FLORIDA WASTEWATER FINAL PAPER 2025/2026
QUESTIONS WITH ANSWERS RATED A+
✔✔What is the purpose of aerating the raw wastewater in an aerated grit chamber? -
✔✔To help make the grit settle more efficiently
✔✔What is the purpose of grit washing? - ✔✔To rinse off excess organic material
✔✔Why can grit and sand entering a treatment plant be harmful? - ✔✔It is abrasive and
will wear out pumps
It will take up valuable treatment capacity
✔✔What is the purpose of primary treatment? - ✔✔Seperate the settleable and
floatable solids from the waste stream using physical processes
Lessen the influent solids burden on the secondary clarifier
✔✔What % of settleable solids can a primary clarifier remove? - ✔✔95 - 99% Settleable
solids
✔✔What % of influent TSS can a primary clarifier remove? - ✔✔40 - 60% TSS
✔✔What % of influent BOD can a primary clarifier remove? - ✔✔25 - 50% BOD
✔✔Why should sludge from a primary clarifier be pumped out frequently? - ✔✔To avoid
septic conditions and odors
✔✔What benefit do baffles provide? - ✔✔They reduce velocity and increase detention
time, preventing short circuiting through a tank
✔✔What is the average detention time for a primary clarifier? - ✔✔1 - 2 hours
✔✔Odor complaints are increasing at the WWTP. The operator finds most odors seem
to be coming from the primary clarifiers where bubbles and chunks of solids are found
on the tank surface. What should be done to correct the problem? - ✔✔Increase the
sludge withdrawal rate from the primary clarifier
✔✔What is the purpose of a gravity thickener? - ✔✔Thicken primary sludge and WAS
prior to anaerobic digestion
✔✔Primary clarifiers are NOT efficient at removing what two types of solids? -
✔✔Dissolved and colloidal
, ✔✔What is mixed liquor? - ✔✔A mixture of influent wastewater and RAS
✔✔What effects would differ between coarse bubble diffusers and fine bubble diffusers?
- ✔✔Coarse - Better mixing but inefficient oxygen transfer
Fine - Better oxygen transfer but not good for mixing
✔✔What function do secondary clarifiers provide? - ✔✔Separation of biological solids
from surrounding water
✔✔Which clarifier or settling basin is more likely to have dark grey to black colored
sludge pop-ups and septic odors? (Primary or Secondary) - ✔✔Primary clarifier
✔✔Where does the majority (about 90%) of the settled solids from the secondary
clarifier go? - ✔✔To the influent end of the aeration tank (RAS)
✔✔What is the sludge age of a wastewater with these characteristics?
High SVI
High F/M
Low MLSS
Low MCRT
High oxygen uptake rate - ✔✔Young sludge
✔✔What is one controllable factor you could change to increase a young sludges age?
- ✔✔Decrease the waste rate
✔✔True or False
WAS changes the floc characteristics of the biomass? - ✔✔True
✔✔What microorganisms are predominant in young sludge? - ✔✔Flagellates
Amoeboids
Free swimming ciliates
✔✔What microorganisms are predominant in old sludge? - ✔✔Rotifers
Nematodes
✔✔What is the sludge age of a wastewater with these characteristics?
Low SVI
Low F/M
High MLSS
High MCRT
QUESTIONS WITH ANSWERS RATED A+
✔✔What is the purpose of aerating the raw wastewater in an aerated grit chamber? -
✔✔To help make the grit settle more efficiently
✔✔What is the purpose of grit washing? - ✔✔To rinse off excess organic material
✔✔Why can grit and sand entering a treatment plant be harmful? - ✔✔It is abrasive and
will wear out pumps
It will take up valuable treatment capacity
✔✔What is the purpose of primary treatment? - ✔✔Seperate the settleable and
floatable solids from the waste stream using physical processes
Lessen the influent solids burden on the secondary clarifier
✔✔What % of settleable solids can a primary clarifier remove? - ✔✔95 - 99% Settleable
solids
✔✔What % of influent TSS can a primary clarifier remove? - ✔✔40 - 60% TSS
✔✔What % of influent BOD can a primary clarifier remove? - ✔✔25 - 50% BOD
✔✔Why should sludge from a primary clarifier be pumped out frequently? - ✔✔To avoid
septic conditions and odors
✔✔What benefit do baffles provide? - ✔✔They reduce velocity and increase detention
time, preventing short circuiting through a tank
✔✔What is the average detention time for a primary clarifier? - ✔✔1 - 2 hours
✔✔Odor complaints are increasing at the WWTP. The operator finds most odors seem
to be coming from the primary clarifiers where bubbles and chunks of solids are found
on the tank surface. What should be done to correct the problem? - ✔✔Increase the
sludge withdrawal rate from the primary clarifier
✔✔What is the purpose of a gravity thickener? - ✔✔Thicken primary sludge and WAS
prior to anaerobic digestion
✔✔Primary clarifiers are NOT efficient at removing what two types of solids? -
✔✔Dissolved and colloidal
, ✔✔What is mixed liquor? - ✔✔A mixture of influent wastewater and RAS
✔✔What effects would differ between coarse bubble diffusers and fine bubble diffusers?
- ✔✔Coarse - Better mixing but inefficient oxygen transfer
Fine - Better oxygen transfer but not good for mixing
✔✔What function do secondary clarifiers provide? - ✔✔Separation of biological solids
from surrounding water
✔✔Which clarifier or settling basin is more likely to have dark grey to black colored
sludge pop-ups and septic odors? (Primary or Secondary) - ✔✔Primary clarifier
✔✔Where does the majority (about 90%) of the settled solids from the secondary
clarifier go? - ✔✔To the influent end of the aeration tank (RAS)
✔✔What is the sludge age of a wastewater with these characteristics?
High SVI
High F/M
Low MLSS
Low MCRT
High oxygen uptake rate - ✔✔Young sludge
✔✔What is one controllable factor you could change to increase a young sludges age?
- ✔✔Decrease the waste rate
✔✔True or False
WAS changes the floc characteristics of the biomass? - ✔✔True
✔✔What microorganisms are predominant in young sludge? - ✔✔Flagellates
Amoeboids
Free swimming ciliates
✔✔What microorganisms are predominant in old sludge? - ✔✔Rotifers
Nematodes
✔✔What is the sludge age of a wastewater with these characteristics?
Low SVI
Low F/M
High MLSS
High MCRT
