FIELD OF THE INVENTION

[0001] The present invention relates generally to reactors and, in particular, to packed bed reactors suitable for use in chemical and biological processes, and specifically, the present invention relates to packed bed reactors for removing contaminants from a wastewater stream.

BACKGROUND OF THE INVENTION

[0002] Packed reactors are commonly used in the chemical, pharmaceutical, waste treatment, and fermentation industries for a variety of processes. In general, packing provides an increase in surface area inside the reactor, based on the surface area to volume ratio of the particular packing selected. Generally, the surface area of the packing provides a surface onto which reaction promoters such as microbes may attach in biological reactors, or onto which reaction promoters such as chemical catalysts may be attached in chemical reactors. Since the reaction process, whether biological or chemical, is generally dependent upon reactant contact and time of contact with the reaction promoter, providing larger surface areas with the reaction promoter within a reactor volume may facilitate reactor size reduction leading to cost savings. Accordingly, the larger the surface area to volume ratio, the smaller volume of reactor is necessary for a particular process.

[0003] Commercially available packing varies widely in shape and may include elements to increase the surface area. For example, a cylindrical packing material may have an axial through bore, to provide both inner and outer surfaces to increase the surface area to volume ratio. In addition, the cylindrical packing may include inner and/or outer ribs or other structure to further increase effective surface area.

[0004] Referring for example more specifically to biological reactors used in waste treatment, the contaminants serve as a food source, generally as a source of carbon and/or nitrogen, for microorganisms on the reactor packing. Bacterial metabolism converts the contaminants to metabolites generally with a simple chemical structure, sometimes degrading the contaminants completely to carbon dioxide and water in an aerobic process, or to methane in an anaerobic process. But in any event, the metabolites usually have no adverse environmental effects.

[0005] U.S. Pat. Pub. No. 2007/0007201, the entirety of which is hereby incorporated by reference, describes an exemplary reactor and discusses various known processes for using such reactors for removing contaminants.

[0006] Some packed bed reactors are fixed bed reactors in which packing material is held in a relatively stationary position by one or more structures, such as grates, screens, or other similar structures. The openings in the retaining structures allows gases and liquids to pass, but solids such as the packing, as well as biological deposits are retained within a space below the retaining structure. In contrast to fixed bed, some reactors allow the packing material to move freely within the reactor.

[0007] In either design, over time the openings of the packing become clogged by solid accumulating on the packing. The clogging restricts the flow through the openings, which, in turn, lowers performance of the reactor. In order to clean the packing, the reactor is often shutdown, which is not desirable.

[0008] Therefore, it would be desirable to have fixed bed reactors which contain packing and which provide for the effective and efficient removal of one or more contaminants from wastewater. It would be additionally desirable to have more effective and efficient processes for removing of one or more contaminants from a fixed bed reactor.

SUMMARY OF THE INVENTION

[0009] A new fixed bed reactor and a process for removing of one or more contaminants have been invented which address one or more of the problems described above. In the new fixed bed reactor, which contains material with is made up of grains (sand, carbon, etc.) or other non-rigid media, one or more of the retaining structures are selectively movable. The moveable retaining structures are moved to allow solid deposits on the packing to be scoured or cleaned off the packing.

[00010] The present invention may therefore be generally characterized, in at least one aspect, as providing a reactor for the biological treatment of wastewater including a vessel having an inlet for wastewater and an outlet for treated wastewater, an gas stream inlet configured to supply an oxygen containing gas stream into the vessel, a packed bed disposed within the vessel, the packed bed including one or more types of packing elements and one or more types of attendant microorganisms, the packed bed being substantially stationary within the vessel, and, a top plate, having a plurality of openings, disposed above the packed bed and configured to move between a first position in which the packing elements are substantially stationary within the fixed bed reactor and a second position in which the packing elements are not substantially stationary within the fixed bed reactor.

[00011] In at least one aspect the present invention may also be generally characterized as providing a fixed bed reactor for treatment of wastewater including a vessel having an inlet for wastewater and an outlet for treated wastewater, a packed bed disposed within the vessel, the packed bed comprises one or more packing elements and one or more types of attendant microorganisms, and a top plate, having a plurality of openings, disposed above the packed bed. The top plate includes a plurality of sections and at least one section from the plurality of sections is a moveable section configured to move between a first position in which the packing elements are substantially stationary within the fixed bed reactor and a second position in which the packing elements are not substantially stationary within the fixed bed reactor.

[00012] The present invention may also be generally characterized, in at least one other aspect, as providing a process for removing at least one contaminant from a wastewater stream in which the process includes passing a wastewater stream into a fixed bed reactor, the wastewater stream including at least one contaminant and the fixed bed reactor including one or more substantially stationary packing elements and one or more types of microorganisms associated with the packing elements, passing a gaseous stream comprising oxygen into the fixed bed reactor so that the one or more types of microorganisms remove the at least one contaminant from the wastewater stream in the presence of oxygen from the oxygen stream, recovering a treated wastewater stream from the fixed bed reactor, and, moving at least a portion of a top plate disposed above the substantially stationary one or more packing elements from a first position in which the packing elements are substantially stationary within the fixed bed reactor to a second position in which the packing elements are not substantially stationary within the fixed bed reactor. The top plate includes a plurality of openings.

[00013] Additional aspects, embodiments, and details of the invention, all of which may be combinable in any manner, are set forth in the following detailed description of the invention.

DETAILED DESCRIPTION OF THE DRAWINGS

[00014] One or more exemplary embodiments of the present invention will be described below in conjunction with the following drawing figures, in which:

[00015] Figure 1 shows a schematic cross section of a reactor according to the present invention;

[00016] Figure 2 shows a schematic cross section of the reactor shown in Figure 1 in which a section of the top plate has been moved;

[00017] Figure 3 shows a top view of a top plate used in a reactor according to the present invention;

[00018] Figure 4 shows a side view of a top plate used in a reactor according to the present invention; and,

[00019] Figure 5 shows a front view of a section of a top plate used in a reactor according to the present invention.

DETAILED DESCRIPTION OF THE INVENTION [00020] One or more embodiments of the present invention will now be described with the understanding that the following description is not intended to be limiting. Furthermore, there is no intention to be bound by any expressed or implied theory presented in the preceding sections or the following detailed description.

[00021] With reference to Figures 1 and 2, a reactor 100 is provided for removing one or more contaminants of materials contained in a feed stream by aerobic or anaerobic microbes. As used herein, the term“contaminant” includes both dissolved and suspended compounds including some (generally degradable) organic compounds, as well as some inorganic nitrogen containing species such as ammonia (NFF) and nitrogen oxides (e.g. N0 ₃ , NO2 etc.) and halogenated organic compounds. The feed stream is typically a wastewater stream.

[00022] The reactor 100 in Figures 1 and 2 comprises a vessel 102 with a horizontal orientation (i.e., the longitudinal axis is generally parallel with the horizon). However, in the practice of this invention, the design, configuration and materials of construction may vary widely and other reactor designs and configurations may be conveniently used.

[00023] The vessel 102 includes an inlet 104 for wastewater, and a gaseous stream inlet 106 configured to supply a gaseous oxygen containing stream into the vessel 102, and an outlet 108 for providing a stream of treated waste water. The gaseous oxygen containing stream is air or another gas stream that is predominately oxygen or contains oxygen. The inlet 104 for wastewater and the gaseous stream inlet 105 utilize distributors for dispersing the streams into the vessel 102. Additionally, the vessel 102 includes one or more gas outlets 109 for venting gases, and one or more drain valves 111 for draining or removing particulate matter that has collected at the bottom of the vessel 102. A packed bed 110 is disposed within the vessel 102 so that wastewater flows through the packed bed 110 when passing from the inlet 104 to the outlet 108.

[00024] The vessel 102 depicted in Figures 1 and 2 is divided in a plurality of sections 1 l3a - 1 l3e. The sections 1 l3a - 1 l3e are separated from each other by walls 115. The walls 115 are solid (i.e., not porous) and extend from a bottom of the vessel 102 to a top of the vessel 102. Each section 1 l3a - 1 l3e includes one of the gas outlets 109 at a top and one of the drain valves 111 at a bottom. Conduits 117 extend from an upper portion of one section 1 l3a-l l3d to a lower portion of the immediately downstream section 1 l3b-l l3d, respectively.

[00025] Thus, wastewater flows into the vessel 102 at the inlet 104 and upward in the first section H3a. From the upper portion of the first section H3a, the wastewater (and particulate matter) flows through the first conduit 117 and is introduced into the lower portion of the second section H3b. The wastewater then flows upward through the second section H3b, while the particulate material falls to the bottom of the second section H3b and be removed from the vessel 102 via the drain valve 111 of the second section H3b. The wastewater in the second section H3b flows upward and to the third section H3c via the second conduit 117, the wastewater in the third section 113c flows upward and to the fourth section 1 l3d via the third conduit 117, and so on and so forth, until the last section 1 l3e. Any particulate, or solid, materials in the wastewater being transferred via the conduits 117 is accumulated in the bottom of a downstream section H3b - H3e or flows out the vessel 102 via the outlet 108. From the top of the last section 1 l3e, treated wastewater is recovered from the vessel 102 via the outlet 108.

[00026] Although not depicted as such, a clarifier or filter may be installed downstream of the reactor 100 which removes any particulate material that is in the treated wastewater recovered from the outlet 108. One of ordinary skill in the art will appreciate that any number of sections 1 l3a - 1 l3e can be used. Additionally, although the vessel 102 is depicted as being a closed top vessel, it is contemplated that the top of the vessel 102 is open to the surrounding atmosphere.

[00027] The packed bed 110 in each of the sections H3a - H3e includes one or more packing elements 114 with one or more types of attendant microorganisms 112 (i.e., microorganisms associated with the packing elements 114). The microorganisms 112 can be supported on a substrate 116 and/or the packing elements 114. As is known in the art, the microorganisms 112 are either aerobic or anaerobic, preferably aerobic, and are capable of metabolizing at least one of the contaminant contained in the wastewater stream on, in or on and in the substrate 116. In general, any of a variety of structures that are capable of providing for open or substantially open regions for fluid flow there through may be used as the packing elements 114 and the substrate 116 within the packed bed 110 provided that the structures include passages (voidage or void space) through which process fluid(s) can flow.

[00028] According to the present invention, the packed bed 110 is substantially stationary within the vessel 102, and specifically within each section 1 l3a - 1 l3e of the vessel 102. As used herein“substantially stationary” means that the packing elements 114 and substrates 116 are stationary or substantially stationary as the process fluid flows through the sections H3a - H3e of the reactor 100. In order to maintain the packed bed 110 as substantially stationary within the sections H3a - H3e of the vessel 102, the reactor 100 includes a top plate 118 disposed above the packed bed 110. The top plate 118 includes a plurality of openings 120 (see Figure 3 having a size that allows the gases and liquids to flow therethrough, but which retains solids materials greater than the size of the openings 120). For example, the openings 120 can have any number of sizes and preferably do not exceed 1.5 square inches, or have a greatest measurement that exceeds two inches. The size of the openings 120 in the top plate 118 can be uniform, or, the top plate 118 can include openings 120 with varying sizes.

[00029] The top plate 118 includes a plurality of sections l22a - l22e, which are configured to move between a first position (Figure 1) and a second position (Figure 2). In the first position, the top plate 118, or each section l22a - l22e thereof, maintains the packed bed 110 substantially stationary. In the second position, the top plate 118 (or the section l22a - l22e) no longer maintains the packed bed 110 substantially stationary and the packing elements 114 and the substrate 116 are free to move around within the vessel 102 (or within the respective section 1 l3a - 1 l3b of the vessel 102). Preferably, a distance between the first and the second positions is smaller than a size of the packing elements 114 and the substrate 116 so that neither flows out of the sections H3a - H3e when the respective section l22a - l22e of the top plate 118 is in the second position. [00030] Turning to Figures 3 and 4, a top plate 118 with four sections l22a - l22d is shown. It is contemplated that each section l22a - l22d, is configured to move between the first position and the second position independently of each other. As depicted in Figure 3, each section l22a - l22d of the top plate 118, when viewed from a top, comprises a rectangular shape that corresponds to the section H3a - H3e of the vessel 102. Thus, the rectangular shapes each comprise a first linear dimension Ll, and a second linear dimension L2, smaller than the first linear dimension Ll . For example, the rectangular shape may measure 3.5 meters by 3 meters (11.5 feet by 10 feet). Thus, each section l22a - l22d of the top plate 118 may have a rectangular shape that is no greater than 3.5 meters by 3 meters. Other shapes and sizes may be used as required and depending on the shape and configuration of the vessel 102.

[00031] Figures 4 and 5 depict a preferred arrangement for moving the sections l22a - l22d of the top plate 118 between the first and second positions. For simplicity of the drawings, only the second section l22b is shown in the detail discussed herein.

[00032] Specifically, each side of the second section l22b of the top plate 118 includes a threaded shaft 124 secured thereto. The threaded shafts 124 are each secured to a shoe 126 attached to one of the sides of the second section l22b of the top plate 118. Other known structures and elements for connecting the threaded shaft 124 may be used without departing from the spirit of the present invention. A gear 128, fixed in position relative to the vessel 102, engages each of the threaded shaft 124, such that teeth 130 of the gears 128 engage the gaps 132 between the threads 134 of the threaded shafts 124. Thus, rotation of the gears 128 will cause the threaded shafts 124, and the second section l22b of the top plate 118, to move up and down within the vessel 102 (in relation to the orientation shown in the drawings). A motor 136 is provided to drive each of the gears 128. While Figure 5 depicts two motors 136 being utilized for moving the second section l22b, it is contemplated that only one motor 136 is used.

[00033] Again, this is merely one contemplated arrangement of providing a movable top plate 118 in the reactor 100 and other modifications can be included. For example, a clutch can be provided to allow the motor to engage and disengage gears associated with different sections l22a - l22d of the top plate 118. Additionally, in the depicted embodiment, the threaded shafts 124 are disposed at a midpoint of a side of the section l22a of the top plate 118. Other positions and numbers of threaded shafts 124 may be used. By providing the reactor 100 with the top plate 118 that is movable, the downtime of the reactor as a result of clogging can be reduced. Furthermore, it is contemplated that one or more tracks or guide elements are provided to guide the sections l22a - l22e of the top plate 118 as they move between the first and second positions.

[00034] In use, a wastewater stream is passed through the inlet 104 into reactor 100. As discussed above, the wastewater stream, in addition to including water or some other liquids, includes at least one contaminant to be removed for various reasons. A gaseous stream comprising oxygen (such as air or a pure oxygen stream) is introduced through the gaseous stream inlet 106 into the reactor 100. Within the packed bed 110, the microorganisms 112 on the substrate 116 and/or the packing elements 114, in the presence of the oxygen, will remove the contaminant(s) from the wastewater. A treated wastewater stream is received from the reactor 100 via the outlet 108. As will be appreciated the treated wastewater stream will have a lower amount of the contaminant(s).

[00035] In order to remove solids that have been accumulating in the packed bed 110 as a result of the removal of the contaminant(s), at least a portion of the top plate 118 is moved, for example, by turning the gear 128. For example, the second section l22b of the top plate 118 is moved upward from the first position (Figure 1) to the second position (Figure 2). In the second position, the packing elements 114 and the substrate 116 of the packed bed 110 are not held in a substantially stationary manner and move about within the section 1 l3a - l33e of the vessel 102. In order to remove accumulated material from the packing elements 114 and the substrate 116, the air flow in the gaseous stream inlet 106 can be increased. The gas bubbling up with the vessel 102 creates turbulence and causes the packing elements 114 and the substrate 116 to move around. This agitation will loosen and remove the accumulated solids from the packing elements 114 and the substrate 116. Any solid materials either settle to the bottom of that section 1 l3a - 1 l3e of the vessel 102, or pass to another section 1 l3b— 1 l3e of the vessel 102 and collect at the bottom of that section 1 l3b - 1 l3e, or be collected in the filter downstream of the reactor 100 (discussed above). In a preferred operation, each section l22a - l22e of the top plate 118 is moved, one at a time, starting closest to the inlet 104 of the vessel 102. Again, as mentioned above, solid materials that accumulate at the bottom of the vessel 102 are removed via the drain valves 111 for each of the sections H3a - H3e of the vessel 102.

[00036] As discussed above, by providing the reactor with a top plate that is movable, the reactor (or individual sections thereof) allows the packed bed to be quickly and efficiently cleaned of contaminants which clog the openings of the elements of the packed bed. The use of the sections allows for different portions of the packed bed to be cleaned at different times.

[00037] It should be appreciated and understood by those of ordinary skill in the art that various other components such as valves, pumps, filters, coolers, etc. were not shown in the drawings as it is believed that the specifics of same are well within the knowledge of those of ordinary skill in the art and a description of same is not necessary for practicing or understanding the embodiments of the present invention.

SPECIFIC EMBODIMENTS

[00038] While the following is described in conjunction with specific embodiments, it will be understood that this description is intended to illustrate and not limit the scope of the preceding description and the appended claims.

[00039] A first embodiment of the invention is a reactor for the biological treatment of wastewater, the reactor comprising a vessel having an inlet for wastewater and an outlet for treated wastewater; a gaseous stream inlet configured to supply an oxygen containing gas into the vessel; a packed bed disposed within the vessel, the packed bed comprising one or more types of packing elements and one or more microorganisms associated with the packing elements; and, a top plate having a plurality of openings and being disposed above the packed bed, the top plate configured to move between a first position in which the packed bed is substantially stationary within the vessel and a second position in which the packed bed is not substantially stationary within the vessel. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein the top plate comprises a plurality of sections, each section configured to move between the first position and the second position. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein each section of the top plate is configured to move independently of other sections from the plurality of sections. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, wherein each section from the plurality of sections, when viewed from a top, comprises a rectangular shape. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the rectangular shapes each comprise a first linear dimension, and a second linear dimension, smaller than the first linear dimensions. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph, the top plate comprises a threaded shaft secured to the top plate. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising a gear configured to engage the threaded shaft and move the top plate between the first position and the second position. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph further comprising a motor configured to drive the gear. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the first embodiment in this paragraph wherein the top plate comprises a plurality of sections, and wherein the threaded shaft is disposed at a midpoint of a side of a section of the top plate.

[00040] A second embodiment of the invention is a fixed bed reactor for treatment of wastewater, the fixed bed reacto comprising a vessel having an inlet for wastewater and an outlet for treated wastewater; a packed bed disposed within the vessel, the packed bed comprising one or more packing elements and one or more types of attendant microorganisms; and, a top plate having a plurality of openings and being disposed above the packed bed, the top plate comprising a plurality of sections, at least one section from the plurality of sections comprising a moveable section configured to move between a first position in which the packed bed is substantially stationary within the vessel and a second position in which the packed bed is not substantially stationary within the vessel.

An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising a threaded shaft secured to the moveable section of the top plate. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising a gear configured to engage the threaded shaft and move the moveable section of the top plate between the first position and the second position. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph further comprising a motor configured to drive the gear. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the sections of the top plate are configured to be moved independently of each other. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein the movable section comprises a rectangular shape, when viewed from the top, and wherein the rectangular shape comprises a first linear dimension, and a second linear dimension, smaller than the first linear dimension. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the second embodiment in this paragraph wherein a size of the rectangular shape does not exceed 3.5 meters by 3 meters. [00041] A third embodiment of the invention is a process from removing at least one contaminant from a wastewater stream, the process comprising passing a wastewater stream into a fixed bed reactor, the wastewater stream comprising at least one contaminant and the fixed bed reactor comprising one or more types of packing elements and one or more types of attendant microorganisms; passing a gaseous stream comprising oxygen into the fixed bed reactor so that the one or more types of microorganisms remove the at least one contaminant from the wastewater stream in the presence of oxygen from the gaseous stream; recovering a treated wastewater stream from the fixed bed reactor; and, moving at least a portion of a top plate disposed above the substantially stationary one or more packing elements from a first position in which the packing elements are substantially stationary within the fixed bed reactor to a second position in which the packing elements are not substantially stationary within the fixed bed reactor, wherein the top plate comprises a plurality of openings. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, wherein the top plate comprises a plurality of sections, each configured to be moved independent of each other. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, further comprising moving a first section of the top plate from the first position to the second position; returning the first section to the first position; and, moving a second section of the top plate from the first position of the second position. An embodiment of the invention is one, any or all of prior embodiments in this paragraph up through the third embodiment in this paragraph, wherein the first section of the top plate is immediately adjacent to the second section.

[00042] Without further elaboration, it is believed that using the preceding description that one skilled in the art can utilize the present invention to its fullest extent and easily ascertain the essential characteristics of this invention, without departing from the spirit and scope thereof, to make various changes and modifications of the invention and to adapt it to various usages and conditions. The preceding preferred specific embodiments are, therefore, to be construed as merely illustrative, and not limiting the remainder of the disclosure in any way whatsoever, and that it is intended to cover various modifications and equivalent arrangements included within the scope of the appended claims.

[00043] In the foregoing, all temperatures are set forth in degrees Celsius and, all parts and percentages are by weight, unless otherwise indicated.

[00044] While at least one exemplary embodiment has been presented in the foregoing detailed description of the invention, it should be appreciated that a vast number of variations exist. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the invention in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing an exemplary embodiment of the invention, it being understood that various changes may be made in the function and arrangement of elements described in an exemplary embodiment without departing from the scope of the invention as set forth in the appended claims and their legal equivalents.

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