Patent ID: 6200468
Filing Date: 2001-03-13
Classification: B01F,C02F,Y02W,Y10S

Abstract:
Wastewater treatment apparatus comprising:a tank, having a bottom surface, equipped for biological treatment of said wastewater;a gas distribution network in said tank including generally horizontal acid resistant supply piping in said tank positioned above said bottom surface and having synthetic resin inner surfaces;a compressor or blower for introducing air into said network;a high pressure storage vessel for introducing HCl gas into said network, intermittently, alone or in admixture with said air;a plurality of flow regulating orifices of fixed or auto-adjustable size distributed about a submerged portion of the network for receiving the aforementioned air and HCl gas and for discharging them at predetermined flow rates into a plurality of plenums downstream of the flow regulating orifices;a plurality of multi-pore ceramic flat plate diffusion elements, free of fastener through holes, in communication with said plenums for receiving said gases, said diffusion elements being members each comprising a multiplicity of closely spaced fine pores of about 120 to about 300 microns in diameter defining paths for discharge of said gases and which exhibit an increase in dynamic wet pressure, as compared to a base condition of said pressure, as a result of deposition of foulants, each of said diffusion elements having, and being in communication, through its plenum, with its own individual flow regulating orifice;at least about 90% of said diffusion elements being capable, when new, of delivering a flux which is within about +/-15% of the average flux of all such elements, when operated at 2 inches of water guage in a dry unsubmerged condition;said diffusion elements having central and boundary portions with enhanced volumetric compression ratios, said central portions having volumetric compression ratios of about 2 to about 20% relative to the portions of the elements surrounded thereby and said boundary portions having outwardly and downwardly inclined upper surfaces at an angle of depression of about 35 to about 60 degrees relative to the horizontal and having volumetric compression ratios of about 10 to about 35% relative to the portions of the elements surrounded by said boundary portion;said diffusion elements each having a bubble release pressure of about 5 to about 10 inches of water guage and a coefficient of variation not greater than about 0.25, said coefficient of variation being based on the values of bubble release pressure measurements at, at least, about 5 equally spaced points along each of two mutually perpendicular reference lines extending across said surface and through the center thereof;said plenums, mounted on said piping at elevated positions relative to said bottom surface, each comprising gas-tight enclosures that enclose the lower surface of said diffusion elements and include upstanding walls facing and adjacent to the sides of the diffusion elements, the peripheries of said elements having annular steps formed about the upper portions of the peripheral surfaces of the diffusion elements for positioning sealing O-rings on said annular step for sealing contact with the respective plenums and elements, said sealing O-rings being comprised of resilient, elastomeric material; andretaining rings indirectly in contact with said elements at their respective peripheries for securing said elements around their entire peripheries to their respective plenums, said retaining rings including upright, cylindrical walls and flanges which at least partly overlie the sealing O-rings, said flanges restraining upward movement of said sealing O-rings and elements, whereby said upward force on said elements acts upwardly on said sealing O-rings and against said sealing O-rings, for increasing the sealing integrity of said sealing O-rings and preventing escape of gas from the plenums at the sides of the elements.