ENVIRONMENT AND ENERGY
21
Wastewater and
industry (Part 2)
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.
Extracted from United Nations World Water Development Report 2017
ADDRESSING THE RESOURCE CHALLENGE
If wastewater is accepted as a positive input,
rather than an unwanted output of industrial
activity demanding disposal, there is a logical and
preferred process from its elimination to proactive
use and recycling.
RECYCLING WASTEWATER AND
RECOVERING BY-PRODUCTS
Recycling within a plant. Overall, industry is in a good
position to use or recycle its wastewater internally. This
might involve the direct use of untreated wastewater,
provided its quality is good enough for the intended purpose.
Cooling and heating water, as well as rainwater, may be
suitable for washing, pH adjustment, and fire protection.
However, process water, which is sufficiently treated
to match resulting quality with intended purpose, has
more potential for recycling, for example in conveying
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materials, rinse water, water-cooling towers, boiler feed,
production line needs, dust suppression, and washing.
This quality is accomplished by decentralised treatment
systems. While the technology is generally available, and
there is a trend to reduce the gap between treatment
and recycling, obstacles may include implementation,
costs not outweighing benefits, long payback periods,
maintenance, and increased energy consumption.
Moreover, the location and availability (intermittent,
batch or continuous production) of the wastewater
stream must fit with its intended use. Using
wastewater or recycling treated wastewater is a
process that can be repeated many times. It not only
reduces the cost for industry of acquiring freshwater
by decreasing intake, particularly in areas or times of
scarcity, but also has the added benefit of reducing
discharges. In this way, the need to meet regulatory
standards and the risk of fines is minimised.
Data shows that
manufacturing is the
greatest generator of
wastewater among the
main industrial sectors.
Co ntinued on page 22 >>
April 2018 Volume 24 I Number 2