Page 128 - CW E-Magazine (26-12-2023)

Point of View

The untreated wastewater largely finds its way to nearby rivers, lakes, and groundwater aquifers, causing contamination and deterioration
of water quality. A Central Pollution Control Board (CPCB) study of 2018 revealed that 13% of Indian river stretches are ‘severely’ polluted,
and 17 ‘moderately’ so. Apart from high Biological Oxygen Demand (BOD) and Chemical Oxygen Demand (COD), high levels of heavy metals,
arsenic, fluorides, and hazardous chemicals are also found in many places, especially in groundwater.

Inadequate and outdated capacity
As per the report, as of 2020-21, 1,469 STPs have been installed in the urban centres of the States and Union Territories of India, with
a total installed capacity of 31,841-mld. While this represents a near-doubling of the number since 2014, its falls well short of the capacity
needed.

An analysis of the technologies used in the installed STPs also reveals that many are outdated. A vast majority still deploy conventional
technologies such as Sequencing Batch Reactors (30%) and Activated Sludge Process (20%), and the share of capacity using more
advanced techniques such as Extended Aeration, Fluidized Aerobic Bed Reactor, Moving Bed Biofilm Reactor, and Up-flow Anaerobic
Sludge Blanket is only about 17%.

Many factors contribute to this state of affairs and include: limited land available for setting up new treatment plants; challenges in
mapping the connectivity of sewage drainage systems; identifying leakages and illegal dumping of sewage; limited data on load gene-
rated and collection points; absence of new technologies that can bring down costs and improve efficiency of treatment; and absence of
collective action between stakeholders from wastewater generation to treated wastewater reuse.
With the pace of urbanisation expected to pick-up, and the number of people expected to live in cities likely to rise to 607-mn by 2030
and to 877-mn by 2050, this is a problem which will only rise in scale and complexity. The demands for freshwater to meet the needs of
urban pockets is even today leading to large-scale diversion of supply from surrounding areas, which raises many social issues. Some of
the water to quench the thirst of Mumbai, for instance, is brought from surface water resources that are closer to Nashik than Mumbai.
Inter-State squabbles over water rights – such as between Tamil Nadu and Karnataka over the sharing of waters of the Cauvery – are a
regular feature today and only exacerbated during times when the rainfall is less than normal (unlike now, when there is a problem of plenty).
Decentralised approaches will help
Participatory approaches with the inclusion of local people can improve the delivery of services. In a decentralised system with less
institutional overlaps, stakeholder participation can help in easy setting up of plants (in addition to less upfront costs), better monitoring of
water quality and thus improve wastewater treatment and reuse. The scope of such decentralised systems, which is high in Class 2 cities
and small towns, is yet to be explored adequately.

The aversion of public in reusing treated wastewater is a reality that will have to be grappled with. However, with effective public
engagement, and change in terminology, the proportion of people in support of potable reuse can and has been increased considerably.
In Singapore, the use of the term recycled water (marketed as NEWater), instead of wastewater, resulted in a 74% social acceptance to
reuse of water.
Improving the industrial efficiency of water use
Notwithstanding the progress made by industry in using water, there is a lot of headspace to grow the industrial efficiency of water use
in India, and bring it first up to standards of countries not very different from us in terms of development. While Indian industry generates $8
worth of industrial output per cubic metre of water consumed, the comparable figure for Brazil and Thailand are $23 and $49 respectively,
and in more industrialised South Korea $96.

Indian industry’s poor water efficiency stems both from its high freshwater draw and low rate of recycle. Correctly pricing this precious
resource is one way to tackle the former, and technological interventions can help improve the latter. The good news is that the tools needed
are well-proven and widely available from competing vendors. What is needed is a holistic approach incorporating the right technologies and
designs, and operating them smartly in line with best practices. Regulators can also play a role by wielding both the carrot and the stick!

While industry’s ability of soak up sewage and treat it to meet at least its own requirements is unlikely to solve the waste problem of
cities, it can make a larger contribution than now – to the benefit of both.
Ravi Raghavan

128 Chemical Weekly December 26, 2023

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