ENVIRONMENT AND ENERGY
19
Wastewater and industry (Part 1)
The extent and nature of industrial wastewater production
highlights the opportunities from the use and recycling of
wastewater, and the recovery of energy and useful by-products.
By Extracted from the United Nations World Water Development Report 2017
The dawn of the industrial revolution in the
eighteenth century in the now developed countries
signalled the beginning of society’s dilemma with
the fate of industrial wastewater. Then and now, as
is so often the case, it was discharged into natural
watercourses in the mistaken belief that ‘the
solution to pollution is dilution’ and that stormwater
was nature’s purgative. information is available from developed countries. In
the EU, for example, limited data show that wastewater
generation has generally decreased. The data also
show that manufacturing is the greatest generator
of wastewater among the main industrial sectors.
Furthermore, data from a few countries indicate that
industry is a major polluter, as only a proportion of
wastewater was treated before being discharged.
Societal and environmental pressures have, over time,
led to a continuously growing movement that urged
industry to reduce the amount of wastewater it produces,
and to treat it before discharge. This has evolved into a
significant paradigm shift, with wastewater now being
seen as a potential resource, and its use or recycling
after suitable treatment as a potential way to benefit
industry economically and financially. An atypical example of quite detailed country-level
information is available from Canada, which conducts
biennial industrial water surveys that include data from
manufacturing, mining and thermal-electric generating
industries. Statistics Canada (2014) reports that the
paper industries produced almost 40% of the volume
of manufacturing discharges, with nearly 80% having
secondary or biological treatment, and accounted for
32% of the volume of recirculated water, with primary
metals accounting for close to 50%.
This in turn complements the bigger picture of ‘green’
industry, corporate social responsibility (CSR), water
stewardship, and sustainable development. These
considerations apply mainly to large industries, some
of which have a global reach into developing countries:
many are moving from high-income countries to
emerging markets. They have the size and resources
to seize opportunities and enter the circular economy.
Lacking this momentum, small- and medium-sized
enterprises (SMEs) and informal industries often
discharge their wastewater into municipal systems
or directly into the environment, either of which
creates another set of challenges and potentially lost
opportunities
EXTENT OF INDUSTRIAL WASTEWATER
GENERATION
As the volume of industrial wastewater is reported on
a limited and sporadic basis, the real extent of this
potential resource is largely unknown. Globally, data
and information concerning the volume of wastewater
produced by industry are very deficient. Moreover, a
distinction needs to be made between the overall volume
of wastewater produced and the volume that is actually
discharged, which is generally lower due to recycling.
One estimate suggests that the volumes of industrial
wastewater will double by 2025. Some consolidated
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Overall, for manufacturing, the recirculation rate
(recirculated water as a percentage of intake) was nearly
51%. For the water costs relating to manufacturing,
about 38% went to effluent treatment and almost 10%
to recirculation. Thermal-electric power was by far the
largest user and discharger of water, of which almost
58% went untreated mainly to surface water bodies.
Its recirculation rate was low, though the volume was
approximately double that of manufacturing.
Mining was somewhat different with a recirculation rate
over 100% (used mainly for processing) and discharge
volumes greater than intake due to dewatering. While
many individual companies do collect and indeed report
their wastewater data as required by regulations, with
some exceptions, there are glaring gaps in all sectors
collecting and collating data on national and global
scales. These gaps will require bridging before water
management policy can attempt to make good progress
in coordinating water use and consumption with
wastewater generation and discharges, the latter being
often overlooked.
NATURE OF INDUSTRIAL WASTEWATER
Data regarding the general characteristics and quality
of industrial wastewater are more available. The toxicity,
Wastewater is now
being seen as a
potential resource,
and its use or
recycling after
suitable treatment
as a potential way
to benefit industry
economically and
financially.
Continued on page 20 >>
March 2018 Volume 24 I Number 1