Abstract: 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.

Abstract: 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.

Abstract: 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.

Abstract: A system for treating wastewater containing selenium has a sequencing batch reactor upstream of a fixed film reactor. The sequencing batch reactor may be operated under anoxic conditions while influent is mixed with residual sludge. The SBR reduces total nitrogen, suspended solids, or both. Selenium is removed in the fixed film reactor by biological reduction to elemental selenium.

Abstract: 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. The housing is integrated with the potting head of a module. The conduit passes through the potting head.

Abstract: A bioreactor has a biofilm supporting bed with at least two types of media. An upper media is relatively porous, preferably porous enough to admit particles of a lower media. In use, wastewater flows downwards through the bed. Soluble nitrogen is reduced in the upper media and converted into nitrogen gas. Nitrogen gas bubbles rise through the upper media and escape from the bed. Selenium is reduced in the lower media and converted into elemental selenium. The elemental selenium is released periodically by backwashing the bed, which may cause fluidization or other expansion of the lower media into the upper media.

Abstract: 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.

Abstract: A bioreactor has a biofilm supporting bed with at least two types of media. An upper media is relatively porous, preferably porous enough to admit particles of a lower media. In use, wastewater flows downwards through the bed. Soluble nitrogen is reduced in the upper media and converted into nitrogen gas. Nitrogen gas bubbles rise through the upper media and escape from the bed. Selenium is reduced in the lower media and converted into elemental selenium. The elemental selenium is released periodically by backwashing the bed, which may cause fluidization or other expansion of the lower media into the upper media.

Abstract: A system for treating wastewater containing selenium has a sequencing batch reactor upstream of a fixed film reactor. The sequencing batch reactor may be operated under anoxic conditions while influent is mixed with residual sludge. The SBR reduces total nitrogen, suspended solids, or both. Selenium is removed in the fixed film reactor by biological reduction to elemental selenium.

Abstract: 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. The housing is integrated with the potting head of a module. The conduit passes through the potting head.

Abstract: A gas sparger for a filtering membrane system produces an intermittent flow of bubbles even if provided with a relatively 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 can comprise a plurality of smaller units or areas. The supply of gas to the sparger may vary in flow rate over larger periods of time in response to changes in conditions in the membrane system to change the time between consecutive bursts of bubbles. A gas supply pipe may have two or more outlets at different elevations in communication with each of two or more units or areas.

Abstract: 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. The housing is integrated with the potting head of a module. The conduit passes through the potting head.

Abstract: In an anaerobic membrane bioreactor (“MBR”), a closed anaerobic process tank contains a membrane filter or is connected to an external tank containing a membrane filter. A pocket of biogas accumulates at the top of the process tank. Biogas is taken from the pocket, pumped to the bottom of the membrane filter to provide bubbles to inhibit membrane fouling, and returned to the pocket. Excess biogas produced as the wastewater is degraded is removed from the system and may be used as a product. However, biogas and liquid are maintained in the system at a pressure above atmospheric, for example 10 kPa or more above atmospheric pressure, sufficient to provide at least a material contribution to the transmembrane pressure driving permeation through the membranes. The overall energy requirements of the system may be reduced. Further, with sufficient pressure, suction pumps attached to the membranes may not be required.

Abstract: A static screen has a plurality of screening bodies and a plurality of aeration devices downstream of the screening bodies. Each aeration device is associated with a set of one or more of the screening bodies. Each aeration device may be a pulsing aerator. The pulsing aerators do not all release air at the same time. Each screening body works through periods of dead end filtration separated by backwashing events. The backwashing events comprise introducing a slug or pulse of air into the bottom of the screening body. Flow through the static screen continues at all times because the screening bodies are not all backwashed at the same time. The static screen may be used to remove trash from water flowing to an immersed membrane unit. Alternatively, the static screen may be used to provide primary wastewater treatment.

Abstract: A gas sparger for a filtering membrane system produces an intermittent flow of bubbles even if provided with a relatively 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 can comprise a plurality of smaller units or areas. The supply of gas to the sparger may vary in flow rate over larger periods of time in response to changes in conditions in the membrane system to change the time between consecutive bursts of bubbles. A gas supply pipe may have two or more outlets at different elevations in communication with each of two or more units or areas. The discharge of gas between two or more units or areas may be synchronized. One or more of a set of units or area may receive a supplied gas at a higher flow rate.

Abstract: The permeate collectors of a set of membrane filter elements are connected in line to form a vertical permeate collection pipe serving the set of elements. The connectors between adjacent elements are configured to allow a disconnected element to move perpendicular to the permeate collectors. When an element is disconnected, it may slide horizontally out of the frame. A connector has a spigot that spans between two sockets when connected. In a membrane assembly, each socket is associated with a permeate collector of a membrane filter element. To disconnect the sockets, the spigot is retracted further into one of the sockets until it is spaced apart from the other socket. With the spigot retracted, one membrane element may move relative to the other in a direction perpendicular to the direction of movement of the spigot.

Abstract: 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. The housing is integrated with the potting head of a module. The conduit passes through the potting head.

Abstract: In an anaerobic membrane bioreactor (“MBR”), a closed anaerobic process tank contains a membrane filter or is connected to an external tank containing a membrane filter. A pocket of biogas accumulates at the top of the process tank. Biogas is taken from the pocket, pumped to the bottom of the membrane filter to provide bubbles to inhibit membrane fouling, and returned to the pocket. Excess biogas produced as the wastewater is degraded is removed from the system and may be used as a product. However, biogas and liquid are maintained in the system at a pressure above atmospheric, for example 10 kPa or more above atmospheric pressure, sufficient to provide at least a material contribution to the transmembrane pressure driving permeation through the membranes. The overall energy requirements of the system may be reduced. Further, with sufficient pressure, suction pumps attached to the membranes may not be required.