Vertical flow constructed wetlands for the treatment of inorganic ...

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NO2 Nitrogen dioxide +4 - NO3 Nitrate ion +5 HNO3 Nitric acid +5 Conventional nitrogen removal is usually achieved biologically by two distinct processes: autotrophic nitrification, the oxidation of ammonia to nitrate (Eqs 2.11, 2.12) and heterotrophic denitrification, the reduction of NO2 - or NO3 - into N2 (Eqs 2.13- 2.15). Other less conventional and recently understood nitrogen removal methods will be discussed later. 2.4.2.1 Nitrification Nitrification has been typically referred to two separate strictly aerobic processes carried out by phylogenetically distinct chemoautotrophic bacterial groups as described below, although it is now recognised that heterotrophic nitrification (Keeney, 1973; Paul and Clark, 1996) and archaeal nitrification (Wuchter et al., 2006) occur and can be of global significance. The first step in nitrification, the oxidation of ammonia to nitrite (Eq 2.11), also called nitritation, is carried out by ammonia oxidising bacteria (AOB). Comparative 16S rRNA sequence analyses of cultured AOB revealed that members of this physiological group are confined to two monophyletic lineages within the class Proteobacteria (Purkhold et al., 2000). One group is affiliated with the gamma- subclass of the class Proteobacteria and includes Nitrosococcus oceani, the other group is affiliated within the beta-subclass of the Proteobacteria and includes the genera Nitrosomonas (including Nitrosococcus mobilis), Nitrosospira, Nitrosolobus and Nitrosovibirio (Purkhold et al., 2000). It has been suggested, however, that Nitrosolobus and Nitrosovibrio should be reclassified within the genus Nitrosospira (Head et al., 1993). NH3 + 1.5O2 � NO2 - + H2O + H + + 84 kcal mol -1 (2.11) Note that 48g of oxygen are necessary for the oxidation of 14g of ammonia nitrogen (3.43gO2/gNH3-N) into nitrite. 18
Biochemically equation 2.11 is subdivided into two reactions (2.12 and 2.13) with hydroxylamine (NH2OH) as an intermediate compound as represented and explained below (Kowalchuk and Stephen, 2001): (A) 2H + + NH3 + 2e - + O2 � NH2OH + H2O (catalysed by AMO) (2.12) (B) NH2OH + H2O � HONO + 4e - + 4H + (catalysed by HAO) (2.13) (C) 2H + + 0.5O2 + 2e - � H2O (electron transport chain, proton motive force) (2.14) The first reaction (A) is catalysed by ammonia monooxygenase (AMO), a membrane bound enzyme and the second (B) is catalysed by hydroxylamine oxidoreductase (HAO), an enzyme associated with the periplasm. In reaction (C) two of the electrons (and H + ) generated by (B) pass via the electron transport chain to the terminal oxidase. The electron transport chain generates a proton motive force necessary for ATP production and therefore cell energy. Two moles of H + are released into the environment lowering the pH of the water. The sum of the three reactions is Eq 2.11 (Kowalchuk and Stephen, 2001). Nitrification of ammonia to nitrate consumes approximately 7.1g of alkalinity (as CaCo3) for each gram of ammonia nitrogen nitrified (USEPA, 1993). The nitrite produced is further oxidised by nitrite oxidising bacteria (NOB) in the second step of nitrification (Eq 2.15). NOB are comprised by the genera Nitrobacter, Nitrospira, Nitrococcus and Nitrospina (Watson et al., 1986; Meicke et al., 1989). The enzyme nitrite oxidoreductase, also know as nitrite dehydrogenase, catalyses nitrate formation (Hagopian and Riley, 1998). NO2 - + 0.5O2 � NO3 - + 17.8 kcal mol -1 (2.15) During the oxidation of nitrite 16g of oxygen are required to oxidise 14g of nitrite nitrogen, (1.14gO2/g NO2 - -N). The final oxygen demand to fully nitrify 1g of NH3- N is therefore 4.57g of O2. Because of this high oxygen demand the elimination of ammonia is of great importance in wastewater treatment in order to prevent oxygen depletion in receiving waters. All chemolithoautotrophs are characterised by the ability to utilise an inorganic chemical substrate (e.g. NH3, NO2 - ) as a source of electrons for the immobilisation of 19
Page 1: Vertical flow constructed wetlands
Page 4 and 5: 1. Journal articles: Items derived
Page 6 and 7: Berryman and Frances Brigg provided
Page 8 and 9: The feasibility of using carbon ric
Page 10 and 11: Table of Contents Items derived fro
Page 13 and 14: 1.1 Industrial wastewaters Chapter
Page 15 and 16: eneficial as long as the water is t
Page 17 and 18: 1.4 Scope of this thesis The main r
Page 19 and 20: Chapter 8 describes the design rati
Page 21 and 22: similar to aerobic ponds, usually s
Page 23 and 24: 2.3 Common uses of constructed wetl
Page 25 and 26: These systems favour settling of su
Page 27 and 28: Total organic carbon (TOC) determin
Page 29: organically bound N is called ammon
Page 33 and 34: oxidised. External carbon sources s
Page 35 and 36: 2009) in FWS wetlands, and also oxy
Page 37 and 38: intensive (Reed et al., 1995). Harv
Page 39 and 40: limited because they only allow the
Page 41 and 42: whose distribution followed a clear
Page 43 and 44: The concentration of heavy metal io
Page 45 and 46: Metal carbonates: When the concentr
Page 47 and 48: and 8.3g Na2SO4/L. The authors attr
Page 49 and 50: therefore were selected for a 97 da
Page 51 and 52: Chapter 3: Salinity impact on nitri
Page 53 and 54: associated with the reduced number
Page 55 and 56: 2000). The theoretical HRT is the a
Page 57 and 58: 3.2.3 Water sampling and analysis W
Page 59 and 60: Table 3.1: Sediment sampling dates
Page 61 and 62: threshold calculation suggested by
Page 63 and 64: 18 days. The plants in T2 wetlands,
Page 65 and 66: Even though known amounts of sea sa
Page 67 and 68: 3.3.3.1 Ammonia removal Ammonia rem
Page 69 and 70: NH 3-N (mg/L) 160 140 120 100 80 60
Page 71 and 72: attempted to be answered in one of
Page 73 and 74: During Phase I, the overall average
Page 75 and 76: NH3-Nconcentration out (mg/L) Figur
Page 77 and 78: to the literature, some peaks have
Page 79 and 80: 3.3.5.2.1 Control wetland TRFLP ana
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% of total peak area 100 90 80 70 6
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% of total peak area 100 90 80 70 6
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3.4 Discussion 3.4.1 Plant health S
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ones reported by Kantawanichkul et
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Chen et al. (2003) observed nitrite
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Ward et al. (2000) found that in th
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Chapter 4: Nitrification and denitr
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Figure 4.1: Experimental set up dem
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of sediment was performed through t
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4.2.7 Data analysis Microsoft Excel
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4.3.2.2 NO3-N Effluent nitrate conc
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The load vs concentration chart pre
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Because the influent pump did not d
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increased during the first two week
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clear seasonal variation in nosZ ge
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4.4 Conclusions The unplanted semi
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Fick 1997; Ingersoll and Baker, 199
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Both systems were planted with nati
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A B C Figure 5.2: A. Containers hol
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5.3.1.1 Implications of storage for
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NO 3-N (mg/L) 100 90 80 70 60 50 40
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COD (mg/L) 600 500 400 300 200 100
Page 125 and 126:
Chapter 6: Heavy metals in a constr
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Figure 6.1: Photo of the constructe
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potassium, phosphorus, sulphur and
Page 131 and 132:
Table 6.2: Mean (standard deviation
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values are comparable to the Aqua R
Page 135 and 136:
On a dry weight basis, macrophyte r
Page 137 and 138:
Chapter 7: Nitrogen removal and amm
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etween the sand surface and 0.3m ab
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profiles were analysed using Genema
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Table 7.1: Monthly total flows, ave
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clones S8-sludge and S9-sand which
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specific 119bp OTU. Even though N.
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Chapter 8: Design and monitoring of
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VF wetlands operated in parallel in
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8.2.1.1.4 Distribution/collection p
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Figure 8.4: Wetland cell 1 on the f
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Figure 8.7: Cell 2 being tested at
Page 159 and 160:
on Figure 8.7. Within a year vegeta
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NH3-N Load (kg/d) 900 800 700 600 5
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The same strong positive correlatio
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construction and planting costs, in
Page 167 and 168:
Considering the findings and limita
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Brant A.H., Jagoe C.H., Kelsey-Wall
Page 171 and 172:
Crites, R., Tchobanoglous, G. (1998
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Gorra, R., Coci, M., Ambrosoli, R.
Page 175 and 176:
Kadlec, R.H., Bastiaens, W.V. and U
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eactors. WEFTEC 79th Annual Technic
Page 179 and 180:
16S rRNA and amoA sequence analysis
Page 181 and 182:
Sun, G. and Austin, D. (2007). Comp
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Wu, Y., Tam, N.F.Y. and Wong, M.H.
Page 185 and 186:
Figure A2: Permeability of the sand
Page 187 and 188:
Treatment 1 wetland Dec-08 Mar-09 A
Page 189 and 190:
Comparison of Surface samples from
Page 191 and 192:
Treatment 1 wetland Mar-09 Figure B
Page 193 and 194:
Appendix C. Complementary results f
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