Algae harvesting and cultivating systems and methods for producing high concentrations of algae product with minimal energy. In an embodiment, a dead-end filtration system and method includes at least one tank and a plurality hollow fiber membranes positioned in the at least one tank. An algae medium is pulled through the hollow fiber membranes such that a retentate and a permeate are produced.

Algae harvesting and cultivating systems and methods for producing high concentrations of algae product with minimal energy. In an embodiment, a dead-end filtration system and method includes at least one tank and a plurality hollow fiber membranes positioned in the at least one tank. An algae medium is pulled through the hollow fiber membranes such that a retentate and a permeate are produced.

A gas sparger produces an intermittent flow of bubbles even if provided with a continuous gas flow. The sparger has a housing to collect a pocket of gas and a conduit to release some of the gas from the pocket when the pocket reaches a sufficient size. Optionally, a cover over an outlet from the conduit may break up or distribute the released gas. A large sparger for use with a commercial membrane module can comprise a plurality of smaller units.

A cleaning device includes: an ozone gas supply portion; an ozone dissolution tank including a gas phase portion in which ozone gas is to be accumulated and a liquid phase portion formed by water in which the ozone gas is to be dissolved; a gas phase portion ozone gas supply pipe for supplying ozone gas from the ozone gas supply portion to the gas phase portion; a liquid phase portion ozone gas supply pipe for supplying ozone gas from the ozone gas supply portion to the liquid phase portion; and an ozone water supply pipe for supplying ozone water generated in the ozone dissolution tank to a filtering secondary side, wherein the ozone water is supplied to the filtering secondary side by the pressure of ozone gas in the gas phase portion.

A method of filtration includes a filtration step in which a liquid to be filtered is filtered through a porous membrane module consisted of a resin having a three-dimensional network structure by external pressure filtration; a cleaning step of cleaning an outer surface of the porous membrane by carrying out backwash of passing a cleaning solution through the porous membrane from an inner surface of the membrane, and air bubbling after the filtration step; and a discharging step of discharging the cleaning solution remaining on the outer surface and inside of the porous membrane after the cleaning step; and in SEM images of a membrane cross section in a membrane thickness direction orthogonal to the inner surface of the porous membrane, a total area of a resin portion having an area of 1 μm.sup.2 or less is 70% or more relative to a total area of the resin portion.

Filter membranes in systems for drinking water, tertiary water treatment and combined sewage overflow, MBR and MBT are efficiently cleaned without use of air scour. In one system the membranes, preferably flat plate membranes, are cleaned by mechanically driven wipers that can clean the surfaces of two adjacent membranes simultaneously. Another system uses water jets to clean the membrane surfaces.

A method for operating a separation membrane module including identifying a clogged portion of the separation membrane module based on a resistance of a lower portion of the separation membrane module, a filtration resistance of a separation membrane portion, and a resistance of an upper portion of the separation membrane module, in a water production system for obtaining treated water by filtering water-to-be-treated with the separation membrane module.

A membrane gas separator with a built-in valve along with a method of open and closing the membrane gas separator are disclosed herein. The membrane separator contains an an inlet chamber, hollow selective fibres, an outlet chamber, a central core element and a flushing space. The membrane separator contains a built-in combined valve in the outlet chamber and a the central space and a check valve at an inlet manifold. The built-in valve contains a throttling section to ensure a reduced backflow of a final product from the outlet manifold to the inner space of hollow fibres, and the sealing section to stop the flow of the flushing medium from the outlet chamber to the flushing space when no inlet medium flows through the separator. The method of opening of the membrane separator includes opening of the sealing section and subsequent opening and deactivation of the throttling section. The method of closing of the membrane separator includes closing and activation of the throttling section and closing of the sealing section.

Algae harvesting and cultivating systems and methods for producing high concentrations of algae product with minimal energy. In an embodiment, a dead-end filtration system and method includes at least one tank and a plurality hollow fiber membranes positioned in the at least one tank. An algae medium is pulled through the hollow fiber membranes such that a retentate and a permeate are produced.

In an immersed membrane system, the influent flows into an open membrane tank. The membrane tank can have multiple horizontally spaced immersed membrane units. The immersed membrane units may have flat sheet membrane elements within a membrane case. One or more ducts are provided in the tank for directing the flow of influent to the immersed membrane units. In some examples, the influent is divided into sub-streams that are fed through baffles to a corresponding immersed membrane unit, optionally in generally equal amounts, optionally in a single pass flow pattern. In a process of operating a membrane tank, the influent flow is directed across the bottom of the membrane tank and divided into multiple portions. Each of the multiple portions is fed directly to the bottom of a corresponding immersed membrane unit located in the tank. The influent may be mixed liquor in a membrane bioreactor (MBR).