Device for treating an effluent and method for treating an effluent

A device for treating an effluent composed of liquid and of solid particles to obtain a treated effluent, comprising:

• a primary filtration device using gravity separation on a rotating cloth having an inlet designed to receive the effluent to be treated and a first and a second outlet, the primary filtration device being designed to separate the effluent into a first flow and a second flow, the first flow comprising the treated effluent, the second flow comprising sludges comprising solid particles, the first flow leaving the primary filtration device through the first outlet and the second flow leaving the primary filtration device through the second outlet, at least one recirculation device designed to recirculate at least a part of the sludges of the second flow, onfigured to be directed toward a treatment unit, to the inlet of the primary filtration device, said second outlet being linked to the at least one recirculation device;
• a separation device configured to separate particles from the sludges of the second flow according to their size or their density, so as to recirculate to the inlet of the primary filtration device particles of a size greater than a predefined size or density;
• a turbidity probe positioned upstream of the inlet of the primary filtration device capable of supplying a measurement of turbidity of the effluent, a turbidity probe positioned downstream of the first outlet of the primary filtration device capable of supplying a measurement of turbidity of the first flow;
• an activation pump for the separation device;
• and
• a means for servocontrolling comprising a computer configured to control the activation pump of the separation device as a function of the measurement of the turbidity of the first flow and/or of a difference between the measurement of turbidity of the first flow and the measurement of turbidity of the effluent, so as to increase the recirculation to the inlet of the primary filtration device of the particles of a size greater than a predefined size or density,
• wherein the primary filtration device comprises a first filter having a mesh of a first diameter designed to retain on the first filter particles having a diameter greater than the first diameter, and
• wherein the first filter is configured so as to form, in combination with the particles retained on the first filter, a second filter having a porosity corresponding to a cut-off threshold less than the first diameter.