Homework 7/1/13

1.

2. 

a. Evaporation, followed by condensation, which removes almost all dissolved substances. 

b. Bacterial action converts dissolved organic contaminants into a few simple compounds. 

c. Filtration through sand and gravel removes nearly all suspended matter. 

3. Floculation is the process where the alum and slaked lime react to form aluminum hydroxide, which is a sticky, jellylike material that traps and removes the suspended particles. 

4. Calcium Oxide, a basic substance, may be added to neutralize such acidic water, thus raising its pH to a proper level. 

5. About 1 ppm of fluoride is added in order to reduce tooth decay. 

6. The advantages of chlorinated drinking water are tremendous. Adding chlorine to water has helped save countless lives by controlling water borne diseases. It also kills disease-producing microorganisms in water. 

7. Yes there is a disadvantage to using chlorination in water treatment. Sometimes, chlorine in water can react with organic compounds produced by decomposing animal and plant matter to form substances that, if in sufficiently high concentrations, can be harmful to human health. An example of such substances is THMs. 

8. Water from a clear mountain stream may require chlorination to make it safe for drinking because the stream might have bacteria or different substances that are not safe and can give people diseases. 

9. An alternative to the use of chlorination in municipal water treatment is using an activated charcoal filter which can remove most organic compounds from water, like THMs. Another alternative is eliminating chlorine and use ozone or ultraviolet light to disinfect the water. 

18. If evaporation stopped, so would condensation and precipitation. Without those crucial steps, the whole cycle would just stop. 

19. If this were not true, than the hydrologic cycle would not include steps like evaporation, which would make water a gas. Therefore, the cycle would not exist because it would not be able to "cycle." 

20. EPA only limits the concentration of THMs instead of eliminating it, because there are alternatives which can eliminate THM health risks. 

21. The processes of evaporation and condensation are similar to distillation. Also, when water passes gravel, sand, and rock, suspended mater are filtered out which is similar to sand filtration. 

22. 

a. 1 ppm fluoride 

b. 7 ppm fluoride

c. 365 ppm fluoride