Abstract:
An alternating anaerobic contact system for treating wastewater through an apparatus including one enclosed vessel partitioned into two or more enclosed chambers wherein each chamber is flow connected to other chambers by conduits or an apparatus including two or more enclosed vessels wherein each vessel is flow connected to other vessels by conduits. Each apparatus comprises at least one conduit which allows for (1) an anaerobic liquor to flow between a pair of chambers or vessels and (2) for treated wastewater to be separated and collected from the anaerobic liquor. Each apparatus overcomes the degassification problems common to anaerobic contact processing by assuring that the partial pressures of each chamber or vessel remain consistent. Each apparatus, furthermore, performs the settling stage of anaerobic contact processing in either a separate chamber or vessel thereby eliminating the need for external tankage, pumps, and piping.

Description:
RELATED APPLICATION 
     This application is a division of Application Ser. No. 08/982,242, filed Dec. 1, 1997, now U.S. Pat. No. 6,096,214, which is hereby incorporated by reference in its entirety. 
    
    
     TECHNICAL FIELD OF THE INVENTION 
     This invention relates to a system applying anaerobic contact processing for the treatment of waste, e.g., wastewater. 
     BACKGROUND OF THE INVENTION 
     In general, two categories of biological processes are available for wastewater treatment: aerobic processes and anaerobic processes. Aerobic processes utilize bacteria which require oxygen to convert organic materials primarily to water and carbon dioxide. Anaerobic processes, on the other hand, utilize bacteria which grow in the absence of oxygen and convert organic materials primarily to the end products methane and carbon dioxide. It has been found that for high strength wastewaters, that is wastewaters having a Chemical Oxygen Demand (COD) greater than 2000 mg/L, anaerobic processes are more advantageous because (1) they require less energy and (2) they produce between one-tenth and one-fifth of the residual biomass resulting from aerobic processes. 
     With respect to the treatment of high strength wastewaters having a Total Suspended Solid (TSS) level greater than 500 mg/L, two categories of anaerobic processes are effective. The first anaerobic process category utilizes anaerobic lagoons which exist as large pits or vessels. With anaerobic lagoons, wastewater is simply introduced into one end of the lagoon whereby suspended anaerobic bacteria within the lagoon degrade both dissolved and particulate organic materials. After an average retention time of several weeks, treated wastewater flows from the anaerobic lagoon. 
     A second anaerobic process category for wastewater treatment is anaerobic contact processing. Anaerobic contact processes utilize a flow-through, closed top reacting vessel containing anaerobic bacteria. Wastewater flowing into the reacting vessel interacts with the anaerobic bacteria, forming an anaerobic liquor. The anaerobic liquor subsequently flows to a settling vessel or clarifier wherein the bacterial solids settle to the bottom of the settling vessel, leaving the relatively clean wastewater to overflow from the top of the settling vessel. Settled solids are then pumped back to the reactor and the process is continued. Before entering the clarifier, the anaerobic liquor passes through a degassifier to minimize the occurrence of super-saturated gases. A typical problem with the anaerobic contact process, however, is achieving good gravity separation of the bacteria from the anaerobic liquor under atmospheric conditions so that only relatively clean wastewater is decanted from the settling vessel. 
     Several embodiments exist for applying anaerobic processes, a more recent embodiment is the anaerobic sequencing batch reactor (ASBR). An ASBR operates by partially filling a reactor vessel containing anaerobic bacteria with wastewater and gently mixing the contents so to assist the anaerobic bacteria in degrading the organic materials of the wastewater. After the anaerobic bacteria react with the wastewater, the mixer is turned off, allowing the anaerobic bacteria to settle to the bottom of the reactor vessel. The treated wastewater is then decanted from the top of the reactor vessel. Limitations, however, of this anaerobic process are (1) the need for a relatively large feed equilization to accommodate the batch operation and 2) the need to provide a variable-level tank, decanter, and gas collection system. 
     For wastewaters having a TSS greater than 500 mg/L, lagoons and anaerobic contact processing systems are more effective in treatment. Lagoons, however, require large land space while anaerobic contact systems are subject to settling problems resulting from inadequate degassification or even regassification in the clarifier. An anaerobic contact system is also costly because it requires multiple components: i.e., a separate equalization reactor, a degassifier, outdoor clarifier vessels, associated return pumps, and piping. 
     The inventor of the invention described herein has developed an apparatus which modifies the conventional application of the anaerobic contact process. Use of this invention precludes the degassification problems occurring in the clarifier device associated with the conventional anaerobic contact process without requiring batch operation or variable-level operation. Additionally, the invention described herein can be manufactured and used at a cost which is much less than that required for an apparatus applying the conventional anaerobic contact process. 
     SUMMARY OF THE INVENTION 
     The present invention is directed to an apparatus and method of using the apparatus for treatment of wastewater. With respect to the invention described herein, wastewater is defined as any liquid or semi-liquid comprising organic material. In general, the invention employs the principles of anaerobic contact processing for the removal of contaminants from wastewater. Typical applications of the invention are for treating wastewaters from the grain and food processing industries, biotechnology and pharmaceutical industries, and livestock wastes; but other applications are not precluded. 
     In one aspect of the invention, a wastewater feed to be treated flows, preferably continuously, into a first vessel (reacting vessel) where it is mixed with anaerobic bacteria, forming an anaerobic liquor. As wastewater continues to flow into the first vessel, a portion of the anaerobic liquor, as a result of the internal pressure of the first vessel, passes into a transfer manifold and flows continuously from the first vessel into a second vessel. Because the mixer of the second vessel is off, the anaerobic bacteria, which are introduced into the second vessel, separate from the anaerobic liquor and settle to the bottom of the second vessel. Treated wastewater rises within the second vessel to a certain level where it passes into an effluent manifold. The treated wastewater then flows, preferably continuously, from the effluent manifold out of the second vessel and into an effluent conduit, where it eventually flows to a municipal wastewater treatment plant or some other like facility. 
     After an appropriate period of time, wastewater feed-flow into the first vessel is stopped and the mixer in the first vessel is turned off. Additionally at this time, there is no influx or efflux of fluid from either the first or second vessel so that the anaerobic bacteria of the anaerobic liquor in the first vessel separate and settle to the bottom of the first vessel. 
     With the influent valve of the first vessel closed, the influent valve of the second vessel is opened and the mixer in the second vessel is turned on. The incoming wastewater feed flows, preferably continuously, to the second vessel (the prior settling vessel) and is mixed with the anaerobic bacteria of the concentrated anaerobic liquor which remained in the second vessel. As wastewater feed continues to flow into the second vessel (the new reacting vessel), a portion of the anaerobic liquor, as a result of the internal pressure within the second vessel, passes into a transfer manifold and flows continuously from the second vessel into the first vessel (the new settling vessel). In the first vessel (the new settling vessel), the anaerobic bacteria separate from the anaerobic liquor and settle to the bottom of the first vessel (the new settling vessel). Treated wastewater rises within the first vessel (the new settling vessel) and passes into an effluent manifold. The treated wastewater then flows from the first vessel (the new settling vessel) into the effluent conduit where it eventually flows to a municipal wastewater treatment plant or some other like facility. 
     Application of the alternating anaerobic contact process can be performed with an apparatus having two or more vessels wherein each pair of vessels in the sequence provide for continuous flow from a current reacting vessel to a current settling vessel. The main aspect of the invention is that as long as there are at least two reacting/settling vessels, the alternating anaerobic contact process can be continuously applied without the requirements of an external clarifier, degassifier or other external piping and pumps between the vessels. 
     In yet another aspect of the invention, a multi-chambered, single-vessel system can be used wherein each chamber acts as a vessel described above. The alternating anaerobic contact process can be continuously applied between chambers of the single vessel as long as a first chamber serves as a reacting chamber while a second chamber serves as a settling chamber during a first stage of operation, and a chamber other than the first chamber acts as a reacting vessel and a chamber other than the second chamber acts as a settling chamber in a second stage of operation. An advantage of the multi-chambered, single vessel system is that only one vessel is required, thereby reducing the cost of the apparatus. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     Other objects and advantages of the invention will become apparent upon reading the following detailed description and upon reference to the drawings, in which: 
     FIG. 1 is a schematical view of a system in accordance with the present invention utilizing an alternating anaerobic contact process. 
     FIGS. 2A,  2 B,  2 C and  2 D are flow schematic diagrams illustrating sequential stages of operation in a modified process when applying the present invention. 
     FIG. 3 is a schematical view of a multi-chambered vessel system utilizing an alternating anaerobic contact process. 
     FIGS. 4A,  4 B and  4 C are flow schematic diagrams illustrating sequential stages of operation in a modified process when applying the multi-chambered vessel system illustrated in FIG.  3 . 
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
     While the invention will be described in connection with preferred embodiments, it shall be understood that the invention is not to be limited to any particular embodiment. On the contrary, each embodiment is intended to cover all alternatives, modifications, and equivalents as may be included within the spirit and scope of the invention as defined in the claims. Thus, each specific structural and functional detail described within merely serves as a teaching mechanism for one skilled in the art. 
     A first preferred embodiment is illustrated in FIG.  1 . The reference numeral  1  represents an apparatus for treating wastewater. Wastewater is defined as any liquid or semi-liquid comprising organic material. In general, the apparatus includes an equalization vessel  50 , a feed system  2 , a first reacting/settling vessel  10 , a second reacting/settling vessel  30 , an effluent system  70 , and a recycle and waste sludge system  80 . 
     The equalization vessel  50  is flow connected to wastewater feed conduit  3 . A wet well or underground vault can also serve as an equalization vessel. Chemical addition system  4  provides additives which mix with the incoming waste in equalization vessel  50 . The chemical addition system  4  assists in providing nutrients for anaerobic bacteria, equalizing the pH, and the initial breakdown of waste. Examples of such chemicals are: acids, caustics, nutrients, and flocculants such as polymers. The equalization vessel  50  also includes a mixing system  60  which further assists in waste breakdown. FIG. 1 illustrates a mechanical type mixing system having a motor  61 . Alternative mixing systems include the use of liquid recirculation. 
     The influent system  2  includes a feed conduit  13 , feed pump  5 , conduit  14 , junction  9 , conduit  6 , junction  12 , feed conduits  16  and  17 , valves  7  and  8 , and connecting nozzles  18  and  19 . One end of conduit  13  flow connects to the equalization vessel  50  while the opposite end flow connects with the feed pump  5 . Conduit  14  flow connects to the outlet of feed pump  5  and to one end of T-joint  9 . A second end of junction  9  attaches to conduit  88  of the recycle system  80 . A third end of junction  9  attaches to the conduit  6 . The conduit  6  flow connects to junction  12 , causing the conduit  6  to bifurcate and form feed conduits  16  and  17 . Feed conduit  16 , containing valve  7 , flow connects to first vessel  10  via nozzle  18 . Feed conduit  17 , containing valve  8 , flow connects to second vessel  30  via nozzle  19 . 
     Reacting/settling vessels  10  and  30  each have a top-wall, a bottom-wall, and a continuous side-wall so as to form an enclosure able to receive wastewater and to contain the liquid contents  11  and  31 . Contents  11  and  31  are mainly comprised of a combination of wastewater and anaerobic bacteria and when sufficiently mixed forms an anaerobic liquor. The anaerobic bacteria can be either naturally occurring or genetically-engineered. Mechanical mixing systems  20  and  40 , which respectively include motors  21  and  41  are positioned in vessels  10  and  30 . Other embodiments for use as a mixing system include biogas and liquid recirculation. The top portion of each of vessels  10  and  30  is flow connected to a gas discharge conduit  90 . Gas conduit  90  provides for gas to be removed from both vessels  10  and  30  so that the internal gas pressures of vessels  10  and  30  remain substantially consistent within and between each vessel. The opposite end of gas discharge conduit  90  flow connects into gas handling system  95 . A number of gas handling systems can function effectively regarding apparatus  1 ; however, a common type of gas handling system includes: flame arrestors, a flare, pressure control valves and condensate traps. Near the bottoms of vessels  10  and  30  respectively reside transfer manifolds  15  and  35 . A common manifold type includes a horizontal conduit having multiple orifices. Transfer manifolds  15  and  35  flow connect to transfer conduit  37  which extends from manifold  15  in vessel  10  to manifold  35  in vessel  30  via a junction  39  so as to permit continuous flow of anaerobic liquor between vessels  10  and  30 . 
     The effluent system  70  includes effluent manifolds  71  and  76 , effluent conduits  72  and  74 , effluent valves  73  and  77 , effluent trap  75 , atmospheric vent  78  and effluent conduit  79 . Effluent manifold  71 , which is located in the top region of the first vessel  10 , is connected to the trap  75  by the conduit  72 , containing the valve  73 . Similarly, the effluent manifold  76 , which is located in the top region of the second vessel  30 , is connected to the trap  75  by the conduit  74 , containing the valve  77 . Effluent trap  75  flow connects to the vent  78  and the effluent conduit  79 . Effluent conduit  79  continues beyond apparatus  1 . FIG. 1 illustrates effluent trap  75  as flowing around and not through vessel  30 . The atmospheric vent  78  can be attached to effluent conduit  79  at any location downstream from the effluent trap  75  to prevent siphoning. 
     The recycle and waste sludge system  80  includes recycle conduit  81 , recycle pump  82 , recycle heat exchanger  83 , waste sludge conduit  84 , valve  85 , junction  86 , and conduits  87  and  88 . Recycle and waste conduit  38  flow connects with recycle conduit  81  and waste sludge conduit  84  at junction  86 . Recycle conduit  81  flow connects with the inlet of the recycle pump  82 . From the outlet of the recycle pump  82 , the conduit  87  flow connects to an inlet of the heat exchanger  83  and conduit  88  flow connects to an outlet of the heat exchanger  83  and to the feed system  2  at the junction  9 . Waste sludge conduit  84 , containing the valve  85 , eventually flow connects to a facility for receiving excess sludge (not shown). Such a recycle and waste sludge system allows excess sludge to be either removed from apparatus  1  or to be recycled for further treatment. 
     In other preferred embodiments of the invention additional vessels can be added and structured in a similar arrangement to that described above. 
     In use, apparatus  1  operates essentially as a wastewater treatment process applying the principles of anaerobic contact processing in a multi-vesseled system. Initiation of the process or system begins with the introduction of wastewater from conduit  3  into the equalization vessel  50 . In vessel  50  the wastewater is mixed by mixing system  60  while concomitantly being treated by chemical addition system  4 . After an appropriate period of time, the wastewater is pumped from the equalization vessel  50  and into conduit  6 . 
     FIGS. 2A,  2 B,  2 C and  2 D provide a two-vesseled schemata regarding a preferred application of alternating anaerobic contact processing of waste. FIGS. 2A,  2 B,  2 C and  2 D, however, illustrate only one of the many possible arrangements or steps for performing alternating anaerobic contact processing. FIG. 2A illustrates the first-half of stage one of the process having valve  7  open and valve  8  closed. With this arrangement, vessel  10  receives the incoming wastewater feed and thereby serves as the initial reacting vessel. Mixing system  20  mixes the contents  11  at a rate sufficient to maintain the anaerobic bacteria in suspension without causing the bacteria to shear. The anaerobic bacteria of vessel  10  begin to react and break down the incoming waste. Gases produced during the reaction of the anaerobic bacteria with the organic materials in the contents  11 —an anaerobic liquor—are removed from the vessel  10  and introduced into gas conduit  90 . 
     Turning back to FIG. 1, a portion of contents  11  in vessel  10  passes into the transfer manifold  15  at a rate based upon the inflow of wastewater feed to the vessel  10 . The orifice size of the transfer manifolds  15  and  35 , and the diameter of the transfer conduit  37  are selected so as to promote the desired flow rate through conduit  37  between vessels  10  and  30 . A portion of the contents  11  continues to flow at such rate through transfer conduit  37  and into vessel  30  via the transfer manifold  35  to become part of the contents  31 . An amount of the portion of contents  11  when in conduit  37  flows into recycle conduit  38  and does not become part of contents  31 . The contents  11  in conduit  38  flow into recycle system  80  and are eventually pumped back into conduit  6 . 
     During the first-half of stage one, the vessel  30  acts as the settling vessel for the contents  31 , which at this point exists mainly as anaerobic liquor. The anaerobic bacteria along with any organic residual solids separate from the remainder of the contents  31  and settle to the bottom of vessel  30 , forming bi-layered contents  31 . The top layer exists as treated wastewater while the bottom layer exists as a mixture of wastewater and biomass. As wastewater feed continues to be fed into the vessel  10 , fluid passes through conduit  37  into vessel  30  causing a portion of the treated wastewater to pass through effluent manifold  76 . The treated wastewater which passed through effluent manifold  76 , passes through open valve  77  and enters effluent conduit  79 . The treated wastewater which flows through conduit  74  has an organic concentration which is substantially less than the organic concentration of the wastewater fed into conduit  13 . Effluent conduit  79  can transport the treated wastewater to a municipal wastewater plant or to storage (not shown). 
     FIG. 2B illustrates the second-half of stage one in the alternating anaerobic contact process. Valves  7  and  77  are closed, thereby discontinuing the flow of wastewater feed into vessel  10  and the flow of treated wastewater from vessel  30 . Mixer  20  in vessel  10  is turned to the off position, allowing solids and anaerobic bacteria of contents  11  to settle within vessel  10 . Since valves  8  and  72  remain closed, there is no flow within either vessel  10  or vessel  30  other than through transfer conduit  37 . As gases are removed, preferably continuously, from both vessels  10  and  30 , there is not any significant flow of fluid through conduit  37  during the stage represented by FIG.  2 B. In contrast, there is a flow through conduit  37  which is at least substantially continuous and at least substantially equal to the flow rate of feed through conduit  6  during any period of time that either vessel  10  or vessel  30  is being employed to conduct the breakdown of organic material by the anaerobic bacteria. The duration of the second-half of stage one typically lasts for a few hours or until a supernatant layer exists within the contents  11  in vessel  10 . Recycle conduit  38  continues to receive an amount of contents  11  flowing through conduit  37  but at a rate less than the rate occurring in the first-half of stage one. 
     FIG.  2 C and FIG. 2D illustrate the first-half and second-half of stage two for alternating anaerobic contact processing where the flows of wastewater and anaerobic liquor are reverse to those first shown by FIG.  2 A and FIG.  2 B. FIG. 2C represents the first-half of stage two of the process having valve  8  now open and valve  7  remaining closed. With this arrangement, vessel  30  receives the incoming wastewater feed and serves as the initial reacting vessel. Mixing system  40  mixes the contents  31  at a rate sufficient to maintain the anaerobic bacteria in suspension. The anaerobic bacteria of vessel  30  react and break down the organic components of the incoming wastewater feed. Gases produced during the reaction of the anaerobic bacteria with the organic materials in the contents  31 —an anaerobic liquor—are removed from the vessel  30  and introduced into gas conduit  90 . Mixing system  20  in vessel  10  is off, permitting solids and anaerobic bacteria of contents  11  to settle in vessel  10 . 
     Turning again back to FIG. 1, a portion of contents  31  passes into the transfer manifold  35  at a rate based upon the rate of inflow of wastewater feed to vessel  30 . The orifice size of the transfer manifolds  15  and  35 , and the diameter of transfer conduit  37  are selected so as to promote the desired flow rate through conduit  37  between vessels  30  and  10 . A portion of contents  31  continues to flow at such rate through transfer conduit  37  and into vessel  10  via transfer manifold  15 . An amount of the portion of contents  31  when in conduit  37  flows into recycle conduit  38  and does not become part of contents  11 . The contents  31  in conduit  38  flow into recycle system  80  and are eventually pumped back into conduit  6 . 
     During the first-half of stage two, vessel  10  acts as the settling vessel for the contents  11 , which at this point exists mainly as anaerobic liquor. The anaerobic bacteria along with any organic residual solids separate from contents  11  and settle within vessel  10 , forming bi-layered contents  11 . The top layer exists as treated wastewater while the bottom layer exists as a mixture of wastewater and biomass. As wastewater feed flows into vessel  30 , a portion of the treated wastewater in vessel  10  passes into effluent manifold  71 . The fluid within effluent manifold  71  passes through conduit  72 , containing open valve  73 , and enters effluent conduit  79 . The treated wastewater which flows through conduit  72  has an organic concentration which is substantially less than the organic concentration of the wastewater fed into conduit  13 . Effluent conduit  79  transports the treated waste to a municipal water system or storage (not shown). 
     FIG. 2D illustrates the second-half of stage two regarding the alternating contact process. Mixer  40  in vessel  30  is turned to the off position allowing solids and the anaerobic bacteria of contents  31  to settle within vessel  30 . Mixer  20  in vessel  10  remains off. Valves  7 ,  8 ,  72  and  77  are closed thereby preventing any influx or efflux into either vessel  10  or  30 . There is no flow within either vessel  10  or vessel  30  other than through transfer conduit  37 . As gases are removed, preferably continuously, from both vessels  10  and  30 , there is not any significant flow of fluid through conduit  37  during the stage represented by FIG.  2 D. In contrast, there is a flow through conduit  37  which is at least substantially continuous and at least substantially equal to the flow rate of feed through conduit  6  during any period of time that either vessel  10  or vessel  30  is being employed to conduct the breakdown of organic material by the anaerobic bacteria. The duration of the stage illustrated in FIG. 2D can continue for a few hours or until a supernatant layer exists within the contents  31 . Recycle conduit  38  continues to receive an amount of contents  31  flowing through conduit  37  but at a rate less than the rate occuring in the first-half of stage two. Waste sludge valve  85  of conduit  84  is opened if it has been determined that the sludge concentration within either or both of vessels  10  or  20  is outside the operational range. 
     The addition of another vessel or vessels to the apparatus  1  of FIG. 1 provides several advantages. For example, a three or more vesseled embodiment can increase the efficiency of the system by avoiding the delays associated with the settling steps illustrated in FIG.  2 B and FIG.  2 D. With a three or more vesseled embodiment the contents of at least one vessel always remain finely settled thereby reducing the time required for fine-settlement in the two-vesseled embodiment. 
     ANOTHER PREFERRED EMBODIMENT 
     The reference numeral  101  of FIG. 3 represents a second preferred embodiment of the invention described herein. In general, the apparatus of FIG. 3 includes an equalization vessel  50 , a feed system  2 , a multi-chambered vessel  105 , an effluent system  170 , and a recycle and waste sludge system  80 . The type, use and arrangement of the equalization vessel, influent system, and recycle system are similar to those described above and illustrated in FIG.  1 . Such structures, therefore, will be omitted from this section of the Detailed Description. Only multi-chambered vessel  105  and effluent system  170  are described as illustrated in FIG.  3 . 
     Multi-chambered vessel  105  has a top-wall, bottom-wall and a continuous side-wall so to form an enclosure able to receive and contain wastewater. Multi-chambered vessel  105  includes internal region  106  and partition walls  107 ,  108  and  109 . Partition walls  107 ,  108  and  109  extend from the side wall of multi-chambered vessel  105  and come into contact with each other at the center of internal region  106 . Partition walls  107 ,  108 , and  109 , furthermore, span between the top and bottom of multi-chambered vessel  105 . Such an arrangement forms reacting/settling chambers  110 ,  130  and  150 . The multi-chambered vessel  105  as illustrated in FIG. 3 consists of three chambers. The multi-chambered apparatus as invented by the inventor; however, can exist as two or more chambers and is therefore not limited to the three-chambered vessel as illustrated in FIG.  3 . For example, a two chambered embodiment exists if partition walls  108  and  109  are removed and partition wall  107  traverses vessel  105 . 
     Turning back to FIG. 3, chambers  110 ,  130  and  150  form an enclosure able to receive wastewater feed and contain contents  111 ,  131  and  151 . Contents  111 ,  131  and  151  exist mainly as a combination of wastewater and anaerobic bacteria. The anaerobic bacteria can either be naturally occurring or genetically engineered. Positioned in chambers  110 ,  130  and  150  are mixing systems  120 ,  140  and  154 , respectively having motors  121 ,  141  and  155 . Other embodiments for use as a mixing system include biogas and liquid recirculation. The top portion of each of chambers  110 ,  130  and  150  is flow connected to gas discharge conduit  190 . The opposite end of conduit  190  flow connects into gas handling system  195 . Near the bottoms of chambers  110 ,  130  and  150  respectively reside transfer manifolds  115 ,  135  and  165 . 
     Transfer manifold  115  of chamber  110  flow connects to transfer/recycle conduit  126 . Conduit  126  bifurcates at junction  124  and forms conduits  127  and  128 . Conduit  127  flow connects to waste sludge conduit  84  at joint  180 . Conduit  128 , containing valve  129 , flow connects to transfer manifold  135  of chamber  130 . Transfer manifold  135  flow connects to transfer/recycle conduit  146 . Transfer/recycle conduit  146  bifurcates at junction  144  and forms conduits  147  and  148 . Conduit  147  flow connects to waste sludge conduit  84  at joint  180 . Conduit  148 , containing valve  149 , flow connects to transfer manifold  165  of chamber  150 . Transfer manifold  165  flow connects to transfer/recycle conduit  166 . Conduit  166  bifurcates at junction  164  and forms conduits  167  and  168 . Conduit  167  flow connects to waste sludge conduit  84  at joint  180 . Conduit  168 , containing valve  169 , flow connects to transfer manifold  115  of chamber  110 , thereby completing a continuous communication amongst each chamber. 
     Effluent system  170  includes effluent manifolds  171 ,  176 , and  156 . Effluent manifolds  171 ,  176 , and  156 , unlike transfer manifolds  115 ,  135 , and  165 , are not part of a continuous communication amongst each chamber. Effluent manifold  171  of chamber  110  flow connects to conduit  132 , Conduit  132 , containing effluent valve  127 , flow connects to effluent conduit  79 . Effluent manifold  176  of chamber  130  flow connects to conduit  134 . Conduit  134 , containing effluent valve  177 , flow connects to effluent conduit  79 . Effluent manifold  156  of chamber  150  flow connects to conduit  133 . Conduit  133 , containing valve  157 , flow connects to effluent conduit  79 . Effluent conduit  79  continues beyond apparatus  101  where effluent trap  75  flow connects to the conduit  79 . An atmospheric vent  78  can be attached to the conduit  79  at any location downstream from the effluent trap  75 . 
     In other preferred embodiments of the invention additional chambers can be formed and structured in a similar arrangement to that described above. 
     In use, the apparatus  101  of FIG.  3  and FIG. 4 operate essentially the same as apparatus  1  of FIG.  1  and FIG. 2 in that each chamber can function as a reactor and settler. Initiation of the process or system begins with the introduction of wastewater from conduit  3  into the equalization vessel  50 . In vessel  50  the wastewater is mixed by mixing system  60  while concomitantly being treated by chemical addition system  4 . After an appropriate period of time, the wastewater is pumped from the equalization vessel  50  and into conduit  6 . 
     FIG. 4A,  4 B and  4 C provide a schemata demonstrating the feed, discharge, and settle stages of alternating anaerobic contact processing when performed in the multi-chambered vessel  105  as illustrated in FIG.  3 . FIG. 4A,  4 B and  4 C, however, demonstrate only one of many possible arrangements or steps for performing alternating anaerobic processing in the multi-chambered vessel  105 . 
     FIG. 4A illustrates valves  143 ,  169  and  127  open and valves  123 ,  129 ,  153 ,  177 ,  149  and  157  closed. With this arrangement, chamber  150  receives the incoming wastewater feed and thereby serves as the initial reacting chamber. Mixing system  154  mixes contents  151  at a rate sufficient to maintain the anaerobic bacteria in suspension without causing the bacteria to shear. The anaerobic bacteria within chamber  150  react and begin to break down the incoming waste. Gases produced during the reaction of the anaerobic bacteria with the organic materials in the contents  151  are removed from chamber  150  and introduced into gas conduit  190 . Mixing systems  120  and  140  respectively of chambers  110  and  130  are off. 
     Looking back at FIG. 3, a portion of contents  151  passes into transfer manifold  165  at a rate based upon the inflow of wastewater feed into chamber  150 . The orifice of the transfer manifolds  165  and  115 , and the diameter of conduits  166  and  168  are selected so as to promote the desired flow rate through conduits  166  and  168 . A portion of contents  151  continues at such rate through conduits  166  and  168  and open valve  169  where it eventually passes into chamber  110  via transfer manifold  115 . An amount of the portion of contents  115  when in conduit  166  flows into conduit  167 . The contents  115  in conduit  167  flow to conduit  181  and into recycle system  80  and are eventually pumped back into conduit  6 . 
     In FIG. 4A, chamber  110  acts as the settling chamber for contents  111  and chamber  130  acts as the settling chamber for contents  131 . The anaerobic bacteria along with any organic residual solids separate from the remainder of contents  111  and settle to the bottom of chamber  110 , forming bi-layered contents  111 . The bottom layer of contents  111  exists as a mixture of wastewater and biomass while the top layer exists as treated wastewater. As wastewater feed continues to be fed into chamber  150 , fluid passes through conduits  166  and  168  causing a portion of the treated wastewater to pass through effluent manifold  171 . The treated wastewater which passed through effluent manifold  171  passes through open valve  127  and enters effluent conduit  79 . The treated wastewater which flows through conduits  166  and  168  has an organic concentration which is substantially less than the organic concentration of the wastewater fed into conduit  13 . Effluent conduit  79  can transport the treated waste to a municipal wastewater plant or storage (not shown). 
     FIG. 4B illustrates valves  123 ,  129  and  177  open and valves  127 ,  153 ,  149 ,  143 ,  157  and  169  closed. With this arrangement, chamber  110  receives the incoming wastewater feed and thereby serves as the reacting chamber. Mixing system  154  in chamber  150  is turned off, allowing the anaerobic bacteria and other solids in the contents  151  to settle for a time period until a supernatant layer exists in contents  151 . Mixing system  140  of chamber  130  is off. Mixing system  120  of chamber  110  is turned on and set at a rate sufficient to maintain the anaerobic bacteria in suspension without causing the bacteria to shear. The anaerobic bacteria within chamber  110  react and begin to break-down the incoming waste. Gases produced during the reaction of the anaerobic bacteria with the organic materials in the contents  111  are removed from chamber  110  and introduced into gas conduit  190 . The recycle system  80  continues to receive an amount of contents  115  but at a rate less than when valve  143  was open. 
     Returning to FIG. 3, a portion of contents  111  in chamber  110  passes into transfer manifold  115  at a rate based upon the inflow of wastewater feed into chamber  110 . The orifice size of the transfer manifolds  115  and  135 , and the diameter of transfer conduits  126  and  128  are selected so as to promote the desired flow rate through conduits  126  and  128 . A portion of the contents  111  continues at such rate through conduits  126  and  128  and open valve  129  where it eventually passes into chamber  130  via transfer manifold  135 . An amount of the portion of contents  111  when in conduit  126  flows into conduit  127 . The contents  115  in conduit  127  flow to conduit  181  and into recycle system  80  and are eventually pumped back into conduit  6 . 
     In FIG. 4B, chamber  130  acts as the settling chamber for contents  131  and chamber  150  acts as the settling chamber for contents  151 . The anaerobic bacteria along with any residual organic solids separate from the remainder of contents  131  and settle to the bottom of chamber  130 , forming bi-layered contents  131 . The bottom layer of contents  131  exists as biomass while the top layer exists as treated wastewater. As wastewater feed continues to be fed into the chamber  110 , fluid passes through conduits  126  and  128  and into chamber  130  causing a portion of the treated wastewater to pass through the effluent manifold  176 . The treated wastewater which passed through effluent manifold  176  passes through open valve  177  and enters effluent conduit  79 . The treated wastewater which flows through conduits  126  and  128  has an organic concentration which is substantially less than the organic concentration of the wastewater fed into conduit  13 . Effluent conduit  79  can transport the treated waste to a municipal wastewater plant or storage (not shown). 
     FIG. 4C further illustrates the feed, discharge, and settle stages occurring within chambers  150 ,  110  and  130 . Regarding FIG. 4C, valves  153 ,  149  and  157  are open while valves  177 ,  143 ,  169 ,  110 ,  127  and  129  are closed. Chamber  130 , therefore, receives the incoming wastewater and acts as the reacting chamber. The mixing system  120  of chamber  110  is turned off allowing the anaerobic bacteria and other solids in the contents  111  to settle for a time period until a clear upper layer exists in contents  111 . Mixing system  154  of chamber  150  is off. Mixing system  140  of chamber  130  is turned on and set at a rate sufficient enough to maintain the anaerobic bacteria in suspension without causing the bacteria to shear. The anaerobic bacteria within chamber  130  react and begin to breakdown the incoming waste. Gases produced during the reaction of the anaerobic bacteria with the organic materials in the contents  131  are removed from chamber  150  and introduced into gas conduit  190 . The recycle system  80  continues to receive an amount of contents  115  but at a rate less than when valve  143  was open. 
     Again turning to FIG. 3, a portion of the contents  131  passes into the transfer manifold  135  at a rate based upon the inflow of wastewater into chamber  130 . The orifice size of the transfer manifolds  135  and  165 , and the diameter of transfer conduits  146  and  148  are selected so as to promote the desired flow rate through conduits  146  and  148  between chambers  150  and  110 . A portion of contents  131  continues at such rate through conduits  146  and  148  and open valve  149  where it eventually passes into chamber  150  via transfer manifold  165 . An amount of the portion of contents  131  within conduit  146  flows into conduit  147 . The contents  131  in conduit  147  flow into conduit  181  and into recycle system  80  and are eventually pumped back into conduit  6 . 
     In FIG. 4C, chamber  150  acts as the settling chamber for contents  151  and chamber  110  acts as the settling chamber for contents  111 . The anaerobic bacteria along with any residual organic solids separate from the remainder of contents  151  and settle to the bottom of chamber  150 , forming bi-layered contents  151 . The bottom layer of contents  151  exists as biomass while the top layer exists as treated wastewater. As wastewater feed continues to be fed in chamber  130 , fluid passes through conduits  146  and  148  and into chamber  150  causing a portion of the treated wastewater to pass through the effluent manifold  156 . The treated wastewater which passed through the effluent manifold  156  passes through open valve  157  and enters effluent conduit  79 . The treated wastewater which flows through conduits  126  and  128  has an organic concentration which is substantially less than the organic concentration of the wastewater fed into conduit  13 . Effluent conduit  79  can transport the treated wastewater to a municipal wastewater plant or storage (not shown). Waste sludge valve  85  of conduit  84  is opened if it has been determined that the sludge concentration within a particular chamber is outside the operational range. 
     The main advantage of the multi-chambered, single vessel embodiment, as illustrated in FIG. 3 over the multi-vesseled embodiment as illustrated in FIG. 1 is that the overall cost for manufacturing the multi-chambered embodiment is significantly less than the overall cost for manufacturing the multi-vesseled embodiment since only one vessel is required. 
     EXAMPLE 1 
     A bench-scale, two-vesseled system, according to the general design of FIG. 1, was fabricated to test the efficacy of the alternating anaerobic contact system. Using two six-liter acrylic vessels, the system was seeded with anaerobic liquor from a municipal wastewater plant and fed daily with wastewater from a food-processing facility. The wastewater mainly originated from corn soaking and milling operations, with any large solids already removed by vibratory screens. 
     The hydraulic and organic loading rates of the bench-scale system were gradually increased over the six months it was in operation. The initial feed rate was one liter per day but was increased to three liters per day by the end of six months. This latter feed rate gave a retention time of four days and an organic loading rate of 2.0-2.5 g Chemical Oxygen Demand (COD)/liter-day. Influent and effluent samples were analyzed to measure the system&#39;s treatment efficiency and to evaluate its process stability. 
     Results demonstrated the Alternating Anaerobic Contact System to be very effective at removing conventional pollutants, as shown in Table 1. Moreover, the wastewater did not require further nutrients to achieve the tabulated results. Settleability of the bacteria from the anaerobic liquor was good even though the anaerobic liquor concentration averaged 13000-18000 mg/L Total Suspended Solids (TSS). The gas yield from the system approximated 320 mL/g COD, a value close to the theoretical maximum gas yield. 
     
       
         
               
               
               
               
             
           
               
                 TABLE 1 
               
               
                   
               
               
                 TEST 
                 RAW 
                 TREATED 
                 REMOVAL 
               
               
                 PARAMETER 
                 WASTEWATER 
                 WASTEWATER 
                 EFFICIENCY 
               
               
                   
               
             
             
               
                 BOD 
                 2800 mg/L 
                 255 mg/L 
                 91.0% 
               
               
                 TSS 
                 2895 mg/L 
                 460 mg/L 
                 84.0% 
               
               
                 COD 
                 9220 mg/L 
                 1000 mg/L  
                 88.0% 
               
               
                 pH 
                 9.5-11.5 
                 6.4-6.8 
               
               
                   
               
               
                 BOD = Biological Oxygen Demand  
               
               
                 TSS = Total Suspended Solids  
               
               
                 COD = Chemical Oxygen Demand