Hybrid high rate anaerobic treatment apparatus

Claim 1

Apparatus for anaerobic biological treatment of waste water comprising: a lower primary reactor containing a suspension of anaerobic sludge for waste water treatment, said reactor having liquid inlet means for introducing waste water therein; an upper secondary reactor disposed vertically above said primary reactor and in liquid and gas communication with said primary reactor over a substantial portion of an upper surface area thereof, said primary reactor having at least as large a volumetric capacity as said secondary reactor; filter bed means provided in said secondary reactor for retaining anaerobic sludge for waste water treatment; liquid outlet means disposed above said filter bed means for withdrawing treated waste water from said secondary reactor; gas outlet means disposed above said filter bed for withdrawing gases from said secondary reactor; and agitation means disposed in said primary reactor and comprising a plurality of liquid withdrawal means spaced around an upper portion of said primary reactor, and a plurality of liquid infeed means spaced around a lower portion of said primary reactor, said liquid withdrawal means and said liquid infeed means each comprising a plurality of horizontally extending pipes, said primary reactor, apart from said horizontally extending pipes, being substantially free from structure obstructing upward flow of liquid and gases through said primary reactor to said secondary reactor.