Filtration Systems Flashcards
Which is the filtration flow rate through a manganese Greensand pressure filter at 100 C ?
a. 1 to 2 gpm/ft2
b. 2 to 3 gpm/ft2
c. 3 to 5 gpm/ft2
d. 5 to 8 gpm/ft2
b. 2 to 3 gpm/ft2
When a filter is ripening, ________.
a. it is need of a backwash.
b. turbidity is just starting to break through.
c. it is becoming more efficient in particle removal.
d. it is beginning to grow algae in the filter bed, walls, and troughs.
c. It is becoming more efficient in particle removal.
Virgin Greensand can be regenerated by soaking the filter bed for several hours in a solution of chlorine containing _______.
a. 50 mg/L Cl2
b. 75 mg/L Cl2
c. 100 mg/L Cl2
d. 200 mg/L Cl2
c. 100 mg/L
Which role does the action of straining of suspended particles play during filtration?
a. Minor
b. Fair
c. Good
d. Major
a. Minor
The turbidity of settlled water before it is applied to the filters, (Post-Sedimentation-Process) should always be kept below?
a. 1 to 2 ntu.
b. 2 to 4 ntu.
c. 5 ntu.
d. 8 to 10 ntu.
a. 1 to 2 ntu
Which is the best process for the removal of turbidity?
a. Anion exchange
b. Coagulation, flocculation, seimentation, and filtration
c. Chemical oxidation
d. Granular activated carbon
b. Coagulation, Flocculation, Sedimentation, Filtration
If filter run times between backwashes are long, for example one week, because high quality (low turbidity) water is being applied to the filters, which problem could still arise?
a. Mudball formation
b. Air binding and formation of mudballs
c. Extended backwashing due to media becoming too compacted
d. Floc breakthrough
d. Floc breakthrough
Gravel displacement in a filter bed from backwash rates with too high of a velocity could eventually cause?
a. compaction of the filter media.
b. loss of media into the backwash troughs.
c. a sand boil.
d. bed shrinkage.
c. a sand-boil.
Virgin Greensand __________.
a. does not require regeneration.
b. requires regeneration with potassium permanganate (1 hour soak with 60 grams KMnO4/ft3).
c. requires regeneration with manganese dioxide (2 hour soak with 25% by weight solution of MnO2).
d. requires regeneration with manganese hydroxide (4 hour soak with 200 grams Mn(OH)2/ft3).
b. requires regeneration with potassium permanganate (1 hour soak with 60 grams KMnO4/ft3)
Which conventional treatment step is eliminated by direct filtration?
a. Oxidation
b. Aeration
c. Flocculation
d. Sedimentation
d. Sedimentation
If crustaceans have clogged the water treatment plant’s filters, which is the most probable solution?
a. Shut down the filters and physically remove them.
b. Shut down one filter at a time and drain; once the crustaceans have died, physically remove them and then repeat process on the other filters.
c. Backwash filters using a very high concentration of ozone in the water.
d. Use a disinfectant that targets the specific organisms in question.
d. Use a disinfectant that targets the specific organisms in question.
Which organism can escape coagulation and thus pass through a granular filter?
a. Giardia
b. Entamoeba
c. Cryptosporidium
d. Naegleria
c. Cryptosporidium
Reverse Osmosis membranes will compact faster with?
a. higher iron content.
b. higher chlorine contact.
c. higher pressure.
d. higher pH.
c. higher Pressure
Which would immediately occur if newly installed manganese greensand was not skimmed of the fines after backwashing and stratification steps were completed?
a. Uneven flow through the bed
b. Cracks would develop in the bed
c. Medball formation
d. Shorter filter runs
d. Shorter filter runs
When a filter is operated at normal flow rates, its ability to trap flocculated particles in suspension is a function of _______.
a. effective size multiplied by uniformity coefficient.
b. effective size multiplied by uniformity coefficient divided by media size.
c. media depth and media size.
d. media depth and uniformity coefficient.
c. Media depth and Media size.
Which is the best solution if iron bacteria are causing corrosion problems in the filters?
a. Protect the metal parts of the filters by adding zinc orthophosphate.
b. Optimize the settling process.
c. Superchlorinate
d. Add lime at 50 mg/L to one filter at a time.
c. Superchlorinate
A conventional water treatment plant with dual media filters has very cold water in the winter and very warm water in the summer. Which should the operator do to compensate for this temperature change?
a. Use more coagulants in the summer per million gallons.
b. Sustain the same bed expansion without media loss by reducing or increasing backwash flow rate.
c. Increase summer bed expansion and inrease winter backwash flow rates.
d. Increase bed expansion in the winter compared to summer in order to remove turbidity.
b. Sustain the same bed expansion without media loss by reducing or increasing backwash flow rate.
How are Reverse Osmosis membranes cleaned once they become fouled?
a. They are soaked in high purity industrial soap for at least 24 hours.
b. They are cleaned with an acid wash.
c. They are cleaned with an acid, then with an industrial soap for 24 hours.
d. They are cleaned first with a high purity industrial soap and then soaked in an acid solution for 3 days.
b. They are cleaned with an acid wash.
Which membrane process is use to treat brackish water or seawater?
a. Microfiltration
b. Nanofiltration
c. Reverse osmosis
d. Ultrafiltration
c. Reverse Osmosis
The amount of reject water from a reverse osmosis unit is dependent on the number of stages in which the membranes are configured and the __________.
a. feed pressure.
b. amount of cations.
c. amount of cations and anions.
d. pH of the water.
a. feed pressure.
Manganese greensand filters can be regenerated by using ____________.
a. a surface wash and an air-water backwash.
b. brine water during backwashing.
c. potassium permanganate solution during backwashing.
d. first a brine solution during the first backwashing cycle followed by potassium permanganate solution for the second backwash cycle.
c. Potassium Permanganate solution during backwashing.
Which material is manganese greensand and which is the coating?
a. Quartz sand coated with manganese hydroxide [Mn(OH)2]
b. Garnet sand coated with manganese dioxide [MnO2]
c. Ilmenite sand coated with manganese hydroxide
d. Glauconite sand coated with manganese dioxide
d. Glaucoonite sand coated with manganese dioxide.
Which is the layer of solids and biological growth that forms on the top of a slow sand filter?
a. Biosolids film
b. Bio-carbonated scale layer
c. Schmutzdecke
d. Saprophytic layer
c. Schmutzdecke
Which filter type utilizes pressure for filtration?
a. Diatomaceous earth filter
b. High-rate filter
c. Rapid sand filter
d. Deep-bed monomedium filter
a. Diatomaceous earth filter
Slow sand filter runs can be as long as ________.
a. 3 months.
b. 4 months.
c. 6 months.
d. 1 year.
c. 6 months.
Gravity rapid sand filters can have head losses as high as ________.
a. 6 ft.
b. 8 ft.
c. 10 ft.
d. 12 ft.
b. 8 feet.
Which group of algae is usually associated with “blinding filters”?
a. Green algae
b. Blue-green algae
c. Pigmented flagellates
d. Diatoms
d. Diatoms
Depending on water temperature, which is the typical backwashing flow rate for a manganese Greensand filter bed?
a. 7 to 8 gpm/ft2
b. 8 to 10 gpm/ft2
c. 10 to 12 gpm/ft2
d. 12 to 14 gpm/ft2
c. 10 to 12 gpm/ft2
The typical filter run time for a high-rate filter system is ______.
a. 8 hours.
b. 24 hours.
c. 48 hours.
d. 72 hours.
b. 24 hours.
Below are four membrane technologies. Which is the correct sequence from larger to smaller pore sizes?
a. Microfiltration, reverse osmosis, ultrafiltration, nanofiltration
b. Microfiltration, ultrafiltration, nanofiltration, reverse osmosis
c. Reverse osmosis, ultrafiltration, microfiltration, nanofiltration
d. Ultrafiltration, microfiltration, reverse osmosis, nanofiltration
b. Microfiltration, Ultrafiltration, Nanofiltration, Reverse Osmosis
Optimum water quality in manganese greensand filters can be attained by backwashing and regenerating the greensand before the effluent manganese level goes above _______.
a. 0.02 mg/L.
b. 0.05 mg/L.
c. 0.10 mg/L.
d. 0.12 mg/L.
b. 0.05 mg/L.
Granular media filters should remove suspende solids including iron and manganese greater than ______.
a. 10 µm.
b. 15 µm.
c. 20 µm.
d. 25 µm.
a. 10 µm.
Which filter media material is given an abrasive number?
a. Garnet
b. Activated carbon
c. Sand
d. Greensand
b. Activated Carbon
Which is the typical filtration rate for high-rate filters?
a. 0.5 to 2.0 gpm/ft2
b. 3.0 to 12.0 gpm/ft2
c. 15.0 to 20.0 gpm/ft2
d. >25.0 gpm/ft2
b. 3.0 to 12.0 gpm/ft2
After backwashing and stratifying newly installed manganese greensand, approximately which percentage of the greensand should be skimmed off?
a. 3%
b. 5%
c. 8 to 9%
d. 12 to 15%
c. 8 to 9%
The media in a slow sand filter is ________.
a. stratified fine.
b. stratified medium.
c. stratified coarse.
d. unstratified.
d. Unstratified.
Clumping of filter media or Ion exchange resin is caused by ___________.
a. electrostatic charges.
b. media or resin breakdown, respectively.
c. temperature and pH of the clay in the water.
d. iron and manganese oxides reacting with the coagulant.
a. electrostatic charges.
Backwash water is what percentage of the totaled filtered water in a conventional rapid sand filter system?
a. 1%
b. 2 to 4%
c. 5 to 6%
d. 6 to 10%
b. 2 to 4%
Why does anthracite always stay on top of sand during backwashing?
a. Because the grain sizes are smaller
b. Because it is lighter and less dense
c. Because of its shape
d. Because of its porosity
b. Because it is lighter and less dense
The length of filter runs for manganese greensand filters can be increased by _________.
a. adding a high molecular weight polymer filter aid.
b. keeping the pH above 9.0 and lowering it after filtration.
c. keeping the pH below 7.3 and raising it after filtration.
d. adding a layer of anthracite above the greensand.
d. adding a layer of anthracite above the greensand.
Which is the most common type of valves used on filters?
a. Gate
b. Globe
c. Butterfly
d. Ball
c. Butterfly
Manganese greensand removes manganese and iron by a combination of ________.
a. adsorption and oxidation.
b. adsorption and absorption.
c. adsorption and precipitate screening.
d. absorption and precipitate screening.
a. adsorption and oxidation.
Which is the best means to remove Giardia Lamblia?
a. Coagulation, flocculation, and filtration
b. Ion exchange
c. Powdered activated carbon
d. Activated alumina
a. Coagulation, flocculation, and filtration