Patent Description:
Waste streams are commonly treated by a wide variety of solutions in order to remove organics, solids, and any other undesirable contaminants therefrom. For example, waste streams may be contacted with activated carbon for a time effective to remove organic contaminants therefrom. In some instances, activated carbon is combined with biological material for the removal of readily biodegradable organics from the waste stream. Thereafter, the resulting treated stream requires removal of suspended solids therefrom.

Conventional wisdom is that the concentration of suspended solids should be kept to a moderate level (~<NUM>/L) in contact with the membrane(s) of such filtration systems. This is due to the fact that elevated solid concentrations typically result in high transmembrane pressure (TMP) during operation. When biological material is utilized, even in combination with activated carbon to remove organic contaminants, the biological material is further thought to cause a rapid rise in transmembrane pressure (TMP) due in part to the consistency of the biological material. Further, long-term operation with the membranes in direct contact with the activated carbon can result in membrane damage. Due to these potential issues, a gravity separation step to further separate solids from the fluid/material to be treated preceding the membrane unit is typically included in membrane filtration systems to reduce or prevent carbon contact with the membranes. In any case, the lower suspended solid limitations for activated carbon or activated carbon/biomass and added components (e.g., clarifiers): (i) reduce efficiency; (ii) add expense, operating time, and materials; and (iii) increase the footprint size of the treatment system. Improved fluid treatment systems that incorporate activated carbon and membrane filtration are thus needed in the art.

In <CIT> a wastewater treatment system is disclosed which includes a bioreactor including activated carbon and a first biological population. The wastewater treatment system may also include a membrane bioreactor and/or a wet oxidation unit. Further, <CIT> discloses a membrane bioreactor which has membranes comprising a supporting structure. A supply unit doses a sorbent such as powdered activated carbon into the membrane bioreactor. The powdered activated carbon is maintained at a concentration in the mixed liquor of <NUM>/L or more. Mixed liquor with the sorbent particles recirculates within the membrane bioreactor at a flow rate of at least twice the feed flow rate. Air bubbles are provided to scour the membranes including during at least part of a permeation step. The sorbent particles are present in the mixed liquor and contact the membranes. Moreover, <NPL> discloses one series of tests involving four bench scale membrane bioreactors operated at sludge retention times of <NUM> days with PAC inventories and steady state biomass concentrations. The characteristics of the mixed liquors from the four reactors were compared.

The invention is explained in the following description in view of the drawings that show:.

In accordance with an aspect of the present invention, there are provided systems and process which now more efficiently remove organic contaminants and solids from a waste stream via contact of the waste stream with at least powdered activated carbon and one or more membranes. In a first aspect, there are disclosed systems and processes which allow powdered activated carbon to be contacted with membrane(s) of a membrane filtration in concentrations not previously thought feasible. In certain embodiments, the membrane(s) of the membrane unit(s) in the treatment systems and processes described herein may be contacted with materials having a relatively high suspended solids (also "SS" herein) concentration. For example, the high suspended solids concentration maybe ≥ about <NUM>/L, and in certain embodiments from about ≥ about <NUM> to about <NUM>/L, without resulting in excessive membrane fouling or damage. In certain embodiments, the suspended solids comprise powdered activated carbon and no biomass. In other embodiments, the suspended solids comprise both powdered activated carbon and biomass. As used herein, the term "about" includes value(s) which are ± <NUM>% of the stated value.

In one aspect, the increased suspended solids relative to known systems and processes is believed to be made possible by the selection of a membrane material which is capable of being contacted by powdered activated carbon without deterioration/damage following repeated use. In particular, the present inventors have surprisingly found that conventional membrane materials (e.g., polyethersulfone (PES) and polyvinylidene fluoride (PVDF) membranes) rapidly degrade/deform when contacted with high suspended solid liquors comprising activated carbon, but that other membranes (e.g., ceramic and polytetrafluoroethylene (PTFE) membranes) do not exhibit the same deficiencies.

In another aspect, when powdered activated carbon and biomass are present and directed to membrane filtration, the inventors have also found that particular ratios of powdered activated carbon to biomass allow for the operation of membrane filtration without the issues, e.g., pressure/fouling issues, typically seen in carbon/biomass systems. In certain embodiments, powdered activated carbon and biomass are provided from a bioreactor in a predetermined ratio, such as from about <NUM>:<NUM> to about <NUM>:<NUM> by weight. While not wishing to be bound by theory, it is believed at such values the powdered activated carbon is present in an amount that when combined with biological material inhibits the adhesion of biomass to the membrane surface (once delivered thereto). In addition, the powdered activated carbon may readily adsorb biomass secretions (extracellular polymeric substances), a known membrane foulant, thereby maintaining stable operating TMPs.

In accordance with an aspect of the present invention, there is provided a treatment process comprising contacting a high suspended solids liquor comprising at least a waste stream and powdered activated carbon therein with one or more membranes of a membrane unit to generate a filtrate, wherein the high suspended solids liquor comprises a suspended solids concentration of at least about <NUM>/L.

In accordance with another aspect, there is provided a treatment process comprising: directing an amount of waste stream comprising an amount of organic contaminants therein to a vessel comprising powdered activated carbon therein to remove the organic contaminants from the waste stream; and directing a first effluent from the vessel to a membrane unit in fluid communication with the vessel to remove solids from the first effluent; wherein a suspended solids (SS) concentration comprising the activated carbon in the first effluent is at least <NUM>/L.

Not according to the invention there is provided a treatment system comprising a membrane unit comprising one or more membranes in contact with a high suspended solids liquor comprising powdered activated carbon and a waste stream comprising organic contaminants and suspended solids, wherein the high suspended solids liquor comprises a suspended solids concentration of at least <NUM>/L.

Disclosed herein is a treatment system comprising: (i) a waste stream source; (ii) a bioreactor comprising powdered activated carbon and a biomass in fluid communication with the waste stream source, wherein the bioreactor is configured to generate a high suspended solids liquor having a suspended solids concentration of at least <NUM>/L, and wherein a weight ratio of the activated carbon to the biomass in the bioreactor is from <NUM>:<NUM> to <NUM>:<NUM>; and (iii) a membrane unit comprising one or more membranes in fluid communication with the bioreactor and configured to receive the high suspended solids liquor from the bioreactor.

Referring now to the drawings, <FIG> illustrates a treatment system <NUM> in accordance with an aspect of the present invention. The system <NUM> comprises a membrane unit <NUM> (hereinafter "membrane(s) or membrane") comprising one or more membranes <NUM>. Within the membrane unit <NUM>, the membranes <NUM> are in contact with a high suspended solids (SS) liquor <NUM>. The high SS liquor <NUM> comprises at least an amount of powdered activated carbon. The membrane unit <NUM> is configured to generate a filtrate <NUM> (from the high SS liquor <NUM>), which may exit from one or more outlets <NUM> of the membrane unit <NUM>. The high SS liquor <NUM> comprises a suspended solids concentration of at least about <NUM>/L, and in a particular embodiment, from about <NUM>/L to about <NUM>/L, and in more particular embodiment from about <NUM>/L to about <NUM>/L.

In certain embodiments, the high SS liquor <NUM> comprises a waste stream which is also treated with powdered activated carbon in the membrane unit <NUM> to remove an amount of organic contaminants from the waste stream. Referring to <FIG>, for example, there is shown a source <NUM> of a waste stream <NUM> having an amount of organic contaminants and solids, e.g., dissolved and/or suspended solids, therein. As shown in in <FIG>, the waste stream <NUM> is delivered to an inlet <NUM> of the membrane unit <NUM> to be treated with powdered activated carbon loaded within the membrane unit <NUM>. In an embodiment, the system <NUM> includes a source <NUM> of powdered activated carbon <NUM>, and an amount of powdered activated carbon <NUM> is delivered from the source <NUM> to an inlet <NUM> (which may be the same as inlet <NUM> or a distinct inlet) of the membrane unit <NUM>. The amount of powdered activated carbon <NUM> is effective to remove/treat the organic contaminants in the waste stream <NUM> delivered to the membrane unit <NUM> by absorption, adsorption, or the like. Optionally, the waste stream <NUM> and the powdered activated carbon <NUM> are combined under continuous or periodic mixing. The waste stream <NUM> is then contacted with the powdered activated carbon <NUM> for an amount of time effective to remove an amount of the organic contaminants from the waste stream <NUM>.

In an aspect, the waste stream <NUM> and the powdered activated carbon <NUM> are provided in amounts that at least collectively provide the high SS liquor <NUM> (at least <NUM>/L) within the membrane unit <NUM>. Periodically or following contact of the waste stream <NUM> with powdered activated carbon to remove at least a majority (> <NUM> % from a starting concentration) of the organic contaminants, a high SS liquor <NUM> is drawn through the one or more membranes <NUM> of the membrane unit <NUM> via a suitable pump or the like to pull the filtrate <NUM> having a reduced suspended solids concentration (relative to the original waste stream <NUM>).

The high SS liquor <NUM> further comprises a waste stream that has already been subjected to treatment with at least powdered activated carbon to remove an amount of organic contaminants therefrom in a discrete vessel or reactor prior to addition to the membrane unit <NUM>. In certain embodiments, at least a majority (> <NUM> % by weight or volume) of the organic contaminants are removed by carbon treatment prior to addition to the membrane unit <NUM>. Referring to <FIG>, for example, the system <NUM> comprises a waste source <NUM> having an outlet <NUM> in fluid communication with an inlet <NUM> of a vessel <NUM>. The waste source <NUM> is configured to deliver an amount of the waste stream <NUM> to the vessel <NUM> which is dosed with an amount of powdered activated carbon <NUM> therein effective to remove a desired amount of organic contaminants from the waste stream <NUM>. In some embodiments, the vessel <NUM> is also in fluid communication with a source of powdered activated carbon (<FIG>). Following treatment within the vessel <NUM>, an effluent which comprises the high SS liquor <NUM> is delivered from an outlet <NUM> of the vessel <NUM> to an inlet <NUM> of the membrane unit <NUM>. The input high SS liquor <NUM> is then drawn through the one or more membranes <NUM> of the membrane unit <NUM> as discussed previously via a suitable pump or the like to generate the filtrate <NUM> having a reduced suspended solids concentration (relative to the original waste stream <NUM>).

In the embodiments described herein, the waste stream <NUM> may refer to any fluid to be treated for organic and solid contaminant removal. In certain embodiments, the waste stream <NUM> may comprise one from an industrial, agricultural, or municipal source. In addition, in certain embodiments, the waste stream <NUM> includes inorganic or organic contaminants capable of being removed by the system <NUM>. In an embodiment, the waste stream <NUM> may comprise a waste stream from an ethylene production or a refinery process, such as an oil refinery process. In certain embodiments, the waste stream <NUM> is one that includes biodegradable contaminants.

The membrane unit <NUM> may comprise one or more porous or semipermeable membranes <NUM> (also referred to as "membrane(s)" or "membrane" for ease of reference). In an embodiment, the membrane <NUM> comprises a microfiltration membrane or an ultrafiltration membrane as is known in the art. In addition, the membrane <NUM> may have any configuration suitable for its intended application, such as a sheet or hollow fibers. Further, the membrane <NUM> may have any suitable porosity and/or permeability for its intended application. Still further, the membrane <NUM> may have any suitable shape and cross sectional area such as, for example, a square, rectangular, or cylindrical shape. In one embodiment, the membrane has a rectangular shape.

Within the membrane unit <NUM>, the one or more membranes <NUM> may be positioned, e.g., vertically, in a treatment zone of the membrane unit <NUM> in such a way as to be completely submerged by the material, e.g., high SS liquor <NUM>, therein during operation. To reiterate, it is appreciated that the SS liquor <NUM> described herein comprises the material in the membrane unit <NUM> that contacts the membrane(s) <NUM> includes at least an amount of powdered activated carbon <NUM>, as well as a fluid, e.g., the waste stream <NUM> (before, concurrently, or following primary treatment for organics removal), or a material derived from the waste stream <NUM> (e.g., reject from the membrane(s) <NUM>. In further embodiments, the high SS liquor <NUM> comprises a biomass population as set forth below.

In certain embodiments, multiple membranes <NUM> may be positioned adjacent one another, or located at predetermined positions and may, but need not, be positioned in the same plane as others or parallel to one another. In addition, in certain embodiments, one or more membranes <NUM> may be mounted directly to the vessel or compartment which forms a treatment zone. Further, one or more membranes <NUM> may be mounted to a removable module support which may be attached to a vessel or compartment forming the treatment zone. In one embodiment, one or more membranes <NUM> may be mounted to a support rack to facilitate membrane maintenance and/or replacement. In another embodiment, any, a portion, or all of the membranes <NUM> described above may be disposed within a corresponding membrane module for housing the membranes <NUM> and facilitating input and output of material into and away from the membranes <NUM>. When so provided, any suitable number of modules may be provided in an array, rack or a cassette located in one or more corresponding feedcontaining vessels or tanks. Further, in an embodiment, the membrane unit <NUM> comprises a plurality of membrane units <NUM>.

In another aspect, as is illustrated by example in <FIG>, the membrane unit <NUM> may include a blower <NUM> for supplying a gas <NUM> to scour the membrane(s) <NUM> and prevent solids build up on a surface of the membrane(s) <NUM> therein. Each blower <NUM> may produce fine bubbles, coarse bubbles, a jet stream of gas, a jet of gas and fluid, and combinations thereof. The gas <NUM> may comprise nitrogen, air, fuel gas, or any other suitable gas. In addition, the blower <NUM> may be positioned in any suitable location, and for the membrane unit <NUM>, the associated blower <NUM> may provide gas along a length of one or more membranes <NUM>. Typically also, a pump (not shown) may be provided to generate a suitable suction force to draw fluid through each membrane <NUM> of the membrane unit <NUM> to generate the filtrate <NUM>.

In operation, in any of the embodiments described herein, the membrane unit <NUM> continuously or intermittently draws the high SS liquor <NUM> to its membrane(s) <NUM>. In certain embodiments, prior thereto or contemporaneously therewith, the waste stream <NUM> is contacted with the powdered activated carbon material <NUM> in the membrane unit <NUM> for a time sufficient to remove an amount of organic contaminants from the waste stream <NUM>. In an embodiment, the waste stream <NUM> is contacted with the powdered activated carbon <NUM> for a period of <NUM> to <NUM> hours, although it is appreciated that the present invention is not so limited. As fluid is drawn through the membrane(s) <NUM> leaving suspended solids and the like in the high SS liquor <NUM> on the reject side of the membrane(s) <NUM> , the membrane unit <NUM> produces the filtrate <NUM> which has permeated or traveled through one or more membranes <NUM> of the membrane unit <NUM>. In certain embodiments, the filtrate <NUM> comprises a reduced organic contaminants concentration and a reduced total suspended solids concentration relative to the waste stream <NUM>. In an embodiment, the filtrate <NUM> comprises an organic concentration level of about <NUM>/L or less. In addition, in an embodiment, the membrane unit <NUM> may be effective to remove at least <NUM> % by weight of suspended solids from the waste stream <NUM>, and in certain embodiments at least <NUM> % by weight of suspended solids are removed from the waste stream <NUM>.

The powdered activated carbon <NUM> may be provided in an amount effective to adsorb or otherwise remove an amount of an organic material from the waste stream <NUM> below a desired or acceptable level. In addition, the powdered activated carbon may be of any suitable particle size. In accordance with an aspect, the systems and processes described herein enable a high SS liquor (≥ <NUM>/L) to be contacted with the membranes <NUM> of the membrane unit <NUM> without significantly damaging the membranes <NUM>. Thus, in an embodiment, the powdered activated carbon <NUM> is provided in an amount effective to bring or assist in bringing the SS concentration of the liquor to an amount ≥ about <NUM>/L, in certain embodiments ≥ about <NUM> to about <NUM>/L, and in particular embodiments from about <NUM> to about <NUM>/L.

In an aspect, the powdered activated carbon <NUM> may be effective to remove an amount of recalcitrant organics therein. As used herein, recalcitrant organics define a class of organics which may be slow or difficult to biodegrade relative to the bulk of organics in the waste stream <NUM>. Examples of recalcitrant organics include synthetic organic chemicals. Other recalcitrant organics include polychlorinated biphenyls, polycyclic aromatic hydrocarbons, polychlorinated dibenzo-p-dioxin, and polychlorinated dibenzofurans. Endocrine disrupting compounds are also a class of recalcitrant organics which can affect hormone systems in organisms, and are found in the environment.

In still another embodiment, it is appreciated that the high SS liquor <NUM> may comprise an amount of a biological population (also referred to as "biological material" or "biomass" herein). The biomass may be provided in an amount effective to treat the waste stream <NUM> and reduce an amount of biodegradable material, including nonrecalcitrant organics, within the waste stream <NUM> to a desired degree. By way of example, a biomass may be provided in the SS liquor <NUM> loaded within the membrane unit <NUM> illustrated in <FIG>. To accomplish this, in an embodiment and as shown in <FIG>, an effective amount of a biomass <NUM> may be provided from a suitable source <NUM> thereof to the membrane unit <NUM>. In an embodiment, the source <NUM> comprises one or more outlets <NUM> in fluid communication with one or more inlets <NUM> to the membrane unit <NUM>. In an embodiment, an amount of the waste stream <NUM> and activated carbon <NUM> are delivered from respective sources (as shown in <FIG>) and are mixed with the biomass <NUM> in the membrane unit <NUM> in order to provide an SS concentration as specified herein of at least about <NUM>/L.

Although including the materials (activated carbon or activated carbon/biological material) directly within the membrane unit <NUM> provides numerous benefits - including greater treatment efficiency and reduced maintenance, materials, equipment, costs, and time, in still other embodiments, the powdered activated carbon <NUM> and the biomass <NUM> may be combined in a bioreactor <NUM> as is known in the art to reduce an amount of organic contaminants in the waste stream <NUM>. As shown in <FIG>, for example, there is illustrated an embodiment of the system <NUM> comprising a bioreactor <NUM> having one or more inlets <NUM> in fluid communication with one or more outlets <NUM> of a waste source <NUM> as previously described herein, which may deliver an amount of a waste stream <NUM> to the bioreactor <NUM>. It is appreciated that the powdered activated carbon <NUM> may be provided separately or collectively to the bioreactor <NUM> from suitable source(s).

The bioreactor <NUM> is operated at suitable conditions and for a duration effective to reduce an amount of organic contaminants in the waste stream <NUM>. When necessary or desired, a blower <NUM> is also in fluid communication with the bioreactor <NUM> to deliver an amount of a gas <NUM> thereto to provide the necessary aeration to the biomass <NUM>. Upon completion of treatment in the bioreactor <NUM>, an effluent <NUM> which comprises a high SS liquor <NUM> as described herein having a SS concentration of at least <NUM>/L is delivered from one or more outlets <NUM> of the bioreactor <NUM> to one or more inlets <NUM> of the membrane unit <NUM>. The high SS liquor <NUM> is then treated within the membrane unit <NUM> as previously described herein to produce the filtrate <NUM>. In this embodiment, the liquor <NUM> comprising the biomass is typically referred to as a mixed liquor, and the SS concentration may be referred to as a mixed liquor suspended solids (MLSS) concentration.

When present, the biological population <NUM> may include any suitable population of bacterial micro-organisms effective to digest biodegradable. Exemplary waste stream treatment systems are described in <CIT>; <CIT>; <CIT>; and <CIT>. The bacteria may comprise any bacteria or combination of bacteria suitable to thrive in anoxic and/or aerobic conditions. Representative aerobic genera include the bacteria Acinetobacter, Pseudomonas, Zoogloea, Achromobacter, Flavobacterium, Norcardia, Bdellovibrio, Mycobacterium, Shpaerotilus, Baggiatoa, Thiothrix, Lecicothrix, and Geotrichum, the nitrifying bacteria Nitrosomonas, and Nitrobacter, and the protozoa Ciliata, Vorticella, Opercularia, and Epistylis. Representative anoxic genera include the denitrifying bacteria Achromobacter, Aerobacter, Alcaligenes, Bacillus, Brevibacterium, Flavobacterium, Lactobacillus, Micrococcus, Proteus, Pserudomonas, and Spirillum. Exemplary anaerobic organisms include Clostridium spp. , Peptococcus anaerobus, Bifidobacterium spp. , Desulfovibrio spp. , Corynebacterium spp. , Lactobacillus, Actinomyces, Staphylococcus and Escherichia coli.

When a biological population is utilized, the combination of powdered activated carbon <NUM> and biological material <NUM> constitutes the majority of the SS (MLSS) concentration and is utilized to remove organic contaminants (recalcitrant and nonrecalcitrant) from the waste stream <NUM>. The addition of the activated carbon <NUM> to biological material <NUM> appears to have a number of benefits aside from their treatment of the waste stream <NUM>. For one, while not wishing to be bound by theory, it is believed that activated carbon <NUM> assists in the absorption of compounds potentially toxic to the biological material <NUM>, thereby protecting the biological material <NUM>. In addition, it is believed that the powdered activated carbon <NUM> may enhance membrane surface renewal once delivered to the membrane unit <NUM>, thereby making the membrane surface(s) thereof less susceptible to undesired fouling. In an embodiment, a weight ratio of the powdered activated carbon <NUM> to biomass <NUM> in the bioreactor <NUM> may be from about <NUM>:<NUM> to about <NUM>:<NUM>, and in a particular embodiment is from about <NUM>:<NUM> to <NUM>:<NUM>.

It is appreciated that the powdered activated carbon <NUM> may be added to the membrane unit <NUM> or bioreactor <NUM> and mixed therein with the biological material <NUM>. In addition, the powdered activated carbon <NUM> may be added to the membrane unit <NUM> or bioreactor before, concurrently with, or subsequent to the addition of waste stream <NUM>. In an embodiment, the bioreactor <NUM> comprises biomass <NUM> and powdered activated carbon <NUM>, collectively or separately, in one or more treatment zones. As used herein, the phrase "treatment zone" is used to denote an individual treatment region. Individual treatment regions may be housed in a single vessel with one or more compartments. Alternatively, individual treatment regions may be housed in separate vessels and a different treatment is carried out in separate vessels. The treatment zone, e.g., the vessel, tank, or compartment, may be sized and shaped according to a desired application and volume of waste stream to be treated to provide a desired retention time. Accordingly, the bioreactor <NUM> may itself comprise one or more vessels.

As mentioned above, conventional wisdom held such higher solids concentrations would likely result in an immediate or rapid increase in TMP at the membrane unit <NUM> upon contact therewith. However, the inventors have found that the suspended solids (SS) concentration could be ≥ about <NUM>/L in contact with the membrane(s) <NUM> without excessive membrane fouling in the membrane unit <NUM> by optimizing the activated carbon/biological material ratio and/or via the selection of the membrane material as described herein. Thus, in an embodiment, an SS concentration of the effluent <NUM> is ≥ about <NUM>/L, in certain embodiments is ≥ about <NUM> to about <NUM>/L, and in particular embodiments is from about <NUM> to about <NUM>/L. Thus, the activated carbon <NUM> and the biological material <NUM> may be provided in the reactor <NUM> in the ratios described above to arrive at these SS values in the liquor which is delivered to the membrane unit <NUM>.

From the bioreactor <NUM>, at least a portion of the effluent <NUM> may be directed from the bioreactor <NUM> to the membrane unit <NUM>, thereby generating a treated stream (filtrate <NUM>) having a reduced suspended solids concentration relative to the effluent <NUM> and/or waste stream <NUM>. From the membrane unit <NUM>, the filtrate <NUM> may be directed to further processing (e.g., polishing), disposal (if appropriate), storage, or transport.

In any of the embodiments described herein, it is appreciated more than one of the described component(s) may be provided if suitable or desired. By way of illustration only, the system <NUM> may comprise multiple membrane units, vessels, bioreactors, or the like as described herein. In certain embodiments, the system <NUM> comprises at least two bioreactors in flow series with one another. The bioreactors may be identical to one another, or may be different, such as by comprising a different composition, such as a different biomass or biomass environment, or a material comprising a different carbon to biomass ratio. In certain embodiments, one of the bioreactors may be operational to treat the waste stream while the other is taken out of service for maintenance, cleaning, or the like. In certain embodiments, when multiple bioreactors are present, it is appreciated that activated carbon may be added to each bioreactor independently.

In still further embodiments, the powdered activated carbon and biomass may be provided in distinct vessels. Thus, in an embodiment, for example, the bioreactor <NUM> does not include activated carbon, and instead a separate vessel (not shown) comprising powdered activated carbon may be installed between the bioreactor <NUM> and the membrane unit <NUM>. In any case (whether internal or external of the membrane unit <NUM>), a waste stream <NUM> may be treated with powdered activated carbon or powdered activated carbon/biological material for a time effective to reduce an amount of organic contaminants and/or biodegradable contaminants therein. In addition, the liquor directed to or within the membrane unit <NUM> again will have an SS concentration of ≥ about <NUM>/L, in certain embodiments is ≥ about <NUM> to about <NUM>/L, and in particular embodiments is from about <NUM> to about <NUM>/L.

In accordance with another aspect, in any of the embodiments described herein, the filtrate (effluent) <NUM> from the membrane unit <NUM> may be delivered from the membrane unit <NUM> to a further processing step, such as a polishing unit <NUM> as shown in <FIG>. In an embodiment, the amount of organic contaminants and solids in the filtrate <NUM> leading to the polishing unit <NUM> is below a predetermined value and/or an amount that would cause fouling of the polishing unit <NUM>.

The polishing unit <NUM> may comprise any suitable apparatus or system suitable for removing total dissolved solids (TDS) and/or inorganics from the a fluid delivered thereto to produce an effluent <NUM> having a desired composition, such as one having a TDS concentration below suitable limitations, such as below limits suitable for discharge or reuse of the effluent <NUM>. The selection of the polishing unit <NUM> is without limitation. In an embodiment, the polishing unit <NUM> may be selected from the group consisting of a nanofiltration, reverse osmosis, ion exchange, electrodeionization, continuous electrodeionization, and an electrodialysis reversal unit. In a particular embodiment, the polishing unit <NUM> comprises a reverse osmosis unit, which removes suspended solids from the filtrate <NUM> by reverse osmosis. In certain embodiments, the effluent from the membrane unit <NUM> may undergo any additional treatment(s) prior to delivery to the polishing unit <NUM>, such as any of silica removal, pH adjustment, anti-scalant addition, and softening upstream from the polishing unit <NUM>.

In still another aspect, referring to <FIG>, it is appreciated that a retentate <NUM> (reject or concentrated solids fraction) that does not travel through the membrane(s) <NUM> is provided from the membrane unit <NUM>. This retentate <NUM> may comprise biomass solids (when biomass is utilized), activated carbon (with or without organics adsorbed thereon), and/or other solids in any other suitable form. In an embodiment, the activated carbon comprises an amount of a spent carbon material. In certain embodiments, at least a portion of the retentate <NUM> is removed from the system <NUM> and delivered to a wet air oxidation (WAO) unit <NUM> as is known in the art for regeneration of the spent carbon material and oxidation of biological solids (when present) and oxidizable materials (e.g., organics) therein. By "spent," it is meant that an ability of the carbon material to remove further target components in a target material has at least decreased. It is appreciated that the spent carbon and/or any further solids may also be removed from the systems described herein ("wasting") at any suitable location in the associated system, such as the membrane unit <NUM>, bioreactor(s), or in any suitable flowpath of the system, and then delivered to the WAO unit <NUM>, or to any other desired location.

In an embodiment, the WAO unit <NUM> comprises one or more dedicated reactor vessels in which regeneration of the spent carbon material and oxidation of relevant components (e.g., organics, inorganics, and/or biological material) may take place under elevated temperature and pressure conditions (relative to atmospheric conditions) in the presence of oxygen. In particular, the components therein may also be heated for a duration and under conditions (e.g., pressure, temperature, and an oxygenated atmosphere) effective for the oxidation and/or regeneration of the spent carbon material to take place so as to produce an effluent <NUM> which includes at least regenerated carbon product. In an embodiment, the regeneration of the spent carbon is done at a pressure from about <NUM> atm to about <NUM> atm and at a temperature from about <NUM> to about <NUM> with the addition of oxygen to the feed stream or the WAO unit.

In certain embodiments, upon regeneration of the spent carbon material, the effluent <NUM> from the WAO unit <NUM> (comprising at least regenerated carbon) may be returned to the membrane unit <NUM>, vessel, or bioreactor as the case may be to provide a desired quantity of activated carbon. In other embodiments, the effluent <NUM> may be directed to a suitable location for storage or transport. In certain embodiments, the effluent <NUM> may comprise a slurry comprising reactivated carbon material and biological material. In still other embodiments, no WAO unit <NUM> is provided in the systems and processes described herein. In this case, a portion or all of retentate <NUM> may be dewatered and then stored, transported as waste, and/or sent offsite for regeneration.

In the systems and processes described herein, it is appreciated that one or more inlets, pathways, outlets, mixers, pumps, valves, coolers, energy sources, flow sensors, or controllers (comprising a microprocessor and a memory), or the like may be included in any of the systems described herein for facilitating the introduction, introduction, output, timing, volume, selection, and direction of flows of any of the components (e.g., MLSS, regenerated carbon, spent carbon, steam, cooling fluids, therein) therein. Moreover, the skilled artisan would understand the volumes, flow rates, and other parameters necessary to achieve the desired result(s).

Typically, MLSS does not exceed <NUM>/L in MBR (membrane bioreactor) applications due to potential fouling / high TMP. Testing showed that <NUM> and even <NUM>/L MLSS can be operated with acceptable TMPs and fouling rates. Referring to <FIG> illustrates that flux has a strong effect on the initial TMP as expected. However, it was surprising to find that the change in initial TMP due to the solids concentration was insignificant despite increasing the MLSS concentration by four times conventional MLSS concentration.

Claim 1:
A treatment process comprising:
contacting a high suspended solids liquor (<NUM>) comprising at least a waste stream (<NUM>) and powdered activated carbon (<NUM>) therein with one or more membranes (<NUM>) of a membrane unit (<NUM>) to generate a filtrate (<NUM>), wherein the membrane (<NUM>) comprises a microfiltration membrane or an ultrafiltration membrane, wherein the high suspended solids liquor (<NUM>) comprises a suspended solids concentration of at least <NUM>/L, wherein the high suspended solids liquor (<NUM>) further comprises an amount of biological material (<NUM>), wherein the biological material (<NUM>) being any suitable population of bacterial micro-organisms effective to digest biodegradable, and wherein a weight ratio of the powdered activated carbon (<NUM>) to the biological material (<NUM>) is from <NUM>:<NUM> to <NUM>:<NUM>.