Biology_Today_-_October_2016

(iii) Streptokinase

(Tissue Plasminogen Activator)

Streptococcus Clearing blood clots inside blood vessels through dissolution

of intravascular fibrin

(iv) Pectinases Byssochlamys fulvo (i) Clearing of fruit juices, (ii) Retting of fibres, (iii) Preparation

of green coffee

(v) Lipases Candida lipolytica,

Geotrichum candidum

(i) Added in detergents for removing oily stains from laundry

(ii) Used in flavouring cheese

(c) Bioactive molecules

Molecule Microbe Function

(i) Cyclosporin A Trichoderma polysporum (i) Anti-fungal, anti-inflammatory and immunosuppressive properties

(ii) Prevent organ transplantation rejection by inhibiting T-cell activation

(ii) Statins Monascus purpureus (i) Inhibit cholesterol synthesis

MICROBES IN SEWAGE
TREATMENT
s Sewage or municipal waste
contains human excreta, organic
wastes and pathogenic bacteria,
thus, should not be directly
passed into rivers, streams and
other water bodies.
s Before disposal, waste water is treated
with heterotrophic microbes present naturally
in sewage. This treatment is carried out in two stages:

Primary Treatment
s Small and large, floating and suspended impurities are
removed by filtration and sedimentation.
s Grit (sand and small pebbles) are removed by
sedimentation. The settled solid form primary sludge and
supernatant forms effluent.

s Effluent is subjected to secondary treatment.

Secondary or Biological

Treatment

s Primary effluent is passed into

aeration tank, liquid is constantly

agitated and air is pumped into it.

s Large number of aerobic

heterotrophic microbes grow in aeration

tank and form flocs.

s Microbes digest organic matter, convert it into microbial

biomass and reduce BOD.

s In settling tank, the bacterial flocs are allowed to undergo

sedimentation. The effluent is passed into natural waters

like rivers and streams. It can also be further treated with

chemicals to purify it.

1. Preliminary Treatment 3. Aeration

Activated Sludge Return

6a. Sludge Disposal

Raw Sludge

Supernatant Liquor Return

5a. Sludge Filter

Pressing and Drying

Two Stage Digestion

To Sludge Disposal

Fig.: Sewage Treatment

4a. Secondary

Digestion

Sludge

Supernatant Liquor

Sludge Gas

Air

Compressors

4. Final
   Settling Tanks


5. Effluent
   to Lake


6. Primary 5. Chlorination
   Settling

3a. Primary

Digestion

Activated

Sludge

Waste

Gas Line to Boiler

Protective Coarse

Bar Screen

Grit settling