Disclosed is a method for treating wastewater containing heavy metal. First, the wastewater containing heavy metal is subjected to a homogenization treatment, such that the water quality of the wastewater containing heavy metal from different processes is homogenized. The homogenized wastewater containing heavy metal is subjected to an anaerobic-aerobic circulating treatment in a membrane bioreactor (2), in which heavy metal ions are reduced by the action of microorganisms in the anaerobic treatment process. The membrane bioreactor (2) is filled with a hollow fiber membrane (3) containing a quinone group, which serves as an electron mediator that can accelerate the enzymatic reduction of heavy metal ions during the anaerobic treatment. During the aerobic treatment, the COD and SS in the wastewater are further removed.

Disclosed are methods of treating wastewater using a membrane bioreactor and achieving a target phosphorus concentration for the membrane permeate stream. These methods include the steps of dosing a wastewater stream with a rare earth clarifying agent and passing the dosed wastewater stream through the membrane to obtain a membrane permeate stream with a permeate concentration that is less than the phosphorus concentration of the influent stream. This permeate concentration also can be equal to or less than a target phosphorus concentration. In the methods as disclosed herein, the rare earth clarifying agent can be chloride salts of one or more rare earth elements and in certain embodiments, the rare earth clarifying agent can be CeCl.sub.3 and LaCl.sub.3.

A membrane separation process is described. The process comprises pumping of a fluid stream through a membrane module to produce a permeate during a plurality of membrane operating cycles. Each membrane operating cycle comprises a filtration cycle and a relaxation cycle. Concentration polarisation is controlled during the process by controlling duration of filtration cycles and relaxation cycles to relatively short duration to maintain the degree of concentration polarisation below a target.

A membrane filtration system and a membrane bio reactor including the same are described. In an example, the membrane filtration system includes: a treatment tank; a membrane support frame disposed in the treatment tank and mounted with a filtration membrane; a reciprocating portion connected to the membrane support frame and reciprocating the membrane support frame; a sliding portion disposed in the treatment tank, connected to the reciprocating portion, and guiding a moving direction of the membrane support frame; and a sludge lifting portion flexibly disposed at a lower end of the membrane support frame to lift sludge accumulated at a lower part of the treatment tank.

Provided is a porous membrane that can be manufactured in uncomplicated steps, has high hydrophilicity and water permeability, and exhibits excellent anti-fouling properties when used in a membrane bioreactor method (MBR method). The porous membrane of the present invention is a porous membrane containing polymer (A) and polymer (B), wherein the polymer (A) is a membrane-forming polymer, the polymer (B) is a polymer having a unit (b1) represented by formula (1) and a unit (b2) based on hydroxyl group-containing (meth)acrylate, and the concentration (mass %) of the unit (b1) is equal to or higher than the concentration (mass %) of the unit (b2) in the porous membrane. ##STR00001##

Disclosed is an apparatus for water treatment, including a membrane separator for solid-liquid separation; and a particle fractionator which has at least two exits of a fractionated solid-liquid mixture produced therein, wherein a liquor containing particles of different sizes including submicron particles is fed to the particle fractionator before a membrane separation by the membrane separator, and wherein a first fraction of the fractionated solid-liquid mixture is returned to the membrane separator from one exit of the at least two exits of the particle fractionator, the first fraction being less than the liquor in terms of content of the submicron particles. This apparatus enables a rapid achievement of suppression of membrane fouling.

An immersed membranes uses aeration (air bubbles rising past the membranes) as a means to scour the membrane surface and keep it clean from solids, or foulants, allowing for continuous and effective operation. In a module of flat sheet membranes, fine bubble aeration is used to create and maintain space between the membrane sheets. The bubbles inhibit the sheets from touching and clogging together, thus reducing their surface area and their productivity. The aeration may be used for scouring, to supply oxygen to biomass and as a spacer to maintain the working surface area of immersed flat sheet membranes. The face-to-face spacing between the membrane sheets may be 4 mm or less. The bubbles may be less than twice the face-to-face spacing between the membrane sheets.

In a process for treating wastewater from a combined gasification and Fischer-Tropsch (F-T) process, feedstock derived from Municipal Solid Waste or the like is gasified in a reactor (R) and treated in a cleanup unit (C) which generates a first wastewater stream (1st WWT STREAM) containing salts and inorganic pollutants. The first wastewater stream is treated in a treatment unit (T1) to remove inorganic pollutants derived from the syngas. The treatment comprises a) degassing, and subsequently b) neutralising the first wastewater stream before treatment in a Dissolved Air Flotation unit (72c) and filtering in a moving sand bed or similar (72d) to remove solids, and a stripping process to remove ammonia. A second wastewater stream (2.sup.nd WWT Stream) containing organic pollutants but being low in salts arises from the F-T process and is treated separately to allow recycling within the F-T process.

A method for treating domestic sewage includes: preliminarily treating the domestic sewage through a grating and a grit chamber, so as to remove large-particle solids in the domestic sewage; and subjecting the domestic sewage after the preliminary treatment to circulating anaerobic-oxic treatment in a membrane bioreactor (MBR). In the oxic treatment process, microorganisms oxidize nitrogen in the sewage into nitrite or nitrate. Under anaerobic conditions, denitrifying bacteria in the microorganisms reduce the nitrate, releasing molecular nitrogen or nitrous oxide. In the present invention, the MBR is filled with a quinone-based hollow fiber membrane. During the microbial denitrification, the quinone acts as an electron transfer carrier to participate in the denitrification to promote the reduction of the nitrate (nitrite), increasing the denitrification rate under anaerobic conditions, and achieving the purpose of efficient denitrification.

A submerged membrane unit has air diffusers located outside of the membrane area in plan view. The diffusers may be mounted in or below a diffuser case. The diffuser case may have walls to direct bubbles towards the membranes. The diffusers may be drop diffusers, for example as in a single drop diffuser assembly. The membrane unit may have polymeric or ceramic membranes, for example ceramic flat plate membranes. In an example, a rectangular shrouded membrane unit has a diffuser case below it that is rectangular in plan view but trapezoidal in side view, with drop diffusers located in the corners of the diffuser case. In a process of treating high strength wastewater, for example thickening or digesting waste sludge, a membrane unit optionally with ceramic plate membranes is immersed in the wastewater. The membranes are sparged with bubbles produced below but beside the membrane unit in a diffuser case.