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CWEA - BOD/COD/DO Flashcards | StudBud
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CWEA - BOD/COD/DO
CWEA - BOD/COD/DO
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1
In the CBOD test, 2-chloro-6-(trichlormethyl)pyridine is used to suppress
Nitrification
Denitrification
Gasification
Carbonation
2
The water quality for BOD dilution and reagent water should be
Type 1 (>10 mΩ and relatively bacteria free)
Type 2 (>1 mΩ and <1000 CFU/mL)
Type 4 (chlorinated and filtered)
Type 3 (0.1 mΩ and bacterial content is unimportant)
3
To prepare a zero DO standard for the membrane electrode test
Add excess Na2SO3 and a trace of CoCl2
Add MnSO2 and shake well
Add alkali iodide azide and let stand for 20 minutes
Add excess NaCl
4
When adjusting the pH of a BOD sample, what normality of NaOH or H2SO4 solution should you use?
0.5 N
2.0 N
Pure sodium hydroxide or sulfuric acid
1.0 N
5
What is the most important parameter affecting biological activity in a wastewater treatment process?
FeCl2
DO
SS
Grease in the influent
6
What is the primary advantage of using a DO probe and meter?
Less care is needed in sampling
Samples can be fixed and analyzed at the operator's convenience
The probe and meter need little or no preparation before using
Measurements can be made directly in the waste stream
7
What method of DO testing is best for field testing wastewater?
Membrane electrode (electrometric) method
lodometric method
Alum flocculation modification
Azide modification
8
The DO uptake of a seed control should never exceed
0.8 mg/L
0.6 mg/L
1.0 mg/L
0.4 mg/L
9
In determining COD by the dichromate reflux method, the endpoint of the titration is reached when
Ferrous ammonium sulfate is completely neutralized
Ferrous ions are no longer oxidized & presence of phenanthroline turns red
Excess ferric ions complex the methyl orange indicator
Ferrous ammonium sulfate is completely oxidized
10
Which sugar compound is used to prepare a standard for a BOD test?
Glucose
Fructose
Sucrose
Maltose
11
Seeding BOD dilution water with a microbial population is necessary when analyzing
Influent wastewater
Receiving streams
Chlorinated effluent
Process effluent
12
The Winkler method is used for determining the level of which of the following?
Free ammonia
Amount of DO
Nonfilterable residue
Fecal coliform levels
13
What is the proper incubator temperature setting for BOD analysis?
68 °F ± 1 °F
20 °C ± 1 °C
4 °C ± 1°C
20 °F ± 1 °F
14
What methods are used for measuring the DO content of a sample?
Infrared and MnO4 modification
The Winkler method and its modifications and membrane electrode method
The nitroferrous electrode and azide modification
The oxygen phosphate method and the membrane electrode method
15
Which of the following solutions is NOT added to BOD dilution water
Na2SO3
CaCl2
FeCl3
MgSO4
16
If DO is present in a BOD sample, what color will the floc turn after the alkaline iodide-sodium azide sol'n is added?
White
Brown
Blue
Purple
17
[DO: lodometric]why should the sample bottle overflow two or three times when collecting a sample under pressure
To prevent the entrainment of air bubbles
To remove excess pollutants
To get a full bottle
To get enough sample
18
What test indicates the rate of oxidation and provides an indirect estimate of the concentration of the waste?
TOC
DO
BOD
TSS
19
Which of the following chemicals is NOT used in a COD test?
Ferroin indicator
Silver sulfate
Mercuric sulfate
Magnesium sulfate
20
If a BOD sample contains more than 9.0 mg/L of DO at 20 °C, you should
Warm the sample above 20 °C
Agitate or aerate the sample at 20 °C
Proceed directly with the test procedure
Cool the sample below 20 °C
21
The oxygen depleted during the 5-day BOD test is used by which of the following?
Microorganisms
Ammonia
Industrial discharges
Chemicals
22
What is the basic formula used to determine BOD?
DO of the dilution water ÷ % of sample
DO of the raw sample x DO of the incubated sample
Oxdepleted of the blank - Oxdepletedof the sample ÷ by the % of sample
Oxdepleted during incubation ÷ by the dilution factor of the sample
23
After 5 days incubation, a BOD sample should have a DO depletion of at least
2.0 mg/L
1.0 mg/L
0.5 mg/L
13.5 mg/L
24
BOD is the
b
c
a
d
25
What does DO refer to?
Dissolved organics
Diamino oxide
Direct oxidation
Dissolved oxygen
26
The equation for calculating BOD in milligrams per liter is
a
d
b
c
27
The "C" in CBOD stands for
Chemical
Compound
Combined
Carbonaceous
28
What is the minimum DO uptake that will produce the most reliable results for BOD test?
2.0 mg/L
1.0 mg/L
0.2 mg/L
2.5 mg/L
29
To ensure the most accurate results for BOD analysis, you should
Store sample at 20 oC
Preserve with sulfuric acid
Preserve with HCl
Test immediately on site
30
Which of the following GGA measurements is the most accurate?
228 mg/L
168 mg/L
198 mg/L
138 mg/L
31
The difference between a CBOD and BOD test is
Incubation temperature above 20 °C
Addition of nitrification inhibitor
Volume of sample used
Incubation period
32
Which modification of the Winkler test is used for biological flocs with high oxygen utilization rates?
Azide
Alum flocculation
MnO4
CuSO-sulfamic acid flocculation
33
The BOD:COD of the influent is 0.6 If the COD of your influent is 360 mg/L, what is the approx BOD of your influent?
20 mg/L
400 mg/L
200 mg/L
600 mg/L
34
A DO sample should not be agitated or remain in contact with the atmosphere because
The acidity in the sample will reduce the dissolved oxygen
The gaseous content of the sample may change
The sample may give off toxic fumes
The solids may not settle out
35
Which of the following phrases represents the relation between the COD and BOD values of a specific wastewater sample?
COD is smaller than BOD
COD is larger than BOD
COD is equal to BOD
COD is unrelated to BOD
36
What is wrong with a COD sample that turns green during the reflux?
All of the oxidizer has been depleted
KCr2O7 solution was not standardized
Too much FAS was added to the sample
COD is below the detection limit
37
The temperature of the incubator used for a BOD test should be maintained at
68 °C
20 °F
35 °F
20 °C
38
Given the following information, determine the COD of the sample
258 mg O2/L
226 mg O2/L
194 mg O2/L
162 mg O2/L
39
If a BOD sample is too acidic or alkaline, you should
Adjust the seed pH to 6.5-7.5
Adjust the sample pH to 6.5-7.5
Adjust the dilution water pH to 6.5-7.5
Adjust the DO level of the sample before processing
40
A DO sample to be analyzed by the Winkler method, which has been acidified in the field, may be held for
8 hours
6 hours
0.5 hour
No time, must be analyzed immediately
