A biological nitrogen removal method based on multistage feeding and anoxic/aerobic chambers for adopting a constant flow operation mode, enabling wastewater subjected to primary treatment to enter a first-stage and a second-stage A/O reaction units from two position points; lifting and refluxing an effluent to an influent end of the first-stage units; lifting and refluxing an effluent to an influent end of the second-stage units; and clarifying, separating and discharging an effluent from an outlet end of a third-stage A/O reaction unit. The wastewater treatment mode combines a process based on two-stage wastewater feeding and three-stage anoxic/aerobic chambers with biofilms in different reaction zones, =optimizing and controlling a reflux ratio of each segment according to an amount of organic matters available for denitrification in influent, reducing the impact of hydraulic loading at the cross section in the reactors while removing organic matters and nitrogen-containing pollutants at a low temperature.

A process for removal of selenium and nitrate from waste water includes both electrochemical and bioprocessing treatment. Embodiments include use of activated walnut shell a growth media for selenium-reducing bacteria.

[Problem] A carrier for retaining anammox bacteria, an anammox bacteria-adhered particle, and a wastewater treatment apparatus are provided that can remarkably reduce the start-up period for obtaining a nitrogen removal speed of 1 kg-N/m.sup.3/day. [Solution] A carrier for retaining anammox bacteria includes carbon particles. The carbon particles are desirably graphite particles, particularly isotropic graphite particles. The carbon particles desirably have a zeta potential of −35 mV to 0 mV and an average particle size of 2 μm to 1000 μm.

A method for treating effluents containing nitrogen in the form of ammonium, implementing chemical reactions for oxidizing and reducing the nitrogen in a sequencing batch reactor, the method including: introducing a volume of effluents to be treated into the reactor, injecting oxygen or air into the reactor for partial oxidation of the ammonium into nitrites and/or nitrates, interrupting the injection of oxygen or air, thus producing gaseous nitrogen, depositing the sludge at the bottom of the reactor and clarifying the content of the reactor close to the surface of same, discharging a clarified fraction of the content of the reactor. The draining and feeding steps occur simultaneously. During the feeding step, the volume of effluents is introduced close to the bottom of the reactor. During the draining step, the clarified fraction of the content of the reactor is discharged close to the surface of the content of the reactor.

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.

A system and method of treating wastewater having at least one undesirable biological species is provided. In accordance with embodiments, a wastewater treatment system is provided comprising a main biological treatment train including at least one first unit operation configured to perform an anaerobic ammonium oxidation process, and at least one subsystem configured to increase a concentration of anammox bacteria in the at least one first unit operation, the treatment system arranged to reduce the concentration of total nitrogen in the wastewater.

A wastewater treatment system and a wastewater treatment process, fluidly combining a one or more SBR (sequencing batch reactor) module/s, in which nitrification and denitrification of the wastewater are performed in sequences and one or more MBR (membrane bioreactor) module/s.

A redox water treatment method comprises first determining the composition of water and whether water treatment requires either oxidation or reduction, or both to optimize nitrogen removal by a bioreactor. Sulfur dioxide (SO.sub.2) is injected into the water to be treated to provide H.sup.+, SO.sub.2, SO.sub.3.sup.=, HSO.sub.3.sup.−, dithionous acid (H.sub.2S.sub.2O.sub.4), and other sulfur intermediate reduction products forming a sulfur dioxide treated water, which behaves either as a reducing agent or an oxidizing agent depending on the strength of the acid concentration, which alters sulfurous acid from a reducing agent to a more powerful oxidizing agent.

Installation and method for processing wastewater, comprising: a) providing wastewater for processing; b) reducing O2 content of said wastewater by unactivated aerobic digestion; c) subsequently to ‘b’, eliminating substantially all O2 from said wastewater by anaerobic digestion; d) subsequently to ‘c’, transferring said wastewater to a closed photobioreactor; and e) subsequently to ‘d’, maintaining said wastewater in said photobioreactor in conditions favorable for algal photosynthesis, thereby allowing algae to grow in said photobioreactor. A method for growing algae is also disclosed whereby time, density and flow speed are controlled. The photobioreactor may have a conduit with two proportions of different cross sections.

Installation and method for processing wastewater, comprising: a) providing wastewater for processing; b) reducing O2 content of said wastewater by unactivated aerobic digestion; c) subsequently to ‘b’, eliminating substantially all O2 from said wastewater by anaerobic digestion; d) subsequently to ‘c’, transferring said wastewater to a closed photobioreactor; and e) subsequently to ‘d’, maintaining said wastewater in said photobioreactor in conditions favorable for algal photosynthesis, thereby allowing algae to grow in said photobioreactor. A method for growing algae is also disclosed whereby time, density and flow speed are controlled. The photobioreactor may have a conduit with two proportions of different cross sections.