22
ENVIRONMENT AND ENERGY
<< Continued from page 21
Primary metal mining accounts
for close to 50% of industrial
discharge on volume.
The ultimate
goal is zero
discharge —
the situation in
which all water
is recycled
within a plant
or traded to
another.
Furthermore, the practice benefits the environment
and adds weight to any social license to operate.
Industrial symbiosis. One notable opportunity
for industrial wastewater use and recycling is the
cooperation between plants in industrial symbiosis.
This can involve the exchange of process water or the
recycling of treated wastewater for purposes similar
to in-plant recycling. Examples include steam or hot
wastewater, or wastewater that contains organic
material and nutrients, and unconverted raw materials
that may be economic to recover: oil, used solvents,
starch and other substances that can be traded
or recycled, perhaps by employing waste registers
between adjacent industries.
The treatment technology options are similar to those for
in-plant purposes and may employ decentralised systems.
These may involve a dedicated centralised wastewater
treatment plant that services all the industries.
Eco-industrial parks. Industrial symbiosis is best seen in
eco-industrial parks, which strategically locate industries
adjacent to one another to take convenient advantage of
wastewater management and recycling. For SMEs, this
April 2018 Volume 24 I Number 2
can be a significant way to save on wastewater treatment
costs. Important factors are the sharing of information
to match needs, reasonable proximity, and reliability of
supply in terms of quantity and quality.
Combined Heat and Power Plants (CHP, or
cogeneration), which require substantially less
cooling water than conventional generation, are
more efficient when they are located near to the
demand for heat and power such as an industrial
complex and as decentralised power supply.
Interesting examples of eco industrial parks are
found in many countries, for example the Shanghai
Chemical Industrial Park in China.
The Kalundborg Industrial Symbiosis is an “industrial
ecosystem” where the by-products of one enterprise
are used as a resource by other enterprises, in a closed
cycle. It began in 1961 with the development of a new
project to use surface water from Lake Tissø for a new
oil refinery with the aim of saving the limited supplies of
groundwater. The City of Kalundborg was in charge of
building the pipeline while the refinery was responsible
for the financing. The upside of eco-industrial park
wastewater arrangements is similar to those for in-
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