Environmental Engineering Reference
In-Depth Information
lower-pressure boilers commonly found at some industrial plants and cogeneration plants
may only require softened water, or water treated by reverse osmosis (RO). Besides deion-
ization technology, treatment concerns may call for the use of specialty chemicals to
control scaling and corrosion. Deaeration towers, oxygen scavenger treatments, and mem-
brane contactors are ways used to remove oxygen from the water.
13.4.3 Condensate Polishing
Condensate polishing is a treatment step in which either deep-bed IX resins, or powdered
resin ilter the steam condensate. The goal is to remove water contaminants (known as
crud) so a power station may reuse the condensate as a feedwater, and to guarantee high-
purity feedwater in once-through supercritical boilers [6].
13.4.4 FGD
FGD treatment involves using technologies such as clariication and thickening to process
the wastewater from sulfur removal pollution-control systems, and to prepare the solids
for disposal.
13.4.5 Drinking Water
Many power stations are in remote locations away from municipal water supplies.
Consequently, one part of the facility operation is the treatment of drinking water for staff
use. This is in addition to other water treatment systems.
13.5 Power Plant Water Use
Thermoelectric generation plants are a major user of water in the United States and world-
wide. Estimates from the US Geological Survey (USGS) are that about 195 billion gallons
of water were used daily (Bgal/d) in 2000 to produce electricity in the United States. This
igure excludes hydroelectric power. Of that amount, about 59.5 Bgal/d comes from saltwa-
ter sources, and the remaining 136 Bgal/d is from freshwater. Of the total amount of water
used by the power industry, 99% comes from surface water.
Although thermoelectric power stations are a major user of freshwater in the United
States, irrigation is slightly higher at 137 Bgal/d. Drinking water accounts for 43 Bgal/d,
while self-supplied industrial withdrawals were 20 Bgal/d. The overall amount of water
use in the United States during 2000 was ~408 Bgal/d [7].
While the power industry uses large amounts of water, it should be noted that much of
this water reenters the environment as either steam or treated efluent placed back into riv-
ers or streams. Therefore, power plant water is not lost and does get reused.
13.5.1 Coming Changes
When considering the power generation sector, it is important to note that it is in the mid-
dle of the debate for how electricity will be produced in the coming decades. Historically,
much of the electricity made in the United States has come from plants fueled by coal.
