Wastewater reuse final (1)

Potable water
from industrial
wastewater
PRESENTED BY:
AVINASH RAI
CHEMICAL ENGG.
(III- YEAR)

Purpose:
To manage water discharged
from industries so as to reduce
the threat of water pollution.

 Pre-treatment.
 Preliminary treatment.
 Primary treatment.
 Secondary treatment.
 Sludge (biosolids) disposal.
STEPS INVOLVED

Pre-treatment
Occurs in business or industry
prior to discharge.
Prevention of toxic chemicals or
excess nutrients being discharged
in wastewater.

Removes large objects and non-
degradable materials.
Protects pumps and equipment
from damage.
Bar screen and grit chamber.
Preliminary Treatment

Preliminary Treatment
Bar Screen
 Catches large
objects that have
gotten into sewer
system such as
bricks, bottles,
pieces of wood,
etc.

Primary Treatment
 A physical process.
 Wastewater flow is slowed down and
suspended solids settle to the bottom
by gravity.
 The material that settles is called
sludge or biosolids.

Secondary treatment
Degrade biological content (dissolved
organic matter) of the sewage
Ex: human waste, food waste, soaps, detergent
Added bacteria and protozoa into sewage
3 different approaches
Fixed film system
Suspended film system
Lagoon system

Fixed Film Systems
Grow microorganisms on substrates such as
rocks, sand or plastic.
Wastewater is spread over the substrate.
Ex: Trickling filters, rotating biological
contactors.

Suspended Film Systems
Stir and suspend microorganisms in
wastewater.
Settled out as a sludge.
Pumped back into the incoming wastewater.
Ex: Activated sludge, extended aeration.

Lagoon Systems
Hold the waste-water for several months.
Natural degradation of sewage.
Usually reeds are preferred.

Sludge treatment
Primary sludge usually have strong odors
Secondary sludge have high concentration
of microorganism
Goals of treatments are:
Reduce odors.
Remove water and reduce volume.
Decompose organic matter.

Sludge disposal
Superheat sludge and convert into small
granules that are rich in nitrogen.
Sell it to local farmer as fertilizer.
Spread sludge cake on the field.
Save landfill space.

Other methods for water
treatment
Chlorination.
UV light radiation.
Ozonation.

Chlorination
Most common.
Advantages: low
cost & effective.
Disadvantages:
chlorine residue
could be harmful
to environment.

UV light radiation
 Damage the genetic
structure of bacteria,
viruses and other
pathogens.
 Advantages: no chemicals
are used
 water taste more natural
 Disadvantages: high
maintenance of the UV-
lamp

Ozonation
 Oxidized most pathogenic microorganisms.
 Advantages: safer than chlorination.
 Fewer disinfection by-product.
 Disadvantage: high cost.

Conclusions
Many current uses for recycled wastewater.
Varying levels of treatment required.
Advantages:
Conserve potable water.
Reduce effluent to environment.
Potential for much greater use in future.

Wastewater reuse final (1)

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