1-PRINCIPLE OF COAGULATION;FLOCCULATION;
In coagulation individual particles agglomerate or combine together.when a coagulant is used in water ;it forms a spongy gelatinous precipitate known as floc whic absorbs fine size particles in water and bind them together ,the whole process results into bigger particles which are easily settle down.
2-COAGULANT USED:
+ALUMINIUM SPHATE AL2 (SO4)3 .18H2O
It is the most widely used and cheap coagulant .it reacts quite quickly giving excellent stable flocs with the naturals alkalinity present in the water as dissolved bicarbonates as follows:
A2(SO4)3.18h2o+3ca(HCO2)2=2AL(OH)3+3ASO4+6co2+18h2o
Alum.coagulant+Naturalalkalinity=flocs+sulphate+....
from the above reaction it is clear that sulphate hardness in the water increse to a small extent.
3-COGULATION AID
-polyelectrolytes which are a long chained organic molecules with reactive groups is used successfully as coagulation aid;it is able to bind a lot of flocs together for better sedimentation.
- chlorine to improve coagulation is applied also as will be desccribed in the disinfection process as prechlorination step.
4- COAGULATION(FLOCCULATION) PROCESS:
- In the first flocculation zone ;a rapid flash mixer is installed for intensive mixing of the coagulant with the raw water.the retrntion time is approx.2min.
- in the second flocculation zone astirrer is mounted which allows the growth of the microflocs caused by the mild strring during a retenation period of about 8 minutes .in which the AL(OH)3 flocs build agglomeration with large surface and are therfore able to bind fine and colloid particles as well absorbing coloured substances in the raw water.
- After flocculation polyelectrolyte is added to the flocculated water and directed to the sedimentation tank after aretention period of about 2 minutes.
5- SEDIMENTATION PROCESS
The flocs in the focculated raw water are allowed to settle down by gravity in asedimentation tankin whic also the lamella clarification techniqye is applid with a surface loading comparatively less than that for the presedimentation zone.the effluent is collected again in a clear well and from ther it should be pumpedto the next process equipment.
In coagulation individual particles agglomerate or combine together.when a coagulant is used in water ;it forms a spongy gelatinous precipitate known as floc whic absorbs fine size particles in water and bind them together ,the whole process results into bigger particles which are easily settle down.
2-COAGULANT USED:
+ALUMINIUM SPHATE AL2 (SO4)3 .18H2O
It is the most widely used and cheap coagulant .it reacts quite quickly giving excellent stable flocs with the naturals alkalinity present in the water as dissolved bicarbonates as follows:
A2(SO4)3.18h2o+3ca(HCO2)2=2AL(OH)3+3ASO4+6co2+18h2o
Alum.coagulant+Naturalalkalinity=flocs+sulphate+....
from the above reaction it is clear that sulphate hardness in the water increse to a small extent.
3-COGULATION AID
-polyelectrolytes which are a long chained organic molecules with reactive groups is used successfully as coagulation aid;it is able to bind a lot of flocs together for better sedimentation.
- chlorine to improve coagulation is applied also as will be desccribed in the disinfection process as prechlorination step.
4- COAGULATION(FLOCCULATION) PROCESS:
- In the first flocculation zone ;a rapid flash mixer is installed for intensive mixing of the coagulant with the raw water.the retrntion time is approx.2min.
- in the second flocculation zone astirrer is mounted which allows the growth of the microflocs caused by the mild strring during a retenation period of about 8 minutes .in which the AL(OH)3 flocs build agglomeration with large surface and are therfore able to bind fine and colloid particles as well absorbing coloured substances in the raw water.
- After flocculation polyelectrolyte is added to the flocculated water and directed to the sedimentation tank after aretention period of about 2 minutes.
5- SEDIMENTATION PROCESS
The flocs in the focculated raw water are allowed to settle down by gravity in asedimentation tankin whic also the lamella clarification techniqye is applid with a surface loading comparatively less than that for the presedimentation zone.the effluent is collected again in a clear well and from ther it should be pumpedto the next process equipment.
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