What is the chemistry behind acid mine drainage?
Acid mine drainage (AMD) is the runoff produced when water comes in contact with exposed rocks containing sulfur-bearing minerals that react with water and air to form sulfuric acid and dissolved iron. This acidic run-off dissolves heavy metals including copper, lead, and mercury which pollute ground and surface water.
What does acid mine drainage do to water?
The resulting waters become rich in sulfuric acid and dissolved iron. As the iron settles out of the water, it can form red, orange, or yellow sediments in the bottom of streams. The acidic runoff further dissolves heavy metals such as copper, lead, mercury into groundwater or surface water.
Does acid mine drainage increase pH?
In this application, a slurry of lime is dispersed into a tank containing acid mine drainage and recycled sludge to increase water pH to about 9. At this pH, most toxic metals become insoluble and precipitate, aided by the presence of recycled sludge.
Which bacteria is responsible for acid mine drainage?
A. ferrooxidans is a chemolithoautotrophic bacteria, due to the oligotrophic nature (low dissolved organic carbon concentration) of acidic environments, and their lack of illumination for phototrophy. Even when in vadose conditions, A. ferrooxidans can survive, if the rock retains moisture and the mine is aerated.
How does acid mine water threaten the environment?
The low pH value of the discharge mine water results in the further dissolution of minerals and release of toxic metals, when it allowed getting discharge into other water bodies. This acidity and high toxic metals concentration are harmful to the vegetation, aquatic life and wild life.
Is acid mine drainage caused by microbes?
For many mines, including coal mines, the drainage is also highly acidic. This acid mine drainage (AMD) is generated when metal sulfide minerals, mainly pyrite, are oxidized in the presence of water and accelerated by the action of chemolithotrophic bacteria.
What is the pH of Acidophile?
2.2. Acidophiles are organisms that grow at an optimum pH below 3–4.
How does acid affect bacterial growth?
Moderate changes in pH modify the ionization of amino-acid functional groups and disrupt hydrogen bonding, which, in turn, promotes changes in the folding of the molecule, promoting denaturation and destroying activity. The optimum growth pH is the most favorable pH for the growth of an organism.
What are acidophilic microbes?
Acidophilic microorganisms are an ecologically and economically important group, which occur in acidic natural (solfataric fields, sulphuric pools) and man-made (eg. Acid mine drainage) environments. Acidophiles possess networked cellular adaptations for regulating intracellular pH.
Why does pH affect bacterial growth?