Abstract: An apparatus for the anaerobic treatment of waste water, including in a same closed enclosure, under a gas pressure, a fermentation zone and a decantation zone, with internal recycling of the slurries from the decantation zone to the fermentation zone, made of at least two attached identical cells in mutual communication. The two cells operate alternately and reciprocally as a fermentation cell and as a decantation cell. Each cell is fitted out, in order to be fed while it operates as a decantation cell, with a gas-lift transfer device with two branches, one of the branches opening into the cell which is attached to that where it is placed.

Abstract: A method for the treatment of activated slurries of waste water, notably of urban waste water, characterized in that the water to be treated, previously subjected to the standard prior treatments such as screening, renewal of sediments, degreasing, and possibly a primary decantation, is directed to a single ventilation or aeration basin with a high mass load where it dwells during a reduced period, from which it is discharged to a clarifier-thickener equipped with inclined parallel plates or tubes, stimulating the separation of the slurry, which is being recycled in the ventilation or aeration basin at a high concentration made necessary by the reduced dwelling time of the water in the basin.

Abstract: A system for treating waste waters including a pair of concentric tanks forming a space therebetween which serves as an aeration chamber. Untreated but screened waste water is discharged into the (annular) space and withdrawn therefrom by a pump which passes the liquid through an oxygenating device which induces air into the liquid. The liquid is then circulated through long tubing wound around the outside peripheral surface of the tank to obtain intimate contact between the gas, liquid and solids therein and to convert dissolved material into insoluble material by a conventional biochemical process. The liquid thus processed in the tubing is introduced into the central or inner tank where the treated solids rise to the surface for recycling in the system while the liquid effluent is filtered and discharged to a river or stream.