• Screening

Process of removing debris from water so that it would not clog up the water treatment processes later on.

Corse screen - Remove bigger debris from the water

Mirco screen - Remove smaller debris from water, it must be consitently washed with high pressure water to prevent it from clogging.

• Coagulation / Flocculation

Colloids are particles which:

1. Big enough to scatter light(Contribute to turbidity)
2. Do not agglomerate
3. Cannot settle over a short period of time as they are very light
4. Large surface area in relation to mass

Coagulation:

Process of destabilizing the negative surface charge of the colloids, hence allowing them to agglomerate. This is done by addition of Alum, eg: Al2(SO)4. Inter-bridging positive charged polymers can also be added to enchance the formation of flocs. They cause colloids to come together and later, colloid-polymer can come together to form a bigger floc.

Flocculcation

A mechanical process which helps the formation for flocs

• Sedimentation

A process where is separates suspended particles from the water such as flocs.
This is done by retaining the water in a clarifier for a period of time to allow the particles to settle to the bottom of the tank.

• Sand filtration

This is a liquid-solid separation process where sand is used as the filter. It removes substances which do not settle during sedimentation, and at the same time, biofilm may be formed to allow futher removal of organic substances.

There are two types of sand filter, one is pressurised which is small and is used in small industries, and another uses gravity for the filteration process.

• Activated Carbon

Removal of taste, odour etc..

• Disinfection

It is done by ozonation, UV light disinfection or chlorination (sodium hyperchlorate).

• Softening

To remove hardness caused by Divalent metallic ions.
Two types: Ion exchange, lime softening

Ion exchange

Resin beads with Cl- attached to the surface of it were used to remove hardness. The metallic ions has more affinity towards the surfaces of the resin bids, hence it replaces Cl- that is attached to the resin bead surface.

Process of using ion exchange bead

1. Operation
2. Backwash
3. Regeneration
4. Rinse

Operation is where by the beads are being used to remove hardness.
Backwash is used before regenerating the beads. It is to remove dirt and other particles that are trapped in between the resin beads.
Concentrated brine solution is used to regenerate the resin beads. It is usually added in excess
Rinse is to remove the excess brine solution from the resin before usage as it might affect the efficiency of hardness removal. (Carried out in two stages, a slow rinsing followed by a fast rinising).

Done. Topic one! haha. But I still have to read all my tutorials and do my BB practice<_< Gosh. Incase I forgot

THINGS TO REMEMBER: Do BBP1 & 2, read tutorials, figure out the 3 equations of alkanility.

Time to play dota woots.. See ya=p