Fouling in membrane bioreactors used in wastewater treatment

An aeration system for a submerged membrane module has a set of aerators connected to an air blower, valves and a controller adapted to alternately provide a higher rate or air flow and a lower rate of air flow in repeated cycles. In an embodiment, the air blower, valves and controller, simultaneously provide the alternating air flow to two or more sets of aerators such that the total air flow is constant, allowing the blower to be operated at a constant speed. In another embodiment, the repeated cycles are of short duration. Transient flow conditions result in the tank water which helps avoid dead spaces and assists in agitating the membranes.

Cyclic aeration system for submerged membrane modules

A process and apparatus is described for filtering water with immersed membranes. In a batch process, permeate is withdrawn while the flow of feed is reduced or stopped at the end of a permeation cycle. The water level is reduced to a level where a portion of the membranes are exposed to air before draining the tank. In this or another process, the level of liquid is reduced to correspond with an area of the membrane fibers having an accumulation of solids. Aeration is provided for a period of time with the liquid at this level to dislodge at least a portion of the solids from the membranes. In these or other processes, the tank is partially drained between cycles to deconcentrate the tank, aeration is provided during backwashing and intermittently while permeating, and/or retentate is withdrawn from the tank during a portion of a permeation step.

Water filtration using immersed membranes

An apparatus to transfer gas to or from a liquid has a flexible and oxygen permeable but liquid water impermeable membrane, a flexible and gas permeable spacer, an inlet conduit, an outlet conduit and a non-rigid restraint system When used for treating wastewater, an aerobic biofilm is cultured adjacent the planar elements, an anoxic biofilm is cultivated adjacent the aerobic biofilm and the wastewater is maintained in an anaerobic state A first reactor for treating wastewater has an anaerobic section, a plurality of gas transfer membrane modules, and an aerobic section A biofilm is cultivated on the surface of the gas transfer membranes in fluid communication with the anaerobic section Biological reduction of COD, BOD, nitrogen and phosphorous are achieved In a second reactor, phosphorous is also removed chemically in a precipitation branch

Membrane module for gas transfer and membrane supported biofilm process

An apparatus is described for withdrawing filtered permeate from a substrate contained in a reservoir at ambient pressure. The apparatus includes a plurality of membrane assemblies. Each assembly has a plurality of hollow fiber filtering membranes, immersed in the reservoir, at least one permeating header with the membranes sealingly secured therein, and a permeate collector to collect the permeate sealingly connected to the at least one permeating header and in fluid communication with lumens of the membranes. The membranes of each assembly extend generally vertically upwards from a first header during permeation. One or more sources of suction are provided in fluid communication with the lumens of the membranes of each assembly through the permeate collectors and apply sufficient suction to withdraw permeate from the lumens of the membranes. An aeration system for discharging bubbles assists in keeping the membranes clean. In other aspects, a method of removing fouling materials from the surface of a plurality of porous membranes includes providing, from within a membrane module, gas bubbles in a uniform distribution relative to the membranes. The bubbles move past the surfaces of the membranes to dislodge fouling materials from them. The membranes are arranged in close proximity to one another and mounted to prevent excessive movement.

Apparatus for withdrawing permeate using an immersed vertical skein of hollow fibre membranes

A membrane separator assembly for separating solids from water includes opposing enclosure wall structures, a membrane module unit, and a gas diffuser disposed below the membrane module unit. The membrane module unit includes a plurality of membrane modules respectively having at least one separating membrane extending between at least two membrane fixing members. At least one of the membrane fixing members has a main passage which is in fluid communication with a membrane passageway. The membrane passageway is accessible to water via permeation through the separating membranes and is inaccessible to solids which are impermeable relative to the separating membranes. The membrane separator assembly is preferably used with a detergent containing percarbonate, preferably sodium percarbonate. The assembly also includes a gas diffuser with two opposing main pipes and branch pipes extending therebetween to avoid undesired pressure differentials when cleaning the assembly.

Membrane separator assembly and method of cleaning the assembly utilizing gas diffuser underneath the assembly

PROBLEM TO BE SOLVED: To provide an operating method of a filtration device capable of efficiently cleaning a separation membrane module with a small quantity of cleaning water and performing stable filtration over a long period. SOLUTION: The filtration device is operated by repeating intermittently the filtration by the separation membrane module 13 with a filtration stopping time interposed, passing cleaning water from a secondary side of the separation membrane module 13 in the filtration stopping time and controlling the time of 1 cycle composed of the filtration time and the filtration stopping time to be <=30 min.

Operation of filtration device

A membrane separator assembly for separating solids from water includes opposing enclosure wall structures (106a, 106b), a membrane module unit (102), and a gas diffuser (104) disposed below the membrane module unit (102). The membrane module unit (102) includes a plurality of membrane modules (103) respectively having at least one separating membrane (113) extending between at least two membrane fixing members (114). At least one of the membrane fixing members (114) has a main passage (115) which is in fluid communication with a membrane passageway. The membrane passageway is accessible to water via permeation through the separating membranes (113) and is inaccessible to solids which are impermeable relative to the separating membranes (113). The membrane separator assembly is preferably used with a detergent containing percarbonate, preferably sodium per carbonate. The detergent may also include a bivalent iron salt and optionally, an oxidizer other than hypochlorite and hydrogen peroxide, a surfactant, a chelating agent and/or a pH regulator.

Membrane assembly for solid-liquid separation, method of cleaning the same, and detergent

An object is to provide a highly integrated hollow fiber membrane module and hollow fiber membrane module unit as filtration processing devices which are appropriate for miniaturization, and to also provide a purification tank with a hollow fiber membrane module unit installed therein. To achieve this there is provided a hollow fiber membrane module in which at least one end of a hollow fiber membrane with hollow fibers deployed in a plane is fixed with a fixing resin to a collector pipe in a fluid tight manner, constructed such that an open ended tip of the hollow fiber membrane is inserted into an aperture provided in the collector pipe, and in this condition, fixing resin is filled into the aperture and hardened, thereby securing the open ended hollow fiber membrane to the collector pipe. Also provided is a hollow fiber membrane module unit wherein a plurality of the hollow fiber membrane modules are positioned proximately, and a purification tank with the hollow fiber membrane module units installed therein.

Hollow fiber membrane module, hollow fiber membrane module unit which utilizes the module, and purification tank with the module unit installed therein

A hollow fiber membrane module capable of being miniaturized and having a high degree of integration as a filtration treatment apparatus. The hollow fiber membrane module is manufactured by liquid-tightly fixing at least one end portion of a hollow fiber membrane, in which a plurality of hollow fibers are arranged planarly, to perforated pipes with a fixing resin, inserting the end-opened hollow fiber membrane into an opening of the perforated pipe, applying and curing a fixing resin in this state, and fixing the perforated pipe to the end-opened hollow fiber membrane. A hollow fiber membrane module unit in which a plurality of hollow fiber membrane modules are arranged, and a septic tank in which such a hollow fiber membrane module unit is provided are also disclosed.

Process of manufacturing a hollow fiber membrane module, process of manufacturing a hollow fiber membrane module unit, and septic tank provided with a module unit thus obtained

Satoshi Miyashita

Papers

Membrane separator assembly and method of cleaning the assembly utilizing gas diffuser underneath the assembly

Operation of filtration device

Membrane assembly for solid-liquid separation, method of cleaning the same, and detergent

Hollow fiber membrane module, hollow fiber membrane module unit which utilizes the module, and purification tank with the module unit installed therein

Process of manufacturing a hollow fiber membrane module, process of manufacturing a hollow fiber membrane module unit, and septic tank provided with a module unit thus obtained