Coiled Pipe Flocculator in conjunction with a Tilted plate Flotator is widely used for removal of emulsified oil, suspended solids etc., present in waste water. Alum and polyelectrolyte are added for floc formation.
Unlike conventional tank flocculators, coiled pipe flocculator is of the plug flow reactor type. The required mixing capacity is obtained by energy exchange due to turbulence.
The coiled pipe flocculator is a novel concept, which facilitates accelerated flocculation with flocs having extremely low variation in size distribution, shape and structure. This phenomenon strongly improves settling or rising characteristics, thus having a favorable effect on the subsequent flotation or sedimentation process.
In conventional flocculators, the settling or rising properties are effects of short-circuiting flows and back mixing, three to five times longer residence time is often required. The pipe flocculator circumvents these problems and results in accelerated flocculation with the extremely flocculated particle. The residence time in the pipe flocculator is normally under half a minute. Thus, the strongly improved settling or rising characteristics have a favorable effect on the subsequent flotation or sedimentation process.
The pipe flocculator offers the following advantages.
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The dosage of polyelectrolyte can be very precise and controlled |
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The residence time is negligible resulting in very short reaction and mixing time |
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No rotating equipment, like in conventional flocculator |
The above advantages provide a substantial impact on the economics in terms of space, power, and chemical agents.
The effluent flows through the flocculator pipes, where at predetermined points, the coagulant and flocculant can be injected.
The optimum length of each section of pipe flocculator is calculated for every individual application to decide the precise location of injection points for various coagulants and flocculants. The coagulant is injected at the entry section of the pipe flocculator where plug flow condition exists. It is dosed through a mixing flange where total mixing is achieved in less than 0.5 sec, by maintaining a very high turbulence value. The injection of coagulants and flocculants at exactly predetermined points on pipe flocculator provides optimum reaction adjustments and offer gradual built up of flocs along the total length of pipe flocculator.
If pipe flocculators are installed with a flotator, air saturated water (recirculating treated water) from the outlet side of the flotator is mixed at the fag end of the flocculator, the flow receives air-saturated water.
The conglomerates are subsequently separated in the TPF (Tilted Plate Flotator).
Particular care is taken for the design of mixing nozzles for coagulants / flocculants to ensure its complete mixing in the liquid phase.
