Welcome to your Wastewater Treatment practice exam.

1. Floatable solids are easy to measure.
2. A well-operated digester normally receives sludge at about__________ % volatile
solid and reduces it to about __________% volatile solids.
3. According to OSHA, which of the following oxygen in air concentration is the
lowest safe concentration for humans to breathe in order to avoid the hazard of
oxygen deficiency?
4. The population equivalent factor for BOD is
5. Which of the following groups of microorganisms are found in a good settling mixed liquor?
6. Which heavy metal is the most stringent for land application?

Grit chambers that are designed to remove grit have a velocity of

8. The purpose of adding sodium thiosulfate to a microbiological (such as fecal coliform) sample bottle is to
9. Which of the following types of wastewater would settling occur most rapidly?
10. The disadvantage of using a constant percentage return activated sludge flow control is
11. Under which one of the following conditions should sludge wasting normally be increased?

The outlet of a forced ventilation system for a chlorinator room should be located

13. If packing is not maintained properly
14. Turbidity in wastewater is caused by:
15. One of the primary reasons why air should be excluded from the digester is that
16. Barminutors and comminutors are installed for different purposes.
17. What are the end products of the aerobic biochemical reaction?
18. Pump maintenance includes:

Pump packing should be:

20. The fusible plug that is in all chlorine cylinders:
21. A piston or diaphragm pump would be used for pumping

Collection system variables that could upset an activated sludge process include

23. What type of pump is not seriously damaged if the discharge valve is closed for a short time, while the pump is running?
24. Which of the following chemicals would be the most effective in achieving a pH adjustment of 8.4 so nitrification can take place in an RBC?

Acids should never be added to chlorine solutions because they:

26. Which of the following is a method for treating flow to the primary settling tank that would increase grease removal efficiency of that unit?
27. Three water borne diseases are:
28. When organic wastes are discharged to receiving water, oxygen is depleted by
29. An application for renewal of an NPDES permit must be submitted ______ days before the previous permit expires.
30. From a public health standpoint, which of the following is the safest sludge for soil conditioning purposes?
31. The major purpose of an inlet baffle in a settling tank is to
32. The primary purpose of forced draft ventilation in lift stations is to
33. High-rate anaerobic digestion refers to the fact that the organic waste material is applied to an anaerobic reactor at high _________ loading rates.
34. As a digester approaches "sour" conditions:
35. The concentration of volatile solids in the feed sludge to a digester is an indirect measure of the
36. Typical detention time in a mesophilic digester is:
37. The presence of white pillowing foam on an aeration tank indicates
38. The chemicals that are added to distilled water for the BOD test serve what purpose?
39. An operator runs a Winkler by the azide modification of the Winkler method. He runs out of standard sodium thiosulfate. Which reagent can be used instead?
40. Sludge wasting from secondary clarifiers, are normally required in order to control
41. The best way to control excessive foaming during start-up of a digester is to
42. The principle function of the zoogleal mass on the trickling filter is to:
43. Which of the following can cause foaming in the anaerobic digesters?
44. Which of the following sets of characteristics describes a good quality of activated sludge?
45. Ultra Violet Irradiation kills bacteria by:
46. Possible techniques for controlling filamentous organisms in an activated sludge process include:
47. Which pump is the best for pumping chemicals?
48. Low sulfonator injector vacuum readings could be caused by
49. A white filamentous growth on the RBC media is indicative of:
50. The temperature versus DO relationship is
51. 1. What state do you live in? 2. What other type of quiz would you like to see?