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Student Projects 2002

Living System photos

Living System Website

 

 

 

 

FABE 652
Ecosystems for waste treatment

Lecture #10
May 20, 2003

 Lab Schedule-only 2 labs left 5/21 & 5/28
Go Over Presentation Format
 Questions

Discussion—Compare Ecological Treatment Systems (ETS) to Conventional Waste Water Treatment Plants (WWTP)

MetCalf & Eddy, Inc. 1991. Wastewater Engineering: Treatment, Disposal, and Reuse. McGraw-Hill, Inc., New York.

Reading for Thursday: Brown, M.T., Ulgiati, S. 1997. Emergy-based indices and ratios to evaluate sustainability: monitoring economies and technology toward environmentally sound innovation. Ecological Engineering. 9: 51-69.

Standard WWTP configurations

  • Primary, Secondary, Tertiary Treatment (Fig. 11-1(d,f,h))

-Primary-physical processes; screening sedimentation

-Secondary-biological and chemical processes remove organic matter

-Tertiary (Advanced)-processes remove nutrients (N,P)
  • Physical Processes

-Screening

-Mixing (flow equalization)

-Sedimentation

-Flocculation (enhance sedimentation)

-Flotation (with fine bubbles)

-Filtration (often with sand and backflush for cleaning)

-Volatilization (gas stripping for VOCs)

  • Chemical Processes

- Precipitation (P removal w/ positive metal ions or lime)

-Adsorption (w/activated carbon for polishing)

-Disinfection (kill organisms w/ CL, O3, UV)
  • Biological Processes

-Activated Sludge (most common method to reduce organic matter, air added to tank, followed by settling and recycle, suspended growth)

-Trickling filters (aerobic attached growth)

-Anaerobic digestion (convert organic material to gases)

  • Fig. 4-1. Bar Screen, Grit Chamber, Primary Clarifier, Trickling Filters/Aeration Tank/Rotating Biological Contactors, Secondary Clarifier, Chlorination
  • Recycling of "activated sludge" is essential-why?
  • Physical, Chemical, Biological Processes

-Physical-Screening, Mixing, Flocculation, Sedimentation, Flotation, Filtration, Volatilization.

-Chemical-Precipitation (P), Adsorption (organics w/ act. C), Disinfection (kill organisms w/ CL, O3, UV)

-Biological-Reduce organic content & nutrients. (Table 8-6) Aerobic, Anaerobic (Fig 8-28), Pond.

  • Sludge is largest constituent removed from wastewater, sludge is by large largest volume, and its processing and disposal is most complex problem in field of wastewater treatment (p.765). expensive!
  • Sludge is .25-12% solids—many methods to increase solids % (i.e. anaerobic, aerobic digestion, physical methods).
  • Many processes involved in treating sludge (Table 12-1)
  • Final sludge disposal-39% land application, 35% landfill, other methods.
  • P removal-physical-Use positively charged metal ions (calcium, Aluminum, iron) to precipitate
  • P removal-biological-microbial assimilation and sludge removal

Discussion Questions:

1. What are similarities/differences between WWTP and ETS?

2. What are benefits of Living Machine compared to WWTP?

3. What are benefits of WWTP compared to Living Machine?

4. How to retrofit conventional WWTP to incorporate more ecological processes? Why?

5. Compare required inputs for WWTP and Living Machine.

6. How do WWTP, wetland treatment systems, Living Machines compare? (Ecological Footprint) (Table 1 Brown & Ulgiati).