Abstract: A method of wastewater treatment employing a modified septic tank with a plurality of troughs arranged to be fed in parallel to control the detention time of wastewater passing through the troughs and minimize the addition of gasses to the effluent wastewater, particularly hydrogen sulphide that is evolved in the lower portion of the tank in connection with the digestion of settled organic solids. A biological treatment unit such as those employing rotating contactors can be provided to treat the effluent from the septic tank. The substantial reduction in hydrogen sulphide in the effluent wastewater from the septic tank makes available a maximum amount of surface for the growth and maintenance of organisms oxidizing carbonaceous and/or nitrogenous pollutants on the downstream rotating contactors.

Abstract: A method utilizing a composite apparatus for the treatment of wastewater to remove settleable and floatable solids and to remove and oxidize organic matter including a treatment tank having at least two horizontally adjacent bays, each of the bays having an upper biological treatment zone separated by a horizontally disposed baffle from a lower settling zone. Raw wastewater enters the lower settling zone of one of the bays wherein settleable and floatable solids are removed, and then turns vertically to flow in a reverse direction through the upper biological treatment zone of each bay. From the upper treatment zones the wastewater is directed into and through the lower settling zone of the second bay from which the treated fluid is removed.