WATER TREATMENT 2026 END OF COURSE QUESTIONS
AND ANSWERS MARKED A+
✔✔What are the objectives of public drinking water treatment - ✔✔1. Provide potable
water for safe human consumption
2. To provide aesthetically acceptable water
- Turbidity
- Color
- Taste
-Odors
✔✔outline the sources of groundwater vs. sources of surface water - ✔✔Groundwater-
-Deep wells (more dissolved materials)
-Shallow wells
Surface Water
-Rivers
-Lakes
-Reservoirs
~sometimes springs
✔✔What is the main process of surface water treatment? Why? - ✔✔Clarification-to
remove suspended particles (turbidity) & color
✔✔What are the main steps during the clarification process - ✔✔Coagulation
Sedimentation
Filtration
Disinfection
✔✔What are the main steps in surface water treatment? Explain each process. -
✔✔Sources -> Rapid mix-> Flocculation-> Sedimentation->sludge out->
Filtration -> Disinfection-> Distribution system
Rapid mix-Provides a dispersion of chemicals into water by mechanical & & hydraulic
mixing
Flocculation- Agitation of chemically treated water to induce coagulation
Sedimentation- particles removed from water by gravity
Filtration- Designed to remove particles that are too small to be removed by
sedimentation
Disinfection- Goals include;
1. remove pathogens by killing them
, 2. provide chorinal residue
✔✔What is the main process used in groundwater treatment? - ✔✔The main process
for groundwater treatment is precipitation to remove hardness & other minerals
✔✔What are the steps for the groundwater treatment process? Explain each step. -
✔✔Supply-> Rapid Mix->Flocculation-> Sedimentation-> sludge out-> Recarbonation
(CO2)-> Filtration-> Disinfection-> Distribution system
Rapid mix-Provides a dispersion of chemicals into water by mechanical & & hydraulic
mixing
Flocculation- Agitation of chemically treated water to induce coagulation
Sedimentation- particles removed from water by gravity
Recarbonation- Goal is to lower pH of softened water
-pH>11 used to precipitate Mg (~or remove)
Filtration- Designed to remove particles that are too small to be removed by
sedimentation
Disinfection- Goals include;
1. remove pathogens by killing them
2. provide chorinal residue
✔✔Flocculation Mechanism - ✔✔Flocs are grouped colloids :) Main process for
removing turbidity
Growth & size of floc depends on
1. Inter-molecular forces
2. Physical action
*Paddles rotate slowly to cause collision of particles- causing growth of flocs to sizes
easily removed by sedimentation
✔✔Types of coagulants used during flocculation processes - ✔✔Alum- Al2(SO4)3`14
H2O
Ferric Chloride- FeCl3
Ferric Sulfate-FeSO4
Polyelectrolytes
✔✔Sedimentation/Settling Mechanisms - ✔✔Floc formation during flocculation &
coagulation are removed using settling
-to achieve settling - flocs passed to settling basins
-Low floc with little turbulence
-3 hr retention time for floc to settle
AND ANSWERS MARKED A+
✔✔What are the objectives of public drinking water treatment - ✔✔1. Provide potable
water for safe human consumption
2. To provide aesthetically acceptable water
- Turbidity
- Color
- Taste
-Odors
✔✔outline the sources of groundwater vs. sources of surface water - ✔✔Groundwater-
-Deep wells (more dissolved materials)
-Shallow wells
Surface Water
-Rivers
-Lakes
-Reservoirs
~sometimes springs
✔✔What is the main process of surface water treatment? Why? - ✔✔Clarification-to
remove suspended particles (turbidity) & color
✔✔What are the main steps during the clarification process - ✔✔Coagulation
Sedimentation
Filtration
Disinfection
✔✔What are the main steps in surface water treatment? Explain each process. -
✔✔Sources -> Rapid mix-> Flocculation-> Sedimentation->sludge out->
Filtration -> Disinfection-> Distribution system
Rapid mix-Provides a dispersion of chemicals into water by mechanical & & hydraulic
mixing
Flocculation- Agitation of chemically treated water to induce coagulation
Sedimentation- particles removed from water by gravity
Filtration- Designed to remove particles that are too small to be removed by
sedimentation
Disinfection- Goals include;
1. remove pathogens by killing them
, 2. provide chorinal residue
✔✔What is the main process used in groundwater treatment? - ✔✔The main process
for groundwater treatment is precipitation to remove hardness & other minerals
✔✔What are the steps for the groundwater treatment process? Explain each step. -
✔✔Supply-> Rapid Mix->Flocculation-> Sedimentation-> sludge out-> Recarbonation
(CO2)-> Filtration-> Disinfection-> Distribution system
Rapid mix-Provides a dispersion of chemicals into water by mechanical & & hydraulic
mixing
Flocculation- Agitation of chemically treated water to induce coagulation
Sedimentation- particles removed from water by gravity
Recarbonation- Goal is to lower pH of softened water
-pH>11 used to precipitate Mg (~or remove)
Filtration- Designed to remove particles that are too small to be removed by
sedimentation
Disinfection- Goals include;
1. remove pathogens by killing them
2. provide chorinal residue
✔✔Flocculation Mechanism - ✔✔Flocs are grouped colloids :) Main process for
removing turbidity
Growth & size of floc depends on
1. Inter-molecular forces
2. Physical action
*Paddles rotate slowly to cause collision of particles- causing growth of flocs to sizes
easily removed by sedimentation
✔✔Types of coagulants used during flocculation processes - ✔✔Alum- Al2(SO4)3`14
H2O
Ferric Chloride- FeCl3
Ferric Sulfate-FeSO4
Polyelectrolytes
✔✔Sedimentation/Settling Mechanisms - ✔✔Floc formation during flocculation &
coagulation are removed using settling
-to achieve settling - flocs passed to settling basins
-Low floc with little turbulence
-3 hr retention time for floc to settle
