02/05/2026
some DAF and sedimentation questions ?
chemist : JJimmy Distributreatment
The main difference between dissolved air flotation (DAF) and sedimentation is that:
A. DAF removes only dissolved solids, sedimentation removes suspended solids
B. DAF uses microbubbles to float solids, sedimentation relies on gravity to settle solids
C. DAF does not require chemicals, sedimentation always requires chemicals
D. DAF is only for drinking water, sedimentation is only for wastewater
Answer: B
DAF is preferred over simple sedimentation when wastewater contains mainly:
A. Heavy grit and sand
B. Dense metal hydroxide sludge
C. Low‑density solids, fats, oils, and grease
D. Only dissolved salts
Answer: C
In a DAF unit, solids are primarily removed from the:
A. Bottom, by gravity sludge scrapers
B. Surface, by skimming of floated sludge
C. Middle of the tank, by filters
D. Inlet, by strainers
Answer: B
Which of the following is the BEST application for DAF instead of sedimentation?
A. Grit removal before primary treatment
B. Thickening dense primary sludge
C. Treating high FOG (fat, oil, grease) food‑processing wastewater
D. Removing heavy sand from stormwater
Answer: C
Conventional sedimentation clarifiers are more appropriate than DAF primarily when:
A. Space is very limited and land is expensive
B. Flow contains mainly heavy, settleable inorganic solids
C. Wastewater is rich in emulsified oils and light organics
D. You need very fast solids separation in minutes
Answer: B
Which statement about algae‑laden surface waters is MOST accurate?
A. Sedimentation is usually better than DAF
B. DAF is often better than conventional gravity settling for algae removal
C. Neither DAF nor sedimentation can remove algae
D. DAF is only used after sedimentation
Answer: B
Compared with primary sedimentation, DAF typically achieves:
A. Lower removal of suspended solids but thicker sludge
B. Similar removal of suspended solids and similar sludge concentration
C. Higher removal of suspended solids and thicker float sludge
D. Lower removal of suspended solids and thinner sludge
Answer: C
Regarding tank size and land area, DAF units generally require:
A. Much more area than sedimentation basins
B. Similar area to large sedimentation tanks
C. Less area because of shorter detention time and higher rate
D. No tank at all, only pipes
Answer: C
Which statement about treatment time is correct?
A. DAF separation occurs in minutes; sedimentation often requires longer detention times
B. Sedimentation is faster than DAF
C. Both processes always require several days
D. DAF and sedimentation always have identical detention time
Answer: A
Compared to sedimentation, DAF usually has:
A. Lower energy use and simpler operation
B. Higher energy use and more complex operation
C. No moving parts and no energy consumption
D. Exactly the same energy demand and complexity
Answer: B
Why is energy consumption typically higher for DAF than for sedimentation?
A. DAF requires heating of wastewater
B. DAF uses recycle pumps and pressurized air saturation
C. Sedimentation requires continuous aeration
D. DAF operates only by gravity
Answer: B
The PRIMARY advantage of DAF over simple sedimentation is its ability to:
A. Remove only dissolved salts
B. Remove low‑density solids and FOG that do not settle well
C. Eliminate the need for chemicals
D. Completely disinfect the water
Answer: B
n a conventional sedimentation tank, solids are removed mainly by:
A. Air flotation and skimming
B. Membrane filtration
C. Gravity settling and sludge scrapers at the bottom
D. Evaporation
Answer: C
Which process is generally simpler to operate and maintain?
A. DAF, because it has bubble generation equipment
B. Sedimentation, because it mainly uses gravity and slower hydraulics
C. Both are equal in complexity
D. DAF, because it uses no chemicals
Answer: B
A plant with limited land but very high FOG loading is MOST likely to choose:
A. Conventional sedimentation only
B. DAF as primary clarification
C. No primary treatment
D. Grit chamber plus sedimentation only
Answer: B
Which statement BEST summarizes DAF vs sedimentation?
A. DAF trades higher energy and complexity for faster, higher‑efficiency removal of light solids and FOG in a smaller footprint
B. DAF is always cheaper and simpler than sedimentation
C. Sedimentation is always better than DAF for any wastewater
D. Both processes are identical except for the tank shape
Answer: A
Water operations · Experience: City of Monterey Park · Education: Alexandria University · Location: Anaheim · 500+ connections on LinkedIn. View Gamaleldin Abdalla’s profile on LinkedIn, a professional community of 1 billion members.
