A. The change of gradient
B. The change of direction
C. The junctions of sewers
D. All of these
A. In freshly produced sewage
B. At sewer pipes
C. In sewer treatment plants
D. None of these
A. Screening
B. Sedimentation
C. Oxidation
D. All the above
A. 0.5 to 1.0 kg
B. 1 kg to 2.0 kg
C. 5 kg to 7.5 kg
D. 7.5 kg to 10 kg
A. 1 in 60
B. 1 in 100
C. 1 in 120
D. None of these
A. Hydrochloric acid
B. Sulphuric acid
C. Nitric acid
D. Citric acid
A. House sewer
B. Out-fall sewer
C. Branch sewer
D. Main sewer
A. Hydrogen sulphide
B. Carbon dioxide
C. Methane
D. Oxygen
A. Carbondioxide
B. Hydrogen sulphide
C. Methane
D. All of these
A. 100 to 500
B. 500 to 1000
C. 1000 to 1500
D. 1500 to 2000