Abstract: Sludge, for example primary sludge or waste activated sludge or both from a wastewater treatment plant, is pre-treated prior to anaerobic digestion. The pre-treatment includes an optional mechanical treatment to reduce the viscosity of the sludge and a biological hydrolysis treatment. The biological hydrolysis treatment may be performed in a series of reactors some of which are maintained at a temperature in the range of 50 to 70° C. The reactors provide a combined residence time in the range of 0.5 to 6 days. Optionally, measurements of the pH of the sludge during or after biological hydrolysis, or the production of biogas from a downstream anaerobic digester, may be considered in adjusting the temperature of one or more of the biological hydrolysis reactors.

Abstract: An anaerobic digester is fed a feedstock, for example sludge from a municipal wastewater treatment plant, and produces a digestate. The digestate is dewatered into a cake. The cake may be dried further, for example in a thermal drier. The cake is treated in a pyrolysis system to produce a synthesis gas and biochar. The gas is sent to the same or another digester to increase its methane production. The char may be used as a soil enhancer.

Abstract: A method of air scouring an immersed membrane is described in this specification. The method comprising a step of adjusting one or more aeration parameters: between successive permeation, back pulse or relaxation cycles; during a permeation cycle; or, between a permeation cycle and a backpulse or relaxation cycle.

Abstract: A method of air scouring an immersed membrane is described in this specification. The method comprises a step of adjusting one or more aeration parameters during a permeation cycle, or between a permeation cycle and a back pulse or relaxation cycle, or between successive cycles. The method may be used with a gas delivery device described in this specification in which a supply of gas is provided to a manifold with multiple ports connected to multiple conduits. The method may further comprise bringing a flow of pressurized gas into a tank to near or below the bottom of a membrane module. At about this elevation, the flow of pressurized gas is split into multiple flows of pressurized gas. Each of the multiple flows of pressurized gas is directed to a different lateral position and then released as bubbles.

Abstract: Sludge, for example primary sludge or waste activated sludge or both from a wastewater treatment plant, is pre-treated prior to anaerobic digestion. The pre-treatment includes an optuional mechanical treatment to reduce the viscosity of the sludge and a biological hydrolysis treatment. The biological hydrolysis treatment may be performed in a series of reactors some of which are maintained at a temperature in the range of 50 to 70° C. The reactors provide a combined residence time in the range of 0.5 to 6 days. Optionally, measurements of the pH of the sludge during or after biological hydrolysis, or the production of biogas from a downstream anaerobic digester, may be considered in adjusting the temperature of one or more of the biological hydrolysis reactors.

Abstract: An ammonia stripper has an aerator and heat exchanger tubing in a tank. The aerator and coil are preferably attached to a frame to form a removable cassette. The cassette may also include a lid for the tank. The tank is preferably rectangular and optionally can be made with the dimensions of a standard shipping container. In a process, water flows through the tank while air bubbles are produced through the aerator. A heating medium such as water flows through the heat exchanger tubing. A gas containing ammonia is withdrawn from a headspace of the tank.

Abstract: An ammonia stripper has an aerator and heat exchanger tubing in a tank. The aerator and coil are preferably attached to a frame to form a removable cassette. The cassette may also include a lid for the tank. The tank is preferably rectangular and optionally can be made with the dimensions of a standard shipping container. In a process, water flows through the tank while air bubbles are produced through the aerator. A heating medium such as water flows through the heat exchanger tubing. A gas containing ammonia is withdrawn from a headspace of the tank.

Abstract: An apparatus for recovering nutrients or water from digestate comprises one or more solid-liquid separation units, an ammonia stripping device, and a gas scrubbing unit. In a process, digestate is separated into a solids portion and a liquid portion. Ammonia is stripped from the liquid portion and converted into an ammonium salt solution which may be sold or used as, or blended with, a fertilizer product. Optionally, at least part of the remaining liquid portion may be concentrated to produce brine. The brine is mixed with the solids portion. The mixture may be dried and used as, or blended with, a fertilizer product. Optionally, a least part of the remaining liquid portion may be re-used as dilution water in a digester. A solids portion of the digestate, and one or both of an ammonium salt solution and a brine, may be used as fertilizer without thermal drying.

Abstract: A screw press has a cylindrical screening section mounted to a frame. The screening section is able to rotate but can be prevented from rotating. A sprayer system is operable to spray water on the screening section. In a cleaning process, the screening section is rotated while water is sprayed against it. Optionally, the power required to rotate the screen may be provided by an auger drive mechanism. The screening section may have openings sized to retain flocculated solids. The screw press may be used to thicken a sludge from a waste water treatment plant.

Abstract: A digester tank has a servicing device that allows access to the interior of the digester tank. The sealing device may have a movable retention wall adapted to resist the pressure of the gas inside the digester by one or more of a) increasing the bending resistance of the retention wall, for example by inflating pockets in the wall, b) forcing the lower edge of the retention wall downwards, for example by weight, a mechanical arm or inflating pockets, and c) providing a mechanical structure within the retention wall, for example a non-moving cage-like structure. A sealing device with a fixed wall has a pipe with an isolation valve between the headspace of the tank and the inside of the sealing device. In operation, a seal may be formed across the separation curtain by raising the level of the liquid contents and closing the isolation valve.

Abstract: Sludge from an anaerobic digester is treated to recover one or more of fibers, or solids or liquids with a high nutrient content. The solids or liquids can be used as a fertilizer. The fibers can be used in a plant growing medium. Solids are separated from liquids in the sludge and dried. The solids may be dried to produce a flake or pellet. Ammonia in the liquids is recovered and used to produce a concentrated acidic ammonium salt solution. This solution may be mixed with the solids to produce a nitrogen enhanced solid. The fibers and solids or liquids can also be used in combination to produce an enhanced plant growing medium. A device and process for removing ammonia from a liquid can be used in the system or separately.

Abstract: Sludge from an anaerobic digester is treated to recover one or more of fibers, or solids or liquids with a high nutrient content. The solids or liquids can be used as a fertilizer. The fibers can be used in a plant growing medium. Solids are separated from liquids in the sludge and dried. The solids may be dried to produce a flake or pellet. Ammonia in the liquids is recovered and used to produce a concentrated acidic ammonium salt solution. This solution may be mixed with the solids to produce a nitrogen enhanced solid. The fibers and solids or liquids can also be used in combination to produce an enhanced plant growing medium. A device and process for removing ammonia from a liquid can be used in the system or separately.

Abstract: An anaerobic digester is fed a feedstock, for example sludge from a municipal wastewater treatment plant, and produces a digestate. The digestate is dewatered into a cake. The cake may be dried further, for example in a thermal drier. The cake is treated in a pyrolysis system to produce a synthesis gas and biochar. The gas is sent to the same or another digester to increase its methane production. The char may be used as a soil enhancer.

Abstract: An ammonia stripper has an aerator and heat exchanger tubing in a tank. The aerator and coil are preferably attached to a frame to form a removable cassette. The cassette may also include a lid for the tank. The tank is preferably rectangular and optionally can be made with the dimensions of a standard shipping container. In a process, water flows through the tank while air bubbles are produced through the aerator. A heating medium such as water flows through the heat exchanger tubing. A gas containing ammonia is withdrawn from a headspace of the tank.

Abstract: An apparatus for recovering nutrients or water from digestate comprises one or more solid-liquid separation units, an ammonia stripping device, and a gas scrubbing unit. In a process, digestate is separated into a solids portion and a liquid portion. Ammonia is stripped from the liquid portion and converted into an ammonium salt solution which may be sold or used as, or blended with, a fertilizer product. Optionally, at least part of the remaining liquid portion may be concentrated to produce brine. The brine is mixed with the solids portion. The mixture may be dried and used as, or blended with, a fertilizer product. Optionally, a least part of the remaining liquid portion may be re-used as dilution water in a digester. A solids portion of the digestate, and one or both of an ammonium salt solution and a brine, may be used as fertilizer without thermal drying.

Abstract: A method of air scouring an immersed membrane is described in this specification. The method comprising a step of adjusting one or more aeration parameters: between successive permeation, back pulse or relaxation cycles; during a permeation cycle; or, between a permeation cycle and a backpulse or relaxation cycle.

Abstract: In a wastewater treatment system, feed water is processed by anaerobic digestion, preferably in an anaerobic moving bed bioreactor (AnMBBR). Effluent from the AnMBBR passes through one or more solid-liquid separation units. A solids portions is treated by hydrolysis or suspended growth anaerobic digestion. A liquid portion of the hydrolysis or suspended growth anaerobic digestion effluent is returned to the AnMBBR or blended with effluent from the AnMBBR. The AnMBBR effluent may be treated with an aerobic moving bed bioreactor (MBBR) before the one or more solid-liquid separation steps. Membrane filtration may provide a first solid-liquid separation step. A thickened waste stream may be withdrawn from a recirculation loop flowing from the first solid-liquid separation unit to the MBBR. Optionally, a solids portion separated from the feed water upstream of the AnMBBR may also be treated by hydrolysis or suspended growth anaerobic digestion.

Abstract: A screw press has a cylindrical screening section mounted to a frame. The screening section is able to rotate but can be prevented from rotating. A sprayer system is operable to spray water on the screening section. In a cleaning process, the screening section is rotated while water is sprayed against it. Optionally, the power required to rotate the screen may be provided by an auger drive mechanism. The screening section may have openings sized to retain flocculated solids. The screw press may be used to thicken a sludge from a waste water treatment plant.

Abstract: Feed water is processed in an anaerobic digester. A solid-liquid separation device, for example a sludge screw thickener, treats a stream drawn from the digester in a recirculation loop. The solids portion is returned to the digester to increase the solids retention time and the TSS concentration in the digester. A liquid portion with less than 5% of the solids in the stream is removed and optionally treated further. The flow rate to the solid-liquid separation device is preferably greater than the influent flow rate. The solid-liquid separation device may receive digestate at a TSS concentration of 4% or more and return a solids portion having a TSS concentration of over 10%. The feed water is preferably one or more industrial waste streams having a COD concentration of 20,000 to 50,000 mg/L and a TSS concentration from 1-5%. The organic loading rate may be 10-12 kg/COD/m3/day.

Abstract: A digester tank has a servicing device that allows access to the interior of the digester tank. The sealing device may have a movable retention wall adapted to resist the pressure of the gas inside the digester by one or more of a) increasing the bending resistance of the retention wall, for example by inflating pockets in the wall, b) forcing the lower edge of the retention wall downwards, for example by weight, a mechanical arm or inflating pockets, and c) providing a mechanical structure within the retention wall, for example a non-moving cage-like structure. A sealing device with a fixed wall has a pipe with an isolation valve between the headspace of the tank and the inside of the sealing device. In operation, a seal may be formed across the separation curtain by raising the level of the liquid contents and closing the isolation valve.