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.

The present application provides a waste water preconditioning system for limiting mercury concentrations in a waste water stream resulting from treatment of a flue gas. The waste water preconditioning system may include a wet flue gas desulfurization system for treating the flue gas with an aqueous alkaline slurry, a sulfite detector to determine the concentration of sulfite in the aqueous alkaline slurry, and to produce the waste water stream with a mercury concentration of less than about five micrograms per liter. The waste water preconditioning system also may include a waste water treatment system downstream of the wet flue gas desulfurization system.

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 system and method of treating wastewater. In one embodiment, the system comprises a biological reactor fluidly connected to a source of wastewater and having a treated wastewater outlet, a fixed film biological reactor connected to the source of wastewater and having a fixed film effluent outlet, and a ballasted system fluidly connected to the fixed film effluent outlet. The ballasted system may comprise a ballast reactor tank configured to provide a ballasted effluent, and a source of ballast material fluidly connected to an inlet of the ballast reactor tank. The system may further comprise a bypass line having an inlet fluidly connected to the source of wastewater, a first outlet fluidly connected to the ballasted system, and a second outlet fluidly connected to the fixed film biological reactor, the bypass line configured to bypass the fixed film biological reactor.

An upflow continuous backwash deep bed sand filter (UCBF) having a recycle line for returning carbonaceous denitrifying bacteria attached to biomass to the influent of the UCBF. The recycle line returns the biomass to the treatment process at a location upstream of the upflow continuous backwash filter. Further, a liquid level control unit is provided that reduces fluctuations and significant drop in the liquid level upstream of the upflow continuous backwash filter, thereby avoiding or minimizing flow turbulences, air induction, and undesirable wastewater aeration resulting in the need to dose excessive carbon source to remove dissolved oxygen in the aerated wastewater.

The present disclosure relates to a biofilter for wastewater digestion, in which a high degree of contaminant removal is obtained with a single device. In order for these levels to be achieved, the following are essential: the shape of the biofilter, the supply/discharge ratio of the biofilter, the position and height of each of the components and, finally, the combination of two packed zones, namely: a random zone, and a zone arranged in the form of ringed or corrugated tube bundles.

A modular liquid waste treatment system is disclosed. In accordance with some embodiments, the system includes a central distribution unit and one or more treatment fins in flow communication therewith. The distribution unit may be configured to receive liquid waste from a given source and distribute that waste, at least in part, to one or more treatment fins. In turn, bacteria present in a given treatment fin treat the liquid waste, and the resultant treated liquid may drain from the fin to the surrounding environment. In some embodiments, a given treatment fin may include porous media providing a large surface area on which bacteria may grow to facilitate treatment. The system may be installed in and/or above the ground, and in some cases may be surrounded, at least in part, with treatment sand and/or other treatment media. The system may be used in aerobic and/or anaerobic processing of liquid waste.

An aquarium filter consists of a housing with three filter elements including a coarse filter, a fine filter and a porous substrate. A pump provides for the flow of water through the filter, so that only part of the flow passes through the porous substrate.

Present invention relates to a method and apparatus for purification of water, said method comprises the steps of feeding the water into a reactor (4) through one or more inlet tubes (1) or inlet zones and feed water an substrate through carrier elements for bio film (5) which have a large protected surface (>200 m2/m3 carrier elements) and large pore volume (>60%), and that the carrier elements are fluidized for the removal of waste sludge, wherein the ratio of charge of the elements (5) by normal duty corresponds to an amount corresponding to 90%-100%, more preferred 92%-100%, and most preferred 92%-99% of the vet volume of the reactor (4), said carrier elements (5) is kept substantially at rest or hindered movement between the times surplus sludge is removed, and that the carrier elements being fluidised for removal of surplus sludge, said carrier elements (5) having a specific gravity in the area of 0.8-1.4, more preferred 0.90-1.1 and most preferred 0.93-0.97, and feed the treated water to one or more outlet zones (7) and one or more outlet tubes (2). The invention also comprises a reactor for performing the method.

Provided is a biological purifier, by which metal ions in untreated waste water containing the metal ions and sulfate ions can be removed in a low temperature environment with a water temperature of 15° C. or less for a long period of time. The biological purifier for untreated waste water containing metal ions and sulfate ions used for removing the metal ions from the untreated waste water by precipitating sulfides of the metal ions, the biological purifier includes chaff retaining sulfate-reducing bacteria; and an organic-containing material containing 5 mass % or more of crude protein.