ABC Wastewater Level 3 Lab Questions
and Answers – Laboratory Practice Exam
Material|| GRADED A+|| LATEST UPDATE
2026
To have significant meaning for laboratory tests of the evaluation of a wastewater
treatment plant's performance the best method of sampling is
A. Grab sampling
B. Hourly sampling
C. Sampling during peak flow
D. Proportional composite sampling
E. Automatic sampling -CORRECTANSWER D. Proportional composite sampling
BOD samples should be collected before chlorination because
A. Chlorine reacts with the buffer solution
B. Chlorine interferes with the activity of organisms
C. Chlorine reacts with the calcium ions
D. Chlorine affects the alkalinity -CORRECTANSWER B. Chlorine interferes with the
activity of organisms
A water sample is "fixed" in the field by
A. Keeping the sample in a Cipolletti device
B. Anchoring the container to the stream bed
C. Adding chemicals to prevent the changing of water quality
D. Maintaining a constant sample temperature of 95° F -CORRECTANSWER C. Adding
chemicals to prevent the changing of water quality
The best procedure for determining the SS of a plant effluent is to analyze
A. A 24-hr composite sample of the effluent
B. A grab sample of the effluent at high flow
C. A grab sample of the effluent at low flow
D. A series of grab samples taken at different times during the day -
CORRECTANSWER A. A 24-hr composite sample of the effluent
A sample obtained by taking portions of wastewater at a collection point in proportion to
the flow is called
A. A most probable number (MPN)
B. A weighted composite
C. A routine sample
D. A bacterial-solids sample -CORRECTANSWER B. A weighted composite
, Settleable solids by volume are determined through the use of
A. A Nessler tube
B. A Kjeldahl flask
C. A Gooch crucible
D. An Imhoff cone -CORRECTANSWER D. An Imhoff cone
The settleable solids test is primarily used to
A. Measure the volume of solids that may be removed by settling tanks
B. Determine the BOD required for treatment
C. Measure the rate of decomposition of organic volatile solids
D. Determine the amount of chlorine required -CORRECTANSWER A. Measure the
volume of solids that may be removed by settling tanks
The standard total SS test requires the Gooch crucible fiber glass mat and solids to be
dried in the oven at
A. 95° C
B. 103° C
C. 110° C
D. 115.5° C -CORRECTANSWER B. 103° C
The SS content of wastewater is most accurately measured by
A. Filtering the sample through a specially prepared filter; drying the filter and material
retained on it in an oven at 103° C; weighing the filter; and determining its added weight
caused by the solids retained
B. Evaporating the sample and weighing the residue
C. Centrifuging the sample and measuring the volume of solids separated from the
liquid
D. Distilling the sample after acidification with sulfuric acid and titrating the distillate with
N sodium hydroxide -CORRECTANSWER A. Filtering the sample through a specially
prepared filter; drying the filter and material retained on it in an oven at 103° C; weighing
the filter; and determining its added weight caused by the solids retained
The amount of sample to be used in determining SS depends on the
A. Amount of grease in the sample
B. Amount of SS in the sample
C. Degree of turbidity of the sample
D. Type of vacuum apparatus available -CORRECTANSWER B. Amount of SS in the
sample
The advantage of the centrifuge test for SS determination in comparison with the other
method is
A. Accuracy of results
B. Large volume of sample it can handle
C. Low cost
and Answers – Laboratory Practice Exam
Material|| GRADED A+|| LATEST UPDATE
2026
To have significant meaning for laboratory tests of the evaluation of a wastewater
treatment plant's performance the best method of sampling is
A. Grab sampling
B. Hourly sampling
C. Sampling during peak flow
D. Proportional composite sampling
E. Automatic sampling -CORRECTANSWER D. Proportional composite sampling
BOD samples should be collected before chlorination because
A. Chlorine reacts with the buffer solution
B. Chlorine interferes with the activity of organisms
C. Chlorine reacts with the calcium ions
D. Chlorine affects the alkalinity -CORRECTANSWER B. Chlorine interferes with the
activity of organisms
A water sample is "fixed" in the field by
A. Keeping the sample in a Cipolletti device
B. Anchoring the container to the stream bed
C. Adding chemicals to prevent the changing of water quality
D. Maintaining a constant sample temperature of 95° F -CORRECTANSWER C. Adding
chemicals to prevent the changing of water quality
The best procedure for determining the SS of a plant effluent is to analyze
A. A 24-hr composite sample of the effluent
B. A grab sample of the effluent at high flow
C. A grab sample of the effluent at low flow
D. A series of grab samples taken at different times during the day -
CORRECTANSWER A. A 24-hr composite sample of the effluent
A sample obtained by taking portions of wastewater at a collection point in proportion to
the flow is called
A. A most probable number (MPN)
B. A weighted composite
C. A routine sample
D. A bacterial-solids sample -CORRECTANSWER B. A weighted composite
, Settleable solids by volume are determined through the use of
A. A Nessler tube
B. A Kjeldahl flask
C. A Gooch crucible
D. An Imhoff cone -CORRECTANSWER D. An Imhoff cone
The settleable solids test is primarily used to
A. Measure the volume of solids that may be removed by settling tanks
B. Determine the BOD required for treatment
C. Measure the rate of decomposition of organic volatile solids
D. Determine the amount of chlorine required -CORRECTANSWER A. Measure the
volume of solids that may be removed by settling tanks
The standard total SS test requires the Gooch crucible fiber glass mat and solids to be
dried in the oven at
A. 95° C
B. 103° C
C. 110° C
D. 115.5° C -CORRECTANSWER B. 103° C
The SS content of wastewater is most accurately measured by
A. Filtering the sample through a specially prepared filter; drying the filter and material
retained on it in an oven at 103° C; weighing the filter; and determining its added weight
caused by the solids retained
B. Evaporating the sample and weighing the residue
C. Centrifuging the sample and measuring the volume of solids separated from the
liquid
D. Distilling the sample after acidification with sulfuric acid and titrating the distillate with
N sodium hydroxide -CORRECTANSWER A. Filtering the sample through a specially
prepared filter; drying the filter and material retained on it in an oven at 103° C; weighing
the filter; and determining its added weight caused by the solids retained
The amount of sample to be used in determining SS depends on the
A. Amount of grease in the sample
B. Amount of SS in the sample
C. Degree of turbidity of the sample
D. Type of vacuum apparatus available -CORRECTANSWER B. Amount of SS in the
sample
The advantage of the centrifuge test for SS determination in comparison with the other
method is
A. Accuracy of results
B. Large volume of sample it can handle
C. Low cost
