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 A thickened waste stream may be withdrawn from a recirculation loop flowing from the first solid-liquid separation unit to the MBBR.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 multi-stage anaerobic digester is designed to treat a high solids, stackable feedstock. The system may also receive a pumpable feedstock such as a slurry or sludge. In a first stage, the digestate circulates in one direction around a raceway such that the digestate may pass a feed inlet multiple times before leaving the first tank. An optional side stream loop withdraws fibrous material from near the top of the reaceway and return digestate with chopped fibers, preferably lower and further along the raceway. An outlet from the raceway located near, but upstream of the feed inlet discharges partially digested substrate to a second stage, which is operated as a stirred tank reactor. The two stages may be provided in a single tank with an internal wall separating a ring shaped outer portion from a cylindrical inner portion. The digester may be operated in a thermophilic temperature range.

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: 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 spray dryer exhaust gas treatment system and process recovers waste heat, removes odors from the exhaust gas, or both. The spray dryer may be used to dry digestate from an anaerobic digester. Spray dryer exhaust is at least partially recirculated to the spray dryer, or condensable vapors are removed from the spray dryer exhaust, or both. Optionally, a bleed from a recirculating exhaust stream may pass through a combustion chamber. Preferably, waste heat is added to the recirculating exhaust stream or used to evaporate water upstream of the spray dryer. In a case where the spray dryer is used to treat digestate, a biogas burner may provide the combustion chamber and a source of waste heat. The system and method reduce odors from spray dryer exhaust by condensing odorous compounds, by combustion, or both while using waste heat and spray dryer exhaust gas recirculation to reduce energy consumption.

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: 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: A rotating screen has one or more panels arranged into a cylinder, or drum. The panels have openings in a micro-screening range, for example 100 microns or less. Wastewater to be screened is fed to the interior of the drum. The drum rotates constantly but the rotation may be discontinuous and the speed of rotation may be variable. The drum may be cleaned by an air knife. If the wastewater contains oil and grease, a short hot water spray may be provided before cleaning with the air knife. Optionally, an internal auger conveys solids down the length of the drum to an outlet. The rotating screen may be used for primary treatment of wastewater. The rotating screen may be used produce screenings with a dried solids concentration of 5% or more, for example 6-7%. The primary sludge may be treated in an anaerobic digester.

Abstract: An apparatus for recovering nutrients from digestate comprises one or more solid-liquid separation steps, and dryer, an ammonia stripping device, and an evaporator. 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 solution or salt which may be used as, or blended with, a fertilizer product. At least part of the remaining liquid portion is concentrated to produce brine. The brine is mixed with the solids portion. The mixture is dried and may be used as, or blended with, a fertilizer product.

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: 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: A waste stream is treated by anaerobic digestion. A process is described involves a step of separating solids from digestate, and returning separated solids to a digester. Optionally, there may be a step of solids separation in which larger solids are removed from the digester. A process and apparatus are described for treating waste sludge from a wastewater treatment plant in an anaerobic digester. Feed sludge is thickened or solids are separated from digestate and returned to the digester. Additional co-digestion waste may be added to the digester. The process and apparatus may be used in a retrofit of an existing wastewater treatment plant.

Abstract: In a waste treatment system and process, relatively low and high solids concentration streams are treated in generally parallel anaerobic reactors. The reactors may share a common wall or gas collecting cover. The reactors may also share a common downstream aerobic treatment unit. Solids produced during downstream treatment of effluent from one or both anaerobic reactors may be returned to the high solids concentration stream. The low solids concentration stream may be treated in an attached growth anaerobic digester.

Abstract: A biofilm carrier screen is adapted for use with a moving bed bioreactor (MBBR). The screen has a screening body connected to an effluent pipe. The effluent pipe optionally has two parts separated by a union, preferably a pitless adapter. The screening body can be lifted from a bioreactor tank for maintenance after disconnecting the union. The screening body may have an aerator to provide bubbles to disperse biofilm carriers from the screening body. The screening bod may extend downwards from a mount near the top of the tank. In the case of an anaerobic MBBR, the screening body may extend downwards from a service box through a cover over the tank.

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: Low strength wastewater such as municipal sewage is treated using an anaerobic digester. In some examples, a wastewater stream is separated into a solids rich portion and a solids lean portion. The solids lean portion is treated, for example to remove nitrogen. The solids rich portion is treated in an anaerobic digester, preferably with influent or recuperative thickening. In another example, the wastewater stream is fed to an anaerobic digester and solid-liquid separation stages downstream of the di-gester return active bacteria and undigested organics to the digester. Both cases may use a process train comprising treatment in an anoxic tank followed by a nitritation tank with a portion of the effluent from the nitritation tank recirculated to the anoxic tank to provide nitritation and denitritation.

Abstract: A process is provided for full treatment of animal manure and other organic slurries containing suspended solids, and dissolved organic matter, nitrogen, and phosphorus, without the need for anaerobic digestion or anaerobic stabilization lagoons. The process includes: centrifugal decanting, flocculation, dissolved air flotation thickening, centrate heating, acidification in fluidized bed reactor, biological removal of phosphorus, nitrogen and dissolved organic matter in microfiltration membrane bioreactor and disinfection with ultraviolet radiation. The process separates liquids from solids, converts solids into organo-mineral fertilizer pellets, and treats the liquid to dischargeable standards. Land application for effluent disposal is not required because the treatment removes all nutrients.

Abstract: A biological fluidized bed apparatus for the treatment of wastewater comprises: a reactor tank having a conical bottom with angles ranging from about 30 to about 80 degrees, and most preferably about 60 degrees from a horizontal plane; an inert media bed within said tank; and a recirculation pipe within said tank having an upper inlet, and a lower conformed outlet fitting within said media. The apparatus is self-contained, and offers easy and uniform expansion for various types of commercially available media. Besides the biological treatment accomplished within the fluidized bed, this reactor provides mechanical solids/gas/liquid separation and upflow sludge blanket clarification to improve effluent quality. Preferred additional features of the apparatus include a rotating surface skimmer and an excess sludge collection and thickening device powered by an externally mounted drive.