Abstract: Described is a two-stage sewage treatment plant (10), in particular for domestic sewage, wherein the first biological purification stage (12) is dimensioned so that besides the carbon load, the mean nitrogen load is maximally degraded. Any peak loads that may appear are degraded in the second biological purification stage (13). This makes possible a space-saving construction and an economical operation. The second biological purification stage (13) is always a two-stage filtering installation with a filter stage (20) for nitrification and a filter stage (21) for denitrification. The first biological purification stage (12) can be an activated sludge stage as per A 131, a pure oxygen activated sludge or likewise a two-stage filtering installation.

Abstract: Process for the biological purification of effluent which makes it possible either to ensure complete treatment of the carbon pollution and the nitrogen pollution at the nominal output, or to remove the biological oxygen demand or BOD only during a substantial increase in the nominal output, especially if it rains, using bacteria in fixed cultures, said process comprising the step of using the modifications of the surrounding environment, that is to say the oxidation-reduction potential which depends on the presence or absence of dissolved oxygen, and the composition of the water in contact with the bacteria, either to modify the enzymatic system of the flora present in the bacterial film of the fixed culture in order to assign to the removal of the BOD a fixed culture which up until then carried out denitrification, or to promote, in the same bacterial film, the development of the most appropriate flora for the desired objective: the removal of the BOD or nitrification.

Abstract: A fluidized bed reactor for the biological treatment of a fluid includes granular treating material through which the fluid to be treated passes upwardly, thereby fluidizing the treating material, during which biological treatment is achieved. A homogeneous distribution of the fluid into the bottom of the granular treating material is achieved by providing a granular transfer material beneath the granular treating material, and introducing the fluid to be treated into the granular transfer material at a speed and under conditions sufficient to impart movement to the granular transfer material causing uniform distribution of the fluid and uniform diffusion thereof upwardly into the granular treating material at a speed sufficient to achieve fluidization thereof.

Abstract: A method for the treatment of liquids containing particles in suspension, by percolation of the liquid from top to bottom through a bed of granular material, notably of a ion exchanger resin, includes treatment cycles of the liquid and regeneration cycles of the resin, preceded by decompaction and washing operations, carried out in the same enclosure the inner space of which is divided into two superimposed compartments in mutual communication. The lower compartment is totally filled with granular material and the upper compartment is partly filled with granular material. The decompaction and washing operations of the granular material contained in the enclosure upper compartment are carried out periodically prior to each regeneration cycle by expanding the granular material by means of a current of liquid flowing from bottom to top.

Abstract: A filtration apparatus includes at least one tangential filtration module ving at least one filtration element defining a conduit arranged in a spiral configuration within an enclosure in the form of a body of revolution. The element defines a helicoidal slope for liquid to be filtered and causes such liquid to pass through the module along a helicoidal path. The liquid is tangentially filtered, and filtrate is delivered to the exterior of the module.

Abstract: An apparatus for the anaerobic filtration of waste water includes a filter of filling material through which the waste water to be treated is passed from the bottom to the top. The filter includes upper and lower superposed layers of filling material separated by an intermediate layer of material. The lower layer is in the form of an ordered arrangement of the material thereof. The upper and intermediate layers each include a loosely packed arrangement of the material thereof.

Abstract: Waste water to be treated is introduced into a filter including granular material for supporting the biomass resulting from an anaerobic treatment operation. During such treatment operation biogas is formed, and the waste water being treated and the granular material supporting the biomass are continuously circulated by injecting a portion of the biogas into a tube extending vertically upwardly through the filter.

Abstract: A treatment column includes a treatment zone which is completely filled with a bed of granular treatment material. A normal treatment operation includes passing a fluid to be treated in a downward direction through the bed of treatment material, thereby treating the fluid. Solid particles suspended in the fluid are removed by the upper portion of the bed of treatment material and are retained therein. Regeneration of the bed is achieved in a countercurrent direction within the treatment column. Retained solid particles are removed from the upper portion of the bed by periodically removing the upper portion only of the bed from the treatment column and transferring such upper portion to a separate washing column whereat the portion of the bed is cleaned and washed. The thus cleaned and washed treatment material is then returned to the upper portion of the treatment zone within the treatment column to replenish the bed.