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Potable Water
What
Is Potable Water?
FLUENCE
NEWS TEAM
Of the more than 2
billion people who lack potable water at home, 263 million must travel 30
minutes per trip to collect it.
With a global
drinking water crisis on the horizon, technologies old and new make the most of
existing water resources
“Potable water”
simply means water that is safe to drink, and it is becoming scarcer in the
world.
Increasing use is
stressing freshwater resources worldwide, and a seemingly endless list of
contaminants can turn once potable water into a health hazard or simply make it
unacceptable aesthetically.
Of the more than 2
billion people who lack potable water at home, 844 million don’t have even
basic drinking water service, including 263 million who must travel 30 minutes
per trip to collect water.
About 159 million
drink untreated surface water.
Unsafe drinking water
is a major cause of diarrheal disease, which kills about 800,000 children under
the age of 5 a year, usually in developing countries, but 90 countries are
expected to fail to reach the goal of universal coverage by 2030.
What Makes Water
Unsuitable for Drinking?
The World Health
Organization (WHO) organizes potable water contamination as organic, inorganic,
radiological, and microbiological, and includes measures of acceptability of
taste, smell, and appearance.
Organic contaminants
are carbon-based chemicals, including solvents and pesticides, which are
introduced through agricultural runoff or industrial discharge.
They can be
responsible for a range of severe health problems from cancer to endocrine
function disruption.
Radiological threats
include radon, cesium, plutonium and uranium.
In North America,
radon is the leading cause of lung cancer in nonsmokers and the leading
environmental cause of cancer mortality overall.
Inorganic pollutants,
such as mineral acids, inorganic salts, metals, cyanides, and sulfates, persist
in the environment.
Heavy metals can
cause neurological problems in humans, especially in the unborn and children,
and also bio-accumulate in some foods.
Arsenic can cause
cancer, skin lesions, cardiovascular disease, diabetes, and cognitive
impairment.
Algal blooms from
nutrients like phosphorus and nitrogen can also introduce cyanotoxins to
drinking water as well.
Waterborne pathogens
including bacteria, viruses, protozoa, and parasites are usually introduced to
water via feces and can cause a range of illness from mild gastroenteritis to
potentially fatal diarrhea, dysentery, hepatitis, typhoid fever, cholera, and
cryptosporidiosis.
Millions are also
infected with waterborne tropical diseases that include trachoma, the most
common cause of preventable blindness.
Also threating
drinking water are so-called “emerging contaminants” or “contamininants of
emerging environmental concern,” which include pharmaceuticals introduced
through sewage and runoff from livestock operations.
Turbidity (lack of
clarity caused by mixed-in particles) can give water an unacceptable taste,
smell, or look.
Whether turbid water
is harmful or just unattractive depends on the material present.
For effective potable
water treatment, it’s important to carefully analyze source water and then
tailor treatment to specific water conditions and standards.
Treating Water for
Potability
Many time-tested
water treatment processes are still in use today in primary treatment stages.
The history of water
treatment goes back thousands of years, as far as Minoan civilization, circa
1700 BCE, and the ancient Egyptians, who first used alum flocculation and
sedimentation to clarify water circa 1500 BCE.
Sedimentation is
allowing particles in turbid water to settle. Alum and other “sticky” additives
known as polyelectrolytes aid the settling process by flocculation, or sticking
particles together into “flocs.”
Flocculation and
sedimentation with clarifiers are common in water treatment plants.
The understanding of
microbiology that came with the work of Dr. John Snow and Louis Pasteur in the
1800s had great implications for water treatment.
Research connected
turbidity to pathogens, and sand filters were first used for treatment of a
public water supply in 1829 London.
Municipal water
systems in the United States followed suit in the early 1900s, and the process
of filtration with layers of sand, gravel, and charcoal remains widespread
today.
But disinfectants
like chlorine in America and ozone in Europe played the largest role in ending
epidemics of waterborne diseases such as typhoid, dysentery, and cholera.
Today, municipal water
supplies routinely prechlorinate to prevent algae and biological growth, or
chlorinate in the final stages of water treatment.
Chlorination in
conjunction with aeration is also used to remove dissolved iron, and aeration
effectively removes volatile organic compounds (VOCs).
Other disinfection
methods include ultraviolet (UV) light and pH adjustment.
Modern Water
Treatments
In modern times,
advances in technology have built on the foundation of older treatments.
For example, aerobic
processes have long been the mainstay of wastewater treatment, particularly for
sewage and other waste streams high in organic or biodegradable content.
In aerobic processes,
microorganisms that thrive in oxygenated water break down organic contaminants
and remove nitrates.
The newest and most
efficient aerobic treatment is found in the membrane aerated biofilm reactor
(MABR), which uses up to 90% less energy for aeration, the most
energy-intensive stage of biological treatment.
In MABR, simultaneous
nitrification-denitrification takes place in a single tank that holds a
spirally wound, air-permeable membrane.
Aeration takes place
at near-atmospheric pressure. MABR, which is notable for its high effluent
quality as well as its energy savings, is available to retrofit existing
plants, as well as in small, packaged systems suitable for decentralized
treatment strategies.
Decentralization
places smaller plants near the point of use, eliminating the need for huge,
regional plants and the costly pipeline networks that are financially out of
reach for many regions.
Other water
purification processes that use membranes have made significant strides since
the 1970s and 1980s, including in reverse osmosis filtration.
Modern filtration in
reverse osmosis (RO) is accomplished by forcing pressurized water through a
membrane that is semi-permeable at the molecular level to exclude unwanted
solutes.
One common way RO is
used in the production of potable water is through desalination. Advances in
the mid-2010s increased its energy and cost-efficiency.
Modern desalination
plants are producing about 50% of Israel’s potable water. Higher recovery rates
and lower consumption of energy and chemicals have made desalination much less
expensive.
Now desalination is
available in scalable and quickly deployed Smart Packaged options suitable for
decentralization.
Anaerobic digestion,
a biological treatment process that relies on microbes that flourish in the
absence of oxygen, is now used to remove organic material and trace organic
contaminants (TOCs) generated by human activity.
TOCs accumulate by
biomagnification and bioaccumulation in organisms and cause irreversible damage
in humans and animals by disrupting endocrine systems and causing tumors.
During the anaerobic
digestion process, microorganisms break down organic compounds, creating a
biogas that is mostly methane. Waste-to-energy systems can also be installed to
collect the methane and use it to generate energy.
Ion exchange, a
chemical process that exchanges unwanted dissolved ions for similarly charged
ions, is used extensively for potabilization in processes including water
softening, demineralization, dealkalization, deionization, and disinfection.
Specialized ion
exchange resins targeted at specific contaminants like nitrates, perchlorate,
and uranium also have become increasingly popular for potable water production.
The Future of Potable
Water
Demand for fresh
water worldwide is projected to increase 55% between 2000 and 2050, and
recently, NASA scientists have determined that freshwater resources are being
used faster than they are being replenished.
Jay
Famiglietti, a senior hydrologist at NASA, has warned, “The water table is
dropping all over the world. There’s not an infinite supply of water.”
Potable water is
fundamental to human life, and we can expect it to be a growing issue for the
foreseeable future.
Fluence brings together breakthrough water-treatment
technologies and proven delivery platforms to optimize the water cycle for the
21st century. We provide the middle market with water, wastewater, and reuse
solutions that can be quickly deployed anywhere in the world, empowering
businesses and communities to make the most of their water resources.
Solutions for the Complete Water Cycle
We offer an integrated range of services across the complete water
cycle, from early-stage evaluation, through design and delivery, to ongoing
support and optimization of water-related assets. Our solutions include:
Energy-efficient technology that lowers capex and opex
Packaged and pre-engineered decentralized treatment solutions for quick
deployment
Tailored financing packages to finance water and wastewater treatment
plants
Constructing and operating water assets under build-operate-transfer
(BOT), operating and financing leases, and reuse-as-a-service (RaaS)
