Environmental Engineering Reference
In-Depth Information
Condensate recovery
Facilities with large numbers of refrigeration and air conditioning equipment can recover
condensate from evaporators, which forms when humidity in the air gets transformed into
liquid water after touching the cold surface of evaporators. This condensate is a relatively pure
source of water with low solid content useful in applications such as in cooling towers, boiler
makeup water, and irrigation. Moreover, this water can be purified by reverse osmosis and
used for other applications needing potable water (GE, 2007).
Water replenishment
In a broad context, water replenishment means recharging water sources such as aquifers by
using runoff or reclaimed municipal water. However, in the context of food processing, water
replenishment is an initiative in the context of water neutrality, which is basically increasing
the efficiency of water consumption and funding projects that benefit the community or the
environment to compensate for the rest. Certainly, “water replenishment” does not mean that
water is returned to where it was withdrawn at the same rate that it was taken. A big volume
of water is shipped with the food product, especially in beverages, so total water replenish-
ment is not possible.
In the end, eventually every single drop of water goes back to the environment, either as
effluents from processing plants or after the consumption of food products. However, this
water has a much lower value (sewer) than when it was extracted, and in most cases it is
returned to the environment at a long distance from where was extracted. This is especially
important when water is extracted from aquifers because the returned water does not go back
to the aquifer.
This idea of water neutrality is a model of perfect water use that implies returning to the
environment the water that was taken as it was taken. Unfortunately, this is not practically
possible, so companies working in water neutrality attempt to mitigate this impossibility by
compensating society with investments in water-related projects.
Water mitigation projects can be one more alternative in the minimization of water impact;
however, it cannot be the only tool.
WASTEWATER TREATMENT
The best way to minimize the impact of wastewater treatment is avoiding the production
of wastewater by optimizing water use and as a result discharging less water down to
the sewer.
Several technologies for wastewater treatment are available including physical, chemical,
and biological (aerobic and anaerobic) systems that are generally applied as a combination.
Aerobic systems
Most of wastewater these days is treated with “activated sludge” systems that use aerobic
organisms to degrade the organic content of wastewater streams and convert it into biomass
and carbon dioxide. The systems are not purely biological because they need the assistance of
physical processes, such as pumping, aeration, sedimentation, and flotation, followed by
chemical treatment.
Activated sludge treatment requires mechanical energy that comes from electricity to:
