Purpose and use

Sludge blanket clarifiers represent such processing devices, which combine destabilization, coagulation, aggregation and separation of suspended substances in one process, along with the thickening and removal of sludge. The design of the device depends on the raw water quality indicators and the required quality of the treated water. During water treatment, the first stage of suspension separation significantly contributes to the treated water quality and operational economy. Pulse clarifiers with a segmented stirrer are used to treat surface and underground water for drinking and utility water. They can also be used for tertiary wastewater treatment.

Use of clarifiers

Clarifiers are suitable for use namely in these cases:
– Surface water treatment, where 2-stage water treatment is required;
– Treatment of ground water containing iron, which can be destabilized and precipitated by aeration;
– Treatment of industrial wastewater and wastewater intended for tertiary treatment that can be precipitated by inorganic coagulates.

Technical description

Pulse clarifiers with a sludge blanket are based on the concept of a rectangular ground plan made of metallic material.
Large tanks are reinforced. The device consists of a flocculation chamber, an area for the sludge blanket and a sludge room.


The device and how it functions are focused on water treatment by chemical precipitation, neutralization, water softening, iron removal, bioflocculation, and other applications and processes used in water treatment. To precipitate, aluminum and iron salts including additional precipitants and polyflocculants can be used.
The raw water is fed into the clarifier through a pressure pipeline terminating at inlet channels placed symmetrically in the flocculator’s upper part. The dosed precipitants are homogenised with the raw water through turbulences and eddies in the supply pipe and subsequently in the static mixers placed in the inlet channels, and at the same time, energy dissipation occurs.

The treated water overflows from the inlet channels into the flocculation chamber. In the flocculation chamber, there is a segmented mechanical stirrer with stirring elements placed horizontally. The water flows from the flocculation chamber into the clarifying area (sludge blanket area) thanks to distribution elements of parallelepiped space formed symmetrically in the lower part of the flocculation chamber. The treated water is distributed from the flocculator area via either a large aperture or horizontally placed laterals (perforated distribution pipes situated above the lower part of the clarifying area) depending on the output, size and area of the clarifying area (sludge blanket area).
A cassette installation with deflectors acting as a slow hydraulic stirrer is inserted into the clarifying area. The sludge blanket grows due to incoming new flocs and goes over an overflow edge into sludge rooms of a truncated prism shape, in which the sludge is thickened. The sludge is periodically drained off the sludge rooms. Flocs flow over into the sludge rooms situated at the flocculation chamber sides through a longitudinal aperture placed in the upper level of the sludge blanket. The floc drain from the sludge blanket surface into the sludge rooms can be forced, for the purpose of use of the sludge to thicken suspensions in the flocculator. An installation consisting of obliquely placed lamellar plates is situated above the upper edge of the aperture of the sludge overflow from the sludge blanket. The clarified water is collected from the sludge blanket area via an overflow from the surface through adjustable saw-toothed edges into a collection channel. At the same time, the clarified water is collected from the sludge rooms from the surface into the collection channel, which is adjustable via a saw-toothed overflow. The clarified water from the collection channel is led into a balancing tank, from which it is pumped into the second separation stage – subsequent filtration.

Performance parameters of CS clarifiers

Clarifiers with other outputs will be offered individually.

A condition for the pulse clarifier design is:
– Minimum upward speed in the sludge blanket area of 0.9 mm/s.
– The maximum upward speed in the sludge blanket area depends on the raw water quality and the selected coagulum. For surface water, this speed is up to 2.0 mm/sec. To increase the speed, additional flocculants can be used.

If the clarifier operation is interrupted for a period of less than 40 minutes, the clarifier can be put back into operation without a worsening of the water quality.

When designing water treatment, a chemical-technological review must be conducted.