This document discusses wastewater, its sources and composition. It describes the wastewater treatment process which includes collection, screening, primary treatment to remove solids, secondary treatment using bacteria, disinfection, and final disposal. It also discusses stormwater drainage challenges during floods and better sanitation practices like vermicomposting toilets and septic tanks to treat sewage. The overall wastewater treatment process aims to remove contaminants and make water reusable or safe for release into water bodies.
2. Introduction
• Wastewater refers to all effluent from a household, hospitals, commercial
organizations and institutions, industries and so on. It is also full of agricultural,
horticultural, stormwater and urban runoff, etc.
The Art Or Practice Of Garden Cultivation And Management Is
Called Horticulture.
Effluent is used to refer to the liquid waste or sewage that is discharged
into water bodies either from treatment plants or direct sources.
All This Wastewater Forms A Sewage. It Has
Evident From The Above That It Has Several
Dissolved And Suspended Impurities.
A contaminant is something that contaminates
a substance such as water or food.
3. Organic Impurities And
Inorganic Impurities
Organic Impurities
• Organic impurities may include the substances
that pollute abiotic components like water, soil etc.
Organic impurities, which pollute water are
collectively called as sewage.
• Organic impurities in sewage include animal
waste, urine, oil, vegetable and fruit waste, faeces,
pesticides and herbicides.
Inorganic Impurities
• Inorganic impurities include phosphates, nitrates
and metals. Inorganic impurities generally do not
contain any carbon, but there are certain
inorganic impurities, which contain carbon like
carbon dioxide.
On the World Water Day, i.e., 22 March 2005, the General Assembly of the United Nations
proclaimed the period 2005-2015 as the International Decade for action on Water for
Life.
4. Flood Water
Drainage
• When it rains heavily, large amount of water comes down in a short period of time.
• If the city does not have a proper storm water drainage system, this water starts overflowing on the streets
and may enter houses.
• This is dangerous for public health and property . sanitation system can overflow during floods. There is also
risk of flood water contaminating drinking water supplies, bursting pipelines, and cause sewers to backflow
or even break.
• This causes a major health risk, as excreta will flow onto the surface. This is the reason behind why cholera
epidemics are common after floods.
• In cities, disposal of domestic sewage is separated from storm water sewage by a separate pipe network.
• This arrangement is more efficient because the amount of storm water can be very large and cannot be
treated in a treatment plant.
5. Sewage Systems
Sewage from each house is collected through the
drainage and the network of pipes called sewers take
them to the wastewater treatment plants from which
it released into water bodies.
6. Wastewater
Treatment
Wastewater treatment is a process used to remove
contaminants and make the water usable.
This is done by many complex processes:
• Wastewater Collection
• Screening
• Primary Treatment
• Secondary Treatment
• Disinfection
7. Wastewater Collection
Wastewater collection systems are designed and built to
collect and wastewater from homes, businesses and
industries.
Water carries waste as dissolved material and suspended
solids.
In most cases the wastewater collection system conveys
wastewater by gravity utilizing the natural slope of the
land.
8. Screening
Screening is one of the first stages
in the process of treating
wastewater.
In this process, the larger objects
are removed from wastewater and
then moved into the grit and sand
removal tank.
9. Primary And Secondary Treatment
Primary Treatment
• Wastewater after screening is taken for primary treatment where all the organic waste is removed.
• Primary treatment is done by pouring the wastewater into big tanks for the solid matter to settle at the
surface of the tanks.
Sludge
• The settled solids, after primary treatment, are called the sludge. It is decomposed by bacteria and the
gas emitted is known as biogas, which can be used as a fuel or can be used to generate electricity.
Secondary Treatment
• Water after primary treatment is passed through a tank called ‘aeration lane’’ where the air is tapped
into the water to increase the growth of bacteria.
• Bacteria break down small particles of sludge that escaped after primary treatment.
10. Activated Sludge
After the secondary treatment, the broken-down
sludge settles down at the base of the huge tank
known as ‘activated sludge’. It contains air in it.
11. Disinfection
• The water is then disinfected by adding Chlorine {𝐶𝑙 −} in it,
or by exposing it to Ultraviolet Rays.
• This kills disease causing germs.
• The water now can be released into water body. Such as a
river or a lake and used for agricultural and industrial
purposes.
12. Better
Housekeeping
Practices And
Sanitation
Better Housekeeping Practices
• Cooking oil and fats should not be thrown down
the drain as the fats clog and block the pipes.
• Used tea leaves, solid food remains, soft
toys, cotton, sanitary towels, etc. should not be
thrown in drains as do not allow free flow of
oxygen. This hampers the degradation process.
Sanitation
• Sanitation generally refers to the provision of
facilities and services for the safe disposal of
human urine and faeces.
• Poor sanitation causes many diseases and health
hazards.
13. Vermicomposting Toilet
• In this process, the waste sewage slurry collected from sewage disposal
systems are treated with earthworms, wigglers and tiger worms.
• They decompose the faecal matter, kitchen waste (organic) and other
households organic waste.
• It is a very simple, hygienic and low water consuming process with no
odour or flies' problem.
14. Septic Tanks
The septic tank is a buried, water-tight container usually made of
concrete, polyethene, in which sewage is collected and allowed to
decompose through bacterial activity before draining by means of a
soak-away.
