Abstract: In a sewage treatment plant with a membrane bioreactor (MBR), raw untreated or partially treated wastewater (influent) and/or mixed liquor in the intensified process is superoxygenated. In a preferred form of the process the influent is superoxygenated such that membrane air scouring requirements are reduced. Influent may be fed to a swing zone where denitrification and nitrification occur simultaneously through process control. In one embodiment superoxygenation is conducted in an internal recycle stream of the mixed liquor, with oxygen content supersaturated preferably to over 300 parts per million. Due to the active evolution of oxygen gas from the supersaturated stream, occurring preferably by seeding the supersaturated stream with air bubbles, the supersaturated oxygen can serve the dual purposes of meeting process oxygen demands and providing part of air scouring requirements for the membranes.

Abstract: Multi-part bow ties are described. Such bow ties include at least a proximal panel that can easily be detached from a distal panel. The proximal and distal panels can be made from different fabrics, fabrics having different colors and/or patterns, etc., and thus enable a user to create bow ties wherein the distal and proximal panels have a different appearance.

Abstract: In a sewage treatment plant with a membrane bioreactor (MBR), raw untreated or partially treated wastewater (influent) and/or mixed liquor in the intensified process is superoxygenated. In a preferred form of the process the influent is superoxygenated such that membrane air scouring requirements are reduced. Influent may be fed to a swing zone where denitrification and nitrification occur simultaneously through process control. In one embodiment superoxygenation is conducted in an internal recycle stream of the mixed liquor, with oxygen content supersaturated preferably to over 300 parts per million. Due to the active evolution of oxygen gas from the supersaturated stream, occurring preferably by seeding the supersaturated stream with air bubbles, the supersaturated oxygen can serve the dual purposes of meeting process oxygen demands and providing part of air scouring requirements for the membranes.

Abstract: In a sewage treatment plant with a membrane bioreactor (MBR), raw untreated or partially treated wastewater (influent) and/or mixed liquor in the intensified process is superoxygenated. In a preferred form of the process the influent is superoxygenated such that membrane air scouring requirements are reduced. Influent may be fed to a swing zone where denitrification and nitrification occur simultaneously through process control. In one embodiment superoxygenation is conducted in an internal recycle stream of the mixed liquor, with oxygen content supersaturated preferably to over 300 parts per million. Due to the active evolution of oxygen gas from the supersaturated stream, occurring preferably by seeding the supersaturated stream with air bubbles, the supersaturated oxygen can serve the dual purposes of meeting process oxygen demands and providing part of air scouring requirements for the membranes.

Abstract: An aerobic digester system in a wastewater treatment plant is made more versatile for different conditions by addition of an equalizer basin or in some embodiments, a bypass pipe. If infeed is received from a sequential batch reactor or from a concentrated septage, for example, the equalizer basin can contain one batch, and then deliver the batch out incrementally to a gravity thickener basin. The equalizer basin also enables the gravity thickener of the system to be removed from service when needed, providing increased flexibility for the system. Importantly, the equalizer or bypass enables versatile modes of operation so that a plant designed for a larger, later flow can operate at an initially low flow or at several levels of flow before reaching the largest design flow. This applies to other conditions of variable flow as well such as seasonal.

Abstract: A clarifier in a sewage treatment process includes efficient scum removal within the influent well, with discharge of the scum and other floatables as a dedicated waste stream separate from return activated sludge and biological scum collected in the clarifier. In one embodiment the scum removal system has an inclined scum ramp at the leading edge of each of two scum removal troughs, with a forward edge below the liquid surface. The scum troughs pass through an arc of rotation, building up scum, which accumulates and is pushed forward by the scum ramp. At least once per revolution, the moving scum ramp approaches a stationary scum surface blade that extends partially under the liquid surface and provides a barrier to the forwardly pushed scum. This blade contacts and slides up the ramp, sweeping the scum up the ramp and into the scum trough.

Abstract: A clarifier in a sewage treatment process includes efficient scum removal within the influent well, with discharge of the scum and other floatables as a dedicated waste stream separate from return activated sludge and biological scum collected in the clarifier. In one embodiment the scum removal system has an inclined scum ramp at the leading edge of each of two scum removal troughs, with a forward edge below the liquid surface. The scum troughs pass through an arc of rotation, building up scum, which accumulates and is pushed forward by the scum ramp. At least once per revolution, the moving scum ramp approaches a stationary scum surface blade that extends partially under the liquid surface and provides a barrier to the forwardly pushed scum. This blade contacts and slides up the ramp, sweeping the scum up the ramp and into the scum trough.

Abstract: A clarifier in a sewage treatment process includes efficient scum removal within the influent well, with discharge of the scum and other floatables as a dedicated waste stream separate from return activated sludge and biological scum collected in the clarifier. Foam contained within the influent well may be treated with bacteria-killing agents or with anti-foaming agents. In one embodiment the scum removal system has an inclined scum ramp at the leading edge of each of two scum removal troughs, with a forward edge below the liquid surface. The scum troughs pass through an arc of rotation, building up scum, which accumulates and is pushed forward by the scum ramp. At least once per revolution, the moving scum ramp approaches a stationary scum surface blade that extends partially under the liquid surface and provides a barrier to the forwardly pushed scum. This blade contacts and slides up the ramp, sweeping the is scum up the ramp and into the scum trough.

Abstract: An aerobic treatment process is operated to reduce overall oxygen requirements, to maintain general pH balance and to produce a low-coliform solids effluent. From the system's clarifier a slurry of concentrated solids is moved to a premix basin, where the slurry is vigorously aerated for a sufficient time to raise microbial activity and dissolved oxygen content. The aerated, microbially active sludge is then moved to a gravity thickener basin, in which solids are allowed to settle to the bottom without aeration, to establish a quiescent state in the settled sludge and also an anoxic stage. This causes the sludge to be denitrified by microbial action, raising and stabilizing the pH of the sludge. Separated supernatant liquid is decanted and removed from the gravity thickener. The sludge is moved into an aerobic digester, where the sludge is aerated and nitrification occurs but using less aeration than normally required in a digester, due to the effect of anoxic/aerobic phases.

Abstract: Improved gas distribution and mixing is achieved in a gas/liquid mixing basin particularly for aerobic or anaerobic sewage digesters. In addition to a draft tube positioned generally centrally in the aeration or anaerobic basin and served by one or more gas-releasing diffusers, the system of the invention includes peripheral draft tubes surrounding the central draft tube, each tube having at least one gas diffuser within. The circulation of liquid and gas bubbles from the larger, central draft tube is supplemented by circulation from the peripheral draft tubes. In particular, "dead areas" or less active areas of the liquid, which are not sufficiently reached by gas-mixing from a single draft tube in many basin configurations, are reached by circulation from the peripheral draft tubes and such dead areas are virtually eliminated.

Abstract: A substantially gas tight tank cover is designed such that the structural beams of the cover serve also as an air distribution system for bubbling air through a liquid in the tank. Vertically oriented gas bubbler and orifice devices include hardware enabling easy access to the orifice and bubbler from the top of the tank cover. The design is such that all necessary maintenance including major repairs can be performed from the cover without draining the basin or removing the cover. The system is particularly adaptable to sewage treatment plants, but is advantageous for other applications as well, wherein gases are to be bubbled through liquids at multiple locations.