MASSACHUSETTS WASTEWATER OPERATOR
GRADE 6 TEST 200 QUESTIONS & CORRECT
ANSWERS LATEST 2026/2027
When are monthly reports due to the MA DEP? - ANSWER-The 15th day of every
month.
What two chemicals are used for DE-CHLORINATION? - ANSWER-Sulfur
dioxide and sulfite salts (including sodium sulfite, sodium bisulfite, and sodium
metabisulfite).
How long are you required to keep MAINTENANCE records? - ANSWER-Three
years.
How long is an NPDES permit valid for before it must be renewed? - ANSWER-
Five years.
What test is used to determine coagulant levels for solids removal? - ANSWER-
Bench test.
What chemical is used to TEST for phosphorus in EFFLUENT? - ANSWER-
Ascorbic Acid.
What type of valve excels in applications of THROTTLING the flow of fluids? -
ANSWER-Butterfly valve.
,For UV treatment systems, how frequently must quartz sleeves be cleaned? -
ANSWER-Every six-to-twelve months.
What are conductivity tests used to measure? - ANSWER-Dissolved solids.
The presence of which gas is dangerous when MIXED with the emissions from an
anaerobic digester? - ANSWER-Oxygen.
What are the three compounds used in wastewater treatment that increase
alkalinity? - ANSWER-Bicarbonate, carbonate, and hydroxide.
What device is used to measure the flow of a gas? - ANSWER-Orifice plate flow
meter.
How long can FOG samples be kept if they are stored properly? - ANSWER-28
days.
Which class of organism present in wastewater is most resistant to chlorine
disinfection? - ANSWER-Spores.
What happens to the chlorine demand of water after nitrification occurs? -
ANSWER-Chlorine demand significantly increases after nitrification.
What is the target ratio of Carbon, Nitrogen, and Phosphorous for the activated
sludge process? - ANSWER-100C : 10N : 1P
What contaminants have the lowest pollutant limits? - ANSWER-Nickel, Zinc, and
Mercury.
, As the amount of carbon dioxide in wastewater increases, the pH will... -
ANSWER-Decrease; become more acidic.
What is "unity of command?" - ANSWER-Employees should report to one
singular "boss" whom all direction comes from.
Describe the term "accuracy." - ANSWER-Accuracy refers to how close a
measurement is to its true value.
What happens to a three-phase motor if one phase were to fail? - ANSWER-The
motor would overheat and incur damage.
What pump is best suited to delivering a specific amount of chemical? -
ANSWER-Diaphragm pump.
If a centrifugal pump with high flow and low static head were to begin
overheating, what is a quick course of action? - ANSWER-Reduce the flow exiting
the pump by throttling the outlet valve incrementally toward the closed position.
This will cool the pump down.
What temperature is the drying oven of a furnace? - ANSWER-103 to 105 degrees
CELCIUS (not F! the test tricks you!)
What is the likely cause of influent from the collections (sewer) system having
CONSISTENTLY low pH? - ANSWER-Waste is decomposing inside of the
collection system.
GRADE 6 TEST 200 QUESTIONS & CORRECT
ANSWERS LATEST 2026/2027
When are monthly reports due to the MA DEP? - ANSWER-The 15th day of every
month.
What two chemicals are used for DE-CHLORINATION? - ANSWER-Sulfur
dioxide and sulfite salts (including sodium sulfite, sodium bisulfite, and sodium
metabisulfite).
How long are you required to keep MAINTENANCE records? - ANSWER-Three
years.
How long is an NPDES permit valid for before it must be renewed? - ANSWER-
Five years.
What test is used to determine coagulant levels for solids removal? - ANSWER-
Bench test.
What chemical is used to TEST for phosphorus in EFFLUENT? - ANSWER-
Ascorbic Acid.
What type of valve excels in applications of THROTTLING the flow of fluids? -
ANSWER-Butterfly valve.
,For UV treatment systems, how frequently must quartz sleeves be cleaned? -
ANSWER-Every six-to-twelve months.
What are conductivity tests used to measure? - ANSWER-Dissolved solids.
The presence of which gas is dangerous when MIXED with the emissions from an
anaerobic digester? - ANSWER-Oxygen.
What are the three compounds used in wastewater treatment that increase
alkalinity? - ANSWER-Bicarbonate, carbonate, and hydroxide.
What device is used to measure the flow of a gas? - ANSWER-Orifice plate flow
meter.
How long can FOG samples be kept if they are stored properly? - ANSWER-28
days.
Which class of organism present in wastewater is most resistant to chlorine
disinfection? - ANSWER-Spores.
What happens to the chlorine demand of water after nitrification occurs? -
ANSWER-Chlorine demand significantly increases after nitrification.
What is the target ratio of Carbon, Nitrogen, and Phosphorous for the activated
sludge process? - ANSWER-100C : 10N : 1P
What contaminants have the lowest pollutant limits? - ANSWER-Nickel, Zinc, and
Mercury.
, As the amount of carbon dioxide in wastewater increases, the pH will... -
ANSWER-Decrease; become more acidic.
What is "unity of command?" - ANSWER-Employees should report to one
singular "boss" whom all direction comes from.
Describe the term "accuracy." - ANSWER-Accuracy refers to how close a
measurement is to its true value.
What happens to a three-phase motor if one phase were to fail? - ANSWER-The
motor would overheat and incur damage.
What pump is best suited to delivering a specific amount of chemical? -
ANSWER-Diaphragm pump.
If a centrifugal pump with high flow and low static head were to begin
overheating, what is a quick course of action? - ANSWER-Reduce the flow exiting
the pump by throttling the outlet valve incrementally toward the closed position.
This will cool the pump down.
What temperature is the drying oven of a furnace? - ANSWER-103 to 105 degrees
CELCIUS (not F! the test tricks you!)
What is the likely cause of influent from the collections (sewer) system having
CONSISTENTLY low pH? - ANSWER-Waste is decomposing inside of the
collection system.
