Download - Liquid waste management
![Page 1: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/1.jpg)
Hari Prasad KafleLecturer, Public Health
Pokhara University
![Page 2: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/2.jpg)
The four things that have spoiled your life
are: “I” and “mine”, “You” and “Yours”.
Forget them.
![Page 3: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/3.jpg)
Sewage is waste water from a community,
containing solid and liquid excreta, derived
from houses, street and yard washing, factories
and industries.
The term sullage is applied to waste water
which does not contain excreta, e.g. waste
water from kitchen and bathrooms.
![Page 4: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/4.jpg)
a. Creation of nuisance, unsightness and
unpleasant ouder.
b. Breeding of flies and mosquitoes.
c. Pollution of soil and water supplies.
d. Contamination of food.
e. Increase in the incidence of disease,
especially enteric and helminthic disease.
![Page 5: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/5.jpg)
![Page 6: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/6.jpg)
Water: 99.9%
0rganic and inorganic solid: 0.1%
One gram faeces may contain about 1000
million E, coli, 10-100 million faecal
streptococci, and 1-10 million spores of Cl.
Perfringens.
![Page 7: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/7.jpg)
To stabilize the organic matters so that it can
be disposed off safely and to convert the
sewage water into an effluent of an acceptable
standard of purity which can be disposed of in
to land, rivers or sea.
A standard test which is an indicator of the
organic content of the sewage is biochemical
oxygen demand(BOD).
![Page 8: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/8.jpg)
BOD is defined as the amount of oxygen
absorbed by a sample of sewage during
specified period, generally five days, at a
specific temperature, generally by living
organism.
BOD value range from 1mg/liter for natural
water to 300 mg/liter for untreated sewage.
![Page 9: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/9.jpg)
Aerobic process: in presence of oxygen
organic matter is broken down into CO2,
water, ammonia, nitrites, nitrates and sulfates
by action of bacterial action including fungi
and protozoa.
Anaerobic process: anaerobic bacteria
decompose organic waste into methane,
ammonia, CO2, and H2.
![Page 10: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/10.jpg)
Landfill/mine reclamation
Secondary Treatment
Air
Raw sewage
Grit
ChamberSludge
Digester
Activated
Sludge
Sludge drying beds
Sedimentation
Tank
Aeration TankFinal
Sedimentation
Tank
Screens Rivers, lakes,
oceans, etc.
Primary Treatment
Disinfection
![Page 11: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/11.jpg)
![Page 12: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/12.jpg)
![Page 13: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/13.jpg)
![Page 14: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/14.jpg)
Primary treatment
◦ solids are separated
Secondary treatment
◦ dissolved biological matter is converted into a solid
mass by using water-borne bacteria
◦ 95% of the suspended molecules should be removed
Tertiary treatment
◦ biological solids are neutralized then disposed, and
treated water may be disinfected chemically or
physically
![Page 15: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/15.jpg)
Mechanical treatment◦ Influx (Influent) ◦ Removal of large objects ◦ Removal of sand and grit ◦ Primary Sedimentation
Biological treatment◦ Trickling bed filter◦Activated sludge
Chemical treatment◦Disinfection
![Page 16: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/16.jpg)
Screening
Great chamber
Primary Sedimentation
![Page 17: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/17.jpg)
Sewage first passed through metal screen to
remove large floating objectives such as pieces
of woods, rags, plastics paces, masses of
garbage and dead animals.
The screen consist of vertical steel bars usually
set 5 cm apart.
![Page 18: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/18.jpg)
![Page 19: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/19.jpg)
After screen sewage is then passed through a
long narrow chamber called as grit chamber or
detritus chamber.
The chamber is about 10-20 meter and
velocity of sewage flow is about 1 foot per
second taking a detention period of 0.5-1
minute.
![Page 20: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/20.jpg)
The grit chamber allows to settle down heavier
solids such as sand and gravel while
permitting the organic matter passing through.
The grit collected at the bottom of camber is
removed periodically or continuously.
![Page 21: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/21.jpg)
![Page 22: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/22.jpg)
After passing through, sewage is then admitted
to a huge rectangular tank called as Primary
sedimentation tank.
Sewage is made to flow very slowly across the
tank at a velocity of 1-2 feet/minute and
retained 6-8 hours in tank.
![Page 23: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/23.jpg)
Nearly 50-70% organic solids settled down
due to gravity.
The sludge is removed mechanically operated
devices and subjected to sludge dryer.
Due to biological action certain treatment
takes place.
Scum at the uppermost layer should be
removed periodically.
![Page 24: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/24.jpg)
![Page 26: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/26.jpg)
The effluent from the primary sedimentation
tank still contains a proportion of organic
matters in solution and numerous living
organism.
It has high oxygen demand and subjected to
further treatment ‘aerobic oxidation’ by one
of the following methods:
Trickling bed filter method
Activated sludge process
![Page 27: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/27.jpg)
Spread wastewater over microorganism.
Made of coke (carbonized coal), limestone
chips or specially fabricated plastic media.
Optimize their thickness by insect or worm
grazing.
![Page 28: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/28.jpg)
![Page 29: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/29.jpg)
![Page 30: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/30.jpg)
![Page 31: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/31.jpg)
To remove suspended solids, nitrogen, and
phosphate
About 90 % removal of BOD5 and SS
About 20 % removal of phosphate
Variable removal levels of viruses, 20-80 %
removal of bacteria and >90 % removal of
protozoa.
![Page 32: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/32.jpg)
Subjected to aeration chamber for aeration for
6-8 hours.
The aeration is accomplished by either
mechanically agitation or by forcing
compressed air continuously from the bottom
of aeration tank.
![Page 33: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/33.jpg)
The organic matter of the sewage get oxidized
into Co2, nitrates and water with the help of
aerobic bacteria.
Best suited for mega and metro cities because
it occupies small space the trickling filter.
![Page 34: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/34.jpg)
![Page 35: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/35.jpg)
The oxidized sewage from the trickling filter
or aeration chamber is led into the secondary
sedimentation tank for 2-3 hours.
The ‘aerated sludge' is pumped back into the
aeration tank for activated sludge process and
finally into the sludge digestion tank.
![Page 36: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/36.jpg)
To inactivate pathogens in wastewater
Several choices
◦ Free chlorine and combined chlorine
◦UV
◦Ozone
◦ Chlorine dioxide
![Page 37: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/37.jpg)
Use for Irrigation
Disposal in river, sea, lakes, ponds etc.
![Page 38: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/38.jpg)
3-4 weeks complete digestion takes place and
it is carried out in sludge drying bed.
Digested sludge is used as organic fertilizer for
agricultural purpose.
![Page 39: Liquid waste management](https://reader030.vdocument.in/reader030/viewer/2022020110/55a616841a28abf4328b47f3/html5/thumbnails/39.jpg)