Abstract: A method for providing a uniform plug flow through an anaerobic wastewater treatment reactor includes distributing incoming wastewater generally evenly near the bottom of reactor and evenly collecting the wastewater near an upper level thereof so as to produce upward plug flow through the reactor during filling, recycle and decanting and minimize horizontal mixing. Such plug flow encourages growth of heavier biomass near the bottom of the reactor where substrate is greatest and discourages growth of light biomass near the top of the reactor where substrate is least. Wastewater is also preferably recycled from the top to the bottom of the reactor. Apparatus is provided to be used in conjunction with the method. The apparatus is also usable in conjunction with a subsequent aerobic sequencing batch reactor.

Abstract: A system for thermophilic aerobic destruction of pathogenic organisms and organic matter within waste water treatment sludge includes a tank for maintaining the sludge and an air transfer apparatus for injecting air into the sludge near the bottom thereof so as to bubble up through the sludge and react exothermically with the thermophilic microorganisms therein so as to kill or destroy the mesophilic micro- organisms within the sludge. The thermophilic reaction is preferably controlled within a desired temperature range by control of the flow of fresh air versus recycled air being injected into the sludge. The fresh air to recycle air ratio can be controlled by several different mechanisms so as to produce the desired temperature range. The air is also utilized to mix the sludge within the tank. A pumping apparatus is also provided for transferring sludge into and out of the tank and for recirculating the sludge for purposes of auxiliary mixing.