Page 127 - CW E-Magazine (26-12-2023)

Point of View

Can the water and wastewater challenges in industry and

urban India present an opportunity?

India has a water and a wastewater problem. And the two are related. Availability of fresh water has been falling in many parts of
the country – be it for agriculture (the largest end-use), personal consumption (cooking, cleaning, drinking), or for industrial use. There
are no easy fixes to this problem and by most counts the water stress levels are expected to rise. Industry, which has the last recourse
to freshwater, has been cognisant of the challenge for some time now, and aside of lobbying for better and cheaper availability, also
made internal arrangements through adoption of technological solutions enabling reuse, reduction and recycle of this precious resource.

Chemicals – a water-intensive industry
Freshwater availability is of great concern for the chemical industry. Generally speaking, this is a water-intensive industry, with some
segments more so than others. Dyestuff and pigment manufacture, for instance, is notorious for using copious quantities of water in
in the manufacturing stage itself, let alone at point of use (when used to colour textiles or leather, for instance). Refineries, petrochemical
plants and fertiliser units, to cite a few other examples, are also large users of water, and this is one reason why they are often located at
coastal locations.

Reducing water footprint is part of the sustainability agenda at many chemical companies today, and there are several success
stories that can be told. The concept of Zero Liquid Discharge (ZLD) has taken a firm foothold in the industry in India, thanks in
substantial measure to government push. Permissions to expand and even operate in some instances are conditional to meeting
ZLD norms. While this demand is legitimate in many instances, it can be an overkill at times, especially when conditions for marine
effluent discharge (after treatment to meet release norms) is possible. Compliance to this norm can lead to significant rise in energy
usage (and carbon footprint), and the argument from industry is that the stipulation is trading one kind of environmental impact
for another. The point to take away from this is that there are no easy solutions when assessing environmental impacts and that a
holistic assessment is needed.

Significant progress
There has been considerable progress in reducing the intensity of water consumption in several chemical industry sub-sectors. Fertiliser
plants, for example, have benefited by changing process equipment, such as using turbines that consumes less steam; or by using seawater
3
for cooling towers. Thanks to many such efforts, water consumption in ammonia-urea integrated plants have reduced from 12.0-m /tonne
urea in 1990-91 to 6.2-m /tonne urea in 2020-21 and in case of complex (NP/NPK) plants reduced from 11.4-m /tonne P O to 4.5-m /tonne
3
3
3
2 5
P O over the same period, as per the Fertiliser Association of India (FAI), an industry lobby group. This translates to reduction of about 50%
2 5
in ammonia-urea plants and 60% in case of complex fertiliser plants.
Another approach is to reuse water from effluent treatment systems. This is typically done by subjecting the wastewater to a series
of treatments, such as clarification using lamella clarifiers, ultrafiltration (UF) and reverse osmosis (RO). Even the RO reject water (which
is a sizeable quantity) is finding use in cooling tower makeup, or treated in multiple-effect evaporators (MEEs), where water vapours are
condensed and used as cooling tower makeup water.
Sewage treatment plants (STPs) are also serving as source of water. As far back as 1991 major industries in the Manali industrial belt,
near Chennai (which has had a long history of acute water shortages), including Madras Refineries Ltd. (MRL), and Madras Fertilizers Ltd.
(MFL), set up such plants to alleviate their water problems. In Mumbai, Rashtriya Chemicals and Fertilisers (RCF) has been doing the same
for more than 20 years, and in 2019, in partnership with Bharat Petroleum Corporation Ltd. (BPCL), an adjacent refinery, set up a second
STP to treat 27.5-mld (million litres per day) of sewage to produce about 15-mld of treated water, doubling its overall capacity to do so.
Even the international airports in Delhi and Mumbai are doing something similar.

The urban sewage problem
This brings us to the second problem – the lack of adequate treatment of sewage in urban pockets of India.

Just how big a problem this is has been brought out by a recent report by Niti Aayog, the nation’s thinktank. The agency reckons
that in 2020-21 urban India generated 72,368-mld of sewage and only 28% (20,236-mld) was treated (not considering some wastewater
treated ‘on-site’, such as in septic tanks).

Chemical Weekly December 26, 2023 127

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