Deep cone and rake style clarifiers are two of the main ways to recover water, yet it is common to define them as “clarifiers” in general. The two processes have very distinct differences that make each one better in certain situations.
Clarifiers are settling tanks built with mechanical means for continuous removal of solids being deposited by sedimentation. A clarifier is generally used to remove solid particulates or suspended solids from liquid for clarification and (or) thickening. Concentrated impurities, discharged from the bottom of the tank are known as sludge.
In this Water Facts, we will explore the two models and discuss in detail some of the advantages of each and highlight where they are most effective.
A key distinction of the dee cone is its height, hence why it is sometimes referred to as a “vertical” deep cone. These decanters are based upon the principle of static decantation which involves the natural precipitation of solid material. Isolating the particle components first using these processes may reduce the volume of downstream water treatment processes like filtration.In Matec silos, the solid particles sink down to the bottom of the structure while the clean water overflows into the drainage system at the top of the silo. This water is discharged into a designated area for clean water.
The sedimentation of the solid material is expedited by using a polyelectrolyte (flocculant), while the design of the cone creates a column of water that presses over the sludge to create the required thickness of mud. The reagents cause finely suspended particles to clump together and form larger and denser particles, called flocs, that settle more quickly and stably. This allows the separation of the solids in the clarifier to occur more efficiently and easily; aiding in the conservation of energy. The cones degree of incline perfects the thickening of mud and the upper cylinder can be used as extra storage space.
This style of clarifier is ideal for the largest water flows. They are limited in height and are provided with an upper sludge thickening system. This type of clarifier is usually recommended when deep cone height is potentially greater than nine meters.
Matec horizontal decanters, like the deep cone, are made with stainless steel in the middle sized versions. The largest horizontal decanters are made with concrete. The decantation process is similar to the vertical clarifier with the exception that the precipitation aid is not in the design of a cone to use pressure to force solids down. In the horizontal decanters, there is a rake mechanism which stirs the sludge through rotation and pushes it to the bottom of the tank.
Discharging is automatic and adjusted based upon the rake effort, to reach the desired thickness. Sensors provide the opening input to the thickener discharge valve and the sludge will go through a flocculant station.