2) Three major processes that occur in natural water purification and three contaminants that the process removes are: evaporation followed by condensation, which removes most dissolved substances, then bacteria converts dissolved organic contaminants into a few simple compounds, and lastly, filtration through sand and gravel removes most suspended matter.
3) The property of aluminum hydroxide that's related to the process of flocculation is its sticky, jelly texture that traps particles.
4) Calcium oxide is sometimes added to municipal water supplies in the last stage of water treatment because it neutralizes acidic water and, as a result, raises the pH to a proper level.
5) 1 ppm of fluoride is added in the last stage of water treatment because it still reduces tooth decay.
6) Advantages of chlorinated drinking water compared to untreated water is that it saves lives by controlling water-born diseases.
7) There are also disadvantages to using chlorination in water treatment because of chloroform, which is a type of THM, a carcinogen (causes cancer).
8) Water from a clear mountain stream may require chlorination because the water was unsafe for drinking.
9) Two alternatives to chlorification in municipal water treatment are charcoal adsorbtion or sand filtration.
18) If water evaporation suddenly stopped the entire hydrologic system would be destroyed.
19) The hydrologic system would be different if water didn't exist in three states because all three stages, liquid solid and vapor, all would not happen.
20) The EPA limits the concentration of THMs to 80 ppb from municipal water supplies because they can cause diseases.
21) The various processes used in water filtration compared to natural purification of water are similar because they contain the same steps, like sand filtration.
22) a) one day - .002 g
b) one week - .014 g
c) one year - .728 g
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