Abstract:
A variable volume bioreactor including a rigid core associated with a light source, an outer expandable growth containment portion located concentrically about the rigid core, a lower end portion associated with an inlet to supply culture medium and an outlet, and an upper end cap with an opening therein through which the rigid core passes, wherein the outer containment portion expands as the cellular biological material contained in said portion grows and expands.

Description:
FIELD OF THE INVENTION 
       [0001]    The present invention relates to bioreactors and particularly to low cost, reusable bioreactors. 
       BACKGROUND ART 
       [0002]    For many years, bioreactors have been considered to be an ideal technical solution for the growing of feedstock for the extraction of oils. Bioreactors have also been suggested as a method to remove carbon dioxide from industrial emissions. The practical use of bioreactors has had limited success due to the cost of building and maintaining the bioreactor vessels and also the difficulty in removing the products from the reactor vessel once mature. 
         [0003]    Bioreactors degrade contaminants in water with microorganisms through attached or suspended biological systems. In suspended growth systems, such as activated sludge, fluidized beds, or sequencing batch reactors, contaminated ground water is circulated in an aeration basin where a microbial population aerobically degrades organic matter and produces CO 2 , H 2 O, and new cells. The cells form a sludge, which is settled out in a clarifier, and is either recycled to the aeration basin or disposed. In attached growth systems, such as upflow fixed film bioreactors, rotating biological contactors (RBCs), and trickling filters, microorganisms are established on an inert support matrix to aerobically degrade water contaminants. 
         [0004]    The two types of devices providing for variable volume during cell culture without compromising sterility of the culture that have been described, moreover, present significant restrictions that hinder their application. Several forms of a chamber for cell culture based on a bag, which conceptually could allow variable volumes for cultures, have been described previously (e.g., U.S. Pat. Nos. 5,686,304 and 5,714,384), but the flexible walls present in these and other bags do not provide tight control of volumes, do not provide rigid surfaces for culture of adherent cells, nor present chambers with well-defined geometries for well-defined perfusions (e.g., uniform hydrodynamic shear stresses required for many adherent cells). Deformability of a wall of a chamber in general (e.g., as practiced by U.S. Pat. No. 6,152,163), leads to these inherent limitations. Alternatively, U.S. Pat. No. 5,707,868 describes the use of a piston-based design as a variable-volume chamber for cell culture. This type of design, similar in concept to other piston-based designs for biotechnological applications described in U.S. Pat. Nos. 5,143,847, 6,007,472, and 6,290,910, are cumbersome mechanically and not well-suited to large, planar cultures of adherent monolayers. 
         [0005]    The present invention has been specifically devised in order to provide a low-cost bioreactor with simple, effective design capable of providing a continuous or reusable process. 
         [0006]    It will be clearly understood that, if a prior art publication is referred to herein, this reference does not constitute an admission that the publication forms part of the common general knowledge in the art in Australia or in any other country. 
       SUMMARY OF THE INVENTION 
       [0007]    The present invention is directed to a bioreactor, which may at least partially overcome at least one of the abovementioned disadvantages or provide the consumer with a useful or commercial choice. 
         [0008]    With the foregoing in view, the present invention in one form, resides broadly in a bioreactor including a rigid core associated with a light source, an outer expandable growth containment portion located concentrically about the rigid core, a lower end portion associated with an inlet to supply culture medium and an outlet, and an upper end cap with an opening therein through which the rigid core passes, wherein the outer containment portion expands as the cellular biological material contained in said portion grows and expands. 
         [0009]    The present invention therefore is intended to provided a device for culturing cellular biological material in the form of solid particles in which the said solid particles are brought into contact with a liquid culture medium, making it possible to keep the density by volume of the said cellular biological material substantially constant with respect to the volume of the said culture medium. 
         [0010]    It has been found that it is advantageous to carry out culturing at a constant density by volume of cells in order to have correct development of the embryos or even to reduce this density by increasing the volume of the culturing enclosure, partly due to the release of certain compounds during maturation of the embryos, it being possible for these compounds to have a stimulating or inhibiting effect on the maturation. 
         [0011]    The bioreactor of the present invention can be adapted for any use, but is particularly well-suited for growing carbon dioxide sequestrating biological material, methane digestion, fuel production or water production. Any biological material or growth culture medium may be used. 
         [0012]    The bioreactor of the present invention may be of any shape, but a cylindrical shape is preferred. Typically, the components of the bioreactor will be located concentrically about a central axis. The bioreactor will normally be substantially vertical in orientation although other orientations may be used. In the vertical orientation, growth of the biological material will force expansion of the containment portion upwardly. 
         [0013]    The bioreactor of the present invention will normally include a liquid culture medium. The biological material will normally be referred to as “solid particles” in order to distinguish them from the liquid culture medium only. 
         [0014]    The bioreactor will of course be provided in differing sizes depending upon application, but preferred sizes are between 1 and 10 meters in height with a particularly preferred configuration of approximately 2 m in overall height (or length) and between 20 cm to 5 m in diameter with a particularly preferred configuration of approximately 20 cm to 1 m in diameter. 
         [0015]    The bioreactor of the present invention also includes a rigid core associated with a light source. The rigid core will typically be oriented substantially vertically. The core is preferably formed of a hollow tubular member which will also preferably be cylindrical. 
         [0016]    The core is preferably manufactured of a translucent plastic such as translucent PVC but other materials for example, strengthened glass may be used. The core is also preferably longer (higher) than the length (height) of a containment portion expanded to maximum expansion. 
         [0017]    The core is preferably maintained substantially vertically by a support frame or an overhead fixing frame. The fixing frame is preferably attached to the core at an upper portion. The attachment between the core and the fixing frame is preferably removable in order to change or repair the light source, for example. 
         [0018]    The rigid core typically extends from adjacent the lower end cap, upwardly. The core is typically provided with a closed bottom and an open top. 
         [0019]    The core is preferably provided with an attachment portion on a lower portion and normally on an outer surface of the closed bottom of the core. 
         [0020]    The dimensions of the core may vary, but for example, for a 6 m high bioreactor, the core is preferably approximately 10 cm in diameter. The dimensions of the core may be as low as 5-10 mm if a fibre optic light source is used. 
         [0021]    The rigid core is associated with a light source preferably a controlled light source to provide optimum conditions for growth of the biological material. Any suitable light source may be used. Examples include fluorescent light or a fiber-optic array. The light source may be controlled to provide a particular wavelength or band of light. 
         [0022]    The bioreactor of the present invention includes an outer expandable growth containment portion located concentrically about the rigid core. The containment portion may include an outer wall and an inner wall with the containment zone defined therebetween. The inner wall is preferably located adjacent the core and the outer wall is then spaced concentrically outwardly therefrom. 
         [0023]    The inner wall of the containment portion is preferably translucent and have a concertina-like configuration allowing length (height) adjustment. The outer wall of the containment portion is preferably opaque and have a concertina-like configuration allowing length (height) adjustment. 
         [0024]    Each of the concertina-like walls will preferably be formed of a flexible material with a plurality of hinge or fold lines extending circumferentially about the wall to allow expansion and contraction. The portions of each wall located between the hinge or fold lines will typically be adapted to maintain a substantially planar shape and resist deformation or bulging of the wall under load. The hinge lines may therefore be the main functional component in allowing the expansion and contraction. 
         [0025]    The preferred material of construction for each of the walls is plastic with the type of plastic chosen to suit the requirements of each of the walls. 
         [0026]    The inner wall may be provide with a closed lower end. The upper end of the inner wall will typically be attached relative to the upper end cap in order to allow the inner wall to be drawn upwardly as the upper cap moves upwardly. An upper end or portion of the inner wall may therefore be provided with an externally threaded portion. 
         [0027]    Both walls will typically be provided with the optimum surface conditions for growth of biological material and material and/or physical characteristics adapted to suit. 
         [0028]    The inner wall is also preferably further provided with an attachment portion adapted to attach to the rigid core attachment portion so that both can be removed from within the outer wall together if required. 
         [0029]    The bioreactor of the present invention includes a lower end portion associated with an inlet to supply culture medium when required, and an outlet. The lower end portion may be a cap, typically a support member that supports the remainder of the bioreactor components. The lower end cap is suitably attached to the outer wall of the containment portion and is preferably sealed thereto, typically to an outer surface of the outer wall. 
         [0030]    The lower end cap is normally sized to define the outer dimension of the expanded reactor. 
         [0031]    The inlet and outlet are preferably in fluid communication with the containment portion. Both the inlet and the outlet are preferably selectively operable and valve assemblies will normally be provided in association with each. The inlet and outlet are typically horizontally opposed to one another. The inlet is typically smaller in diameter than the outlet. 
         [0032]    The bioreactor of the present invention includes an upper end cap with an opening therein through which the rigid core passes. The upper end cap is preferably attached to the outer wall in a manner similar to the lower end cap. The upper end cap will normally be formed of a material similar to that used to form the lower end cap namely a metal or more typically, a plastic material. 
         [0033]    The upper end cap usually attaches to the inner wall of the containment portion. The opening in the upper end cap for the rigid core is normally located centrally with a secondary opening provided for a bleed/pressure relief valve. The secondary opening is normally threaded to provide a removable attachment means for the bleed/pressure relief valve. 
         [0034]    The central opening may have an associated collar to attach the inner wall of the containment portion thereto. The collar will preferably be annular to receive the rigid core and then extend through the central opening in the upper end cap which will be suitably dimensioned to receive both the rigid core and the collar. 
         [0035]    The collar will normally be provided with an outer seating portion to locate the collar on the end cap and be engaged there. An O-ring or similar sealing means will also be provided on the collar in an internal seating groove to form a fluid tight seal with the outer surface of the rigid core. The lower portion of the collar will be provided with an internally threaded portion engageable with the externally threaded portion on the inner wall of the containment portion. 
         [0036]    In an alternative embodiment, the containment portion may be provided between the outer containment wall and the light source, without an inner wall. According to this configuration, the movable end cap (typically the upper end cap) will normally be provided with a sealing grommet associated with the opening in the end. The sealing grommet preferably closely receives the light source and is slidable upwardly and downwardly relative to the light source. The sliding action will also assist with keeping the light source clean. 
         [0037]    In use, an initiating portion of a chosen biological material is placed or fed into the containment portion of the bioreactor, together with a suitable initial charge of culture medium. The conditions within the containment portion are thereafter controlled to optimise growth in the bioreactor. As the material grows the containment portion expands. Once mature, the rigid core and inner wall can be removed as can the mature material, and the containment portion can either be cleansed and collapsed ready for re-use or the mature material can simply be removed, and a new culture medium inserted, with the remnants of the mature material providing the starter biological material for the new batch. The remnants will typically be trapped during compression or collapse of the containment portion between the concertina parts of the wall(s). 
         [0038]    The outer wall of a particularly preferred embodiment may be additionally supported through the provision of one or more reinforcement members. The reinforcement members will normally act to support the flexible material used as the outer wall in order to assist with maintaining the shape of the outer wall. 
         [0039]    Various configurations and numbers of reinforcement members may be used. For example, according to one preferred embodiment, a plurality of annular or ring-shaped reinforcement members can be provided, spaced over the height of the outer wall with a portion of the ring supporting the outer wall. The reinforcement members can be provided either on the inside of the outer wall on the outside of the outer wall. 
         [0040]    Where the reinforcement members of this embodiment are provided internally, the reinforcement members may be provided in a portion of the outer wall which bulges outwardly, and where the reinforcement members of this embodiment are provided externally of the outer wall, the ring members will typically be provided in portions of the outer wall between outward bulges. 
         [0041]    In an alternate embodiment, a helical reinforcement member may be provided within (or outside) the outer wall. Provision of a helical reinforcement member is advantageous in the as well as supporting the outer wall during expansion, the helical coil is also self aligning when of the outer wall is compressed. 
         [0042]    In a further preferred embodiment, the reinforcement members may be integrated into the outer wall and formed therewith. In this form, the reinforcement members may preferably be a portion of the wall with increased thickness. Normally, the reinforcement members/portions of this embodiment may be provided as an outwardly bulging part of the outer wall. According to this embodiment, the outer wall may be manufactured by extrusion of a particular thickness of wall portion and then stretching a portion of that wall to decreased thickness leaving thickened reinforcement portions interspersed with the thinner wall portions. 
         [0043]    According to further embodiments of the invention, a plurality of bioreactors may be provided mounted on a base member. The base members may form a part of a fixed assembly or a portable assembly. 
         [0044]    The base member will typically be provided with utilities such as heating and a biological material inlet and outlet with appropriate connections to each bioreactor. Each bioreactor is typically attached to the base through the provision of a base fitting and attaching the outer wall of the bioreactor to the base fitting. Typically, the connection between the base fitting and the bioreactor will be formed using a clamping means. 
         [0045]    Preferably, the base member will be a structural member capable of being lifted by lifting means such as a forklift. The base member will preferably be provided with a biological material feed inlet and a biological material outlet with appropriate connections to each of the bioreactor is mounted on the base member. The base member will also preferably include a conduit for a heating medium with an inlet and an outlet and a conduit in communication with each of the bioreactors. 
         [0046]    The base member is preferably configured so that more than one base member and can be located adjacent one another and the heating medium inlet and outlet as well as the biological material inlet and outlet of adjacent base members are aligned or communicate. This will allow a single pump means to move heating medium through all of the base members and another single pump means to move on biological material through all of the base members. Preferably, the biological material conduit and the heating medium conduit are co-current. 
         [0047]    The inlets and outlets of the base member will preferably be associated with valve means. 
         [0048]    The present invention is particularly adapted to use salt water or brine based bacteria. 
         [0049]    Using appropriate bacteria, the inventor has found that a single bioreactor with a maximum height of approximately 2 m and approximately 30 cm in diameter can absorb up to 2.75 kg in a 24 hour period of carbon dioxide. 
         [0050]    According to an alternative embodiment, there may be a secondary chamber provided surrounding the bioreactor of the invention. The secondary chamber will typically be a process vessel and according to a preferred embodiment will also be a bioreactor. This embodiment of the invention is preferably adapted for use on portable or transportable equipment to treat particularly emissions from the equipment. 
         [0051]    According to this embodiment, the secondary chamber will be a secondary bioreactor to treat the incoming material to remove the same or different pollutants as the inner, primary bioreactor. The inlet will preferably be into the secondary chamber and normally towards a lower portion of the secondary chamber. Located at or towards an upper portion of the secondary chamber is typically an outlet which is in turn connected to a lower inlet into the primary bioreactor. 
         [0052]    The primary bioreactor and secondary bioreactor are preferably separated by a separating assembly which will normally be rigid. The separating assembly will normally have a substantially centrally located outlet which according to a preferred embodiment, is coaxially mounted with the light source. 
         [0053]    Both bioreactors may be variable volume according to this embodiment or only the inner, primary bioreactor may be variable volume. Culture medium and growth medium will normally be provided in portion between the separating assembly and the secondary chamber wall. Oxygen supply apparatus may also be provided in a lower portion of the secondary bioreactor. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0054]    Various embodiments of the invention will be described with reference to the following drawings, in which: 
           [0055]      FIG. 1  is a schematic view from the side of a bioreactor according to a preferred aspect of the present invention, in a partially expanded condition. 
           [0056]      FIG. 2  is a schematic view from the side of the bioreactor illustrated in  FIG. 1  in a compressed condition. 
           [0057]      FIG. 3  is a detailed section view of an upper portion of the bioreactor illustrated in  FIG. 1 . 
           [0058]      FIG. 4  is a sectional elevation view of a containment portion according to a preferred embodiment. 
           [0059]      FIG. 5  is a sectional elevation view of a containment portion according to an alternative embodiment. 
           [0060]      FIG. 6  is a sectional elevation view of a containment portion according to an alternative embodiment. 
           [0061]      FIG. 7  is a sectional elevation view of a containment portion according to an alternative embodiment. 
           [0062]      FIG. 8  is a sectional elevation view of a containment portion according to an alternative embodiment. 
           [0063]      FIG. 9  is a sectional elevation view of a containment portion according to an alternative embodiment. 
           [0064]      FIG. 10  is a view from above of a base mount for a cluster of four bioreactors with attendant utilities according to a preferred embodiment. 
           [0065]      FIG. 11  is a side elevation view of the base mount of  FIG. 10  with containment portions attached. 
           [0066]      FIG. 12  is a sectional side elevation view of bioreactor cluster according to a first preferred embodiment, in a partially extended condition. 
           [0067]      FIG. 13  is a view from above of a base mount for a cluster of four bioreactors with attendant utilities according to a preferred embodiment. 
           [0068]      FIG. 14  is a side elevation view of the base mount of  FIG. 13  with containment portions attached. 
           [0069]      FIG. 15  is a sectional side elevation view of bioreactor cluster according to a first preferred embodiment, in a fully extended condition. 
           [0070]      FIG. 16  is a view from above of a base mount for a cluster of four bioreactors with attendant utilities according to a preferred embodiment. 
           [0071]      FIG. 17  is a side elevation view of the base mount of  FIG. 16  with containment portions attached. 
           [0072]      FIG. 18  is a sectional side elevation view of bioreactor cluster according to a second preferred embodiment, in a partially extended condition. 
           [0073]      FIG. 19  is a view from above of a base mount for a cluster of four bioreactors with attendant utilities according to a preferred embodiment. 
           [0074]      FIG. 20  is a side elevation view of the base mount of  FIG. 19  with containment portions attached. 
           [0075]      FIG. 21  is a sectional side elevation view of bioreactor cluster according to a second preferred embodiment, in a fully extended condition. 
           [0076]      FIG. 22  is a view from above of a base mount for a cluster of four bioreactors with attendant utilities according to a preferred embodiment. 
           [0077]      FIG. 23  is a side elevation view of the base mount of  FIG. 22  with containment portions attached. 
           [0078]      FIG. 24  is a sectional side elevation view of bioreactor cluster according to a third preferred embodiment, in a partially extended condition. 
           [0079]      FIG. 25  is a view from above of a base mount for a cluster of four bioreactors with attendant utilities according to a preferred embodiment. 
           [0080]      FIG. 26  is a side elevation view of the base mount of  FIG. 25  with containment portions attached. 
           [0081]      FIG. 27  is a sectional side elevation view of bioreactor cluster according to a third preferred embodiment, in a fully extended condition. 
           [0082]      FIG. 28  is a view from above of a base mount for a cluster of four bioreactors with attendant utilities according to a preferred embodiment. 
           [0083]      FIG. 29  is a side elevation view of the base mount of  FIG. 28  with containment portions attached. 
           [0084]      FIG. 30  is a sectional side elevation view of bioreactor cluster according to a fourth preferred embodiment, in a partially extended condition. 
           [0085]      FIG. 31  is a view from above of a base mount for a cluster of four bioreactors with attendant utilities according to a preferred embodiment. 
           [0086]      FIG. 32  is a detail sectional elevation view of a portion of a containment portion according to a fourth preferred embodiment. 
           [0087]      FIG. 33  is a side elevation view of the base mount of  FIG. 32  with containment portions attached. 
           [0088]      FIG. 34  is a sectional side elevation view of a bioreactor cluster according to a fourth preferred embodiment, in a fully extended condition. 
           [0089]      FIG. 35  is a sectional side view of a bioreactor assembly with an outer secondary bioreactor according to a preferred embodiment, with the primary bioreactor in partially extended condition. 
           [0090]      FIG. 36  is a sectional side view of the bioreactor assembly illustrated in  FIG. 35  with the primary bioreactor in a fully extended condition. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT 
       [0091]    According to a preferred aspect of the present invention, an expandable bioreactor is provided. 
         [0092]    The bioreactor  10  of the illustrated embodiment includes a rigid core  11  associated with a light source  12 , an outer expandable growth containment portion located concentrically about the rigid core  11 , a lower end cap  13  with an inlet  14  to supply culture medium and an outlet  15 , and an upper end cap  16  with an opening  17  therein through which the rigid core  11  passes. 
         [0093]    The rigid core  11  of the illustrated embodiment is oriented substantially vertically. The core  11  is formed of a hollow tubular member which is cylindrical. 
         [0094]    The core  11  is manufactured of a translucent plastic such as translucent PVC. As illustrated in  FIG. 1  in particular, the core  11  is longer (higher) then the length (height) of a containment portion expended to maximum expansion. 
         [0095]    The core  11  is maintained substantially vertically by an overhead fixing frame  18 . The fixing frame  18  is attached to the core  11  at an upper end. The rigid core  11  extends from adjacent to the lower end cap  13  upwardly. The core is provided with a closed bottom and an open top. 
         [0096]    The core  11  is also provided with an attachment portion  19  on an outer surface of the closed bottom of the core  11 . 
         [0097]    The rigid core  11  is associated with a light source  12  preferably a controlled light source to provide optimum conditions for growth of the biological material. According to the illustrated embodiment, a fluorescent light extending over the height of the containment portion is used. 
         [0098]    The outer expandable growth containment portion is located concentrically about the rigid core. The containment portion includes an outer wall  20  and an inner wall  21  with the containment zone defined therebetween. The inner wall  21  is located adjacent the core  11  and the outer wall  20  is then spaced concentrically outwardly therefrom. 
         [0099]    The inner wall  21  of the containment portion is translucent and has a concertina-like configuration allowing length (height) adjustment as does the outer wall of the containment portion, though the outer wall  20  is preferably opaque. 
         [0100]    Each of the concertina-like walls is formed of a flexible material with a plurality of hinge or fold lines  22  extending circumferentially about the wall to allow expansion and contraction. The portions  23  of each wall located between the hinge or fold lines  22  are adapted to maintain a substantially planar shape and resist deformation or bulging of the wall. 
         [0101]    The inner wall  21  is provided with a closed lower end. As illustrated best in  FIG. 3 , the upper end of the inner wall  21  is attached relative to the upper end cap  16  in order to allow the inner wall  21  to be drawn upwardly as the upper cap  16  moves upwardly. An upper portion of the inner wall  21  is provided with an externally threaded portion. 
         [0102]    The inner wall  21  is also provided with an attachment portion adapted to attach to the rigid core  11  attachment portion  19  so that both can be removed from within the outer wall  20  together if required. 
         [0103]    The lower end cap  13  is attached to the outer wall  20  of the containment portion and is sealed thereto. The lower end cap  13  is sized to define the outer dimension of the expanded bioreactor as is illustrated in the lower portion of the bioreactor in  FIG. 1 . 
         [0104]    The inlet  14  and outlet  15  are in fluid communication with the containment portion. The inlet  14  and outlet  15  are horizontally opposed to one another with the inlet  14  being smaller in diameter than the outlet  15 . 
         [0105]    The upper end cap  16  is attached to the outer wall  20  in a manner similar to the lower end cap  13 . 
         [0106]    The upper end cap  16  attaches to the inner wall  21  of the containment portion. The main opening  17  in the upper end cap  16  for the rigid core  11  is located centrally with a secondary opening  24  provided for a bleed/pressure relief valve  25 . The secondary opening  24  is threaded to provide a removable attachment means for the bleed/pressure relief valve  25 . 
         [0107]    The main opening  17  has an associated collar  26  to attach the inner wall  21  of the containment portion thereto. The collar  26  is annular to receive the rigid core  11  and then extend through the main opening  17  in the upper end cap  16  which will be suitably dimensioned to receive both the rigid core  11  and the collar  26 . The collar  26  has an outer seating portion to locate the collar  26  on the upper end cap  16  and be engaged there. An O-ring sealing means  27  is also provided on the collar  26  in an internal seating groove to form a fluid tight seal with the outer surface of the rigid core  11 . The lower portion of the collar  26  is provided with an internally threaded portion engageable with the externally threaded portion on the inner wall  21  of the containment portion. 
         [0108]    Various configurations and numbers of reinforcement members  28  used according to preferred embodiments are illustrated in  FIGS. 4 to 9 . For example, according to the embodiment illustrated in  FIGS. 4 and 5 , a plurality of annular or ring-shaped reinforcement members  28  are provided, spaced over the height of the outer wall  20  with a portion of the reinforcing member supporting the outer wall  20 . 
         [0109]    The reinforcement members  28  can be provided either on the inside of the outer wall or outside of the outer wall as illustrated in  FIG. 8 . Where the reinforcement members  28  are provided internally, the reinforcement members are provided in a portion of the outer wall  20  which bulges outwardly (as illustrated in  FIG. 4  in particular), and where the reinforcement members  28  are provided externally of the outer wall  20 , the ring members will typically be provided in portions of the outer wall  20  between outward bulges. 
         [0110]    In the embodiment illustrated in  FIGS. 6 and 7 , a helical reinforcement member  28  is provided within the outer wall  20 . 
         [0111]    In the further embodiment illustrated in  FIG. 9 , the reinforcement members  28  can be integrated into the outer wall  20  and formed therewith. In this form, the outer wall  20  is manufactured by extrusion of a particular thickness of wall portion and then stretching a portion of the wall down to decreased wall thickness leaving thickened reinforcement portions  28  interspersed with the thinner wall portions. 
         [0112]    As illustrated in  FIGS. 10 to 34 , a plurality of bioreactors  10  can be provided mounted on a base member  36 . Each base member  36  is provided with utilities such as a heating conduit  34  and a biological material inlet  29  and outlet  30  with appropriate connections to each bioreactor  10 . Each bioreactor  10  is typically attached to the base member  36  through the provision of a base fitting  31  and attaching the outer wall  20  of the bioreactor  10  to the base fitting  31 . Typically, the connection between the base fitting  31  and the bioreactor  10  will be formed using a clamping means  35 . 
         [0113]    The conduit  34  for the heating medium will have an inlet  32  and an outlet  33  and be in communication with each of the bioreactors  10  of the base member. 
         [0114]    Each base member is configured so that more than one base member  36  and can be located adjacent one another to create a modular assembly and the heating medium inlet  32  and outlet  33  as well as the biological material inlet  29  and outlet  30  of adjacent base members  36  are aligned or communicate. This will allow a single pump means (not shown) to move heating medium through all of the base members  36  and another single pump means to move on biological material through all of the base members  36 . 
         [0115]    According to an alternative embodiment illustrated in  FIGS. 35 and 36 , there may be a secondary chamber  37  provided surrounding the bioreactor  10  of the invention. The secondary chamber  37  is a process vessel and is a bioreactor. 
         [0116]    According to the illustrated embodiment, the secondary chamber  37  is a secondary bioreactor to treat the incoming material to remove the same or different pollutants as the inner, primary bioreactor  10 . The inlet  38  will preferably be into the secondary chamber  37  towards a lower portion of the secondary chamber  37 . Located at or towards an upper portion of the secondary chamber  37  is an outlet  39  which is in turn connected to a lower inlet  14  into the primary bioreactor  10  by a transfer pipe  42 . 
         [0117]    The primary bioreactor  10  and secondary bioreactor chamber  37  are separated by a rigid separating wall  40 . The separating wall  40  has a substantially centrally located outlet  41  which according to a illustrated embodiment, is coaxially mounted with the light source. 
         [0118]    In the present specification and claims (if any), the word “comprising” and its derivatives including “comprises” and “comprise” include each of the stated integers but does not exclude the inclusion of one or more further integers. Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure, or characteristic described in connection with the embodiment is included in at least one embodiment of the present invention. Thus, the appearance of the phrases “in one embodiment” or “in an embodiment” in various places throughout this specification are not necessarily all referring to the same embodiment. Furthermore, the particular features, structures, or characteristics may be combined in any suitable manner in one or more combinations.