analysis of a pilot-scale anaerobic baffled reactor treating domestic ...

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A net increase in free and saline ammonia was observed between the values measured in the ABR inflow and outflow streams. This was attributed to liberation of organically bound nitrogen during anaerobic digestion (Section 2.1.1.3) (Speece, 1996). Ammonia [mgN/ℓ] 120 100 80 60 40 20 0 Aug00 Sep00 Oct00 Nov00 Dec00 Jan01 Feb01 0 100 200 300 400 Figure 4.7: Phase I: ABR inflow (♦) and outflow (□) free and saline ammonia (NH3+NH4 + ) concentrations. Data for 60 h (red), 32 h (green) and 20 h (blue) T-HRT (timer and PLC control) are shown. Linear trend lines in 32 and 20 h T-HRT periods show increasing outflow free and saline ammonia concentration trend. The amount of free and saline ammonia released appeared to increase over the 32 h T-HRT period (green points in Figure 4.7), then decrease as a result of the change in flow rate on day 205 and subsequently increase again during the 20 h T-HRT period. Regression analysis showed that the upward trend in outflow free and saline ammonia data was significant at the 90% confidence level (P=0.06) the 32 h T-HRT period and highly significant at the 95% confidence level (P=0.006) for the 20 h T-HRT period. These data imply that a decrease in the extent of treatment (i.e. amount of biodegradable material from the feed that is degraded) occurred as a result of the change in feeding rate, but that the extent of treatment increased with time during each of the feeding rate periods. It was observed that at end of 20 h T-HRT, the outlet free and saline ammonia concentration was often greater than the average inflow Total Kjeldahl Nitrogen (TKN) 1 value measured in the WWTP influent wastewater (a value of 42 mgTKN-N/ℓ is reported in the inflow). This value may indicate that solids that had previously accumulated were digested in the 20 h T-HRT period. This implies that micro-organism actively digested solids at a rate faster than they were supplied in this period, and would account for the apparently increasing extent of treatment that is inferred from the data presented. 1 Total Kjeldahl Nitrogen (TKN) is a lumped measurement of free and saline ammonia and organically bound nitrogen. 70 Mar01 Day Apr01 May01 Jun01 60 h HRT 32 h HRT 20 h HRT PLC control Jul01 Aug01 Effluent Influent 0.5
4.3.5 Phosphorus Figure 4.8 presents inflow and outflow phosphorus concentrations for the three operating periods. Total phosphorus analyses, (achieved by pre-digesting samples) were undertaken on samples from the ABR inlet, while analysis of only soluble phosphate was performed on outflow samples. Phosphorus [mgP/ℓ] 25 20 15 10 Figure 4.8: Phase I: ABR total inflow (♦) and soluble outflow (□) phosphate. Data for 60 h (red), 32 h (green) and 20 h (blue) T-HRT (timer and PLC control) are shown. Between day 50 and day 200 outflow phosphorus concentrations were significantly lower than inflow concentrations. This should not be regarded as biological phosphorus removal since a mass balance cannot be calculated from the two dissimilar measurements (soluble and total phosphorus). No significant phosphorus reduction can be expected under ordinary circumstances from an anaerobic system (Speece, 1996). The cause of the low soluble phosphorus concentrations in the outflow from day 50 to 200 is not fully understood. Two possible explanations are: • Low biomass concentration during the early days of operation resulted in little liberation of phosphorus from organically bound forms, thus low soluble phosphorus content would be observed in the outflow. • If a substantial portion of the phosphorus in the inflow is associated with particulate material, then low outflow soluble phosphorus content reflects the hypothesis presented in Section 4.3.2 that during the early days of operation, the predominant treatment mechanism is retention of solid material as opposed to biological reduction of organic material. 4.4 COMPARTMENT DYNAMICS: PHASE I In this section the results of analyses on measurements made within compartments are presented. 4.4.1 Height of sludge bed 5 0 Aug00 Sep00 Oct00 Nov00 Dec00 Jan01 Feb01 0 100 200 300 400 In previous publications of data from this operating period, solids concentration was excluded from presented results since the samples obtained did not represent average compartment conditions (Dama et al., 2002). However, on closer examination, the data were shown to shed light on the mechanism and rate of sludge build-up in the reactor: sludge builds up in earlier compartments sooner than in later 71 Mar01 Day Apr01 May01 Jun01 60 h HRT 32 h HRT 20 h HRT Influent PLC control Jul01 Aug01 Effluent 0.5
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ANALYSIS OF A PILOT-SCALE ANAEROBIC
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i DECLARATIONS I, Katherine Maria F
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My deepest thanks must be extended
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vii TABLE OF CONTENTS ANALYSIS OF A
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5.3 Feed characteristics and loadin
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xi LIST OF TABLES Table 1.1: List o
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xiii LIST OF FIGURES Figure 1.1: Gr
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Figure 5.1 Installation of the ABR
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Figure 6.8: WEST® representation o
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xix LIST OF ABBREVIATIONS A-HRT App
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1 1 INTRODUCTION The work presented
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obtained from anaerobic systems rel
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• Lalbahadur (MTech, 2005) perfor
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1.7 ORGANISATION OF THE THESIS This
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9 2 LITERATURE REVIEW A detailed re
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• Disintegration of composite par
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Homoacetogens are one of the most v
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Most of the control in anaerobic di
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therefore the sensitivity of the ov
Page 43 and 44: ∆Gº (W) [kcal] -10 -8 -6 -4 -2 L
Page 45 and 46: For systems with low potential for
Page 47 and 48: design of the digester in which the
Page 49 and 50: 2.2.2 Expanded granular sludge bed
Page 51 and 52: fact that for most non-ideal flow s
Page 53 and 54: hydrolysis steps to convert them to
Page 55 and 56: from the clarified zone between the
Page 57 and 58: Table 2.4: Typical pathogen surviva
Page 59: Table 2.5: Studies using anaerobic
Page 62 and 63: • There is no requirement for bio
Page 64 and 65: Kennedy and Barriault (2005) perfor
Page 66 and 67: methanogenic (Akunna and Clark, 200
Page 68 and 69: and 6 h with no significant differe
Page 70 and 71: 2.5.1.12 Granule formation in ABRs
Page 72 and 73: • A baffled reactor is described
Page 74 and 75: 2.5.3.4 Scanning electron microscop
Page 76 and 77: spacing on flow patterns in a singl
Page 78 and 79: Figure 3.5: Orthographic projection
Page 80 and 81: PLC calculated the fraction of that
Page 82 and 83: epresent buulk conditionns. Compart
Page 85 and 86: The rreactor was initially commmiss
Page 87 and 88: Phase I Phase II Phase III Phase IV
Page 89 and 90: Table 4.1: Characteristics of degri
Page 91 and 92: Table 4.2: Pilot-scale ABR approxim
Page 93: COD [mgCOD/ℓ] 2000 1800 1600 1400
Page 97 and 98: Observation of sludge in compartmen
Page 99 and 100: Another interesting observation is
Page 101 and 102: 4.4.3 pH pH measurements were perfo
Page 103 and 104: esult in low pH values. The reasons
Page 105 and 106: 4.5 SUMMARY: PHASE I - OPERATION AT
Page 107 and 108: than the optimal range for methanog
Page 109 and 110: 5 EXPERIMENTAL PHASES II-IV: KINGSB
Page 111 and 112: sludge on a number of occasions. Wh
Page 113 and 114: On days 99 and 100 of Phase III, a
Page 115 and 116: 5.3.2 Analysis of variations in fee
Page 117 and 118: Table 5.2: Pilot-scale ABR average
Page 119 and 120: 5.4.1.2 Phase III In Phase III, (Fi
Page 121 and 122: Phase II: Alkalinity [mgCaCO3/ℓ]
Page 123 and 124: Eq. 5-1 However, at a COD/SO4 2- ra
Page 125 and 126: wastewater was probably higher than
Page 127 and 128: 5.5.2.2 Damping Figure 5.12 and Fig
Page 129 and 130: • The outflow COD values were not
Page 131 and 132: • Information about the volume of
Page 133 and 134: As with the total volume of sludge
Page 135 and 136: It is not clear why the rate of acc
Page 137 and 138: most compartments was exactly 6.5,
Page 139 and 140: Soluble COD [mg/ℓ] 600 500 400 30
Page 141 and 142: pathogens and parasites, which may
Page 143 and 144: % Probe of DAPI % Probe of DAPI % P
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later compartments at all. Furtherm
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and 4, with decreasing observations
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• The mechanism of sludge build-u
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Table 5.6: Inflow and outflow chara
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Behling et al. (1997) studied the p
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organisms in previous compartments.
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velocities. Unfortunately, these tw
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Thus for a fixed sludge load, at hi
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sampling was not possible since in
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Wentzel (2006) recommends a COD to
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6.2.1.4 Calculation of CH4 producti
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organically bound N) or that N accu
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All VFA is consumed in the process,
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However, these assumptions are clea
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The calculated pH value is compared
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influent alkalinity will increase d
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The original objective to develop a
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• It was not possible to simulate
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employed for a medium strength wast
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6.6.4 Alternative baffle design Thi
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6.7.3 Monitoring requirements The m
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compartments (Section 6.1.1) pH val
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generally about anaerobic digestion
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7.1.1.6 Effect of sludge age on bio
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7.1.2.4 Critical design parameters
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172
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Batstone D. J., Keller J., Angelida
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Gopala K. G. V. T. (2007). Treatmen
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MacLeod F. A., Guiot S. R. and Cost
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Sasse L. (1998). Decentralised wast
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Wanasen (2003). Upgrading conventio
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METTHODS OFF SAMPLINNG AND ANNALYSI
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3.6 Enumeration of total coliforms
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that the means are the same, or con
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And the significance of the regress
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ADDITIONAL RESULTS 193 APPENDIX A3
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Table A3. 1 cont. Phase I Phase II
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each of the eight compartments were
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3.2 Pathogen indicator organisms A
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APPLIED VS. APPARENT HYDRAULIC RETE
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19 h apparent HRT 14 h apparent HRT
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205 APPENDIX A5 CALCULATION OF SOLI
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i.e. the average SRT of an accumula
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X X = P Inert ⋅ where Xinert is t
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iodegradable organic material may b
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Substituting Eq. A6- 1 in Eq. A6- 7
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1.5 Implementation of steady-state
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X = 7⋅ Y = 7 Z = 7⋅ A = 7⋅ (
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Dama, P., Bell J., Naidoo, V., Foxo
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Lalbahadur T. (2004) Characterisati
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