Lecture 23 Home Water and Bottled by 0ww0RNy


									Drinking Water Treatment

          Surface Water


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.
          Initial Treatment

           90 – 99% viruses

screens   Sedimentation       Filtration
        Final Treatment

     Disinfection and Fluoridation

Chlorine Gas         Sodium Fluoride (NaF)
Hypochlorite         Sodium fluorosilicate
Home Water Quality
Florida’s Drinking Water
Confined Aquifer

     Pumped well

                   Plio-pliestocene (sands)

                   Miocene (clays)
                   Eocene Limestone

Potential Problems:
        • Hardness
        • Iron + manganese
        • Sulfur (sulfides)
        • Salt/Salinity
        • Pathogens (bacteria/viruses)
        • Metals
        • Organics
     Can be toxic or nuisance contaminants
Nuisance Contamination

                                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
      Hardness Treatment
Water softeners      35 gal/day/person

        Hard water


                                         Soft water
    Cation Exchange Resins

Ca2+, Mg2+
                    Na   Na                      Na
               Na                           Na
              Na           Na        Mg2+           Na
                            Na      Na               Na
             Na Neg. Charge         Na Neg charge
               Na              Na     Na
                    Na Na Na                 Na Na

                                                       4 Na+
Water Hardness and Soap Scum


                                      Oil drop

SO4-                           SO4-

           Sodium dodecylsulfate

             Extremely soluble

  Na+      -SO

Ca+2   +

             Less soluble
Harmful Contaminants
  Drinking Water
    Potable Water

Free of
• Pathogens
• Harmful Minerals/Metals
• Organic Chemicals

Acute Toxicity      Within 48 hours

Chronic Toxicity   • Long term
                   • Frequent exposure
                   • Small amounts
                   • Pb, As, Hg
     Heavy Metals

Metal          MCL (mg/L)
Lead                0.05
Silver              0.05
Mercury             0.0002

MCL = Maximum Contaminant Level
            Other Metals
Trace Metals      required metabolic catalysts

    Cobalt     Toxicity =   > 40 x requirement

          NO3-          MCL = 10 mg/L

          Organic Waste Disposal

            NO3-                         NO2-
Methemoglobin is a form of hemoglobin that does not bind oxygen.

     Infants under 6 months are particularly susceptible

Coliform bacteria          MCL < 1 bacterium / 100 ml
(fecal contamination)

Non-coliform bacteria MCL < 200 bacteria / 100 ml

Single required test: Sanitary Quality

Suggested test: mineral/metal content

Chlorination      Most common


UV Radiation
Ultraviolet Radiation

    Scrambled DNA
Home Treatment
                    Water Filters

                                    Ceramic Filtration
                                    Ion Exchange

3-stage water filtration
 Ion Exchange Filters


Pb2+, Hg2+
                       Na   Na                          Na
                  Na                               Na
                 Na           Na            Pb2+           Na
                               Na          Na               Na
                Na Neg. Charge             Na Neg charge
                  Na              Na         Na
                       Na Na Na                     Na Na

             Finite Capacity
                                                              4 Na+
                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
       Activated Carbon
       Activation by heating

Extremely porous with high surface area: 500 m2/g
            Activated Carbon

Particle size removal > 0.5 microns (bacteria, fungi)
            Activated Carbon

Absorption: spontaneous movement of primarily
            organic contaminants from water to
            carbon matrix.

Pesticides, volatile organics
Carbon Filter Removal
    2,4-D                  MTBE
    2.4.5-TP (Silvex)      O-Dichlorobenzene
    Alachlor               P-Dichlorobenzene
    Atrazine               Styrene
    Carbofuran             Tetrachloroethene
    Chlordane              Toluene
    Endrin                 Trichloroethene
    Heptachlor Epoxide
    Lindane                Antidepressants
    Methoxychlor           Steroids/Hormones
    Simazine               Prednisone,
    Toxaphene              Prednisolone,
    Benzene                Progesterone,
    Carbon Tetrachloride   Testosterone,
    Chlorobenzene          Cortisol/Hydrocortisone
Reverse Osmosis
  Extremely Effective
              Net movement of water

                                       Salt molecule
of water
              No salts

               Membrane permeable to
                    Water only
                 Reverse Osmosis

Purified water

       Membrane permeable to
            Water only

                               Contaminants to drain

   Energy intensive
   Saline/contaminant by-product
   inefficient: high volume reject water
        Activated Carbon Filters

     Chlorine      Tastes    Organics

         Ion Exchange Resins
          Removal of charged
          Contaminants (metals)

           Reverse Osmosis
Sediments, viruses, bacteria, dissolved solutes
What about Bottled Water?
        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
             What’s 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
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 water’s 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
                   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
            polyethylene terephthalate (PET) bottles

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
            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
            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

To top