Abstract: The invention includes a pretensioned mesh insert and method for providing a pretensioned mesh insert for a traveling water screen basket. First and second mated screen panels are secured together to place one of the screen panels under tension and the other of the screen panels under compression so that it bows outwardly from the screen under tension. The structure of the invention operates to reduce the fatigue experienced by the screen panels.

Abstract: Disclosed herein is a wastewater treatment facility comprising a structure defining first and second tank portions; a shaft rotatably supported by the structure; a first biological reactor in the first tank portion and including a first rotatable biological contactor mounted to the shaft and having a diameter; and a second biological reactor in the second tank portion and including a second rotatable biological contactor mounted to the shaft and having a diameter greater than the diameter of the first rotating biological contactor.

Abstract: A venting apparatus for bubble contactor employed in liquid treatment apparatus for removing fuel constituents from water. The liquid treatment apparatus includes an oxygenator for dissolving oxygen in the water prior to its introduction into a biological fluid bed reactor to support biological action in the reactor. The oxygenator includes a bubble contactor having a bubble contact chamber, and a venting apparatus for venting the bubble contactor when the bubble swarm in the contact chamber grows too large. The venting apparatus includes a lower valve assembly including a valve having a float mechanism for sensing unacceptable accumulations of gas bubbles in the lower part of the bubble contactor, below the desired lower level of the contact zone. The float also functions to open the valve to release the excess undissolved gas.

Abstract: A venting apparatus for a bubble contactor used to dissolve oxygen in water prior to introducing the water into a biological fluid bed reactor that, under aerobic conditions, removes potentially combustible contaminants from the water for removing fuel constituents from water. The venting apparatus includes a float-operated valve wherein the float senses the existence of a gas space in the upper part of the bubble contactor and is operable to open the valve to vent the gas space. Such a space is potentially capable of supporting a combustible mixture of oxygen and fuel constituents which could be ignited by a source, such as a static electric discharge. The valve remains closed under normal conditions when no significant gas space exists to prevent the needless waste of oxygen.

Abstract: A vaporless liquid containment system for storing volatile and other liquids while preventing the formation and escape of vapors. The vessel includes a base and a first membrane, the first membrane defines a fluid containment space for containing stored liquid. A fluid-tight gas containment space is located above the first membrane. The gas containment space is adapted to house a gas under pressure. As liquid to be stored is supplied to and withdrawn from the fluid containment space, the gas housed in the gas containment space supplies fluid pressure to the first membrane so that the pressure on the first membrane is maintained above the vapor pressure of the stored liquid. This prevents the formation of vapor caused by the evaporation of the stored liquid.

Abstract: Disclosed herein is a wastewater treatment facility including a stacked tank clarifier having a lower tank, and an upper tank above the lower tank, the upper tank having a bottom defining a ceiling of the lower tank, and the lower tank further having a floor. The wastewater treatment facility includes a mechanism for scraping the ceiling of the lower tank. The mechanism includes a driven endless chain loop in the lower tank, and a buoyant member carried by the chain loop.

Abstract: A pressure relief valve selectively permitting fluid flow through the valve if the pressure on one side of the valve exceeds the pressure on the other side of the valve by a set amount, the pressure relief valve including a first valve member having a valve seat surface, and a movable valve member adapted to releasably engage the first valve member. The movable valve member includes a body portion having a periphery, the periphery having a downwardly extending annular flange engaging the valve seat surface. The downwardly extending annular flange includes a generally spherical valve surface adapted to provide a seal with the valve seat surface by engaging a resilient sealing ring on the valve seat surface. A flexible diaphragm causes movement of the movable valve member away from the valve seat when the pressure on the other side of the valve exceeds the pressure on the one side of the valve by a selected amount.

Abstract: A clamp or clamping member for securing a screen to a support, the clamp having a clamping face adapted to engage the screen and an opposite face, opposite sides and opposite ends. The junction between the clamping face and at least one of the opposite sides forms a curved surface between the clamping face and that side. This curved surface is adapted to engage a screen fixed to the support and the curved surface defines a radius in a plane transverse to the clamping face and the opposite sides. The clamp additionally includes an opening extending therethrough from the opposite surface to the clamping surface, the opening being elongated in the direction between the opposite sides and adapted to allow variable location of a bolt with respect to the clamp for securing the clamping member and the screen to the support.

Abstract: A link assembly for a lightweight, non-metallic, conveyor or load transmission chain having significantly greater strength and other performance improvements compared to previous non-metallic chain links is disclosed. Each link assembly includes: a pair of identical sidebars each comprised of high-strength filamentary material wound in an elongated loop configuration and fixed in a matrix of hardened resin; a connecting pin having a stiff reinforced composite core and a skin-tight sleeve of non-abrasive material; low friction bushing means between the sidebars and connecting pin; and retaining means for holding the assembly together.Methods of making the unique sidebar and connecting pin components are also disclosed.

Abstract: A sprocket assembly, particularly adapted for use in wastewater settling tanks, is provided, which assembly is adapted to be supported on a shaft having a longitudinal axis. The sprocket assembly includes a polymeric sleeve adapted to be mounted on the axially extending shaft, the sleeve including a low friction bearing surface formed of ultra high molecular weight polyethylene. The sprocket assembly further includes a sprocket wheel adapted to be mounted on the bearing surface of the sleeve for rotation relative to the sleeve about the longitudinal axis of the shaft. Seals are further provided to inhibit the introduction of grit between the sleeve and the sprocket wheel.

Abstract: A method of making a split bearing sleeve having flanges at the opposed ends thereof for mounting a sprocket wheel on an axially extending shaft is disclosed herein. The method includes the steps of providing a mold having axially aligned recessed areas for the flanges and an intermediate area extending between the recessed areas for the flanges, placing a thin strip of polyethylene in the intermediate axially extending area such that the strip extends partially into the recessed flange areas, and pouring heated polyurethane into the mold to fill the recessed areas for the flanges and the intermediate axially extending area to encapsulate the thin strip in the recessed flange areas.

Abstract: A sprocket assembly, particularly adapted for use in wastewater settling tanks, is provided, which assembly is adapted to be supported on a shaft having a longitudinal axis. The sprocket assembly includes a polymeric sleeve adapted to be mounted on the axially extending shaft, the sleeve including a low friction bearing surface formed of ultra high molecular weight polyethylene. The sprocket assembly further includes a sprocket wheel adapted to be mounted on the bearing surface of the sleeve for rotation relative to the sleeve about the longitudinal axis of the shaft. Seals are further provided to inhibit the introduction of grit between the sleeve and the sprocket wheel.

Abstract: In an orbal wastewater treatment process including a plurality of concentric, annular basins or channels having surface aeration means, wastewater and recycled activated sludge are mixed in a first channel by a combination of the surface aeration means and introducing an oxygen-containing gas such as air into the lower portion of the zone under conditions which produce a complete mix reaction and sufficient oxygen is supplied to meet the biological oxygen demands of the mixed liquor. The gas is introduced, preferably by a plurality of fine bubble membrane diffusers, in the form of fine bubbles having a diameter of less than about 4 mm. The mixed liquor is sequentially oxidized in second and third channels by a combination of surface aeration means and introducing an oxygen-containing gas into the lower portions of the channels, preferably by fine bubble membrane diffusers.

Abstract: Wastewater and recycled activated sludge are homogeneously mixed in a first aeration zone by injecting an oxygen-containing gas such as air into the lower portion of the zone under conditions which produce a complete mix reaction and sufficient oxygen is supplied to meet the biological oxygen demands of the mixed liquor. The gas is introduced, preferably by a plurality of fine bubble membrane diffusers, in the form of fine bubbles having a diameter less than about 4 mm. The bubbles provide both the mixing to keep solids in suspension and the oxygen required to maintain the overall dissolved oxygen content in the first aeration zone as close to 0 as possible. The mixed liquor is sequentially contacted with an oxygen-containing gas in second and third aeration zones under conditions which produce a complete mix reaction, preferably by fine bubble membrane diffusers, clarified and a portion of the settled sludge is recycled to the first aeration zone.

Abstract: A flight attachment is provided for a drive chain comprised of a plurality of overlapping links pivotally connected by pins so that stress loads transmitted through the chain by flight are transferred through the chain pivot pins and not through the chain side bars. The flight attachment comprises a pair of flight brackets, one located on each side of a link of the chain and connected to the chain in cantilever fashion by elongate, laterally extending pivot pins. The flight brackets are constructed and arranged to accept a collector flight securely mounted thereon.

Abstract: A link assembly for a lightweight, non-metallic, conveyor or load transmission chain having significantly greater strength and other performance improvements compared to previous non-metallic chain links is disclosed. Each link assembly includes: a pair of identical sidebars each comprised of high-strength filamentary material wound in an elongated loop configuration and fixed in a matrix of hardened resin; a connecting pin having a stiff reinforced composite core and a skin-tight sleee of non-abrasive material; low friction bushing means between the sidebars and connecting pin; and retaining means for holding the assembly together.Methods of making the unique sidebar and connecting pin components are also disclosed.

Abstract: A low pressure gas storage system comprising an annular anchor ring, a granular bed within the ring, a flexible membrane of gas storage chamber positioned above the bed, and a flexible membrane of air chamber encompassing the gas storage chamber and exerting pressure thereon; and a plurality of flexible, radially-extending restraining means positioned against and over the air chamber to exert a predetermined pressure thereon.

Abstract: A link assembly for a lightweight, non-metallic, conveyor or load transmission chain having significantly greater strength and other performance improvements compared to previous non-metallic chain links is disclosed. Each link assembly includes a pair of identical sidebars each comprised of high-strength filamentary material wound in an elongated loop configuration and fixed in a matrix of hardened resin and a connecting pin having a stiff reinforced composite core and a surrounding sleeve of low friction wear resistant material.

Abstract: A method and apparatus for enhancing the settleability of suspended wastewater solids is provided for a wastewater treatment system comprising a primary clarifier apparatus, a compartmentalized, sequential secondary biological treatment apparatus such as a rotating biological contactor tank, and a secondary clarifier, wherein a portion of waste sludge from the clarifier is diverted to compartments of the rotating biological contactor tank to enhance the flocculation of the suspended waste solids. The diverted sludge particles serve as flocculation nuclei which promote settleability and lower turbidity once the effluent reaches the secondary clarifier.

Abstract: A wastewater treatment apparatus is disclosed in which a rotating biological contactor rotatably mounted on a horizontal shaft is deeply submerged in a wastewater tank, so that a substantial portion of attached biomass does not come into contact with the ambient air. A plurality of gas conduits are disposed in the tank beneath the rotating contactor and are positioned to provide rotational energy to the contactor, to serve as the principal source of oxygen for the submerged biomass and to regulate the rotational velocity of the biological contactor so that the oxygen containing air bubbles are caused to rise into the central region of media rather than being swept along and confined to the outer radius of the media as it rotates.