluid to grit separator  51 . Check valve  88  is arranged in line with pipe  20   c  to permit flow of fluid from sludge classification press  52  to solids concentrator  53  and to pipe  20   j  where pipe  20   j  is in fluid communication with pipe  20   c  while preventing the reverse flow of fluid to sludge classification press  52 . Check valve  89  is arranged in line with pipe  20   d  to permit flow of fluid from sludge thickener  53  to digester  54  and to pipe  20   j  where pipe  20   j  is in fluid communication with pipe  20   d  while preventing the reverse flow of fluid to sludge thickener  53 . 
     The system of  FIG. 12  operates in substantially the same manner as the corresponding elements of  FIG. 5  when valves  64 ,  65 ,  85  and  87  are closed and valves  66 ,  84 ,  86  and  87  are opened. The system is dynamically configured to optimally and most efficiently separator biological materials from the incoming sludge by a combination of continuous monitoring of the sludge characteristics undergoing treatment and a priori knowledge of the sludge characteristics. By way of example, upon receiving sludge from an industrial beverage or food processing source known to have little grit and high solids content, the sludge treatment system of  FIG. 12  may be configured to route material past the grit separator and sludge thickener by closing valves  66  and  84  and opening valves  64 , 65 , 84 , 86  and  87 . Upon receiving sludge known to have a great deal of grit, but little biologically-digestible materials, the sludge treatment system of  FIG. 12  may be configured to separate grit from the fluid and discharge both by closing valves  64 , 65  and  84  and opening valve  69 . 
     While the invention has been described by reference to various specific embodiments, it should be understood that numerous changes may be made within the spirit and scope of the inventive concepts described. Accordingly, it is intended that the invention not be limited to the described embodiments, but will have full scope defined by the language of the following claims.

Technology Classification (CPC): 2