There are provided processes for treating wastewater. The processes can comprise treating a mixture comprising the wastewater and an activated sludge, in a single reactor, with an electric current having a density of less than about 55 A/m.sup.2, by means of at least one anode and at least one cathode that define therebetween an electrical zone for treating the mixture; exposing the mixture to an intermittent ON/OFF electrical exposure mode to the electric current in which an OFF period of time is about 1 to about 10 times longer than an ON period of time; and maintaining an adequate oxidation-reduction potential in the single reactor. Such processes allow for substantial removal of carbon, nitrogen and phosphorus from the wastewater in the single reactor of various forms and for obtaining another mixture comprising a treated wastewater and solids.

The present invention relates to an apparatus for biological sewage treatment, including a concentrated mixed liquor driving device that uses a gas to drive a concentrated mixed liquor to flow. The present invention further relates to a method for biological sewage treatment, including a step of using a gas to drive a concentrated mixed liquor to flow. The gas can be an aeration gas, especially an oxygen-containing aeration gas after aeration treatment. The apparatus and method of the present invention can sufficiently utilize the energy and oxygen of the aeration gas, so that the energy consumption and maintenance cost of whole apparatus are reduced, biological sewage treatment effects are improved, and sludge floating is prevented. In addition, the apparatus of present invention has advantages of high performance, energy saving, high reliability, and good movability.

A water cleaning system 1 includes an aerobic region 90 including breeding water 9 containing organic matter and oxygen, an aerobic layer 6 linking with the aerobic region 90 and inhabited by aerobic bacteria, a facultative anaerobic layer 5 provided adjacent to the aerobic layer 6 and inhabited by facultative anaerobic bacteria, an obligatory anaerobic layer 4 provided adjacent to the facultative anaerobic layer 5, inhabited by obligatory anaerobic bacteria, and made of andosol 40, an anaerobic space 3 having an anaerobic environment, allowing the obligatory anaerobic bacteria inhabiting the obligatory anaerobic layer 4 and products therefrom to flow therein, and a tube 18 as linking means linking the anaerobic space 3 and the aerobic region 90.

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.

A method and installation for treating wastewater containing ammonia includes feeding activated sludge from an aeration tank into a hydrocyclone. The sludge is separated into a specifically heavy fraction containing mostly anaerobic ammonia-oxidizing bacteria (anammox) and a specifically light fraction containing mostly aerobic oxidizing bacteria (AOB), which are returned to the aeration tank. The hydrocyclone includes a roughened inner wall surface for at least partially removing an organic or inorganic cover layer disposed on the anaerobic ammonium-oxidizing bacteria (anammox).

Processes and compositions for removal nitrogen, organic and inorganic contaminants from wastewater using Feammox bacterium are provided.

Process for treating effluents containing nitrogen in ammonium form, using a sequential biological reactor (1), according to which: a volume of effluents to be treated in one complete cycle is introduced into the biological reactor in one or more successive fractions by volume, each fraction by volume being treated during a subcycle; each subcycle comprises a phase of feeding with a fraction by volume, and at least a first aerated step, during which total or partial oxidation of the ammonium to nitrites takes place by injection of air or of oxygen into the effluent, a settling out and emptying step taking place after the end of the complete cycle; the weight of N—NH.sub.4 to be treated is determined from the volume of effluents in the reactor at the end of the feeding phase, and from the difference between the initial N—NH.sub.4 concentration in the reactor and a concentration desired at the end of the aerated step, a maximum aeration time TM is dedicated to the aerated step, and an initial air flow rate Qairinit, for the beginning of the aerated step, is determined by taking into account the weight of N—NH.sub.4 to be treated and the maximum aeration time TM.

Process for treating effluents containing nitrogen in ammonium form, using a sequential biological reactor (1), according to which: a volume of effluents to be treated in one complete cycle is introduced into the biological reactor in one or more successive fractions by volume, each fraction by volume being treated during a subcycle; each subcycle comprises a phase of feeding with a fraction by volume, and at least a first aerated step, during which total or partial oxidation of the ammonium to nitrites takes place by injection of air or of oxygen into the effluent, a settling out and emptying step taking place after the end of the complete cycle; the weight of N—NH.sub.4 to be treated is determined from the volume of effluents in the reactor at the end of the feeding phase, and from the difference between the initial N—NH.sub.4 concentration in the reactor and a concentration desired at the end of the aerated step, a maximum aeration time TM is dedicated to the aerated step, and an initial air flow rate Qairinit, for the beginning of the aerated step, is determined by taking into account the weight of N—NH.sub.4 to be treated and the maximum aeration time TM.

A process for reducing the production of sludge by municipal or industrial wastewater purification plants, comprising a step of mesophilic or thermophilic anaerobic digestion (20), or anaerobic digestion combining these two operating modes, of a stream of sludge to be treated (1), and at least one biological solubilization anaerobic treatment step (30); the process comprises, upstream of the anaerobic digestion step, a step of dehydration (10) of the sludge to be treated, followed by a step of mixing (15) the dehydrated sludge with a recirculated fraction of sludge that is more liquid, originating from recycling of the digestion (20), and/or from the anaerobic treatment step (30), and/or centrates originating from a final dehydration (50) of the treated sludge, wherein the recirculation rate is chosen such that the mixture has a dryness suitable for digestion, this mixture then being directed towards the digestion.

A process for reducing the production of sludge by municipal or industrial wastewater purification plants, comprising a step of mesophilic or thermophilic anaerobic digestion (20), or anaerobic digestion combining these two operating modes, of a stream of sludge to be treated (1), and at least one biological solubilization anaerobic treatment step (30); the process comprises, upstream of the anaerobic digestion step, a step of dehydration (10) of the sludge to be treated, followed by a step of mixing (15) the dehydrated sludge with a recirculated fraction of sludge that is more liquid, originating from recycling of the digestion (20), and/or from the anaerobic treatment step (30), and/or centrates originating from a final dehydration (50) of the treated sludge, wherein the recirculation rate is chosen such that the mixture has a dryness suitable for digestion, this mixture then being directed towards the digestion.