232
if enough food is provided for over seven billion people now on the earth, the water
required could fill a canal 10 m deep, 100 m wide, and 2100 km long. Another major
water use is industrial, which occupies 22% of water use worldwide [5].
Industrial Use
Major application of industrial water use includes thermoelectric power plants, manufacturing plants, ore and oil refineries, and hydroelectric dams. Water in these processes can play the role of cooling agent, solvent, and chemical reagent. Though water
withdrawal may be high in some industries, these consumptions are still much lower
than that in agriculture. Industrial water uses can also include renewable power generation. Hydroelectric power derives energy from the force of water flowing downhill,
driving a turbine connected to a generator, which is a low-cost, nonpolluting, renewable energy source. It can be used for load following and can provide continuous
power. Another way to produce hydroelectricity depends on the Sun. First, heat from
the sun evaporates water, and the vapor then condenses as rain in higher altitudes,
flows downhill, and produces electricity. Except for the two plants above, pumped storage hydroelectric plants use grid electricity to pump water uphill when energy demand
is low, and then use the stored water to produce electricity when demand is high.
Hydroelectric power plants require the creation of artificial lake. Due to the larger
surface area exposed to the elements, evaporation from this lake is higher compared to
a natural river, as well as the water consumption. The process of driving water through
the turbine and tunnels or pipes briefly removes the water from natural environment,
creating water withdrawal, which impact on wildlife varies largely depending on the
design of the plant. Another industrial water use is pressurized water, which is often
used in water blasting, water jet cutters, and high-pressure water guns. These uses not
only work well and safe, but also have no harm to the environment. Cooling of machinery from overheating is also an industrial water use, which only occupies a small proportion of water consumption. In many large-scale industrial processes like oil refining,
fertilizer production, other chemical plant uses, thermoelectric power production, and
natural gas extraction from shale rock, water is also used. Discharge of untreated water
coming from these processes is pollution, which includes discharged solutes (chemical
pollution) and increased water temperature (thermal pollution). These industrial water
uses mentioned above normally require pure water and apply a variety of purification
techniques both in water supply and discharge. Most of the pure water is produced onsite from natural freshwater or municipal gray water. Industrial consumption of water
is generally much lower than withdrawal because laws require industrial gray water to
be treated and disposed to the environment. One exception is the thermoelectric power
plant using cooling towers with high consumption of water equal to their withdrawal
because most of the withdrawn water is evaporated as part of the cooling process. In
addition, business activities including entertainment expand quickly nowadays, which
increases the demand of water supply and sanitation, and further leads to higher pressure on water resources and natural ecosystem.
12 Potable Water
if enough food is provided for over seven billion people now on the earth, the water
required could fill a canal 10 m deep, 100 m wide, and 2100 km long. Another major
water use is industrial, which occupies 22% of water use worldwide [5].
Industrial Use
Major application of industrial water use includes thermoelectric power plants, manufacturing plants, ore and oil refineries, and hydroelectric dams. Water in these processes can play the role of cooling agent, solvent, and chemical reagent. Though water
withdrawal may be high in some industries, these consumptions are still much lower
than that in agriculture. Industrial water uses can also include renewable power generation. Hydroelectric power derives energy from the force of water flowing downhill,
driving a turbine connected to a generator, which is a low-cost, nonpolluting, renewable energy source. It can be used for load following and can provide continuous
power. Another way to produce hydroelectricity depends on the Sun. First, heat from
the sun evaporates water, and the vapor then condenses as rain in higher altitudes,
flows downhill, and produces electricity. Except for the two plants above, pumped storage hydroelectric plants use grid electricity to pump water uphill when energy demand
is low, and then use the stored water to produce electricity when demand is high.
Hydroelectric power plants require the creation of artificial lake. Due to the larger
surface area exposed to the elements, evaporation from this lake is higher compared to
a natural river, as well as the water consumption. The process of driving water through
the turbine and tunnels or pipes briefly removes the water from natural environment,
creating water withdrawal, which impact on wildlife varies largely depending on the
design of the plant. Another industrial water use is pressurized water, which is often
used in water blasting, water jet cutters, and high-pressure water guns. These uses not
only work well and safe, but also have no harm to the environment. Cooling of machinery from overheating is also an industrial water use, which only occupies a small proportion of water consumption. In many large-scale industrial processes like oil refining,
fertilizer production, other chemical plant uses, thermoelectric power production, and
natural gas extraction from shale rock, water is also used. Discharge of untreated water
coming from these processes is pollution, which includes discharged solutes (chemical
pollution) and increased water temperature (thermal pollution). These industrial water
uses mentioned above normally require pure water and apply a variety of purification
techniques both in water supply and discharge. Most of the pure water is produced onsite from natural freshwater or municipal gray water. Industrial consumption of water
is generally much lower than withdrawal because laws require industrial gray water to
be treated and disposed to the environment. One exception is the thermoelectric power
plant using cooling towers with high consumption of water equal to their withdrawal
because most of the withdrawn water is evaporated as part of the cooling process. In
addition, business activities including entertainment expand quickly nowadays, which
increases the demand of water supply and sanitation, and further leads to higher pressure on water resources and natural ecosystem.
12 Potable Water