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 digester 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.

An extraction manifold for extracting digestate from a covered lagoon digester includes a digester vessel being shaped generally as a rectangular prism lacking an upward facing face and having a floor sloping generally downward from an intake face to an extraction face of the digester vessel. The intake face and extraction face are oriented vertically, situated in opposed relation on a longer horizontal axis. Each effluent pipe terminates in an extraction nozzle on one end and an independently addressable actuatable valve on the opposite end. Each actuatable valve communicates with a manifold plenum such that actuation of the valve draws digestate from the floor in a region of the floor adjacent to the extraction face and in proximity to the extraction nozzle. A valve controller actuates valves to remove digestate from the region of the floor adjacent to the extraction face. The valve controller includes sensors to monitor biogas production.

Disclosed is a modified activated sludge-based two-compartment treatment method for processing nitrate-contaminated drinking water. Raw water is firstly sent to a first TiO.sub.2-modified denitrifying activated sludge bioreactor (2), wherein organic carbon source is added in a controlled amount, and nitrate is partly reduced with nitrite being accumulated. Then, the effluent from the first bioreactor is sent to a second TiO.sub.2-modified denitrifying activated sludge bioreactor (3), wherein organic carbon source and hydrogen gas are supplemented, and remaining nitrate and accumulated nitrite are reduced to nitrogen gas. The denitrified effluent from the second bioreactor is sent to a settling tank (4), and TiO.sub.2-containing precipitates collected from the settling tank receive sequential alkaline and acidic treatment before being injected into the first bioreactor (2) for TiO.sub.2 recycling. The effluent from the settling tank (4), after having been subjected to ozone disinfection and activated carbon filtration, has suitable pH and bicarbonate alkalinity, and the concentrations of nitrate, nitrite and water soluble organics meet the safety standard for drinking water. Also disclosed is a modified activated sludge-based two-compartment treatment device for processing nitrate-contaminated drinking water.

A biological reactor system treats concentrated contaminated water with a combination of upflow and downflow bioreactors that are downstream from a reverse osmosis or other concentrator. The system may have a fail safe configuration where flush water may be introduced to the reactors in the event of a power failure or when taking the reactors offline. Many reverse osmosis systems introduce antiscalant treatments upstream so that the reverse osmosis filters do not scale. However, such treatments result in superconcentrated conditions of the antiscalants in the contaminated water processed by the bioreactors. A flushing system may deconcentrate the bioreactors to prevent the antiscalants from precipitating and fouling the bioreactors.

A high-concentration sewage treatment system for self-sufficiency of energy is provided. The system includes a hydrolysis acidification device, an anaerobic reactor, a sludge treatment device, a desulfurization tower, and a biogas power generation device. The hydrolysis acidification device includes a hydrolysis acidification tank, a first sedimentation tank, a first overflow water tank and an overflow pipe. The sludge treatment device includes a second sedimentation tank, a second overflow water tank, an inlet pipe and a dissolved oxygen meter. The second overflow water tank communicates with the hydrolysis acidification tank through a return pipe. The inlet pipe defines a jet hole. A regulating valve is connected to the inlet pipe. The regulating valve controls a speed and a height of mixed liquid in the jet hole. A high-concentration sewage treatment method for self-sufficiency of energy is also provided.

A method and an apparatus for maintaining a stable microbial community in a combined anaerobic-aerobic waste processing system. The system comprises cycling of waste activated sludge between reactors, thereby ensuring a healthy microbial community and an efficient waste decomposition.

Integrated methanogenic anaerobic reactor and membrane bioreactor, and method for eliminating organic matter and nitrogen in urban or industrial wastewater, preferably with COD concentrations between 150 and 5000 mg/L and where the eliminations of total nitrogen that occur are between 15 and 50 mg/L, at temperatures above 15° C. The wastewater treatment takes place thanks to three stages of treatment: methanogenic anaerobic stage, anoxic stage with biofilms and suspended biomass and aerobic filtration stage with biofilms and suspended biomass.

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.

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.

Systems and methods for treating multi-component waste streams. In general, systems and methods described herein employ a first chamber and a second chamber separated by a barrier and a filtration component that is fluidically connected to the first and second chambers. A waste stream to be treated will flow into the first chamber for treatment of the carbon-containing waste, then into the filtration component for the separation of the stream into a solid waste fraction and a liquid waste fraction.