N2O production in a single stage nitritation/anammox MBBR process

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Denitrification produces alkalinity and pH is generally raised by the process. pH optimum is ranging from 7-9 depending on local conditions (Henze et al., 1997). Cell synthesis in the anammox reaction is increasing pH and the process is active in a pH range from 6.5-9 with an optimum around 8 (Egli et al., 2001). 2.2.4 Substrate Nitrifying, denitrifying and anammox bacteria are all dependent on different substrates for energy and cellular growth as discussed above. The ability to utilise their substrate varies between bacterial species. This implies that a species with high affinity for its substrate will be better at utilising the substrate at low concentration and therefore outcompete species with lower affinity for the substrate. The half saturation constant, which is the substrate concentration when the growth rate is half of maximum, is often used to compare how well adapted different microorganisms are to their substrates. The half saturation constant or Ks value for ammonium oxidisers in a nitrifying biofilm airlift reactor was found to correspond to a NH4-N concentration of 11 mg/l. And the microorganisms were inhibited by NH4-N concentrations of 3300 ±1400 mg/l. (Carvallo et al., 2002) Denitrification rate and capacity is very dependent on available organic carbon source. External carbon sources like methanol, ethanol and acetic acid are readily biodegradable and give much higher denitrification rates than denitrification with organic compounds found in the waste water (Ødegaard, 1993). Anammox bacteria have high affinity for their substrates ammonia and nitrite, the Ks values are below chemical detection level (
2.3 Biofilm reactors Biofilm reactors can be used for nutrient removal in wastewater treatment and are commonly used in biological nitrogen removal. Bacteria with the ability to adhere to solid surfaces are colonising and growing in high concentrations in a biofilm attached to a fixed surface. The carrier material can be solid or free moving made out of stone, wood or plastic. Biofilm thickness varies with the hydrodynamics and growth conditions of the system, (Metcalf & Eddy, 2003). The fixed polymer film formed by the bacteria protects them from toxics and being washed out of the system (Henze et al., 1997). Figure 3. Illustration of different types of bioflim reactors. (Adapted from Ødegaard, 1993). Biofilters are designed to achieve high and efficient nutrient removal rates in compact and energy efficient systems. Operating conditions should be such that transfer rates of substrates from the water bulk phase to the microbial community assures efficient removal rates and development of a biofilm thickness satisfying the microbial demands in a certain biologic process. This makes different available biofilm technologies suitable for varied microbial processes. Figure 3 illustrates some of the available biofilm technologies shortly described in the following text. 2.3.1 Trickling filter Trickling filters are biological reactors where the wastewater is sprinkled over a filter bed at the top. The water is then allowed to percolate through a fixed bed material made out of stone or plastic. Volumetric flow rates are controlling the biofilm thickness and 11
Page 1: Water and Environmental Engineering
Page 5 and 6: Summary Wastewaters contain abundan
Page 7: Acknowledgements I would like to ex
Page 11 and 12: Table of content Chapter 1 ........
Page 13 and 14: Chapter 1 1. Introduction Nitrogen
Page 15 and 16: 1.3 Objectives The aim with this ma
Page 17 and 18: Chapter 2 2. Background 2.1 Biologi
Page 19 and 20: are intermediates in the chemical r
Page 21: minimum concentration of 2 mg/l sho
Page 25 and 26: 2.3.4 Moving bed reactor Another wa
Page 27 and 28: To enable efficient nutrient remova
Page 29 and 30: The Canon process is often implemen
Page 31 and 32: 2.5.1 Nitrification as a source of
Page 33 and 34: Table 3. N 2O emission from differe
Page 35 and 36: The microsensor is connected to a p
Page 37 and 38: Chapter 3 3. Material and Methods 3
Page 39 and 40: 3.3 Analytical methods Concentratio
Page 41 and 42: Figure 11. Calibration setup for mi
Page 43 and 44: Chapter 4 4. Results 4.1 Process pe
Page 45 and 46: 10 8 DO concentration, pH & tempera
Page 47 and 48: concentration), while the maximum p
Page 49 and 50: of N2O during aeration was slightly
Page 51 and 52: Table 13. Average N 2O concentratio
Page 53 and 54: 12 NO₂-N (mg/l) 10 8 6 4 2 NO₂-
Page 55 and 56: Aeration 1.6 (l/min) with carriers
Page 57 and 58: % produced N₂O 12 10 8 6 4 2 Prod
Page 59 and 60: laboratory system might be underest
Page 63: 6. Conclusions The following conclu
Page 67 and 68: 8. References Abma W.R., Schultz C.
Page 69 and 70: Hippen A., Rosenwinkel K-H., Baumga
Page 71 and 72: Metcalf & Eddy I. (2003). Wastewate
Page 73:
van Niftrik L.A., Fuerst J.A., Sinn
Page 79 and 80:
Appendix B Calculations of N2O emis
Page 81 and 82:
The rN value is calculated with the
Page 83 and 84:
Appendix C Microsensor measurements
Page 85 and 86:
12 090927 Prolonged unaerated perio
Page 87:
12 091016 Continuously operation, D
Page 90 and 91:
350 090921 NH₄-N 350 090922 NH₄
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300 090926 Prolonged unaerated peri
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091010 NOx-N 091013 NOx-N NOx-N (mg
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35 091015 NO₃-N 70 091016 NOx-N 3
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350 091018 NH₄-N 35 091018NO₃-N
Page 100 and 101:
The bacteria performing the microbi
Page 102 and 103:
Typical profiles of how N2O and DO
Page 104 and 105:
12 10 091014 Continously operation,
Page 106:
Mulder A.V.A, Robertson L.A., Kuene
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N2O production in a single stage nitritation/anammox MBBR process

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