Download Homework L4M15_WWT_HW

Homework for Module 15 – Waste Water Treatment Plants
1. Why do we have to treat wastewater?
2. What is the difference between municipal and industrial wastewater?
3. Define effluent
4. Define receiving water
5. What might downstream users be using the river water for?
6. Describe the importance of the operator’s role with respect to downstream water users.
In your answer, describe why downstream water users may consider the water treatment
plant (or the operator) an adversary.
7. Define organic waste.
8. Define inorganic waste.
9. In some communities, the municipal plant may receive water from an industrial
operation, and treat this water along with the domestic wastes. What industries produce
organic wastes?
10. What industries produce inorganic wastes?
11. What is the difference between primary and secondary treatment?
12. Define aerobic bacteria
13. Define anaerobic bacteria
14. What is an Imhoff Cone?
15. Define biochemical oxygen demand (BOD)
16. What causes oxygen depletion when organic wastes are discharged to water? In your
answer, list the bad outcomes if oxygen depletion occurs.
17. Define septic
18. Define nutrient cycle
19. What nutrients are usually of concern in receiving waters?
20. In the nitrate cycle, which step produces ammonium?
21. If no dissolved oxygen is present in a receiving water, what is the endpoint (a) of the
carbon cycle? (b) Of the sulfur compounds?
22. What does NPDES stand for?
23. What types of things might have discharge limits on a NPDES permit that is granted
for a municipal wastewater treatment plant?
24. Name 3 waterborne diseases that are caused by pathogenic organisms.
25. When water is flowing through the city sewers to the sewage treatment plant, what
problem can occur if it takes a long time?
26.Why can combined sewers be a problem?
27. Why is the screening step included in waste water treatment?
28. What does detention time in a clarifier accomplish?
29. How are scum and sludge removed from a clarifier?
30. What occurs during secondary treatment?
31. How are the large populations of microorganisms in the effluents from the trickling
filters, rotating biological contactors, and activated sludge tanks removed from the flow?
32. What two steps are performed on sewage sludge before it is disposed?
33. When are waste treatment ponds used instead of sedimentation tanks, trickling filters,
etc.?
34. How long a detention time is required within waste treatment ponds in order to
remove solids and harmful bacteria?