The document discusses aeration options for wastewater facilities in Nebraska. It notes that many facilities currently use activated sludge, oxidation ditches, or lagoon systems. Stricter wastewater standards may require these facilities to improve aeration. Retrofitting existing systems can be challenging due to space, budget, or workforce constraints. The document promotes using venturi aeration, which uses pump pressure and no moving parts to inject air through pipes. Venturi systems provide oxygenation with a small footprint and easy installation/maintenance requirements, making them a good retrofitting option for lagoons, tanks, and ditches.

1. Aeration from Afar
Brian Gongol, M.Ed.
DJ Gongol & Associates, Inc.
Nebraska Rural Water Association Annual Conference
Kearney, Nebraska | March 14, 2023

2. Aeration and you
Nebraska wastewater facilities:
• 3 | RBCs
• 9 | trickling filters
• 23 | SBRs
• 26 | oxidation ditches
• 64 | activated sludge

3. Aeration and you
Nebraska wastewater facilities:
• 3 | RBCs
• 9 | trickling filters
• 23 | SBRs
• 26 | oxidation ditches
• 64 | activated sludge
10 | aerated lagoons
319 | non-aerated lagoons

4. Nothing is certain about the future

5. Except maybe more stringent standards
• No backsliding
• No degradation
• No fewer problems than we had yesterday

6. Hot
off
the press

7. Almost anything you do is going to require more or
better air

8. How do you get more air?
• Push it in mechanically
• Diffuse it in
• Induce it in

9. Retrofitting: The name of the game

10. Who faces inconvenient limitations?

11. Constrained sites
• Not a lot of available room to put new facilities or equipment
• “Landlocked” conditions
• Resistance from nearby landowners

12. Capacity limitations
• Need to conserve volume inside existing tanks

13. Workforce limitations
• Hard to find skilled workers
• Service calls can be expensive and backlogged
• Increasingly specialized equipment is hard to maintain
• Lone operators
• We’re all getting older every day

14. Reasons for hesitation about other
options

15. Mechanical pushing
• Don’t put power cords in the water
unless you’ve exhausted your other
options

16. Mechanical pushing
• Don’t put power cords in the water
unless you’ve exhausted your other
options
• Don’t send equipment “out to sea” if
it’s hard to recover

17. Diffusion
• Submerged diffusers are hard to
retrieve

18. Diffusion
• Submerged diffusers are hard to
retrieve
• Diffusers are very good at promoting
sedimentation
• Sooner or later, you’ll have to clean
them

19. Diffusion
• Submerged diffusers are hard to
retrieve

20. Aerating from shore

21. Gives equipment climate control

22. Favors oiling and greasing

23. Permits monitoring for signs of trouble

24. Permits ease of access

25. Allows single-operator O&M

26. Permits fine-tuning of performance

27. Decreases volume required in existing tanks and
spaces

28. Let’s talk Venturi aeration

29. Static device added after the pump discharge

30. Pump discharge pressure induces ambient air

31. High velocity through the nozzle creates the
pressure drop

32. Air mixes with the pumped liquid almost instantly

33. Size ranges
• 2” pipe | 50-150 gpm | 82 lb/day oxygen
• 3” pipe | 180-350 gpm | 253 lb/day oxygen
• 4” pipe | 400-650 gpm | 359 lb/day oxygen
• 6” pipe | 800-1300 gpm | 857 lb/day oxygen
(maximum amount of transferred useable oxygen, not the actual amount of
oxygen produced by the Venturi)

34. Easy to install and monitor

35. No moving parts

36. Pumps sized to fit

37. Installation generally fits within 6’ x 6’ footprint

38. Inlet and outlet locations piped as needed

39. Easy to isolate for maintenance

40. Lagoon retrofitting

41. Tank retrofitting

42. Oxidation ditch retrofitting

43. Can be portable/engine-driven for seasonal
applications

44. Lots of detention time? Perfect!
• Treat it like a barbecue: Low and slow

45. A little planning, piping, and baffling

46. Comparable horsepower-to-oxygen for mechanical
aerators

47. Comparable to blower performance over 10 hp

48. Diffusers will move more oxygen, but…

49. Designed well, you get both air and mixing