Abstract: Process employing the technique of ballasted flocculation with a step of injection, into the liquid to be clarified, of a ballast consisting of a granular material and of a polymer, followed by a flocculation step which leads to the formation of a ballasted floc, and by an accelerated settling step, said ballast being recirculated into the flocculation step, either as it is or after cleaning, wherein said process includes two recirculation regimes: a high-energy regime ensuring draw-off of the ballast contained in the ballasted floc, removal of the floc in the form of sludge and recycling of the cleaned ballast into the flocculation unit and, a low-energy regime ensuring transfer of the ballasted floc into the flocculation unit as long as the ballast ratio in the flocculator is greater than a predetermined level, this low-energy regime remaining in service while the high-energy regime is being put into action, but then being shut down during the operation of the high-energy regime, the two systems being emp

Abstract: The present invention relates to a filtering apparatus and the method of washing such an apparatus. The filtering apparatus with an upward flow of a fluid to be treated in an enclosure (7) closed at least at one end (15) and containing a fixed floating bed of filtering particles (16) of a density less than that of the fluid to be treated, is characterized in that the pipe (3) for discharging the filtered materials in suspension has the form of a lyre with vent (5) and dimensions allowing the column of fluid contained in the enclosure to be emptied at a speed higher than the minimum fluidization speed, the filtering particles having a characteristic mass per unit volume between 5 kg/m.sup.3 and 500 kg/m.sup.3 and a pipe (1) for intake of the fluid to be treated is disposed in a zone at the lower end of the enclosure situated below the lower level of the fixed floating bed and above the upper level (30) of the waste discharge pipe (3).

Abstract: The present invention concerns an oxidation and biological reduction reactor for liquid to be treated by upwards circulation and recirculation including, within a longitudinal vertical enclosure 5 accessible by an admission 9, a lower layer 1 of biomass fixation made of material whose density is lower than that of the liquid and an upper layer of fixation 3 of biomass made of material whose density is higher than that of the liquid, characterized in that the lower layer 1 is separated from the upper layer 3 by a transverse wall 2 preventing the passage of filtration materials between a lower zone located under the wall 2 and an upper zone above the wall 2, an oxidation gas input 8 under the upper layer 3 and above the wall 2, an outlet 10 for the treated liquid is recycled by a pump 12 and an outer pipe 11 on the inlet 9.

Abstract: A method of backwashing bundles of inside-skin tubular filter membranes in modules, in which:a circuit is provided so that dead-end mode filtering takes place with the tubular membranes being fed from one end while cross-flow mode filtering takes place with the tubular membranes being fed from the other end, thereby ensuring in both cases that the major portion of the matter stopped by the membranes collects in the same relatively small zone in the bundles of membranes contained in the modules;water is drawn off from the periphery of the modules; andbackwashing is performed in two stages: a first stage in which all of the backwashing water is used for cleaning said relatively small zone and in which the recirculation loop that enables cross-flow filtering to be performed is closed; and a second stage in which the backwashing water is caused to pass through all of the membranes and all the recirculation loop.Apparatus for implementing the method is also described and is shown in FIG.

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: An ascending flux lamellar decantation apparatus for treating a liquid having a plurality of parallel lamellar modules which define a plurality of ducts disposed within an enclosure. The apparatus includes a channel aligned parallel to the lamellar modules for introducing liquids into the apparatus. The apparatus further includes a repartition device for maintaining hydraulic flux of liquids, which repartition device is positioned above at least one of the lamellar modules. The repartition device is made of a plurality of hydraulically independent sections of substantially equal size such that the treated liquid flow in each section is equal. The repartition device further includes a treated liquid recovery means for collecting treated liquid.

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 device for the collection of water from a granular material bed filter includes means for injecting water and air through the filtration bed as well as an outer chute provided with a weir for the discharge of water, characterized in that it is made of a storage capacity placed between the filter and the discharge chute and defined by a vertical perforated wall such as a grid situated in vertical alignment with the filter vertical wall, and a plane slanting inwardly to the inside of the filter, said slanting plane connecting the weir for the discharge of the water via the chute to the filter wall situated below the vertical perforated wall such as the grid.

Abstract: Waste water to be treated is introduced into an enclosed gas tight oxygenation chamber. An oxygen-containing gas is also introduced into the oxygenation chamber, at a pressure higher than atmospheric pressure, such that oxygen from the gas is dissolved in the waste water in a quantity higher than the saturation concentration value of oxygen in the waste water at atmospheric pressure, thereby superoxygenating the waste water. The thus superoxygenated waste water, maintained at such pressure higher than atmospheric pressure, is then passed into an enclosed gas tight filtering chamber which is separate from the oxygenation chamber and which is also maintained at such pressure higher than atmospheric pressure. No other oxygen, other than the oxygen dissolved in the waste water, is introduced into the interior of the filtering chamber.

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.