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

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Because wetlands are passive systems relying on physical, chemical and biological activities occurring in the water, macrophytes, substrates and their respective interfaces, they usually require a larger land area per volume of water to be treated than other conventional wastewater treatment systems. While wastewater spends only a few hours in conventional systems, the retention time is in the order of days in wetland systems. Once built, wetlands are very cheap to operate, requiring minimum maintenance and low ongoing costs. Some of the main benefits of using treatment wetlands include (DLWC, 1998): • lower capital and operating costs; • greater intangible benefits (habitat creation, opportunities for community involvement and environmental education; • greater potential stability and reliability. According to Wallace (2010) some of the drivers for the uptake of constructed wetlands by industries are: the ability, or desire, to trade land for mechanical complexity, which results in substantially less maintenance and operator input; the recognition that industrial contamination is inherently long-term, therefore the operating cost savings offered by wetland systems presents a compelling value proposition for industry; the contamination source is in a remote or difficult to access situation, so the intrinsic stability of wetland ecosystem processes are favourable in terms of regulatory compliance. Considerable research has been conducted into the different areas of constructed wetland for industrial wastewater treatment. Common themes may include influence of plants on treatment, types of media, types of wetland system and wastewater, pollutant removal mechanisms, and others. It has become clear that microbial processes dictate the performance of wetlands designed to treat nitrogen rich wastewaters. There is still a lack of knowledge concerning the nitrogen transforming microbial community composition within constructed wetlands treating fresh and saline industrial wastewaters. Monitoring how these systems perform in large scale industrial applications allows the dataset of systems operating in Australia to increase. Generating performance data is not only essential to wetland modelling and design but also demonstrates the efficacy of such technology. 4
1.4 Scope of this thesis The main research question of this thesis is: can vertical flow constructed wetlands be used to effectively treat nitrogen rich inorganic industrial wastewaters? In order to answer this question, three research themes have been developed, all three themes revolve around the applicability of using VFCWs to treat nitrogen rich inorganic wastewater and stormwater runoff from CSBP Ltd, a chemical and fertiliser manufacturer located in Kwinana, Western Australia. The first theme is the study of nitrification and denitrification in these systems and the characterisation of the bacterial groups responsible for nitrogen transformations, in particular the ammonia oxidising bacteria (AOB) and denitrifying bacteria (DB) present in the substrate. As part of this study the effects of varying NaCl concentrations on nitrification and denitrification and respective bacterial groups were investigated. The second research theme is the use of high organic carbon content industrial wastewaters as low cost external carbon source to improve denitrification and nitrogen removal. The third theme is the performance assessment and optimisation of full scale systems operational at CSBP Ltd. The specific objectives of this study were to: • Verify the feasibility of using VFCWs to remove nitrogen from fresh and saline industrial wastewaters. • Verify the impact of gradual and abrupt increases of NaCl on nitrification efficiency and on AOB in VFCWs. • Characterise the AOB and DB communities in fresh and saline VFCWs supplemented with external carbon. • Determine the suitability of low cost carbon sources to improve nitrate removal in VFCWs. • Design VFCWs systems to achieve nitrification of up to 1600m 3 /day of ammonia rich wastewater. • Monitor nitrogen and heavy metal removal performance in a full scale VF wetlands and how heavy metals distribute in the sediment and plant tissue. 5
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: eneficial as long as the water is t
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 and 30: organically bound N is called ammon
Page 31 and 32: Biochemically equation 2.11 is subd
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
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3.3.3.1 Ammonia removal Ammonia rem
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NH 3-N (mg/L) 160 140 120 100 80 60
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attempted to be answered in one of
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During Phase I, the overall average
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NH3-Nconcentration out (mg/L) Figur
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to the literature, some peaks have
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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
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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
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Table 6.2: Mean (standard deviation
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values are comparable to the Aqua R
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On a dry weight basis, macrophyte r
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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
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on Figure 8.7. Within a year vegeta
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NH3-N Load (kg/d) 900 800 700 600 5
Page 163 and 164:
The same strong positive correlatio
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construction and planting costs, in
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Considering the findings and limita
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Brant A.H., Jagoe C.H., Kelsey-Wall
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Crites, R., Tchobanoglous, G. (1998
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Gorra, R., Coci, M., Ambrosoli, R.
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Kadlec, R.H., Bastiaens, W.V. and U
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eactors. WEFTEC 79th Annual Technic
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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.
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Figure A2: Permeability of the sand
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Treatment 1 wetland Dec-08 Mar-09 A
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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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