Primary Water Treatment Flocculation Tanks

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Primary Water Treatment Flocculation Tanks Specification

  • Manufactured from PP
  • Wier and mixer bridges

Primary Water Treatment Flocculation Tanks

Primary Water Treatment Flocculation Tanks 2 or 3 stage flash mixer with double wiers and mixer bridge.  Conventional coagulation, flocculation or sedimentation practices are essential pre-treatments in a 2 Stage Flocculation Tank for a range of water purification systems. Flocculent chemicals are used in water treatment processes for removal of unwanted solids and contamination to produce cleaner, safer and potentially drinkable water. Other applications include sewage treatment, cheese production, and brewing. It is also used in surface and physical chemistry, biology, and civil engineering.

What are the processes in Primary Water Treatment Flocculation Tanks?

Flocculation, or sometimes referred to as clarification, consists of four distinctive processes – coagulation, flash mixing, flocculation, and clarification. Sufficient time and velocity are necessary to maximise the effectiveness of the flocculent so that the individual parts come together in the 2 stage flash mixer.

  • Step 1. Adding the Flocculent & Flash Mixing

  • During the coagulation process, chemical coagulants, also known as flocculants, are added to the water to destabilise the smaller individual particles and cause them to begin aggregating.  After the flocculent is introduced, the water is mixed vigorously by the flash mixer so that the chemicals are evenly dispersed throughout the water. This particular step plays a large role in the effectiveness of water treatment. So that the chemicals are evenly distributed it is flash mixed from 30-60 seconds. Coagulation actually begins during the flash mixing process as the coagulants neutralise the electrical charge of the fine particles. This stops the repulsion of the individual particles and allows them to begin sticking together to form bigger ‘flocs’.
  • Step 2. Flocculation

  • After the initial more aggressive mixing, flocculation begins after slowing down the mixing so that the smaller particles produced during the coagulation start adhering together. The flocculation stage usually goes continues for around 30-45 minutes in a flocculation tank that may have several compartments. Each of these compartments has a different mixing speed, and the speed decreases as the water flows from the top of the basin to its bottom. This approach allows the growing flocs to form without being shattered by the mixing blades.
    After the flocculation process, most of the particles should have bonded together, which is called the Floc. Floc consists of larger masses of particulates bonded together in clusters of about 0.1 to 3 mm in size. It is critical that the floc is not too small otherwise, it doesn’t settle well enough or too big otherwise, it will likely break apart in the flocculation tank.

Coagulation and Flocculation

Groundwater and surface water contain both dissolved and suspended particles. Coagulation and flocculation are used to separate the portion of the suspended solids from the water. Suspended particles vary in source, charge, particle size, shape, and density. Correct application of coagulation and flocculation depends upon these factors. Suspended solids in water have a negative charge and since they have the same type of surface charge, they repel each other when they come close together. Therefore, suspended solids will remain in suspension and will not clump together and settle out of the water, unless proper coagulation and flocculation are used. Coagulation and flocculation occur in successive steps, allowing particle collision and growth of floc. This is then followed by sedimentation.  If coagulation is incomplete, the flocculation step will be unsuccessful, and if flocculation is incomplete, sedimentation will be unsuccessful.

Additional information


2m3, 6m3

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