Contaminants in Ground Water
This presentation is the property of its rightful owner.
Sponsored Links
1 / 7

Contaminants in Ground Water PowerPoint PPT Presentation


  • 55 Views
  • Uploaded on
  • Presentation posted in: General

Contaminants in Ground Water. Organic: • Chlorinated solvents • Pesticides • BTX component of gasoline • MTBE component of gasoline Inorganic: • Nitrates (animal waste, fertilizers, atmospheric deposition, sewage; form from oxidation of, e.g., NH 3 )

Download Presentation

Contaminants in Ground Water

An Image/Link below is provided (as is) to download presentation

Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author.While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server.


- - - - - - - - - - - - - - - - - - - - - - - - - - E N D - - - - - - - - - - - - - - - - - - - - - - - - - -

Presentation Transcript


Contaminants in ground water

Contaminants in Ground Water

Organic:

• Chlorinated solvents

• Pesticides

• BTX component of gasoline

• MTBE component of gasoline

Inorganic:

• Nitrates (animal waste, fertilizers, atmospheric deposition, sewage; form from oxidation of, e.g., NH3)

• Phosphates (detergents, fertilizers, sewage)

Biological:

• Bacteria (e.g., E. coli)


Contaminants in ground water

Treatment of Contaminated Water

For organic contamination:

1) Pump and treat

• Activated charcoal

2) In situ methods

• Reduction of chloroorganics by Fe(s)

3) Bioremediation (anaerobic or aerobic)

• Alkylated benzenes from gasoline (aerobic)

•PCE, TCE (anaerobic)

For nitrates:

• Denitrifying bacteria in presence of reducing carbon compound (e.g., MeOH) (Expensive)

For phosphates:

• Precipitate as Ca3(PO4)2, Ca5(PO4)3OH by adding Ca(OH)2


Contaminants in ground water

Methods of Disinfection of Water

1) Chlorination

• HOCl

• NaOCl or Ca(OCl)2

Problem: Formation of THMs (trihalomethanes)

2) Ozone

• Generate on site via electrical discharge

3) Chlorine dioxide (ClO2·) -- oxidizes organic matter

• Must generate on site via oxidation of Na2ClO2-

4) Ultraviolet light (Hg vapor lamps, UV-C)

5) Biofiltration


Contaminants in ground water

Typical Method for Treating Water for Household Use

1) Settling of suspended material

2) Aeration (aids oxidation of readily oxidized organic matter)

3) Preliminary chlorine treatment (remove bacteria, other organic material via oxidation)

4) Remove particulate matter by causing it to coagulate (via flocculating agent, e.g. Al2(SO4)3)

5) Add lime to control pH and aid flocculation

6) Final chlorine treatment

7) Can also use activated charcoal, add fluoride source for dental health (e.g. Na2SiF6)


Contaminants in ground water

Sewage Treatment

Primary treatment:

• Separate large particles via mechanical screening, then settling

• Solid thus separated is then disposed of

Secondary treatment:

• Biological treatment -- aerobic bacteria

• Sludge from this stage can be used as fertilizer. Potential problems:

> Pathogens

> Undecomposed toxic organic compounds

> Toxic heavy metals

• Can use lagoons instead of treatment

Tertiary treatment:

• Can include some or all of a variety of processes (on next viewgraph)


Contaminants in ground water

Techniques for Tertiary Treatment of Water

1) Removing colloidal organic matter by addition of Al2(SO4)3, filtering

2) Removal of Phosphate (via precipitation as Ca(PO4)3OH by addition of Ca(OH)2

3) Use of activated charcoal to remove dissolved organic compounds

4) Removal of heavy metal ions via precipitation of their (insoluble) hydroxide or sulfide salts (by adding OH- or S-)

5) Removal of iron by aerating at high pH

6) Reverse osmosis

7) Electrodialysis (like rev. osmosis, but use electric current to draw ions out of solution)

8) Ion Exchange (replace H+, OH- with dissolved species)

9) Partial freezing (pure water freezes out)


  • Login