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Water treatment: Transitioning from a product to a
service
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Water
is a finite resource and its availability is increasingly constrained.
Industry, not surprisingly, has the last recourse to water, and in several
parts of the world its availability is posing a constraint to growth,
including for the chemical industry. These circumstances, however, offer
significant opportunities for several companies that offer solutions to treat
water – to either use in chemical processes or for discharge into receiving
bodies. Regulations governing both the tapping of surface & underground
waters, and the discharge of effluents are tightening everywhere – including
in India – and driving investments and technological developments in water
purification and wastewater treatment.
Lowering the water footprint
The
chemical industry has a hefty water footprint. Water is used in the industry
for several purposes: in the process itself, as a solvent, for cooling &
heating etc. Like several other industries, the chemical industry largely now
depends on conventional sources of water to meet its needs. These could be
surface sources such as rivers, ponds and lakes; or underground ones such as
wells, springs etc.
Progressive
chemical companies across the world are however closely evaluating their
water footprint and setting targets for lowering water usage, as part of
their sustainability initiatives, even as they grow their businesses. They
are taking several approaches to do this. Process modification is one option,
but can be technically challenging. In some instances, there is even a
juggling of the portfolio to eliminate products that pose heavy demands on
water. Pigment or dyes manufacturing, for instance, requires copious
quantities of water, including in several steps of washings to get to the
desired quality. It is a matter of concern that manufacture of these has
largely shifted to China and India – countries severely stressed for water –
for environmental reasons.
The
most common approaches to reduce consumption of freshwater are through
recycling and reuse, and by switching to ‘grey’ or wastewaters, or even
seawater. These alternate waters are usually abundant and come at next to no
cost, but their quality upgradation calls for significant investments.
Recycle and reuse – segregation is key
For
industries looking to treat wastewater prior to discharge, onsite recycle
also affords an opportunity to recover valuable products that could have
substantial economic value.
The
key here is segregation of effluent streams at source, characterisation of
its chemical composition and the design of appropriate treatment schemes. It
should be borne in mind that effluent treatments are most effective when
volumes are low and concentrations high. Each stream has its own physical
properties (colour, pH, temperature), chemical composition (organics, inorganics),
volumes (large, medium, small), characteristics (COD, BOD, TDS etc.),
toxicity and hazards. End-of-pipe treatments that mix several result in a
complex stream that contains a cocktail of chemicals (50 or even more), each
with its own resiliency to generic treatment options.
Some
industries – notably pharmaceuticals – have legitimate concerns on adopting
water recycling schemes due fears that these may lead to accumulation of
impurities, affect process yields and even quality of the active pharmaceutical
ingredient (API). There are also concerns that regulators or even customers
may not approve such schemes. Above all, the economics of recycling are often
not compelling enough, as profit margins are still high and savings realised
not significant enough.
While
it is difficult to sell recycling schemes in API syntheses, that need not be
the case in the earlier stages of making their intermediates. The processes
to make them typically involve multi-step synthesis, diverse chemistries and
create pollution despite efforts to adopt ‘green’ routes. Customer approvals
are also more easily forthcoming for intermediates than for APIs.
Recovery of by-products – crucial for economics
The
recovery of valuable components in the waste streams is integral to success of
these treatment schemes and to justify investment costs. Several success
stories exist right here – in the manufacture of speciality chemicals, dyes,
APIs etc. These industries have high waste generation per unit of the desired
product (e-factor), and are ones in which India is seen to be globally
competitive.
Tertiary
treatment solutions such as ultra-filtration, reverse osmosis and multiple
effect evaporation can enable chemical companies operate with zero liquid
discharge (ZLD). Their adoption may no longer be a choice, as regulators are
making these mandatory to receive consent to operate. Economics of these
projects are attractive, with payback periods of a couple of years, when
combined with recovery of valuable by-products that would otherwise have been
consigned to the solid wastes.
Using alternate waters
Another
approach to reducing freshwater consumption is to use wastewaters or even
seawater to meet process or cooling needs.
While
treatment of sewage by chemical and biological treatment are well known, the
treated water is usually discharged into reservoirs. Making them available
for industrial use or even potable use is uncommon, but technologically
achievable even today. Singapore’s successful experiment to turn ‘grey’ water
into potable water is an outstanding achievement that few others have dared
emulate. The challenges here are not just technological, but also of
perception.
Sewage
treatment can be carried out in centralised sewage treatment plants (STPs) or
in decentralised ones, and each comes with its pros and cons. Centralised
facilities can be built to a larger size – and so leverage economies of scale
– and with a higher level of automation, to ensure consistent performance.
They are typically located far from dwellings, but that implies additional
costs for pumping the sewage in and the treated water out. Decentralised
systems, on the other hand, can be located close to the point of generation
of the wastewater and are well suited for areas where, for example, sewer
lines are not available. They can even be designed for recovery of
by-products.
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 by availability
and cost of energy. In the end, it comes down to choosing between capital and
operating costs.
Policy support crucial
Investments
in STPs for meeting water needs in industry have so far taken place when no
fresh water supply was available. Several power plants have turned to sewage
from nearby towns and found the economics attractive. Costs of treated water
typically come to just about a third of that of municipal supplies (assuming
it was available), with no problems in quality.
But
broader scale use of sewage is still missing. For that to happen several
challenges will need to be overcome. For a start, the policies need to
encourage capital flows into the sector. Pricing of water and wastewater need
to provide an economic incentive to upgrade water. Firm contractual
agreements for supply of wastewater and for offtake of treated water are just
as important. Technology choices matter, but are best left to investors who
should know more about it than regulators.
Transition to services model
Heightened
regulatory and sustainability mandates have increased demand for water
purification and wastewater treatment, and so provided opportunities for
manufacturers of water treatment chemicals. Globally, this is an industry
valued at about $23-bn globally and growing at 6-9% annually.
India’s
water treatment chemicals industry is still in its infancy – both in terms of
size and the complexity of offerings. In some segments – such as ion exchange
resins, for example – it has companies that are both indigenous and
international, and a few are competitive even in export markets.
Globally,
the water treatment business has transitioned to one wherein major companies
go beyond offering just chemicals and instead offer a comprehensive package
that includes service – maintaining equipment, minimising downtime, ensuring
promised performance, improving efficiencies etc. This locks the service
provider into a higher margin business engagement than a transactional sale
of chemicals would do. This is the direction India’s leading water treatment
companies are also taking.
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- Ravi
Raghavan Chwkly16may17
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