process for waste water treatment

1. Primary Treatment
1. Bars Screening:- Giant rakesallow waterto pass,butcatch large trash like sticks,rags,
and stonesetc.
2. Primary ClarificationTank/settling tank: - Sludge settlesoutatthe bottomwhile grease
is skimmedof the top.
3. Flocculation/ coagulation:- For removal of small andsuspendedsolids.Itinvolves
additionof coagulates whichtakes the suspendedimpurities togetherand settle
down
Secondary Treatment
Itbasically includes the removal of all dissolved solids which can be done by
following processes.
 By activated sludge:- in this process the influent coming from primary treatment is
send to aeration tank ,where air is supplied to the influent so that the microbes
present in the sludge become active and start decanting or eatthe dissolved organics .
Some portion of activated sludge from clarifier is send back to aeration tank.

2.  Lagoon system:-in this process the waste water is hold for several months it involves
the natural degradation of sewage.
Many other process ex. Trickling filter,
Tertiary treatment
Used to raise the effluent quality before discharging into environment.
Disinfection: - Thepurpose of disinfection in the treatment of waste water is to
substantially reduce the number of microorganism in the water to be discharged back
into the environment for the later use of drinking, bathing, irrigation, etc
Disinfecting agents: - Ozone, Hydrogen peroxide, UV radiation, chlorine
Waste water treatment can easily be understood by following diagram.
Comingfrom
primary
treatment

3. Industrial/sewage water treatment flow sheat.