Abstract: In a ring channel aeration system, circulation is provided by one or more hydraulic jumps while the major portion of the energy consumed in aeration is allocated to the release of oxidative process gas through horizontally non-propulsive bubble release means having an oxygen transfer efficiency of at least about 6. The hydraulic jump(s) may be powered by discharge of gas (e.g. the same gas used for aeration) through gas discharge means, in which case the system of gas discharge means and bubble release means may have an overall oxygen transfer efficiency of at least about 6. The invention has advantages of flexibility and resultant energy savings as compared to single device circulation/aeration systems, in that excessive energy need not be consumed in aeration to obtain the requisite circulation and vice versa.

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.