Basic Concepts of Reusing Industrial Wastewater
Heightened
public awareness and stricter application of effluent standards by the
authorities has led to industrial wastewater reuse being given a lot of
importance. Advanced technologies have also led to such reuse becoming
feasible and economical.
The Potential for Industrial Wastewater Reuse
Depletion
of water sources is the net result of the use of water for industrial
purposes. In addition to this, the discharge of industrial wastewater,
which is normally highly contaminated, does lead to pollution of
groundwater. All this has necessitated the reuse of industrial
wastewater after adequate treatment, and there has been a vast
improvement in the methods of treating industrial wastewater so that it
can be safely reused.
The potential for wastewater reuse depends
on the volume, the concentration of pollutants, and their
characteristics. The various technologies developed for such treatment
each have their own area of specialization and costs for setting up. Biomimcry
is one of the latest advances that imitates the ecological system and
transforms waste material in water into nutrients while the water can be
reused for the industrial activity or other activities that require
water. Technology has also led to the creation of portable units
to treat industrial wastewater reducing the need for land and space
required for treatment. Many civic authorities also separately treat
wastewater and supply such treated water to industries.
It
is estimated that water consumption is cut down by at least 50 percent
by industrial wastewater reuse and this figure can even go high as 95
percent. While the use of water used in boilers by cooling has been
always prevalent, it is now becoming imperative for industries that use a
lot of water to consider the reuse of wastewater because of the costs
of looking for water sources and to reduce the consumption of it. This
has also been vastly influenced by environmental concerns.
Industries
that have a very high potential for industrial wastewater reuse are
those of glass, steel, cotton textiles, pulp, and paper. There are other
industries like food processing, chemicals, fertilizers, dairies,
petroleum refining, and distilleries that have a potential also for
reuse of industrial wastewater. There are however industries like
tanneries, rubber, pesticides, paint manufacturing and aluminum where
the potential is very low because of the high concentration of
pollutants in the wastewater and inadequate cheap technologies for
treating such wastewater.
Industrial Wastewater Reuse Technologies
Technologies
that are used to treat industrial wastewater for reuse can include
refinements of methods of precipitation and sedimentation, biological
treatment, evaporation and crystallization, filtration through media or
membranes, disinfection, reverse osmosis or ion exchange.
Deciding
on the right technology will depend on mechanical constraints like
corrosion, biological growth, and scaling. The capital costs of setting
up the treatment plants and the costs of chemicals or other inputs
required to be constantly replaced can also determine the technology
adopted by an industry. Finally environmental constraints can also make
their presence felt, especially where the industries are very close to
large cities or residential areas or even environmentally fragile
surroundings.
It is necessary to see that all the potential
sources of wastewater in an industry are identified and the quantity and
quality from each source correctly estimated. Treatment of industrial
wastewater is reduced when the number of steps required for the
treatment is the least. Quite often the retention of wastewater itself
serves as a means of some treatment, though this may require large
capital costs in the retaining tanks, which mainly act to create
sediments of the waste that can then be separately treated.
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