3.2 Sewage Pollution
Discharge of untreated sewage in water bodies is one of the major sources of water
pollution. The urban population in India jumped from 25.8 million in 1901 to about
387 million (estimated) in 2011.
3 This has thrown up two major problems—
shortage of water and generation of sewage. In view of the population increase,
demand of freshwater for all uses will increase and so will the amount of sewage.
An estimated 62,000 million liters per day (MLD) sewage is generated in urban
areas, while the treatment capacity across India is only 23,277 MLD or 37% of
sewage generated.
4 Thus, there exists a large gap between generation and treatment
of wastewater in India. The Central Pollution Control Board (CPCB) carried out an
inventorization of sewage treatment plants (STPs) located in India in the year 2014–
15 and found that out of 816 STPs, 522 are operational, 79 are non-operational, 145
are under construction and 70 are proposed for construction.
5
Projected wastewater from India’s towns and cities may cross 120,000 MLD by
2051, while rural India will also generate not less than 50,000 MLD.
6 Where will all
this sewage go? Unless sustainable technologies and systems to treat this sewage are
found, effects on water quality and health of the people will be disastrous. Wastewater
management plans will need to address this increasing pace of wastewater generation.
3.3 Centralized Versus Decentralized Wastewater Treatment
Wastewater treatment systems can be centralized where large volumes of water are
treated in sewage treatment plants involving a network of pipes, major excavations
and big manholes. On the other hand, there can be onsite decentralized treatment
systems where wastewater from a single household or a colony is treated with small
excavations and reusing the effluent.
7
Centralized sewage treatment plants come with their own set of costs and
challenges. These are cost intensive and involve transport of waste to centralized
systems for treatment. This involves the creation of infrastructure and the use of
energy for pumping over long distances.
Often this is because of the operation and maintenance cost and high energy
cost. Even if plan funds are available for setting up the large STPs, there is dearth of
funds for its high maintenance and energy cost. This may be a major reason why
even the existing treatment capacity is not effectively utilized, and operation and
3
Census of India, 2011, Ministry of Home Affairs, Government of India.
4
Handbook of Urban Statistics, 2016, Ministry of Urban Development, Government of India.
5
Inventorization of Sewage Treatment Plants, 2015, Central Pollution Control Board.
6
Kamyotra and Bhardwaj (2011).
7
Guidelines for Decentralized Wastewater Treatment; (2012); Ministry of Urban Development,
Government of India.
72
I. Khurana and R. Sen
Discharge of untreated sewage in water bodies is one of the major sources of water
pollution. The urban population in India jumped from 25.8 million in 1901 to about
387 million (estimated) in 2011.
3 This has thrown up two major problems—
shortage of water and generation of sewage. In view of the population increase,
demand of freshwater for all uses will increase and so will the amount of sewage.
An estimated 62,000 million liters per day (MLD) sewage is generated in urban
areas, while the treatment capacity across India is only 23,277 MLD or 37% of
sewage generated.
4 Thus, there exists a large gap between generation and treatment
of wastewater in India. The Central Pollution Control Board (CPCB) carried out an
inventorization of sewage treatment plants (STPs) located in India in the year 2014–
15 and found that out of 816 STPs, 522 are operational, 79 are non-operational, 145
are under construction and 70 are proposed for construction.
5
Projected wastewater from India’s towns and cities may cross 120,000 MLD by
2051, while rural India will also generate not less than 50,000 MLD.
6 Where will all
this sewage go? Unless sustainable technologies and systems to treat this sewage are
found, effects on water quality and health of the people will be disastrous. Wastewater
management plans will need to address this increasing pace of wastewater generation.
3.3 Centralized Versus Decentralized Wastewater Treatment
Wastewater treatment systems can be centralized where large volumes of water are
treated in sewage treatment plants involving a network of pipes, major excavations
and big manholes. On the other hand, there can be onsite decentralized treatment
systems where wastewater from a single household or a colony is treated with small
excavations and reusing the effluent.
7
Centralized sewage treatment plants come with their own set of costs and
challenges. These are cost intensive and involve transport of waste to centralized
systems for treatment. This involves the creation of infrastructure and the use of
energy for pumping over long distances.
Often this is because of the operation and maintenance cost and high energy
cost. Even if plan funds are available for setting up the large STPs, there is dearth of
funds for its high maintenance and energy cost. This may be a major reason why
even the existing treatment capacity is not effectively utilized, and operation and
3
Census of India, 2011, Ministry of Home Affairs, Government of India.
4
Handbook of Urban Statistics, 2016, Ministry of Urban Development, Government of India.
5
Inventorization of Sewage Treatment Plants, 2015, Central Pollution Control Board.
6
Kamyotra and Bhardwaj (2011).
7
Guidelines for Decentralized Wastewater Treatment; (2012); Ministry of Urban Development,
Government of India.
72
I. Khurana and R. Sen