Dewatering Equipment: Types and Consideration of Dewatering Equipment

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In this article, we will discuss Dewatering Equipment.



Dewatering equipment is employed to perform dewatering on construction sites, which is defined as the process of removing water from another material like saturated soil or sludge. The removal of water is achieved by using a force generated by vacuum or centrifugal motion.

Dewatering equipment saves money by decreasing solids handling and disposal charges. It is another way and economical choice compared with heat drying systems for water removal.

The selection of dewatering equipment relies on the corrosion potential of the material removed and the contaminants present in the liquid. As the reactivity of the liquid raises, the equipment is built with more durable materials.




  1. Types of Dewatering Equipment  

The commonly used types of dewatering equipment are as follows:

a. Centrifuges

b. Drying beds

c. Vacuum filters

d. Filter presses

e. Sludge lagoons

f. Gravity and low-pressure devices


a. Centrifuges

Centrifuges terminate solids from liquids through the process of sedimentation and centrifugal force. The solids or sludge are provided through the stationary feed tube. The sludge pushes with acceleration through the ports in the conveyor shaft, which is then spread to the periphery of the bowl.

The bow spins at high speed which simultaneously diverges water from the solids. The separated solids are compressed against the bowl wall. The solids are then transferred to the centrifuges drying stage and the liquid diverged is released continuously over the weir arrangements around the sides of the bowl.



b. Vacuum Filters

A vacuum filter is equipment that makes a vacuum to remove water from the solids. The filter consists of a drum immersed in a cake or sludge. A filtering medium is positioned over the drum. The whole arrangement of valves and pipes is such that the vacuum is used on the inner side of the filter medium when the drum rotates.

The rotation of the drum removes water from the sludge. When the drum carries the sludge into the atmosphere, the cake layer formed is chipped by a knife blade.

The benefit of vacuum filters bypasses the need for heat treatment or digestion before the disposal or incineration process.


Vacuum filters


c. Filter Presses

This equipment utilizes a filter medium to divide solids from liquids. A filter press collects the solids in the hole between two or more porous plates.

The solids collected are then forced into the cavities by forcing water over them either through plate pressure or by build-up solid pressure.


Filter Presses


d. Drying Beds

The collection of drying beds consists of a perforated or open joint drainage pipe positioned within a gravel base layer, again covered with a layer of sand.

The sludge accumulated is positioned over this sand layer and permitted to dry. The water from the sludge is terminated by evaporation and gravity movement to the underlying gravel base. This water is carried out through the drainage pipe positioned in the gravel base.

With time, the sludge dries, and gaps develop on the surface. These cracks permit the evaporation of lower layers of the sludge.

The design parameters of a drying bed include:

I. Depth of sludge

ii. Moisture content of sludge

iii. Availability of sand bed area


Drying Beds


e. Sludge Lagoons

Sludge lagoons are excavated areas employed to deposit and dry the sludge for several months to years. The depth of a sludge lagoon can range from 2-6 feet.


Sludge Lagoons


f. Gravity and Low-Pressure Devices

These devices make benefit from a set of drying beds and low-pressure pressing devices. The low-pressure belt presses and the gravity bed permit increased solid-water separation.

The equipment offers simplicity, low cost, negligible noise, low energy, and maintenance costs. This is the right choice for smaller treatment and operation plants.


Gravity and Low-Pressure Devices




  2. Dewatering Equipment Preference Considerations  

The preference for the most effective dewatering equipment for construction activities is conditional on:

a. Drying conditions

b. Cost

c. Sludge characteristics

d. Available area

The drying conditions and cost controls are the primary factors controlling the selection of dewatering equipment.

An engineer or industrial buyer must be conscious of the sludge characteristics or corrosion potential of the water to be dewatered. The solids diverged may contain hazardous contaminants or unwanted compositions that may affect the execution of the equipment. For highly reactive sludge, dewatering equipment like filter presses or gravity/low-pressure devices requires chemical conditioning before dewatering.




Read Also: Rebar Couplers



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