Decentralised Wastewater
Treatment in India
There
is a large gap between generation and treatment of wastewater in India.
According to the Swachhta status report 2016, released by the Ministry
of Statistics and Programme Implementation, just 59.3% of the population
and 56.4% wards in India (both rural and urban) are reported to have
sewer network for disposal of wastewater. This indicates only a marginal
improvement from around 50% sewer connections in the year 2011 (as per
Census 2011).
As per the Central Pollution Control Board (CPCB)
report ‘Status of Sewage Treatment in India’, the total treatment
capacity gap between the waste water generation and its treatment in
Class I and Class II cities of India combined is as high as 70%.
At the current rate of progress of sewer
network and infrastructure development, it shall take several decades to
achieve safe disposal of liquid waste in Indian cities. Even the
existing treatment capacity is not effectively utilised due to operation
and maintenance issues. Nearly 39% plants are not conforming to the
general standards prescribed under the Environmental (Protection) Rules
for discharge into streams as per the CPCB’s survey report . In a number
of cities, the existing treatment capacity remains under utilised while
a lot of sewage is discharged without treatment. There is a need to
adopt new ways of dealing with wastewater, which are affordable and
sustainable. Indian cities must adopt a hybrid approach of centralised
as well as decentralised planning to bridge the gap in wastewater
treatment and abate the water scarcity and rising levels of water
pollution.
Decentralised management of wastewater has
been defined as the collection, treatment and reuse of wastewater at or
near the point of generation. It is being considered as an alternative
to or complement the large, centralised collection and treatment
systems. A commonly used acronym for decentralised wastewater treatment
system is DEWATS. For example, the majority of new development in cities
occurs at the outer edge, and as cities grow larger and larger it
becomes less feasible to connect these new developments with the
existing sewer network. Decentralised collection and treatment systems
are becoming a more common approach for suburban housing developments.
For small communities and individual
households, a broad range of technologies are available for treating
wastewater. At one end of the spectrum are technologies that use gravity
flow, have few or no moving parts, and rely on natural processes to
achieve most of the treatment. These technologies tend to be lower cost,
have few or no energy requirements, and require less operation and
maintenance.
In an endeavour to promote nature based
solutions for wastewater treatment, Technology and Action for Rural
Advancement (TARA), the social enterprise wing of the Development
Alternatives Group with support from Japanese International Cooperation
Agency (JICA), has partnered with a Japanese company Taisei Kougyou, to
validate and promote their soil based decentralised wastewater treatment
technology - Taisei Soil System (TSS) in India. The objective of the
project is to do the field validation of TSS to tackle the problem of
wastewater treatment in a decentralised manner, to establish a business
model for the pay-for-use public toilets and the formulation of
dissemination plan for the technology. One of the best advantages of the
TSS system is that it does not require any mechanical, electrical or
chemical inputs for on-going operations. Once constructed, the system
keeps running for decades with no touch operations and near zero
maintenance, which is one of the most essential features for success in
an Indian scenario, where due to lack of proper operation and
maintenance systems, wastewater treatment technologies are more prone to
failure. Other key features of the technology are as mentioned below:
• It is a zero-discharge system of
wastewater treatment.
• The system treats the wastewater by
aerobic treatment in the soil absorption field.
• The system is installed underground.
Consequently, the top surface area is available for plantation. The
plants absorb water from the soil absorption field.
• 98% or more reduction of Biological Oxygen
Demand.
• The system can handle large load
variations hence best suitable for Indian scenario.
The pilot plant of the TSS system has been
successfully running in Varanasi (4000 L/day) since June 2019 where the
wastewater from a community toilet near a school is being treated by the
TSS system. Another pilot plant in Muzaffarnagar (8000 L/day) is under
construction and will be ready by early 2020. The agreement has been
done with the Municipal Cooperation/ Municipality in both the cities,
who have extended all their possible support to make the project a
success including the availability of land, testing support and
connection with the respective departments to propagate the technology
after the validation is completed.
Endnotes
-
https://nrcd.nic.in/writereaddata/FileUpload/NewItem_210_
Inventorization_of_Sewage-Treatment_Plant.pdf
-
Small and Decentralized Systems for
Wastewater Treatment and Reuse -Kara L. Nelson." National Research
Council. 2005 ■
Utkarsh, Neha, Pramod
usethia@devalt.org, nagarwal@devalt.org, pkumar@devalt.org
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