Engineered Systems for Water Purification

Coagulation, Flocculation, Sedimentation, Rapid Sand Filter, Disinfection

process for water purification

Coagulation

process that neutralizes the charge of particles and therefore making them “sticky”

Aluminum sulfate

example of coagulant

negative

common charge of particles in natural waters

Flocculation

physical combination of the coagulated particles forming flocs

Sedimentation

done in a gravity settling tank that allows the heavier than water to settle at the bottom

Filtration

Environmental engineers have learned to apply natural purification of water through its movement to soil and sand

backwashing

The suspended solids that escape the flocculation and settling processes are caught on the filter sand particles and eventually the rapid sand filter becomes clogged and must be cleaned through a process called

The suspended solids trapped within the filter are released and escape with the wash water.

Disinfection

destroy whatever pathogenic organisms present. The disinfectant commonly used is chlorine.

5, 2

Usually, _ mg/L of chlorine is added but residual chlorine must be _ mg/L to ensure disinfection.

Chlorine Dioxide

can also be used as a disinfectant. it possesses theoretically 25 times greater oxidizing power than chlorine