Bioreactor with membrane filtration and wastewater treatment method

Abstract

The present disclosure provides a wastewater treatment system comprising at least one bioreactor tank in which biomass grows. A nanofiltration, ultrafiltration or microfiltration membrane is mounted in the bioreactor tank. The membrane is in fluid communication with the liquid outlet to discharge the permeate effluent. The membrane is operable to filter biologically treated wastewater without substantially filtering biomass growing in the bioreactor tank. For example, permeation through the membrane may be performed only when the biomass settles and the membrane is exposed to substantially clear wastewater above the settled biomass. Alternatively or additionally, the bioreactor tank may include a non-permeable effluent outlet, and may simultaneously produce a non-permeable effluent and a membrane permeable effluent.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims priority to and the benefit of U.S. Provisional Patent Application No. 63 / 389,126, filed on July 14, 2022, which is incorporated herein by reference. Technical Field

[0003] This specification relates to a bioreactor including membrane filtration, and associated wastewater treatment methods. Background Art

[0004] The following paragraphs are not an admission that anything discussed therein is prior art or part of the known knowledge of a person skilled in the art.

[0005] Membrane bioreactors (MBRs) combine membrane filtration processes (such as microfiltration or ultrafiltration) with biological wastewater treatment processes. The biological treatment process uses activated sludge to aerobic oxidation of organic matter. MBR systems may include submerged membrane bioreactors, in which the filtration membrane is located inside the bioreactor and immersed in the biomass. Alternatively, an MBR system may include a side stream membrane bioreactor, in which the filtration membrane is located outside the reactor, in a filtration unit downstream of the aerobic tank.

[0006] Sequencing batch reactors (SBRs) treat wastewater using an activated sludge treatment process in a fill-and-aeration or fill-and-draw system. SBR process steps are implemented using a single batch reactor, and multiple batch reactors are used in a predetermined operating sequence with overlapping treatment cycles. For example, a variable water level SBR implements a fill and aeration feed and uses a three-step sequence such as: fill / aeration, followed by settling, and then decantation / drawing of the effluent. A constant water level SBR implements a fill and draw feed and uses a three-step sequence such as: fill and draw, followed by aeration, and then settling.

[0007] U.S. Patent No. 7,547,394 describes an apparatus and method for treating wastewater using aerobic granules. The patent states that, generally, the granules can be grown in a sequencing batch reactor having 3 stages. In the first stage, feed can be provided to the reactor in the usual plug flow form in the absence of air while effluent is withdrawn from the reactor. This simultaneously charges the reactor with feed, removes treated effluent from the previous batch, and provides a period of anaerobic digestion. In the second stage, the reactor can be aerated and mixed. The aeration rate can be cycled to provide aerobic and anoxic conditions to oxidize COD and provide nitrification and denitrification. In the third stage, mixing and aeration can be stopped to allow the granules to settle and the treated effluent to rise to the top of the reactor. Summary of the invention

[0008] The following description is intended to introduce the specification to the reader, but does not define any invention. One or more inventions may reside in any combination or subcombination of the device elements or method steps described below or elsewhere in this document. The inventors do not waive or claim any right to any one or more inventions disclosed in this specification simply because they are not described in the claims.

[0009] In one aspect, the present invention provides a wastewater treatment system that may include a sequencing batch reactor having a plurality of bioreactor tanks.

[0010] In one embodiment, the present invention provides a wastewater treatment system comprising a sequencing batch reactor comprising a plurality of bioreactor tanks, each of which grows biomass therein and has a liquid inlet for inflowing wastewater. The system also includes a plurality of nanofiltration, ultrafiltration or microfiltration membranes mounted in the bioreactor tanks, the membranes being in fluid communication with a liquid outlet for discharging permeate effluent. The membranes filter the biologically treated wastewater without filtering the biomass grown in the bioreactor tanks.

[0011] In another embodiment, the present invention provides a wastewater treatment system, which includes a biological treatment reactor. The biological treatment reactor includes a bioreactor tank, which grows biomass in a biomass portion of the bioreactor tank and has a liquid inlet for inflow of wastewater. The biological treatment reactor also includes: a nanofiltration, ultrafiltration or microfiltration membrane located in the filtration portion of the bioreactor tank, the membrane is in fluid communication with a permeate effluent outlet; and a non-permeate effluent outlet located in the filtration portion of the bioreactor tank.

[0012] In yet another embodiment, the present invention provides a wastewater treatment system comprising: a bioreactor tank having a biomass processing portion and a filtration portion; a liquid inlet for an influent wastewater stream, the liquid inlet being positioned to discharge the wastewater into the biomass processing portion of the bioreactor tank; a nanofiltration, ultrafiltration, or microfiltration membrane in the filtration portion of the bioreactor tank, the membrane being fluidly connected to a liquid outlet for a permeate effluent discharge stream; and a biomass aerator located below the membrane and positioned to aerate at least the biomass processing portion of the bioreactor tank.

[0013] In another aspect, the invention provides a method for treating wastewater.

[0014] In one embodiment, the present invention provides a method for treating influent wastewater in a batch reactor, the reactor comprising a bioreactor tank and a nanofiltration, ultrafiltration or microfiltration membrane located in the bioreactor tank. The method comprises: treating substantially clear wastewater with a nanofiltration, ultrafiltration or microfiltration membrane in the bioreactor tank to produce a permeate effluent, while adding the influent wastewater to the sludge below the wastewater treated by the membrane.

[0015] In another embodiment, the present invention provides a method for treating influent wastewater in a batch reactor, the reactor comprising a bioreactor tank and a nanofiltration, ultrafiltration or microfiltration membrane located in the bioreactor tank. The method comprises: adding the influent wastewater to sludge located at the bottom of the bioreactor tank; generating a permeate effluent from the nanofiltration, ultrafiltration or microfiltration membrane and optionally generating an overflow effluent; and aerobically treating the sludge in a process comprising simultaneous nitrification and denitrification without generating a permeate effluent from the nanofiltration, ultrafiltration or microfiltration membrane.

[0016] In yet another embodiment, the present invention provides a method for treating influent wastewater in a batch reactor, the reactor comprising a nanofiltration, ultrafiltration or microfiltration membrane. The method includes adding the influent wastewater to the sludge layer in the bioreactor tank without significantly disturbing the sludge layer, while withdrawing the permeate effluent from the nanofiltration, ultrafiltration or microfiltration membrane, and optionally withdrawing the overflow effluent to keep the volume substantially constant. The method also includes treating the influent wastewater and sludge under anoxic or anaerobic conditions to reduce the concentration of particulate biodegradable chemical oxygen demand (COD) in the influent wastewater; and aerobic treatment of the sludge in a process including simultaneous nitrification and denitrification and oxidation of soluble biodegradable COD, while not producing permeate effluent from the nanofiltration, ultrafiltration or microfiltration membrane. The method optionally includes allowing at least some of the solids suspended by the aerobic treatment to settle and reform the sludge layer.

[0017] In other embodiments, the present invention provides a wastewater treatment system and method, as disclosed in U.S. Patent No. 7,547,394, which is incorporated herein by reference, except that the reactor tank includes a nanofiltration, microfiltration or ultrafiltration membrane located at the top of the reactor tank. In some embodiments, during operation, penetration through the membrane is only implemented when the biomass has settled and the membrane is exposed to clarified wastewater above the settled biomass. Membrane penetration can be implemented during feeding, that is, when the wastewater is fed into the particle bed. Membrane penetration can be implemented simultaneously with the generation of overflow effluent.

[0018] In one embodiment, the present invention provides a method for treating wastewater, comprising the steps of: a) providing a set of sequencing batch reactors; and b) feeding wastewater through a particle bed in each reactor for a period of time, while filtering clarified wastewater above the particle bed through a nanofiltration, microfiltration or ultrafiltration membrane. The feeding time is a portion of the cycle time of each reactor, and the feeding time of each reactor multiplied by the number of reactors is generally equal to the cycle time of each reactor.

[0019] In another embodiment, the present invention provides a method for treating wastewater, comprising: (a) feeding wastewater to an area in a bioreactor having particles, while filtering wastewater from a clarified wastewater area in the bioreactor through a nanofiltration, microfiltration or ultrafiltration membrane; (b) treating the wastewater with particles under anaerobic conditions; (c) treating the wastewater with particles under aerobic conditions; (d) allowing the particles to settle; (e) withdrawing treated wastewater from the area having particles; (f) mixing the particles with the wastewater at least during step (c); and (g) stopping mixing the particles with the wastewater during step (d) to settle the particles.

[0020] In yet another embodiment, the present invention provides a method for treating wastewater, comprising the steps of: a) providing a set of sequencing batch reactors; and b) feeding the wastewater through the particle bed in each reactor for a period of time that is a fraction of the cycle time of each reactor, while producing both (A) a nanofiltration, microfiltration or ultrafiltration membrane effluent and (B) an overflow effluent. The feed time per reactor multiplied by the number of reactors is generally equal to the cycle time per reactor.

[0021] In yet another embodiment, the present invention provides a method for treating wastewater. The method comprises: (a) feeding wastewater to a region having particles; (b) treating wastewater with particles under anaerobic conditions; (c) treating wastewater with particles under aerobic conditions; (d) allowing particles to settle; (e) extracting treated wastewater from the region having particles; (f) mixing particles with wastewater at least during step (c); (g) stopping mixing particles with wastewater during step (d) to settle particles; and (h) during step (a) and optionally step (b), simultaneously generating both (A) nanofiltration, microfiltration or ultrafiltration membrane effluent and (B) overflow effluent. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings.

[0023] Figure 1 is a schematic diagram of a wastewater treatment system according to the present disclosure.

[0024] Figure 2 is a schematic diagram of a wastewater treatment cycle according to the present disclosure. DETAILED DESCRIPTION

[0025] The present disclosure provides a wastewater treatment system, which includes at least one bioreactor tank in which biomass is grown. The bioreactor tank includes a liquid inlet for inflowing wastewater. A nanofiltration, ultrafiltration or microfiltration membrane is installed in the bioreactor tank. The membrane is in fluid communication with a liquid outlet to discharge a permeate effluent.

[0026] The membrane can be operated to filter biologically treated wastewater without filtering the biomass grown in the bioreactor pool substantially. For example, only when the biomass settles and the membrane is exposed to the substantially clear wastewater above the settling biomass, the permeation through the membrane can be implemented. Alternatively or additionally, the bioreactor pool may include a non-permeable effluent outlet, and non-permeable effluent and membrane permeate effluent may be produced simultaneously. Non-permeable effluent and membrane permeate effluent may be discharged with a merged effluent stream or a separate effluent stream according to downstream uses and / or regulations. For example, the merged effluent may be discharged into the environment more advantageously than only discharging non-permeable effluent, because the merged effluent has a lower concentration level due to the higher permeation quality of the membrane permeate effluent. If the membrane permeate effluent is used for the production of irrigation, urban, agricultural, industrial or regenerated drinking water, it may be more advantageous to discharge the effluent separately.

[0027] In the context of the present disclosure, the expressions "settled biomass", "sludge" and "sludge layer" are used interchangeably. The settled biomass is produced after the mixed biomass has settled in the bioreactor. During the settling stage, the mixed liquor suspended solids (MLSS) may increase in concentration starting from a concentration in the range of 3 to 10 g MLSS per liter (g / L), increasing to a concentration in the range of, for example, 6 to 40 g / L at the end of the settling stage. The settled sludge may be further thickened from a MLSS concentration in the range of 3 to 10 g / L to a concentration in the range of 8 to 40 g / L, preferably 10 to 20 g / L.

[0028] The substantially clear wastewater above the settled biomass may be wastewater having an MLSS concentration of less than 6 g / L, such as about 2 g / L or less, or about 1 g / L or less. In certain embodiments, the substantially clear wastewater may have an MLSS concentration of less than 0.1 g / L.

[0029] In some embodiments according to the present disclosure, a membrane permeate effluent may be produced when the settled biomass has an MLSS concentration greater than 4 g / L (e.g., a concentration in the range of 4 to 40 g / L or in the range of 10 to 20 g / L, or a concentration of about 6 g / L) and the substantially clear wastewater above the settled biomass has an MLSS concentration of less than 15 g / L (e.g., a concentration of less than 3 g / L). In a specific embodiment, a membrane permeate effluent may be produced when the settled biomass has an MLSS concentration of 10 to 20 g / L and the substantially clear wastewater above the settled biomass has an MLSS concentration of less than 3 g / L.

[0030] The membrane can be exposed to different concentrations of substantially clear wastewater. For example, the membrane can be operated when (a) the upper third of the membrane is exposed to wastewater with an MLSS concentration of less than 0.5 g / L, (b) the middle third of the membrane is exposed to wastewater with an MLSS concentration of 0.5 to 1 g / L, and (c) the lower third of the membrane is exposed to wastewater with an MLSS concentration of 1 to 3 g / L.

[0031] The membrane can be from about 20 to about 160 L / m 2 / hr (LMH) flux, such as about 50 to about 75 LMH flux. In an exemplary system with a scale of up to 2 million gallons per day (2 MGD) of a single bioreactor, the bioreactor pool may contain a sufficient number of membrane cassettes to provide up to 16,000 m 2 Membrane surface area for production at 20 LMH, and up to 2000 m 2 The membrane surface area is used for production at 160LMH.

[0032] The membrane can be positioned to filter from the filtration portion of the bioreactor tank. The filtration portion of the bioreactor tank can be in the upper portion of the tank when the settled biomass is in the lower portion of the tank. The filtration portion can be defined by a substantially clear layer of wastewater above the settled biomass. The settled biomass can define the biomass portion of the tank.

[0033] It should be understood that when the reactor tank has substantially settled biomass, references to the "filtration portion" and "biomass portion" of the reactor tank refer to the reactor tank itself. The height of the membrane may be about 2.7 m (e.g., 2.62 m to 2.74 m). The height of the bioreactor tank may be about 4.5 to about 8.0 meters, for example, about 7.5 meters. The upper 30% to 60%, for example, the upper 35% to 50%, of the bioreactor tank may constitute the filtration portion.

[0034] The bioreactor pool may include a liquid inlet positioned to join the inflowing wastewater to the settling biomass without significantly disturbing the biomass. The bioreactor pool may include a static or dynamic mixing device located upstream of the liquid inlet to enhance the mixing and uniform distribution of the wastewater added to the bioreactor pool. The liquid inlet may be fed to the bioreactor pool via multiple pipelines, and these pipelines may substantially uniformly distribute the inflowing wastewater to the bottom of the bioreactor pool, thereby allowing the sludge that settles to rise in the bioreactor without disturbing the interface between the biomass and the substantially clear wastewater. The substantially uniform distribution of the inflowing wastewater may increase the exchange and contact time between the inflowing wastewater and the sludge bed, thereby improving the uptake of microorganisms to the substrate. In certain embodiments, the liquid inlet may include substantially uniformly distributed liquid holes in the vertical portion of the bioreactor pool. In one embodiment, a plurality of liquid holes may be at the bottom of the bioreactor pool, and when looking down at the bioreactor pool, may be in substantially uniform distribution.

[0035] When the influent wastewater is added to the bioreactor tank, the biomass may have properties that help reduce the circulation of the settled biomass into the filtration portion of the bioreactor tank. For example, the settling rate of the biomass may be significantly faster than that of the activated sludge flocs. The biomass sludge volume index (mL / g) based on a 10-minute settling reading ("SVI10") may be within 10% of the SVI ("SVI30") based on a 30-minute settling reading. In some embodiments, the SVI5 of the biomass may be within 10% of the SVI30. The biomass may be a granular sludge or a dense sludge.

[0036] The biomass used in the systems or methods according to the present disclosure may have one or more of the following characteristics:

[0037] A settling velocity greater than 1.2 m / h, such as 1.2 to 9.0 m / h, or greater than 10 m / h;

[0038] dSVI (diluted dSVI) of 100 mL / g or less, such as 35 to 100 mL / g, such as 50 to 80 mL / g;

[0039] 50 to 90% by weight of flocs, such as 50 to 80% by weight of flocs, preferably flocs with an average particle size of less than 200 μm, such as less than 100 μm;

[0040] 10 to 85 wt% of the particles, such as 20 to 60 wt% of the particles, preferably have an average particle size greater than 100 μm, such as 100 to 1000 μm, 200 to 5000 μm or 200 to 500 μm.

[0041] In a specific embodiment, the biomass according to the present disclosure has a dSVI of 45-100 mL / g; 20-60% of particles larger than 200 μm; and particles with an average particle size of 200-1000 μm, preferably 200-500 μm.

[0042] Wastewater treatment systems can be operated with intermittent membrane filtration, where membrane filtration is limited to process periods when the biomass is essentially in a settled state. Limiting membrane filtration to such periods exposes the membrane to lower concentrations of solids (MLSS) than membrane filtration in a submerged membrane bioreactor or a lateral flow membrane bioreactor. Lower concentrations of MLSS permeate can result in reduced variation in membrane flux during permeation, reduced fouling, or both.

[0043] The wastewater treatment system may include a biomass aerator in a bioreactor tank. The biomass aerator may be positioned to aerate at least the biomass grown in the bioreactor tank. For example, the biomass aerator may be arranged in or below the biomass portion of the tank. The biomass aerator may be a full bottom aerator. The biomass aerator may be suitable for providing enough oxygen to the bioreactor so that it has a dissolved oxygen concentration of about 2.0 to 4.0 mg / L, such as a concentration of about 3.0 mg / L. The biomass aerator may be a fine bubble aerator, producing bubbles with a diameter less than 3 mm. Microporous aeration may provide a standard oxygen transfer efficiency (SOTE) of more than 2% during aeration. SOTE is a function of the depth of the bioreactor, and microporous aeration may provide 5.0 to 6.0% / m water depth. In certain embodiments, using a microporous aerator at about 4 to 8 m below the liquid surface may provide a SOTE of 20% to 48%.

[0044] The wastewater treatment system may include a membrane-scouring aerator, such as an aerator that captures process air from a biomass aerator and releases coarse aeration bubbles. The coarse aeration bubble diameter used for membrane scouring may be greater than 3 mm. Coarse bubble aeration can provide 3.3% to 4.0% / m water depth. In some embodiments, the use of a membrane-scouring aerator at about 2 to 4 meters below the liquid surface can provide a SOTE of about 7% to 16%. The membrane-scouring aerator can be an aerator as disclosed in WO2014077803, which is incorporated herein by reference, such as the LEAP® sold by SUEZ Water Technologies & Solutions. TM Aerator system that can be used with ZeeWeed, also sold by SUEZ Water Technologies & Solutions TMThe membrane flushing aerator can be arranged in the bioreactor tank so that when the biomass is substantially settled, the membrane flushing aerator is located above the settled biomass and below the membrane. In this way, the membrane flushing aerator can flush the membrane without significantly disturbing the settled biomass.

[0045] The bioreactor may additionally include a surplus activated sludge (WAS) outlet, or a WAS separation and recirculation system. The WAS separation and recirculation system may include a gravimetric selection and recirculation system; or a hydrocyclone in fluid communication with the WAS outlet and the return WAS stream.

[0046] The wastewater treatment system may additionally include a pretreatment system, a buffer tank, or both, which are located upstream of the bioreactor tank and are in fluid communication with the liquid inlet for the influent wastewater. The wastewater treatment system may additionally or alternatively include a post-treatment system located downstream of the bioreactor tank. The post-treatment system may be one or more treatment units that provide: nanofiltration, ultrafiltration, or microfiltration of the remaining activated sludge effluent; reduction or removal of compounds that cause soluble chemical oxygen demand (COD) and / or biological oxygen demand (BOD); reduction or removal of soluble phosphorus; or any combination thereof. Some systems according to the present disclosure may discharge a portion of the remaining activated sludge effluent without further treatment.

[0047] The wastewater treatment system may additionally include a source of powdered activated carbon (PAC). PAC may be added directly to the bioreactor tank or to the influent wastewater stream.

[0048] Wastewater treatment systems or methods according to the present disclosure can use submerged membranes. The membrane may have one or more of the following features. The membrane may be a hollow fiber membrane. The membrane may be a nonionic hydrophilic membrane, such as polyvinylidene fluoride (PVDF) or a modified polyethersulfone (PES) membrane or a ceramic membrane. The membrane may have an average pore size of about 0.1 nm to about 10 μm, such as about 0.1 nm to about 10 nm, such as about 0.01 μm to about 10 μm, such as about 0.01 μm to about 0.1 μm (such as about 0.02 μm to about 0.04 μm), or about 0.1 μm to about 10 μm. The membrane may have a molecular weight cutoff (MWCO) of about 200 Da to about 750 kDa. The membrane may have a permeability greater than 900 lmh / bar. In a system or method for removing micropollutants, it may be particularly desirable to use a nanofiltration membrane.

[0049] The membrane may be ZeeWeed sold by Suez Water Technologies & Solutions TM Submerged ultrafiltration membrane. The membrane may be a ZeeWeed 500 or ZeeWeed 1000 membrane.

[0050] Wastewater treatment system according to the present disclosure may include multiple bioreactors as described above, wherein multiple bioreactors are incorporated into sequencing batch reactor (SBR). Because SBR can be used to adapt intermittent processing to a large continuous, possibly variable rate feed flow. In SBR, multiple reactors are provided in parallel and fed in sequence. Each bioreactor can be cyclically operated, and it includes: a feeding stage, an anaerobic or anoxic treatment stage, an aerobic treatment stage and an optional settling stage. In the feeding stage, biomass is maintained as the biomass of basic settling. In certain embodiments, only in the feeding stage, membrane permeate effluent and optional overflow effluent are produced.

[0051] The feed phase and the anaerobic or anoxic treatment phase may overlap partially or completely. If the SBR uses dense or granular sludge, the aerobic treatment phase may include simultaneous nitrification and denitrification even if the aeration rate is not cycled to provide aerobic and anoxic conditions.

[0052] The present invention also provides a method for treating influent wastewater in a batch reactor, the batch reactor comprising a bioreactor tank and a nanofiltration, ultrafiltration or microfiltration membrane located in the bioreactor tank. The method disclosed herein can be implemented with a system or bioreactor as disclosed above, or can incorporate one or more features of a system or bioreactor as disclosed above.

[0053] The method includes adding the influent wastewater to the sludge at the bottom of the bioreactor tank and producing a permeate effluent from a nanofiltration, ultrafiltration or microfiltration membrane, and optionally a feed stage for producing an overflow effluent. The overflow effluent can be combined with the permeate effluent. In some embodiments, the permeate effluent can be produced by filtering the substantially clear wastewater above the sludge.

[0054] The influent wastewater may be about 8 to about 40 kg MLSS / m 2 / h solid loading rate, for example, about 8 kg MLSS / m 2 / h daily average flow rate (ADF) or about 15kgMLSS / m 2 / h of peak hour flow (PHF).

[0055] The method may include producing a permeate effluent while adding the influent wastewater to the sludge. The volume of the wastewater may remain substantially constant. Alternatively or additionally, the method may include aerobically treating the sludge in a process including simultaneous nitrification and denitrification without producing a permeate effluent from a nanofiltration, ultrafiltration or microfiltration membrane. Aerobic treatment may include intermittent aeration of the biomass, for example to prevent settling of biomass solids, but maintaining the dissolved oxygen concentration at a level that promotes anoxic conversion of nitrates to nitrogen.

[0056] The influent wastewater can be added to the sludge without significantly disturbing the sludge. For example, the influent wastewater can be added at an upward flow rate of about 1.0 to about 4.0 m / h, such as an average daily flow rate (ADF) of about 2.5 m / h or a peak hour flow rate (PHF) of about 3.3 m / h.

[0057] It should be understood that in the context of the present disclosure, the expression "significantly disturbing the settled biomass" refers to mixing the settled biomass in a manner that increases the MLSS concentration of the wastewater around the membrane to a level greater than 6.0 g / L. Preferably, the MLSS concentration of the wastewater around the membrane is maintained at a level less than 2 g / L, such as less than 1 g / L, more preferably less than 0.5 g / L.

[0058] The addition of influent wastewater and the production of permeate effluent can be performed by repeated filling and pumping cycles. The filling and pumping cycles may include the simultaneous addition of influent wastewater and the production of membrane permeate effluent. Each filling and pumping cycle may be performed for a predetermined period of time, or may be stopped at a predetermined transmembrane pressure (TMP) or fouling rate. The filling and pumping cycle may be performed for a period of 15 minutes to 1 hour. The maximum allowable TMP or the maximum allowable fouling rate may be used to trigger a backwash period. The TMP limit may be a transmembrane pressure of 5psi to 13psi. Continuous filling and pumping cycles may be separated by relaxation and / or backwashing periods. The length of the relaxation period or backwashing period may be from about 30 seconds to about 1 minute. The backwashing flow rate may be 30L / m 2 / h (LMH) or more. Backwashing may additionally include chemical cleaning.

[0059] A specific embodiment of adding influent wastewater and generating permeate effluent includes: (i) adding influent wastewater and generating permeate effluent simultaneously for 30 minutes; (ii) relaxing for 30 seconds; (iii) adding influent wastewater and generating permeate effluent simultaneously until TMP is 10 psi; (iv) backwashing for 1 minute; and (v) adding influent wastewater and generating permeate effluent simultaneously for 30 minutes. In this embodiment, steps (i), (iii) and (v) correspond to three filling and suction cycles, and steps (ii) and (iv) correspond to relaxation and backwashing periods.

[0060] Another specific embodiment of adding influent wastewater and generating permeate effluent includes: (i) generating permeate effluent for 15 minutes, (ii) adding influent wastewater, (iii) backwashing for 30 seconds, (iv) generating permeate effluent for 15 minutes, (v) adding influent wastewater. In this embodiment, steps (i) and (ii) together, and steps (iv) and (v) together, each correspond to a filling and aspiration cycle.

[0061] During the fill and pump cycles, the wastewater influent can be distributed uniformly enough to the biomass portion of the bioreactor tank so that the biomass rises in a piston flow manner without disturbing the interface between the biomass and the substantially clear wastewater, thereby pushing the substantially clear wastewater to the bioreactor outlet and / or membrane.

[0062] Methods according to the present disclosure may include membrane flushing when permeate effluent is produced, during relaxation and / or backwash periods, or both. Membrane flushing may include continuous or intermittent aeration. The flushing aeration gas may be provided by accumulating bubbles diffused from the biomass and intermittently releasing the flushing bubbles, or by an external gas source. The flushing aeration bubbles may be released by an aerator located below the membrane but above the sludge. Methods including membrane flushing may include flushing the membrane with continuous or intermittent aeration when permeate effluent is produced; flushing the membrane with continuous or intermittent aeration when influent wastewater is added to the sludge; or both.

[0063] The method according to the present disclosure may include treating the sludge anoxically or anaerobically in a process that reduces the concentration of particulate biodegradable chemical oxygen demand (COD) in the influent wastewater. The anoxic or anaerobic treatment may maintain the dissolved oxygen concentration of the biomass at less than 0.2 mg / L, for example, at a concentration of 0.0 to 0.1 mg / L. The anoxic or anaerobic treatment may maintain the redox potential (ORP) level of the biomass at -100 to +50 mV ENH (H2 electrode reference) to enhance biological phosphorus removal. The anoxic or anaerobic treatment may maintain the redox potential (ORP) level of the biomass at +50 to +200 mV ENH (H2 electrode reference) to enhance denitrification and the reduction of nitrates (NO3-N). The anoxic or anaerobic treatment may be maintained for about 45 minutes to about 90 minutes, for example, about 65 minutes, and then transferred to a subsequent treatment stage, such as an aerobic treatment stage. The anoxic or anaerobic treatment may produce volatile fatty acids from biodegradable COD. The sludge may be subjected to anoxic or anaerobic treatment conditions during at least a portion of the feed phase. Even in processes involving flushed membrane aeration, the sludge may be subjected to anoxic or anaerobic treatment conditions when the flushing aeration does not significantly disturb the settled biomass.

[0064] Methods according to the present disclosure may include aerobic treatment of sludge in a process including simultaneous nitrification and denitrification and / or oxidation of soluble biodegradable COD. The aerobic treatment stage may include aeration, biomass mixing, or both. In some embodiments, the aerobic treatment stage results in a MLSS concentration of up to 8.0 g / L in the liquid surrounding the membrane, such as about 4.0 g / L to about 8.0 g / L. The dissolved oxygen concentration in the aerobic treatment stage may be about 0.2 to 4.0 mg / L, such as about 3.0 mg / L. In an exemplary method according to the present disclosure, during the aerobic treatment stage, the membrane does not produce permeate effluent, such as when the dissolved oxygen concentration of the bioreactor is above 2.0 mg / L. In some methods, the length of the aeration treatment stage may be about 45 minutes to about 130 minutes. The level of ammonia and / or dissolved oxygen can be measured in the aeration treatment stage. When the ammonia level drops to less than 5.0 mg NH4-N / L (e.g., less than 1.0 mg NH4-N / L) and the total nitrogen (TN) is less than 10 mg / L, the aeration treatment stage can be terminated. Soluble biodegradable COD can be fermented by biomass into volatile fatty acids (VFA). Polyphosphate accumulating bacteria (PAO) can store VFA in cells as polyhydroxybutyrate (PHB) and release intracellular polyP (polyP) into the environment as PO4-P.

[0065] The method according to the present disclosure may include a settling phase. In the settling phase, solids suspended in the aerobic treatment phase can be allowed to settle to reform sludge and substantially clear wastewater. Preferably, no permeate effluent is produced before the sludge reforms. The settling phase may include a membrane backwash period, with optional chemical cleaning.

[0066] A portion of the sludge may be removed from the bioreactor. The removed sludge may be selected or treated to separate a higher density fraction from a lower density fraction.

[0067] In an exemplary system, the removed sludge can be processed in a gravity selection and recirculation system or a hydrocyclone. Gravity selection can apply 10 to 20G of force and shear force to the removed sludge. The higher density fraction can be recycled to the bioreactor, for example by adding the higher density fraction to the influent wastewater. The lower density fraction can be discarded or processed in a downstream process. Exemplary gravity selection and recirculation systems are disclosed in WO 2014 / 085662 A1, US 2015 / 0376043 A1 and EP 3978447. An example of a gravity selection and recirculation system is the inDENSE sold by NEWport GmbH, Austria. TMSystem. Recycling the higher density fraction of the sludge to the bioreactor can provide a selective pressure to grow dense biomass and particles. Recycling the higher density fraction of the sludge can produce particles with a dSVI of 45 to 100 mL / g, and their size can be mainly 200 to 1000 μm. The sludge bed can ultimately include a layer of particles with essentially the same particle size distribution. That is, the particle size distribution of the particles at the top of the sludge layer is essentially the same as the particle size distribution of the particles at the bottom of the sludge layer.

[0068] In other exemplary systems, the sludge to be removed can be selected from a certain position (e.g., the upper part of the sludge bed) in the bioreactor, which has a higher than average concentration of fine particles, fine flocs, light flocs, or any combination thereof. The sludge at the upper part of the sludge bed corresponds to the lower density fraction of the sludge in the bioreactor. Selecting sludge from such a position can keep denser and larger particles in the lower part of the sludge bed. Due to exposure to BOD and biodegradable BOD (rbBOD) in the feeding and suction cycles, the particles at the lower part of the sludge bed may preferentially grow over the particles or flocs at the upper part. The dSVI of the resulting particles can be less than 50mL / g, for example, 20 to 40mL / g, and the size of most of the particles is 2 to 5mm in diameter. The sludge bed may eventually contain multiple layers of particles with different particle size distributions. That is, the particle size distribution of the layer at the top of the sludge is different from the particle size distribution of the layer at the bottom of the sludge.

[0069] A portion of the removed sludge, such as a lower density fraction of the removed sludge, can be processed in a downstream process comprising one or more of: ultrafiltration, microfiltration, reduction or removal of compounds that contribute to soluble chemical oxygen demand (COD) and / or biological oxygen demand (BOD), reduction or removal of soluble phosphorus.

[0070] The methods according to the present disclosure may also include a wastewater pretreatment step, a buffering step, or both. Buffering the flow of the influent wastewater, for example by adding the influent wastewater to a buffer tank and feeding it to the bioreactor from the buffer tank, can regulate or smooth the peak influent flow rate and can reduce the total membrane area required to treat the wastewater. The reduction in membrane area will be compared to the same system without the buffer tank. Regulating or smoothing the influent flow rate can reduce the ratio of overflow effluent to membrane permeate effluent by allowing the membrane to operate at its highest permeation rate during more of the feed phases.

[0071] The biomass grown in the disclosed method and system can be grown under conditions that promote the growth of granular sludge or dense sludge, for example using the method or system disclosed in WO2022069705, which is incorporated herein by reference. Biomass can be grown in a bioreactor, for example, including multiple sludge blowdown lines between maximum and minimum blowdown levels. Sludge removed from different blowdown levels using different blowdown lines can have different densities. Recirculating higher density sludge to the reactor can provide selective pressure to grow dense biomass and particles.

[0072] In a particular method according to the present disclosure, the method includes: adding influent wastewater to a sludge layer in a bioreactor tank without significantly disturbing the sludge layer, while withdrawing permeate effluent from a nanofiltration, ultrafiltration or microfiltration membrane located in the bioreactor tank, and optionally withdrawing overflow effluent to maintain a substantially constant volume. The method also includes treating the influent wastewater and sludge under anoxic or anaerobic conditions to reduce the concentration of particulate biodegradable chemical oxygen demand (COD) in the influent wastewater; and aerobically treating the sludge in a process including simultaneous nitrification and denitrification and oxidation of soluble biodegradable COD without producing permeate effluent from the nanofiltration, ultrafiltration or microfiltration membrane. The method includes an optional settling stage, in which at least some of the solids suspended by the aerobic treatment are allowed to settle and reform the sludge layer.

[0073] As discussed in detail above:

[0074] When at least a portion of the influent wastewater is added to the sludge blanket, the sludge blanket may be subjected to anoxic or anaerobic conditions;

[0075] Aerobic treatment may include the use of aerators located below or within the sludge blanket to mix the sludge in the sludge blanket and optionally flush the membranes;

[0076] The method may include intermittent or continuous membrane flushing without significantly disturbing the sludge blanket, for example by using aerators located above the sludge blanket and below the membrane;

[0077] Withdrawing a permeate effluent from the nanofiltration, ultrafiltration or microfiltration membrane may include membrane filtration of the substantially clear wastewater; and / or

[0078] • The method may include multiple fill and pump cycles where influent wastewater is added while permeate effluent is pumped out during each aerobic treatment cycle.

[0079] Intermittent or continuous membrane flushing may be performed during the membrane filtration period, the non-membrane filtration period, the membrane backwash period, or any combination thereof. Intermittent or continuous membrane flushing may be performed while the influent wastewater is added to the sludge blanket. Intermittent membrane flushing may include accumulating process gas bubbles released from the sludge blanket in the LEAP aerator and intermittently releasing larger flushing bubbles.

[0080] The continuous filling and pumping cycles may be separated by: a backwash period, a relaxation period, a chemical cleaning period, or any combination thereof.

[0081] In another specific method according to the present disclosure, the method includes the steps of: providing a set of sequencing batch reactors; and feeding wastewater through a bed of particles in each reactor for a period of time while: (1) filtering clarified wastewater above the bed of particles through a nanofiltration, microfiltration or ultrafiltration membrane, (2) producing a membrane effluent and an overflow effluent, or (3) both. The feed time is a fraction of the cycle time of each reactor; and the feed time of each reactor multiplied by the number of reactors is generally equal to the cycle time of each reactor. The cycle time of the reactor can be from 2 to 10 hours and can depend on variables such as influent flow rate and load scenario.

[0082] Each cycle may include anaerobic treatment of the wastewater with the particles; and aerobic treatment of the wastewater with the particles. The aerobic treatment may include simultaneous nitrification and denitrification.

[0083] In yet another specific method according to the present disclosure, the method includes: feeding wastewater to a zone in a bioreactor having particles, while: (1) filtering the wastewater from a clarified wastewater zone in the bioreactor through a nanofiltration, microfiltration, or ultrafiltration membrane, (2) producing a membrane effluent and an overflow effluent, or (3) both. The method also includes treating the wastewater with particles under anaerobic conditions; treating the wastewater with particles under aerobic conditions; settling the particles; withdrawing the treated wastewater from the zone having particles; mixing the particles with the wastewater at least during the treatment under aerobic conditions; and, stopping mixing the particles with the wastewater during the settling step to allow the particles to settle.

[0084] The method and system according to the present invention can be used to treat municipal wastewater, which may have the following characteristics: a COD / BOD5 ratio of 1.8 to 3.0; a TSS / BOD5 ratio of 0.7 to 1.2; a VSS / TSS ratio of 0.65 to 0.85; a BOD5 / TKN ratio of 3.0 to 7.0, such as 4.0 to 5.0, such as about 5.0; a BOD / TP ratio of 20 to 40, such as about 30; and a N-NH4 / TKN ratio of 0.6 to 0.8. The TSS level of municipal wastewater may be 100 to 700 mg / L, for example, about 300 mg / L; the cBOD5 level is 100 to 700 mg / L, for example, about 300 mg / L; the COD level is 200 to 1000 mg / L, for example, about 650 mg / L; the TKN level is 200 to 100 mg / L, for example, about 60 mg / L; the N-NH4 level is 10 to 70 mg / L, for example, about 40 mg / L, and the total phosphorus level is 3 to 20 mg / L, for example, about 10 mg / L.

[0085] Figure 1 An embodiment of a wastewater system according to the present disclosure is shown. The wastewater system (100) includes a bioreactor (102) having an influent wastewater inlet (104), a nanofiltration, microfiltration or ultrafiltration membrane (106) located at the top of the bioreactor, and a permeate effluent outlet (108) in fluid communication with the membrane (106). The bioreactor (102) includes a biomass aerator (110) at the bottom of the bioreactor. The bioreactor (102) shows a substantially clear wastewater (114) with settled biomass (112) at the bottom of the bioreactor, and around the membrane (106). The settled biomass (112) and the substantially clear wastewater (114) define an interface (116). In certain operating stages, such as in an aerobic treatment stage, the biomass may be dispersed throughout the bioreactor, while the settled biomass will not be present in the bioreactor.

[0086] An optional membrane flush aerator (118) is shown located above the settled biomass (112) and below the membrane (106). Figure 1 In the embodiment of the present invention, aerator (118) is shown to provide flushing bubbles. Bioreactor (102) is also shown to include an optional overflow effluent outlet (120).

[0087] The system (100) also shows an optional excess activated sludge (WAS) separation and recirculation system (122). The WAS separation and recirculation system (122) is in fluid communication with the WAS outlet (124) from the bioreactor and produces a return WAS stream (126) and a WAS effluent stream (128). The WAS effluent stream (128) can be processed in a downstream phosphate removal unit (not shown) or can be discharged from the system (100) without further processing.

[0088] The illustrated system (100) also includes an optional pretreatment unit (130), a buffer tank (132), and a primary clarification unit (134). An alternative system may place the buffer tank downstream of the primary settling unit. The pretreatment unit (130) may include a solids separator, such as a coarse solids screen or a fine solids screen; an oil or grease separator; or any combination thereof. Wastewater, such as municipal wastewater, enters the pretreatment unit (130). Coarse solids are removed and permeate is transferred to the buffer tank (132), which regulates the peak influent flow rate of the incoming wastewater. The wastewater is transferred to the primary clarification unit (134), where primary sludge is removed and effluent is transferred to the bioreactor tank (102) via the influent wastewater inlet (104).

[0089] The system (100) may include features that promote the growth of granular sludge or compacted sludge, or operate under conditions that promote their growth. The system (100) may include, for example, a feed unit for adding a microbial carrier material (not shown) such as powdered activated carbon (PAC) particles to the bioreactor. Adding microbial carrier material to the bioreactor may accelerate granulation or densification. PAC may reduce the level of dissolved organic or inorganic micropollutants.

[0090] Figure 2 An embodiment of a wastewater treatment cycle according to the present disclosure is shown. The treatment cycle (200) shown depicts different stages of reaction in a batch reactor rather than a process flow diagram. The treatment cycle (200) includes a feed phase (202) in which the influent wastewater is fed into a bioreactor equipped with a settling biomass and a nanofiltration, microfiltration or ultrafiltration membrane while a permeate effluent is produced from the membrane. The feed phase (202) includes multiple filling and pumping cycles, each of which (204) is separated by a relaxation and / or backwashing period (206).

[0091] The illustrated treatment cycle (200) also includes an anaerobic or anoxic treatment phase (208). Figure 2The anaerobic treatment stage (208) is shown as after the feeding stage (202), but at least a portion of the two stages can occur simultaneously. For example, the influent wastewater (204) can be sent to the settling biomass while the settling biomass is under anaerobic or anoxic conditions. In the anaerobic or anoxic treatment stage (208), particulate biodegradable chemical oxygen demand (COD) in the influent is hydrolyzed into soluble biodegradable COD, which can be further consumed by the biomass microorganisms.

[0092] The illustrated treatment cycle (200) also includes an aerobic treatment stage (210), wherein the biomass is aerated and maintained at a dissolved oxygen concentration sufficient to promote the oxidation of organic matter to carbon dioxide, the oxidation of ammonia to nitrite, and the oxidation of nitrite to nitrate. When the biomass is a dense biomass, the interior of the biomass particles remains under anoxic conditions due to the resistance of dissolved oxygen to diffuse from the bulk liquid into the interior of the biomass particles. The anoxic portion of the biomass particles reduces nitrates to nitrogen gas in the denitrification process. In combination, the aerobic treatment stage (210) includes simultaneous nitrification and denitrification (SND).

[0093] The illustrated treatment cycle (200) includes an optional anoxic treatment stage (212) in which the biomass is intermittently aerated to keep the biomass solids suspended, but at a dissolved oxygen concentration that promotes anoxic conversion of remaining nitrates to nitrogen gas.

[0094] No permeate effluent is produced during the aerobic treatment stage (210) or the anoxic treatment stage (212).

[0095] The illustrated treatment cycle (200) includes an optional settling stage (214). In the settling stage (214), the biomass is not mixed and at least some of the solids suspended by the aerobic treatment are allowed to settle and reform into the settled biomass. Figure 2 The settling stage (214) shown in FIG. 1 includes the optional steps of separating a lower density fraction from a higher density fraction of the settled biomass, recycling the higher density fraction back to the bioreactor, and producing a sludge effluent including the lower density fraction. These steps are not shown in FIG. Figure 2 Once the settled biomass reforms, the processing cycle (200) may restart at the feed stage (202).

[0096] During peak flow rates into the system, the feed phase (202) may include the generation of overflow effluent (not shown) in addition to the permeate effluent. Depending on the flow rate into the system, the overflow effluent may account for 0 to 99% of the total volume discharged from the bioreactor during the feed phase (202).

[0097] Treating wastewater using the method according to the present invention without subsequent downstream tertiary treatment of the membrane permeate effluent, such as without biological phosphorus removal combined with iron coagulant polishing, can produce an effluent having the following characteristics: a TSS concentration of less than 5 mg / L, such as 3 to 5 mg / LTSS or undetectable levels of TSS; a BOD concentration of less than 5 to 15 mg / L; a COD concentration of less than 50 mg / L; a total nitrogen concentration of 10 to 30 mg / L; and a total phosphorus concentration of 0.03 to 0.5 mg / L.

[0098] Tables 1 and 2 show the use of ZeeWeed TM Preliminary design of an exemplary system of ultrafiltration membranes.

[0099] Table 1 - "Exemplary System 1" shows a system that removes sludge from the upper sludge bed to support granulation, having a size that is 100% permeable at the peak hourly flow rate (PHF), and does not discharge a membrane overflow effluent. "Exemplary System 2" shows a system that uses a gravity selection and recirculation system to support granulation, having a size that is 100% permeable at the peak hourly flow rate (PHF), and does not discharge a membrane overflow effluent.

[0100]

[0101]

[0102]

[0103]

[0104] Table 2 - "Exemplary System 3" shows a system using a gravity selection and recirculation system to support granulation, having a membrane sized to be 100% permeable at an average daily flow rate (ADF), and discharging an overflow effluent at a PHF. "Exemplary System 4" shows a system using a gravity selection and recirculation system to support granulation, having a membrane sized to be 80% permeable at an average daily flow rate (ADF) and 20% permeable at a PHF.

[0105]

[0106]

[0107]

[0108] In the foregoing description, for the purpose of explanation, many details are set forth in order to provide a thorough understanding of the embodiments. However, those skilled in the art will appreciate that these specific details are not required. Therefore, what is described is merely an illustration of the application of the embodiments, and many modifications and variations may be made in accordance with the above teachings.

[0109] Since the above description only provides examples, those skilled in the art may modify and change the specific examples. Therefore, the scope of the claims should not be limited by the specific examples described herein, but should be interpreted in a manner consistent with the entire specification.

Claims

1. A wastewater treatment system, comprising: a sequencing batch reactor comprising a plurality of bioreactor cells, each bioreactor cell growing biomass therein and comprising a liquid inlet for influent wastewater, and a plurality of nanofiltration, ultrafiltration or microfiltration membranes mounted in the bioreactor tank, the membranes being in fluid communication with a liquid outlet for discharging a permeate effluent, The membranes filter the biologically treated wastewater but not the biomass grown in the bioreactor tanks.

2. The wastewater treatment system according to claim 1, wherein the membrane is located in an upper portion of the bioreactor tank, the biomass grows in a lower portion of the bioreactor tank, and the biomass does not grow in an upper portion of the bioreactor tank.

3. A wastewater treatment system according to claim 1 or 2, wherein the liquid inlet is positioned to add influent wastewater to the biomass without significantly disturbing the biomass.

4. The wastewater treatment system according to any one of claims 1 to 3, It further includes a plurality of biomass aerators, at least one biomass aerator in each bioreactor tank and positioned to at least aerate the biomass grown in the bioreactor tank, And optionally further comprising a plurality of membrane flushing aerators, at least one membrane flushing aerator in each bioreactor tank and arranged above the biomass to flush the membrane without significantly disturbing the biomass.

5. A wastewater treatment system according to any one of claims 1 to 4, further comprising a non-permeate effluent outlet located in the bioreactor tank to discharge overflow effluent, and optionally further comprising a combined overflow effluent and permeate effluent stream.

6. A wastewater treatment system, comprising a biological treatment reactor, wherein the biological treatment reactor comprises: a bioreactor tank that grows biomass in a biomass portion of the bioreactor tank and includes a liquid inlet for influent wastewater; a nanofiltration, ultrafiltration or microfiltration membrane located in the filtration portion of the bioreactor tank, the membrane being in fluid communication with the permeate effluent outlet; and The non-permeate effluent outlet is located in the filtration section of the bioreactor tank.

7. The wastewater treatment system of claim 6, further comprising an outlet stream combining the permeate effluent and the non-permeate effluent.

8. A wastewater treatment system according to claim 6 or 7, wherein the biomass portion of the bioreactor tank does not overlap with the filtration portion of the bioreactor tank, for example wherein the biomass portion of the bioreactor tank is located below the filtration portion of the bioreactor tank.

9. A wastewater treatment system according to any one of claims 6 to 8, wherein the liquid inlet is positioned to add wastewater to the biomass portion of the bioreactor tank without significantly disturbing the biomass.

10. A wastewater treatment system according to any one of claims 6 to 9, wherein the biological treatment reactor further comprises a biomass aerator positioned to aerate at least the biomass grown in the bioreactor tank, And optionally further comprising a membrane flush aerator disposed above the biomass to flush the membrane without significantly disturbing the biomass.

11. The wastewater treatment system according to any one of claims 1 to 10, wherein the biomass: Having a settling velocity greater than 1.2 m / h, such as 1.2 to 9.0 m / h, or greater than 10 m / h; having a dSVI of 100 ml / g or less, such as 35 to 100 mL / g, such as 50 to 80 mL / g; Having 50 to 90% by weight of flocs, such as 50 to 80% by weight of flocs, preferably flocs with an average particle size of less than 200 μm, such as less than 100 μm; 10 to 85% by weight of the particles, such as 20 to 60% by weight of the particles, preferably have an average particle size greater than 100 μm, such as 100 to 1000 μm, 200 to 5000 μm, 200 to 1000 μm or 200 to 500 μm; or any combination thereof.

12. A wastewater treatment system comprising: a bioreactor tank having a biomass processing section and a filtration section; a liquid inlet for an influent wastewater stream, the liquid inlet being positioned to discharge the wastewater to a biomass processing portion of the bioreactor tank; a nanofiltration, ultrafiltration or microfiltration membrane located in the filtration portion of the bioreactor tank, the membrane being in fluid communication with a liquid outlet for a permeate effluent discharge stream; as well as A biomass aerator is located below the membrane and positioned to aerate at least the biomass processing portion of the bioreactor tank.

13. The wastewater treatment system of claim 12, wherein an upper portion of the bioreactor tank comprises the filtration section.

14. A wastewater treatment system according to claim 12 or 13, wherein the liquid inlet for the incoming wastewater stream comprises liquid holes distributed substantially evenly within the biomass processing portion of the bioreactor tank.

15. The wastewater treatment system according to any one of claims 12 to 14, wherein The bioreactor tank further comprises a non-permeate effluent outlet for overflow effluent, And the wastewater treatment system optionally further comprises a combined effluent stream for overflow effluent and permeate effluent.

16. The wastewater treatment system of any one of claims 12 to 15, further comprising a membrane flush aerator located below the membrane and above the biomass processing portion of the bioreactor tank.

17. The wastewater treatment system according to any one of claims 1 to 16, wherein the bioreactor further comprises: Excess activated sludge (WAS) outlet, or WAS separation and recirculation systems, such as gravity selection and recirculation systems; or a hydrocyclone in fluid communication with the WAS outlet and the return WAS flow.

18. The wastewater treatment system according to any one of claims 1 to 17, further comprising: a pretreatment system, a buffer tank, or both, located upstream of the bioreactor tank and in fluid communication with a liquid inlet for influent wastewater; A post-treatment system located downstream of the bioreactor tank; Or both.

19. The wastewater treatment system of claim 18, wherein the post-treatment system provides: Nanofiltration, ultrafiltration or microfiltration of residual activated sludge effluent; Reduction or removal of compounds that contribute to soluble chemical oxygen demand (COD) and / or biological oxygen demand (BOD); Reduction or removal of soluble phosphorus; or any combination thereof.

20. The wastewater treatment system according to any one of claims 1 to 19, wherein the membrane: It is a hollow fiber membrane; It is a non-ionic hydrophilic membrane, such as polyvinylidene fluoride (PVDF) or modified polyethersulfone (PES) membrane or ceramic membrane; having an average pore size of about 0.1 nm to about 10 μm, for example, about 0.1 nm to about 10 nm, for example, about 0.01 μm to about 10 μm, for example, about 0.01 μm to about 0.1 μm, such as about 0.02 μm to about 0.04 μm, or about 0.1 μm to about 10 μm; Has a permeability greater than 900lmh / bar; a molecular weight cutoff (MWCO) of about 200 Da to about 750 kDa; or any combination thereof.

21. A method for treating influent wastewater in a batch reactor, the reactor comprising a bioreactor tank and a nanofiltration, ultrafiltration or microfiltration membrane located in the bioreactor tank, the method comprising: Substantially clear wastewater is treated with nanofiltration, ultrafiltration or microfiltration membranes in bioreactor tanks to produce a permeate effluent while the influent wastewater is added to the sludge below the membrane treated wastewater.

22. The method of claim 21 further comprising producing an overflow effluent comprising substantially clear wastewater upon adding the influent wastewater to the sludge, and optionally combining the overflow effluent with the permeate effluent.

23. A method according to claim 21 or 22, wherein the volume of wastewater in the bioreactor tank is maintained at a substantially constant volume.

24. The method according to any one of claims 21 to 23, further comprising: The sludge is treated anoxically or anaerobically in a process that reduces the concentration of particulate biodegradable chemical oxygen demand (COD) in the influent wastewater. Preferably, the anoxic or anaerobic treatment comprises the following treatments: (a) a dissolved oxygen concentration of less than 0.2 mg / L, such as a concentration of 0 to 0.1 mg / L; (b) an ORP level of -100 to +50 mV ENH; and / or (c) an ORP level of +50 to +200 mV ENH; Preferably, wherein the anoxic or anaerobic treatment produces volatile fatty acids from biodegradable COD; as well as Optionally, wherein the anoxic or anaerobic treatment comprises treating the substantially clear wastewater in the bioreactor tank with a nanofiltration, ultrafiltration or microfiltration membrane while adding the influent wastewater to the sludge.

25. The method according to any one of claims 21 to 24, further comprising: aerobic treatment of the sludge in a process comprising simultaneous nitrification and denitrification and / or oxidation of soluble biodegradable COD, preferably without producing a permeate effluent from a nanofiltration, ultrafiltration or microfiltration membrane during said aerobic treatment, Preferably, wherein the aerobic treatment is carried out at a dissolved oxygen concentration of about 0.2 to 4.0 mg / L, for example at a concentration of about 3.0 mg / L; Preferably, wherein the aerobic treatment comprises both simultaneous nitrification and denitrification and soluble biodegradable COD oxidation, and the aerobic treatment produces carbon dioxide and nitrogen.

26. The method according to any one of claims 21 to 25, further comprising: The suspended solids are allowed to settle to form a sludge and substantially clear wastewater, preferably without concurrently filtering the suspended solids, and more preferably concurrently backwashing the membranes, wherein the sludge is located below the membranes and the membranes are in a layer of substantially clear wastewater.

27. A method for treating influent wastewater in a batch reactor, the reactor comprising a bioreactor tank and a nanofiltration, ultrafiltration or microfiltration membrane located in the bioreactor tank, the method comprising: The influent wastewater is added to the sludge located at the bottom of the bioreactor tank; producing a permeate effluent from the nanofiltration, ultrafiltration or microfiltration membrane and optionally producing an overflow effluent; as well as The sludge is treated aerobically in a process involving simultaneous nitrification and denitrification without producing a permeate effluent from a nanofiltration, ultrafiltration or microfiltration membrane.

28. A method according to claim 27, wherein the aerobic treatment is carried out at a dissolved oxygen concentration of about 0.2 to 4.0 mg / L, such as at a concentration of about 3.0 mg / L, and preferably wherein the bioreactor has a dissolved oxygen concentration above 2.0 mg / L without producing a permeate effluent.

29. The method according to claim 27 or 28, further comprising: The suspended solids are allowed to settle to form a sludge and substantially clear wastewater, preferably without concurrently filtering the suspended solids, and more preferably concurrently backwashing the membranes, wherein the sludge is located below the membranes and the membranes are in a layer of substantially clear wastewater.

30. The method according to any one of claims 27 to 29, further comprising: The sludge is treated anoxically or anaerobically in a process that reduces the concentration of particulate biodegradable chemical oxygen demand (COD) in the influent wastewater. Preferably, the anoxic or anaerobic treatment comprises the following treatments: (a) a dissolved oxygen concentration of less than 0.2 mg / L, such as a concentration of 0 to 0.1 mg / L; (b) an ORP level of -100 to +50 mV ENH; and / or (c) an ORP level of +50 to +200 mV ENH; Preferably, wherein the anoxic or anaerobic treatment produces volatile fatty acids from biodegradable COD; preferably, wherein the anoxic or anaerobic treatment comprises producing a permeate effluent, an optional overflow effluent, and adding the influent wastewater to the sludge.

31. A method according to any one of claims 27 to 30, wherein the permeate effluent and the optional overflow effluent are produced simultaneously with the addition of the influent wastewater.

32. A method according to any one of claims 21 to 31, wherein adding the influent wastewater to the sludge does not significantly disturb the biomass, for example wherein the adding comprises raising the biomass without disturbing the interface between the biomass and the wastewater above the biomass.

33. The method according to any one of claims 21 to 32, further comprising: flushing the membrane with continuous or intermittent aeration as permeate effluent is produced; and / or The membrane is flushed with continuous or intermittent aeration while the influent wastewater is added to the sludge.

34. The method according to any one of claims 21 to 33, further comprising: removing at least a portion of the sludge from the bioreactor tank, and optionally (a) recycling the higher density fraction of the removed sludge, for example by adding said higher density fraction to the influent wastewater, and (b) discarding the lower density fraction of the removed sludge.

35. The method of claim 34, further comprising treating a portion of the removed sludge, such as the lower density fraction, to: Nanofiltration, ultrafiltration or microfiltration; Reduction or removal of compounds that contribute to soluble chemical oxygen demand (COD) and / or biological oxygen demand (BOD); Reduction or removal of soluble phosphorus; or any combination thereof 36. The method according to any one of claims 21 to 35, further comprising: Pre-treat the wastewater, regulate the influent wastewater flow to adjust for peak influent flow rates, or both.

37. The method of claim 36, wherein pre-treating the wastewater comprises treating it using a solid separator, a grease separator, or a combination thereof.

38. The method of any one of claims 21 to 37, further comprising treating the wastewater to conditions that promote the growth of granular sludge or dense sludge, such as: A settling velocity greater than 1.2 m / h, such as 1.2 to 9.0 m / h, or greater than 10 m / h; having a dSVI of 100 ml / g or less, such as 35 to 100 mL / g, such as 50 to 80 mL / g; Having 50 to 90% by weight of flocs, such as 50 to 80% by weight of flocs, preferably flocs with an average particle size of less than 200 μm, such as less than 100 μm; 10 to 85% by weight of the particles, such as 20 to 60% by weight of the particles, preferably have an average particle size greater than 100 μm, such as 100 to 1000 μm, 200 to 5000 μm, 200 to 1000 μm or 200 to 500 μm; or any combination thereof.

39. A method for treating influent wastewater in a batch reactor comprising a nanofiltration, ultrafiltration or microfiltration membrane, comprising: adding influent wastewater to the sludge blanket in the bioreactor tank without significantly disturbing the sludge blanket while simultaneously withdrawing permeate effluent and, optionally, overflow effluent from the nanofiltration, ultrafiltration or microfiltration membrane to maintain a substantially constant volume; Treating influent wastewater and sludge under anoxic or anaerobic conditions to reduce the concentration of particulate biodegradable chemical oxygen demand (COD) in the influent wastewater; Aerobic treatment of sludge in a process involving simultaneous nitrification and denitrification and oxidation of soluble biodegradable COD without generating a permeate effluent from a nanofiltration, ultrafiltration or microfiltration membrane; and, optionally, allowing at least some of the solids suspended by the aerobic treatment to settle and reform the sludge blanket, Preferably, the anoxic or anaerobic treatment comprises the following treatments: (a) a dissolved oxygen concentration of less than 0.2 mg / L, such as a concentration of 0 to 0.1 mg / L; (b) an ORP level of -100 to +50 mV ENH; and / or (c) an ORP level of +50 to +200 mV ENH; Preferably, wherein the anoxic or anaerobic treatment produces volatile fatty acids from biodegradable COD.

40. The method of claim 39, wherein the method comprises adding the influent wastewater to the sludge blanket under anoxic or anaerobic conditions.

41. A method according to claim 39 or 40, wherein the aerobic treatment comprises mixing the sludge in the sludge blanket using an aerator located below or within the sludge blanket and optionally flushing the membrane.

42. The method of any one of claims 39 to 41 further comprising intermittently or continuously flushing the membrane without significantly disturbing the sludge blanket, for example by using aerators located above the sludge blanket and below the membrane.

43. The method of claim 42, wherein the intermittent or continuous membrane flushing is performed during a membrane filtration period, a non-membrane filtration period, a membrane backwash period, or any combination thereof.

44. The method of claim 42 or 43, wherein adding the influent wastewater to the sludge blanket comprises intermittent or continuous membrane flushing.

45. The method of claim 44, wherein the intermittent membrane flushing comprises focusing process gas released from the sludge blanket in a LEAP aerator and intermittently releasing larger flushing bubbles.

46. ​​The method of any one of claims 39 to 45, wherein withdrawing a permeate effluent from the nanofiltration, ultrafiltration or microfiltration membrane comprises subjecting the substantially clear wastewater to membrane filtration.

47. A method according to any one of claims 39 to 46, wherein the method comprises a plurality of cycles wherein influent wastewater is added while permeate effluent is withdrawn in each aerobic treatment cycle.

48. The method of claim 47, wherein each cycle of adding influent wastewater while withdrawing permeate effluent is separated by a backwash period, a relaxation period, a chemical cleaning period, or any combination thereof.

49. A method for treating wastewater, comprising the following steps: a. Providing a set of sequencing batch reactors; as well as b. feeding the wastewater through the particle bed in each reactor for a period of time, while filtering the clarified wastewater above the particle bed through a nanofiltration, microfiltration or ultrafiltration membrane, wherein the feeding time is a portion of the cycle time of each reactor; The feed time per reactor multiplied by the number of reactors generally equals the cycle time per reactor.

50. The method of claim 49, wherein each cycle comprises: i. Anaerobic treatment of wastewater using particles; as well as ii. Aerobic treatment of wastewater using particles.

51. The method of claim 50, wherein aerobic treatment of wastewater with particles comprises simultaneous nitrification and denitrification.

52. The method of any one of claims 49 to 51 further comprising producing an overflow effluent during the feed time.

53. A method for treating wastewater, comprising: (a) feeding wastewater to a zone in a bioreactor having particles while filtering wastewater from a clarified wastewater zone in the bioreactor through a nanofiltration, microfiltration or ultrafiltration membrane; (b) treating wastewater using particles under anaerobic conditions; (c) treating wastewater using particles under aerobic conditions; (d) Settled particles; (e) extracting treated wastewater from the area containing the particles; (f) mixing the particles with the wastewater at least during step (c); and, (g) stopping the mixing of the particles with the wastewater during step (d) to allow the particles to settle.

54. A method for treating wastewater, comprising the following steps: a. Providing a set of sequencing batch reactors; as well as b. feeding the wastewater through the particle bed in each reactor for a period of time that is a portion of the cycle time of each reactor while producing both (A) a nanofiltration, microfiltration or ultrafiltration membrane effluent and (B) an overflow effluent; The feed time per reactor multiplied by the number of reactors generally equals the cycle time per reactor.

55. The method of claim 54, wherein each cycle comprises: i. Anaerobic treatment of wastewater using particles; as well as ii. Aerobic treatment of wastewater using particles.

56. The method of claim 55, wherein aerobic treatment of wastewater with particles comprises simultaneous nitrification and denitrification.

57. The method of any one of claims 49 to 51 further comprising simultaneously feeding wastewater through the particle bed and producing a membrane effluent.

58. A method for treating wastewater, comprising: (a) feeding wastewater to an area having particles; (b) treating wastewater using particles under anaerobic conditions; (c) treating wastewater using particles under aerobic conditions; (d) Settled particles; (e) extracting treated wastewater from the area containing the particles; (f) mixing the particles with the wastewater at least during step (c); (g) stopping mixing the particles with the wastewater during step (d) to settle the particles; and (h) during step (a) and optionally step (b), simultaneously producing both (A) a nanofiltration, microfiltration or ultrafiltration membrane effluent and (B) an overflow effluent.

59. The method of claim 53 or 58, wherein treating the wastewater under aerobic conditions comprises simultaneous nitrification and denitrification.

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