Abstract: The disclosure relates to obtaining dynamic wet pressure in a wastewater treatment plant. A difusser submerged in wastewater is connected to an air supply. This diffuser has an air flow regulator, a diffusion element to discharge the air into the wastewater, and a plenum situated between the element and the flow regulator. Pressure taps sense pressure in the pipe and the plenum. Manometers are used to determine hydrostatic head, pressure drop across the element, and pressure drop across the air flow regulator. Air flow regulator pressure drop and pressure/flow characteristics may be used, with other required information, to calculate dynamic wet pressure across the diffusion element.

Abstract: A liquid treatment apparatus comprising a gas distribution network in a water impound; a device for introducing treating gas into the network; a source of cleaning agent; a device for intermittently introducing the cleaning agent into the network alone or in admixture with the treating gas; a plurality of synthetic thermoplastic or thermoset resin plenums; a plurality of a least ten diffusion elements sealingly engaged and in communication with the plenums for receiving the treating gas and cleaning agent, the elements having air diffusion pores extending therethrough, but being free of through-holes other than air diffusion pores, the pores defining paths for discharge of the treating gas and cleaning agent and which exhibit an increase in dynamic wet pressure and/or bubble release pressure as a result of deposition of foulants; retaining ring engaging the diffusion elements about their peripheries for securing the elements to the plenums; sealing device adjacent the peripheries of the diffusion elements for

Abstract: Cleaning of multi-pore diffusion elements in place with cleaning gases while submerged in liquid media by applying said elements in improved gas cleaning apparatus. Such apparatus may for example include diffusion element retaining rings or other retaining devices, positioned at the peripheries of the respective elements, for securing them in gas-tight relationship with their respective plenums for preventing escape of treating and cleaning gas. Another aspect of the apparatus includes diffusers having diffusion elements with upper and lower surfaces bounded by porous peripheral sides, said diffusers also including apparatus for preventing escape of air through the element sides. In another embodiment of diffusers with diffusion elements having upper and lower surfaces bounded by peripheral sides, there are plenums comprising gas tight enclosures that enclose these lower surfaces and that include upstanding walls facing and adjacent to said sides.

Abstract: Cleaning of multi-pore diffusion elements in place with cleaning gases while submerged in liquid media by applying said cleaning gases intermittently or continuously to said diffusion elements between predetermined limits of operating pressure and flow through flow regulation means and plenums for the respective diffusion elements.

Abstract: A sewage aeration system comprising a header pipe, plenums of synthetic thermoplastic or thermoset resin with side walls inclined upwardly and outwardly to diffusion element support means, generally horizontal diffusion elements free of through-holes other than air diffusion pores, retaining means securing the elements about their peripheries to the plenums, sealing means adjacent the peripheries of the diffusion elements and airflow regulator members which terminate in the plenums beneath the horizontal diffusion elements.

Abstract: Gas diffusion elements, formed of a body of solid particles which have been shaped, pressed and rendered coherent by bonding or sintering in a compacted form having pores, are disclosed. Said elements include a peripheral, annular zone of relatively small proportions having lesser permeability, greater density or lesser height than at least a portion of the remainder of the element. In accordance with the invention, a boundary zone is provided adjacent to and inwardly of the peripheral zone, in which boundary zone there is a progressive increase, continuous or step-wise, in the apparent volumetric compression ratio of the element, in the direction of the pheripheral zone, or towards a vertical surface which is near the periphery of the element. Such element may provide improved gas, e.g. oxygen transfer efficiency and therefore holds promise of improving the efficiency and economics of gas transfer processes, such as for instance treatment of sewage or other waste water with air, oxygen and/or ozone.

Abstract: Gas diffusion elements, formed of a body of solid particles which have been shaped, pressed and rendered coherent by bonding or sintering in a compacted form having pores, and having an enhanced apparent volumetric compression ratio in a central zone and in a boundary zone thereof, are disclosed. Such elements have a generally horizontal portion including an upper gas discharge surface having a bubble release pressure in water, by a test disclosed herein, in the range of about 2 to about 20 inches of water. Among the preferred embodiments is an element whose gas discharge surface has the property that its coefficient of variation is not greater than about 0.25, based on the values of bubble release pressure at a plurality of points over said surface. Such elements may provide improved gas, e.g. oxygen, transfer efficiency, and therefore hold promise of improving the efficiency and economics of gas transfer processes, such as for instance treatment of sewage or other wastewater with air, oxygen and/or ozone.

Abstract: Gas diffusion elements, formed of a body of solid particles which has been shaped, pressed and rendered coherent by bonding or sintering in a compacted form having pores, and having an enhanced apparent volumetric compression ratio in a central zone thereof, are disclosed. Such elements have a generally horizontal portion including an upper gas discharge surface having a bubble release pressure in water, by a test disclosed herein, in the range of about 2 to about 20 inches of water. Among the preferred embodiments is an element whose gas discharge surface has the property that its coefficient of variation is not greater than about 0.25, based on the values of bubble release pressure at a plurality of points over said surface. Such elements may provide improved gas, e.g. oxygen, transfer efficiency, and therefore hold promise of improving the efficiency and economics of gas transfer processes, such as for instance treatment of sewage or other waste water with air, oxygen and/or ozone.

Abstract: Drop-back of solids into the drum pool of a rotary microscreen is reduced by applying a limited gas pressure differential across an unsubmerged portion of the screen cloth. The pressure is not for the purpose of increasing the driving force, .DELTA.H, of the liquid passing through the cloth. For purposes of this disclosure, .DELTA.H is the pressure differential existing across the screen below the surface of both the drum pool and tank pool. In fact, assuming other factors remain equal, application of a gas pressure differential to an unsubmerged portion of the screen cloth, with consequent reduction in drum pool suspended solids concentration, will normally reduce .DELTA.H even though the gas pressure also acts on the surface of the drum pool. More significantly, the invention enables operation of a microscreen unit at increased flow capacity at a given .DELTA.H. Whatever pressure is applied, there will be some reduction of torque, bearing load and wear at any given .DELTA.H.

Abstract: A process and apparatus for decreasing the phosphorus content of waste water by means of contacting the waste water with the products of aqueous reaction with elemental iron, preferably subjecting the mixture to sequential aerobic and anaerobic conditions, and concentration of the suspended solids fraction which contains the major portion of the influent phosphorus in solid stable form, and separating the relatively clear liquid fraction therefrom.Contacting the waste water with products of the aqueous reaction with elemental iron may be brought about by recycling at least part of the separated solids through at least part of the process.

Abstract: Lengths of pipe are joined together in above- or below-ground telephone conduit systems by flexible sleeves having specified coefficient of friction, column expansibility and pull-out resistance and containing helically oriented high modulus reinforcement, bonded or encapsulated in elastomeric material. The resultant pipe assemblies represent a significant improvement over previously known cemented conduit-coupling arrangements. Pipe sections may be quickly and economically joined without field application of adhesive, to provide water-tight, pull-out-resistant joints which will accomodate significant bending moments and shearing forces.

Abstract: Lengths of "plain-end" pipe are joined together in underground sewer or drainage systems by flexible sleeves having a specified column expansibility and shear-resistance and containing high modulus helically oriented reinforcement, bonded or encapsulated in elastomeric material. The resultant pipe assemblies represent a significant improvement over previously known "plain-end" pipe-coupling arrangements and bell and spigot pipe assemblies. Pipe sections may be quickly and economically joined without inserting packing, to provide a water-tight, shear-resistant joint which will accomodate significant angular misalignment and circumferential variation. Even if lubricant is placed on the inner surfaces of the flexible sleeves to reduce assembly forces, the resultant pipe assemblies still exhibit more than adequate resistance against shear loads and water infiltration.

Abstract: Filtration in an internal rotary filter system is improved by externally impacting the filter screen as it rotates with a programmed spray of liquid that is varied from a relatively low to a relatively high pressure. In certain instances, this programmed spray is controlled by an electric timer circuit so arranged that the high pressure spray is on for a period of time which does not too unduly burden the system with fluid, but which is sufficient period of time to prevent slime formation on the screen. This can for instance keep the screen free of slime when no germicidal agent (e.g. Cl.sub.2) is employed.

Abstract: Cleaning of multi-pore diffusion elements in place with cleaning gases while submerged in liquid media by applying said cleaning gases intermittently or continuously to said diffusion elements between predetermined limits of operating pressure and flow through flow regulation means and plenums for the respective diffusion elements.