Pulsed sludge bed settling method and device

A settling method using a pulsed sludge bed for the treatment of any type of liquid, particularly water, employing at least one powdered or granular reactant, in which:

• the liquid and the reactant(s) for the treatment are contained in a tank comprising, at the base thereof, means for uniformly injecting liquid to be treated over the entire surface thereof;
• the treated liquid is discharged into the top portion, at the upper level of the liquid in the tank;
• the liquid to be treated is fed into the tank in pulses, causing alternating vertical movements of the sludge bed;
• and
• a portion of the sludge spills over into at least one concentrator when the upper level of the raised sludge bed exceeds a spillover level (Ld), wherein the amplitude of the alternating vertical movements of the sludge bed is varied between at least two values, one of these values corresponding to a high sludge bed level (Nh2) below the spillover level, with discharge of neither sludge nor reactant, and the other of these values corresponding to a high sludge bed level (Nh1) above the spillover level (Ld) with discharge of sludge and reactant.

A settling device using a pulsed sludge bed for the treatment of any type of liquid, particularly water, employing at least one powdered or granular reactant, comprising:

• a tank (1, 1.1) containing the liquid undergoing treatment and the reactant(s);
• at the base of the tank, means (2) for uniformly injecting liquid to be treated over the entire surface thereof;
• a means (3) for discharging the treated liquid into the top portion of the settler, defining the upper liquid level (S) in the tank;
• a bell (5) rising above the liquid level and communicating with the base of the tank;
• an inlet pipe (7) for the liquid to be treated, which opens into the bell;
• a suction means (8) provided at the top portion of the bell;
• a control means for filling the bell with liquid in a filling time (T0) and raising the liquid in the bell to a level (Hh) and for rapidly lowering the level in the bell by an amount (ΔH) over an expulsion time (T1) with an expulsion effect through the sludge bed, which is raised;
• and
• at least one concentrator (12) into which a portion of the sludge spills over when the sludge bed is raised to a level equal to or above the spillover level,
• wherein the control means (11) is designed to vary the drop in height in the bell (5) and to give it at least two values (ΔH1;
• ΔH2), the lower value (ΔH2) of which ensures that the sludge bed is raised to a level (NH2) below the spillover level (Ld) and there is no discharge of sludge and reactant, whereas the higher value (ΔH1) ensures that the sludge bed is raised to a level (NH1) equal to or above the spillover level (Ld) and that there is discharge of sludge and reactant.