Water treatment Flashcards
What is the process of clarification?
coagulants are added to percipitate out small particles and microorganisms (occurs before filtration
What does chlorine dissolve in water to form?
hypochlorous and hydrochloric acids
How does chlorine kill bacteria and organisms?
It forms hypochlorous and hypochloric acids which denature proteins
What is the most common chlorine source
sodium hypchrorite (NaOCl)
Name two gases commonly found dissolved in water?
O2 and CO2
What are 3 metal ions found in water?
Ca2+, Mg2+, and Na+
Name a significant drawback of using chlorine that results from water containing chlroine being exposed to sunlight
chlorine forms radicals when irradiated
What does air stripping remove from water?
gaseous or low boiling points substances (like volatile organic chemicals (VOCs))
How does air stipping work?(describe the process)
water is sprayed down a tower against an air updraft
What is an advantage of air stripping?
inexpensive
Name 3 drawbacks of air stripping
- pollutes the air (dissolved gases and low boiling point substances are now realeased into the air)
- doesnt kill microorganisms
- not long lasting (VOCs can redissolve)
How is ozone prepared?
it is prepared by passing high voltage discharge through dry air
Ozone is ____ O molecules bonded together
three
Name an advantage of ozonation
there is no chemicals left in the water
Name 3 drawbacks of ozonation
- more expensive than chlorination
- ozone cannot be stored and transported so it must be made on site
- ozone is an oxidizing agent so it isnt very effective on susbtances that prefer reduction
How does UV radiation kill microorganisms?
damages the DNA of the microorganism (the energy breaks secondary and primary structures)
What are two advantages ti UV radiation?
- no chemicals or additives left in the water
- very reliable
Name two disadvantages of UV radiation
- microorganisms are killed but because there is no chemical additives they can be reintroduced
- the chamber that the water is treated in must be transparent to UV
Hardness is a measure of the “____” content in water
____ ____
mineral
dissolved ions
What is the dominant contributer to water hardness in freshwater systems?
Ca2+
What is the result of the formation of “scum”?
Soap will not lather properly
How is soap scum formed
the hydrophilic head of water is attracted to the Ca2+. The combination of the soap and Ca2+ in insoluble in water and so the soap does not lather
What is “scale”?
deposits of CaCO3
The dissolution of CaCO3 is ____ (Endothermic/exothermic)
exothermic
What is the result of the dissolution of CaCO3 being exothermic
Heat causes the CaCO3 to precipitate
Are metal carbonates soluble in water? Are carbonate soluble in water?
Metal carbonates are soluble in water and carbonates are insoluble in water
A ____ agent can be used to prevent scum
sequestering
How do sequestering agents prevent soap scum?
the sequestering agent isolates/surrounds the cation
Name 3 sequestering agents
TPP 5-
EDTA 4-
Hydroxycarboxalates
Name 2 non chemical additive water softening methods
- purification by distallation
- purification by ion exhange
