Drinking Water Treatment

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Drinking Water Treatment
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Intakes
Surface Water Reservoirs Groundwater
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Aeration The water is mixed to liberate
dissolved gases and to suspended particles in the
water column.
Flocculation The materials and particles
present in drinking water (clay, organic
material, metals, microorganisms) are often quite
small and so will not settle out from the water
column without assistance. To help the settling
process along, "coagulating" compounds are added
to the water, and suspended particles "stick" to
these compounds and create large and heavy clumps
of material.
Filtration The water is run through a series of
filters which trap and remove particles still
remaining in the water column. Typically, beds of
sand or charcoal are used to accomplish this
task.
Disinfection The water, now largely free of
particles and microorganisms, is treated to
destroy any remaining disease-causing pathogens.
This is commonly done with chlorination or
ultraviolet radiation.
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Initial Treatment
90 99 viruses
screens
Sedimentation (flocculation)
Filtration
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Final Treatment
Disinfection and Fluoridation
Sodium Fluoride (NaF) Sodium fluorosilicate
Chlorine Gas Hypochlorite
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Home Water Quality
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Floridas Drinking Water
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Confined Aquifer
Pumped well
Plio-pliestocene (sands)
Miocene (clays)
Eocene Limestone
Limestone
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Potential Problems

• Hardness
• Iron manganese
• Sulfur (sulfides)
• Salt/Salinity
• Pathogens (bacteria/viruses)
• Metals
• Organics

Can be toxic or nuisance contaminants
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Nuisance Contamination
Hardness Iron Turbidity Color Odor Taste
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Hardness
Calcium Deposits
Calcium Magnesium
Classification mg/l or ppm
Soft 0 - 17.1
Slightly hard 17.1 - 60
Moderately hard 60 - 120
Hard 120 - 180
Very Hard 180 over
Soap scum, scale, cooking problems
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Hardness Treatment
Water softeners 35 gal/day/person
Hard water
Cation Exchange Resin
Soft water
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Cation Exchange Resins
Ca2, Mg2
Na
Na
Na
Na
Na
Mg2
Na
Na
Na
Neg. Charge
Neg charge
Na
Na
Na
Na
Na
Ca2
Na
Na
Na
Na
Na
Na
Na
Na
4 Na
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Water Hardness and Soap Scum
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Soap/Detergent
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Sodium dodecylsulfate
Extremely soluble
Na
Ca2

Less soluble
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Harmful Contaminants
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Drinking Water
Potable Water
Free of

• Pathogens
• Harmful Minerals/Metals
• Organic Chemicals

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Toxicity

• Within 48 hours
• Long term
• Frequent exposure
• Small amounts
• Pb, As, Hg

Acute Toxicity Chronic Toxicity
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Contaminants
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Heavy Metals
Metal MCL (mg/L)
Lead 0.05 Silver 0.05 Mercury 0.0002
MCL Maximum Contaminant Level
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Other Metals
Trace Metals required metabolic catalysts
Manganese Iron Cobalt Copper Zinc Molybdenum Chrom
ium
Toxicity gt 40 x requirement
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Nitrates
NO3-
MCL 10 mg/L
Agriculture Organic Waste Disposal
bacteria
NO3-
NO2-
Methemoglobin is a form of hemoglobin that does
not bind oxygen.
Infants under 6 months are particularly
susceptible
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Pathogens
Coliform bacteria MCL lt 1 bacterium /
100 ml
(fecal contamination)
Non-coliform bacteria
MCL lt 200 bacteria / 100 ml
Single required test Sanitary Quality
Suggested test mineral/metal content
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Treatment
Sanitation/Disinfection
Chlorination Most common Boiling UV
Radiation
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Ultraviolet Radiation
Scrambled DNA
Bacteria Viruses Mold Yeast Algae
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Home Treatment
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Water Filters
Ceramic Filtration
Ion Exchange
Carbon
3-stage water filtration
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Ion Exchange Filters
Metals
Pb2, Hg2
Na
Na
Na
Na
Na
Pb2
Na
Na
Na
Neg. Charge
Neg charge
Na
Na
Na
Na
Na
Hg2
Na
Na
Na
Na
Na
Na
Na
Na
Finite Capacity
4 Na
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Most Common Filtration
Solid Carbon Block faucet mount filters
     The solid carbon block faucet mount
filters are reasonably effective in      
reducing contaminants.      These filters, by
nature, are quite smalland because filter
effectiveness is       dependent on contact time
of the water with the filter media, a larger,
high-quality       solid carbon block filter
will be more effective at reducing contaminants
at the       same flow rate.          a
high-quality solid block activated carbon
replacement filter will filter water for      
between 7 and 10 cents per gallon.  2 gallons of
filtered water per day would cost       between
50 and 100 per year
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Activated Carbon
Activation by heating
Extremely porous with high surface area 500 m2/g
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Activated Carbon
Filtration
Particle size removal gt 0.5 microns (bacteria,
fungi)
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Activated Carbon
Absorption spontaneous movement of primarily
organic contaminants from water
to carbon matrix.
Pesticides, volatile organics
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Carbon Filter Removal
Ethylbenzene Monochlorobenzene MTBE O-Dichlorobenz
ene P-Dichlorobenzene Styrene Tetrachloroethene To
luene Trichloroethene VOCs Antidepressants Steroi
ds/Hormones Prednisone, Prednisolone, Progesterone
, Testosterone, Cortisol/Hydrocortisone Antibiotic
s
2,4-D 2.4.5-TP (Silvex) Alachlor Atrazine Carbofur
an Chlordane Endrin Heptachlor Epoxide Lindane Met
hoxychlor Simazine Toxaphene Benzene Carbon
Tetrachloride Chlorobenzene
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Reverse Osmosis
Extremely Effective
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Osmosis
Net movement of water
Salt molecule
Spontaneous movement of water
No salts
Membrane permeable to Water only
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Reverse Osmosis
Purified water
pressure
Membrane permeable to Water only
Contaminants to drain
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Drawbacks
Energy intensive Saline/contaminant
by-product inefficient high volume reject water
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Activated Carbon Filters
Tastes Odors
Chlorine
Organics
Ion Exchange Resins
Removal of charged Contaminants (metals)
Reverse Osmosis
Sediments, viruses, bacteria, dissolved solutes
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What about Bottled Water?
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The global consumption of bottled water reached
41 billion gallons in 2004, up 57 percent in
just five years.
In 2007, US consumers purchased more than 33
billion liters of bottled water
More than 5 trillion gallons of bottled water is
shipped internationally each year.
Supplying Americans with plastic water bottles
for one year consumes more than 47 million
gallons of oil
According to a NRDC study, U.S. consumers paid
between 240 and 10,000 times more per gallon for
bottled water than for tap water
For the price of one bottle of Evian, Americans
can receive 1,000 gallons of tap water
The energy required to produce 33 billion liters
is equivalent to 32-54 million barrels of oil
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Whats the Source?
More than 25 percent of bottled water comes from
a public source.
National Resource Defense Council
If water is packaged as "purified" or "drinking
water," It likely originated from a municipal
water supply, and unless the water has been
substantially altered, it must state on the
label that the water comes from a municipal 
source.
Both Aquafina (Pepsi) and Dasani (Coca-Cola)
originate from municipal water systems
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Artesian water, groundwater, spring water, well
water - water from an underground aquifer which
may or may not be treated. Well water and
artesian water are tapped through a well. Spring
water is collected as it flows spontaneously to
the surface or via a borehole. Ground water can
be either.
Distilled water - steam from boiling water is
recondensed and bottled. Distilling water kills
microbes and removes waters natural minerals
Drinking water water intended for human
consumption and sealed in bottles or other
containers with no ingredients except that it may
optionally contain safe and suitable
disinfectants. Fluoride may be added within
limitations
Purified water - water that originates from any
source but has been treated to meet the U.S.
Pharmacopeia definition of purified water.
Purified water is essentially free of all
chemicals. Reverse osmosis is often used.
Other terms used on the label about the source,
such as glacier water or mountain water," are
not regulated standards of identity and may not
indicate that the water is necessarily from a
pristine area
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Is it safe?
Most bottled water appears to be safe. (NRDC
independent testing of 1000 bottles)
EPA sets standards for tap water provided by
public water systems the Food and Drug
Administration sets bottled water standards
based on EPA's tap water standards
Most bottled water is treated more than tap
water however, some is treated less or not
treated at all .
About 22 percent of the brands tested by NRDC
contained, in at least one sample, some chemical
contaminant
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PET
polyethylene terephthalate (PET) bottles
phthalates
known to disrupt testosterone and other hormones,
can leach into bottled water overtime.
One study found that water that had been stored
for 10 weeks in plastic bottles contained
phthalates, suggesting that the chemicals could
be coming from the bottle, the plastic cap or the
liner
It also appears possible that some as-yet
unidentified chemicals in plastics have the
potential to interfere with estrogen and other
reproductive hormones
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Antimony
Royal Society of Chemistry Publication
The study stressed that amounts of antimony were
well below official recommended levels. But it
also discovered that the levels almost doubled
when the bottles were stored for three months
The study collected 48 brands of water in PET
bottles from its source in the ground at a German
bottling plant. The water had 4 ppt of antimony
before being bottled, the contents of a new
bottle had 360 ppt and one opened three months
later had 700 ppt.
The U.S. EPA has established 6.0 parts per
billion (ppb) as a safe level
The health effects of antimony ingestion are not
well known
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Where are all the old bottles?
88 of water bottles are not recycled
In 2005, 2 million tons of plastic water bottles
were not recycled
In 2006, 2 billion half-liter bottles of water
were shipped to U.S. ports
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