Page 132 - CW E-Magazine (11-6-2024)

Point of View

While treatment of sewage by chemical and biological treatment is well known, the treated water is usually discharged into reservoirs.
Making it available for industrial or potable use is less common (the latter more so), but that is changing. Singapore’s successful experiment
to turn ‘grey’ water into potable water is an outstanding achievement few others have emulated.

Treating municipal sewage for industrial use has not taken off in India the way it should, partly because of the challenges associated
with getting together diverse entities – municipal authorities, water treatment companies, and water consuming units. But where such
units have been set up, they have served well. In one example in Mumbai, sewage is recycled and reused in industrial applications, saving
freshwater intake equivalent to the annual consumption of 30,000 families!

It is also possible to incorporate energy recovery schemes, utilising methane produced in anaerobic digesters, to further improve
project viability.

For broader use of sewage several aspects need to be addressed: the pricing of water and wastewater, so as to provide an economic
incentive; as well as contractual agreements for supply of wastewater and offtake of treated water. Technology choices matter, but best
left to investors, not regulators.

Seawater desalination is probably the last option for industries that have no other recourse to water but are located at or near the
coast. Technologies include thermal systems such as multiple effect distillation or multi-stage evaporation, to membrane-based ones,
and choice is determined largely by the cost of energy.
Chemical industry lowers water footprints
Though the chemical industry is one of the biggest water consumer in itself, it is also a provider of materials and technologies that
enable several other sectors improve their water management.
In agriculture ‘drip irrigation’ using perforated pipes made from polyvinyl chloride (PVC) resin delivers precise quantities of water, near
the roots where they are most needed. Superabsorbent polymers made from acrylic polymers, to cite another example, retain many times
their own weight of water, and play a role in delivering water efficiently to root systems. To prevent evaporative loss of water from water
bodies, polymeric systems that form a thin film on top of the water, are used.

From products to services
India’s water treatment chemicals industry is still in its infancy – both in size and complexity of offerings. In some segments – such
as ion exchange resins, for example – it has companies that are both indigenous and international, and competitive.

Globally, the water treatment business has transitioned to one wherein companies go beyond offering just products and instead present
a comprehensive package that also bundles service – maintaining equipment, minimising downtime, ensuring promised performance,
improving efficiencies, etc. This locks them into a higher margin business engagement than a transactional sale of chemicals does.

Role for planners
Investors in chemical projects typically look to fiscal benefits and sops available from industrial development authorities and local
governments, when evaluating potential sites for their projects, besides availability of feedstock, general infrastructure (roads, pipelines,
rail connectivity, power, etc.) and industry-specific infrastructure (pipelines, effluent treatment facilities, etc.). They will do well to consider
the availability of water – both now and in the future – and its quality.

The chemical parks that are proposed for different parts of the country must estimate water requirements well into the future when
all units are up and running, and plan for this situation, if they are to attract investors. At times, it is seen that while the initial availability
of water is adequate, the situation changes as demand goes up.

Holistic approach needed
A holistic approach is needed to cope with the fresh water needs of the country in the coming decades. The good news is that cutting
down wasteful consumption will have little deleterious effect: estimates suggest that water consumption for industries could be curtailed
by 40-90%, agriculture by 10-15%, and cities by more than 33%, with no sacrifice of economic output or quality of life.
Ravi Raghavan

132 Chemical Weekly June 11, 2024

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