1. An Analytical Comparison between Secondary Wastewater Treatment Methods; Constructed Wetlands (CW), Modified Ludzack-Ettinger (MLE), and Sequencing Batch Reactors (SBR)
An Analytical Comparison between Secondary Wastewater Treatment Methods; Constructed Wetlands (CW), Modified Ludzack-Ettinger (MLE), and Sequencing Batch Reactors (SBR)
Jacqueline German
CBE 555
March 9, 2015

2. Water is essential for life with one of the most important sectors relating to water that helps sustain life on earth being wastewater treatment
The research evidence showed that SBRs appear to be the most optimal design out of the three analyzed for food industry application.
No new water is being made, just recycled
2.5 billion people in the world don’t even have access to a clean safe toilet

3. Overview Background of Secondary Wastewater Treatment
Constructed Wetlands (CW)
Modified Ludzack-Ettinger (MLE)
Sequencing Batch Reactors (SBRs)
Evaluation Matrix on basis of cost, and phosphorus removal efficiency for a 100,000 gallon/day plant
Research on SBR systems
Conclusion

4. Secondary wastewater treatment is responsible for removing excess dissolved organics
Secondary (biological) treatment removes the dissolved organic matter that escapes primary treatment. This is achieved by microbes consuming the organic matter as food, and converting it to carbon dioxide, water, and energy for their own growth and reproduction. The biological process is then followed by additional settling tanks (“secondary sedimentation", see photo) to remove more of the suspended solids. About 85% of the suspended solids and BOD can be removed by a well running plant with secondary treatment. Secondary treatment technologies include the basic activated sludge process, the variants of pond and constructed wetland systems, trickling filters and other forms of treatment which use biological activity to break down organic matter.
More than 98 percent of the nation's wastewater treatment facilities only provide secondary treatment (

5. Animations and youtube videos of the wastewater treatment process
162 L sewage/day

6. Focus on nitrogen removal due to the severity of ammonia toxicity to fish from even extremely small levels
Heavy organic pollution can lead to “dead zones” where no fish can be found; sudden releases of heavy organic loads can lead to dramatic “fishkills” (World Bank,
Autochemotrophs (Aeration stage)
Heterorophs (Anoxic Stage)
Denitrificationanoxic

7. Phosphorus removal is important due to its characteristics of being a good fertilizer ingredient (e.g. for algae)
Phosphorus Accumulating Organisms (PAOs) are obligate aerobes. They can store food, but not process it.
Heterotrophs who help with removing carbon from organic material

8. Average Inflow Values (Secondary Treatment System) COD500 mg/L NH3-N25 mg/L TN45 mg/L PO4-P 10 (9.88 mg/L)
Chemical Oxygen Demand

9. Constructed Wetlands (CW)

10. Constructed Wetlands (CW) generally contain five principal concepts:
(1) substrates with various rates of hydraulic conductivity,
(2) plants adapted to water-saturated anaerobic substrates,
(3) a water column,
(4) (in)vertebrates, and
(5) aerobic and anaerobic microbial populations, assisting in this (Hammer, 1989)

11. Constructed Wetlands (CW) can require 10 times more land

12. Cost analysis concluded that constructed wetlands cost start around 51,700 US$ (Oppelt, 2000)
From Brix (1993)
From Shutes (2001)
“These systems efficiencies have been documented to reach 77% for ammonia nitrogen and 82% for total phosphorus (yearly mean),” (15)
98% reduction of BOD and 90-98% suspended solids, averages of 60-90% nutrient removal
Constructed Wetlands Cost= 40,000 US $ Construction Cost+ 8,200 US$ Excavation and Earthwork+1,500 US$ Inlet/outlet structures+~2,000 US $/year for O&M=51,700 US $ (Oppelt, 2000)
10 mgP/L*0.18=1.8 mgP/L

13. Modified Ludzack-Ettinger (MLE)

14. The MLE process involves a series of tanks
Anoxic phase you have medium sludge production
Aerobic phase is when you have more sludge (biomass) produced (larger tank)
Anoxic Stage NO3-NO2(Nitrate-Nitrite) N2+H2O
Aeration Stage NH4 (Ammonia)+O2 NO3-NO2
(Nitrate-Nitrite)

15. MLE process should be built with a two train minimum
City of Lincoln, Russia which supports a design flow of 4 MGD
Robindale, Texas which supports a design flow of 14.5 MGD

16. Cost analysis concluded that the MLE method had a total cost around 1,069,400 US$ (Hartman and Cleland, 2007)
From Song et al. (2003)
“Application of sludge ozonation to the [MLE with] MBR system was significantly effective for the minimization of excess sludge production as well as for the enhancement of nutrient removal,” (359).
Alum or iron salts
10 mgP/L*0.46=4.6 mgP/L

17. Sequencing Batch Reactor (SBRs)

18. Sequencing batch reactors operate with many of the process that the MLE tanks due in series in one tank
Benefits include
Decreased variation in construction
Decreased variation in operation
Decreased space necessary
Other key features include (1) controlled filamentous growth, (2) more complete settling due to lack of flow through various tanks, (3) odor reduced since there are no clarifier qualities, (4) insufficient MLSS is unlikely due to the lack of clarifiers and return sludge pumps, and (5) most importantly components are easily adaptable to existing basins (Mikkelson, 1995)

19. Much like the MLE process, it is necessary to implement this system in parallel

20. Sequencing batch reactors are documented to have a total cost around 1,066,000 US$ (Hartman and Cleland, 2007)
Mikkelson (1995)
Wilderer et al. (2001)
“Based upon 1986 EPA cost comparison of a 1.0 MGD facility, the installation of an SBR represented 10% cost savings as compared to a flow-through [e.g MLE] system,” (38)
This method can more easily tolerate hydraulic or organic “shock” loads with its flexible aeration design (Mikkelson, 1995) overall aeration efficiency enhanced to 30%
10 mgP/L*0.15=1.5 mgP/L

21. Evaluation Matrix

22. Evaluation of CW, MLE, and SBRs yield SBR as the most optimal solution

23. SBR Wastewater Research

24. Background on Research
Has been running for around 4 years
Two Liter system
Five phased systems
Aeration levels around 0.2 mg/L during aerobic phase

25. Research on lowering aeration levels while still keeping nutrient removal efficiencies high
Also use aeration during pretreatment to “shake up liquids”. Bubbling oxygen through the water also keeps the organic material suspended while it forces 'grit' (coffeegrounds, sand and other small, dense particles) to settle out. Grit is pumped out of the tanks and taken to landfills.
As organic matter decays, it uses up oxygen. Aeration replenishes the oxygen.

26. Average Inflow Values (Secondary Treatment System) COD500 mg/L NH3-N25 mg/L TN45 mg/L PO4-P 10 (9.88 mg/L)

28. Removal efficiencies between 83- 100%
For COD =98.9%
For NH3 =92.8%
For P =82.9%

29. However while nutrient removal is stable, TSS/VSS is not

30. Conclusion

31. Thank you for listening raise your hand to ask a question
Feel free to
raise your hand to ask a question

32. Bibliography/Graphics
Slide 2: wastewater/,
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Slide 6: lange.ma/countrysites/action_q/download%3Bdocument/DOK_ID/ /type/pdf/lkz/MA/spkz/fr/TO KEN/ZnetjKCx8xj3bU3qN6jNAaemUMk/M/LY2QgA
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Slide 10: Brix, H. (1993). Wastewater treatment in constructed wetlands: system design, removal processes, and treatment performance. Constructed wetlands for water quality improvement, 10.
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Slide 14: Vidal, N., Poch, M., Martí, E., & Rodríguez‐Roda, I. (2002). Evaluation of the environmental implications to include structural changes in a wastewater treatment plant. Journal of Chemical Technology and Biotechnology, 77(11), 1207
Slide 15: design-build-projects/robindale-wwtp-renovation-expansion/
Slide 18: Wilderer, P. A., Irvine, R. L., & Goronszy, M. C. (2001). Sequencing batch
reactor technology. Intelligence Water Association (IWA) Alliance House, London, UK, 29
Slide 19: 20, Wilderer et al., 2001

33. Bibliography/Graphics
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Slide 2: facilities-program
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Hammer, D. A. (Ed.). (1989). Constructed wetlands for wastewater treatment: municipal, industrial and agricultural. CRC Press.
Hartman, P. and Cleland, J. (2007). Wastewater Treatment Performance and Cost Data to Support an Affordability Analysis for Water Quality Standards. Prepared by ICF international for Montana Department of Environmental Quality.
Oppelt, T. (2000). Constructed Wetlands Treatment of Municipal Wastewaters Enivonmental Protection Agency (EPA) Manual. Cincinnati, Ohio
Slide 34: facilities-program