Question: For a given discharge, the efficiency of sedimentation tank can be increased by______________?

• 1. increasing the depth of tank
• 2. decreasing the depth of tank
• 3. increasing the surface area of tank
• 4. decreasing the surface area of tank

Question: The settling velocity of a particle in a sedimentation tank depends on__________________?

• 1. depth of tank
• 2. surface area of tank
• 3. both depth and surface area of tank
• 4. none of the above

Question: The overflow rate for plain sedimentation tanks is about__________________?

• 1. 500 to 750 litres/hour/ m2
• 2. 1000 to 1250 litres/hour/ m2
• 3. 1250 to 1500 litres/hour/m2
• 4. 1500 to 2000 litres/hour/m2

Question: The settling velocity of a particle in a sedimentation tank increases if_________________?

• 1. particle size is decreased
• 2. the surface area of tank is increased
• 3. the depth of tank is decreased
• 4. none of the above

Question: The velocity of flow of water in a sedimentation tank is about__________________?

• 1. 5 to 10 cm/sec.
• 2. 15 to 30 cm/sec.
• 3. 15 to 30 cm/minute
• 4. 15 to 30 cm/hour

Question: The amount of residual chlorine left in public water supply for safety against pathogenic bacteria is about______________?

• 1. 0.01 to 0.05 ppm
• 2. 0.05 to 0.5 ppm
• 3. 0.5 to 1.0 ppm
• 4. 1.0 to 5.0 ppm

Question: Orthotolidine test is used for determination of________________?

• 1. dissolved oxygen
• 2. residual chlorine
• 3. biochemical oxygen demand
• 4. dose of coagulant

Question: On standard silica scale, the turbidity in drinking water should be limited to_______________?

• 1. 10 ppm
• 2. 20 ppm
• 3. 30 ppm
• 4. 50 ppm

Question: Which of the following values of pH represents a stronger acid?

• 1. 2
• 2. 5
• 3. 7
• 4. 10

Question: Standard EDTA (ethylene diamine tetra acetic aciD. solution is used to determine the_______________?

• 1. hardness in water
• 2. turbidity in water
• 3. dissolved oxygen in water
• 4. residual chlorine in water