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Figure A4. 3 shows the significance of correlation for apparent hydraulic retention times between 12 and 18 h. Significance of correlation coefficient, P Figure A4. 3: Significance (P) of correlation coefficient between inflow and outflow alkalinity concentration measurements for apparent hydraulic retention times between 12 h and 18 h. Low values of P indicate increased correlation between inflow and outflow. The blue line indicates the two-tailed 95 % confidence level. Assuming that this methodology for determining apparent hydraulic retention time is reasonable, the most probable correlation between inflow and outflow alkalinity are for an apparent hydraulic retention time of between 14 h and 17 h, with a minimum P value at 16 h. If the value for apparent hydraulic retention is set to less than 12 h or more than 18 h, the correlation coefficient becomes negative (i.e. an increase in inflow concentration is related to a decrease in outflow concentration); therefore these ranges were not considered. 3 CONCLUSION 1 0.8 0.6 0.4 0.2 0 10 12 14 16 18 20 Apparent hydraulic retention time [h] Thus it was tentatively estimated that the apparent hydraulic retention time i.e. the amount of time that the bulk of the liquid flow spent in the pilot-scale ABR, was around 16 h. This value was used when superimposing outlet data over inlet data in Figure 5.12 and Figure 5.13 to show possible correspondence between the data sets. The A-HRT for this period was calculated to be 21.8 h, i.e. the proposed apparent HRT was approximately 75% of the applied HRT. Ideally, these observations should have been confirmed by a tracer study. 204
205 APPENDIX A5 CALCULATION OF SOLIDS RETENTION TIME (SRT) IN STEADY-STATE AND ACCUMULATING SYSTEMS The solids retention time of a system is often regarded as an indicator that can be used to assess the condition of digestion, and diagnose reactor ills. In this section, the concept of sludge age or solids retention time in an accumulating system is considered. 1 ZEEMAN AND LETTINGA MODEL OF SLUDGE AGE Assuming the sludge concentration in the reactor (X), the fraction of the influent suspended solids that is removed in the reactor (R) and the fraction of R that is removed through hydrolysis (H) are known: SRT is defined as the ratio of the sludge concentration in the reactor X [g COD/ℓ] to the (reactor) net sludge production XP [gCOD/ℓ.d] SRT = X X P Eq. A5- 1 The net sludge production is calculated from the OLR [kg COD/m 3 .d] and the fraction of the total COD that is associated with suspended solids fSS = CODss/CODtotal: 1 = OLR ⋅ f ⋅ R ⋅ 1 X P SS ( − H ) Eq. A5- 2 The OLR by definition is the ratio of COD influent concentration CODin [g COD/m 3 ] to the hydraulic retention time HRT [d]: COD OLR = in HRT Eq. A5- 3 Eq. A5- 1, Eq. A5- 2 and Eq. A5- 3 may be solved simultaneously to show that for a desired SRT, the HRT may be calculated by Eq. A5- 4 f SS HRT = ⎛ COD ⎞ ⎜ ⋅ ⋅ R ⋅ in X ⎟ 1 ⎝ ⎠ ( − H ) ⋅ SRT Eq. A5- 4 1 The calculation of excess sludge production does not differentiate between influent suspended solids that accumulate in the reactor and solids that are biomass grown on the hydrolysed COD since these components are measured together in the sludge COD concentration measurement. (Zeeman and Lettinga, 1999)
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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
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∆Gº (W) [kcal] -10 -8 -6 -4 -2 L
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For systems with low potential for
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design of the digester in which the
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2.2.2 Expanded granular sludge bed
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fact that for most non-ideal flow s
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hydrolysis steps to convert them to
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from the clarified zone between the
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Table 2.4: Typical pathogen surviva
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Table 2.5: Studies using anaerobic
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• There is no requirement for bio
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Kennedy and Barriault (2005) perfor
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methanogenic (Akunna and Clark, 200
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and 6 h with no significant differe
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2.5.1.12 Granule formation in ABRs
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• A baffled reactor is described
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2.5.3.4 Scanning electron microscop
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spacing on flow patterns in a singl
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Figure 3.5: Orthographic projection
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PLC calculated the fraction of that
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epresent buulk conditionns. Compart
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The rreactor was initially commmiss
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Phase I Phase II Phase III Phase IV
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Table 4.1: Characteristics of degri
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Table 4.2: Pilot-scale ABR approxim
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COD [mgCOD/ℓ] 2000 1800 1600 1400
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4.3.5 Phosphorus Figure 4.8 present
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Observation of sludge in compartmen
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Another interesting observation is
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4.4.3 pH pH measurements were perfo
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esult in low pH values. The reasons
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4.5 SUMMARY: PHASE I - OPERATION AT
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than the optimal range for methanog
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5 EXPERIMENTAL PHASES II-IV: KINGSB
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sludge on a number of occasions. Wh
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On days 99 and 100 of Phase III, a
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5.3.2 Analysis of variations in fee
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Table 5.2: Pilot-scale ABR average
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5.4.1.2 Phase III In Phase III, (Fi
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Phase II: Alkalinity [mgCaCO3/ℓ]
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Eq. 5-1 However, at a COD/SO4 2- ra
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wastewater was probably higher than
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5.5.2.2 Damping Figure 5.12 and Fig
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• The outflow COD values were not
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• Information about the volume of
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As with the total volume of sludge
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It is not clear why the rate of acc
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most compartments was exactly 6.5,
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Soluble COD [mg/ℓ] 600 500 400 30
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pathogens and parasites, which may
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% 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
Page 178 and 179: The original objective to develop a
Page 180 and 181: • It was not possible to simulate
Page 182 and 183: employed for a medium strength wast
Page 184 and 185: 6.6.4 Alternative baffle design Thi
Page 186 and 187: 6.7.3 Monitoring requirements The m
Page 188 and 189: compartments (Section 6.1.1) pH val
Page 190 and 191: generally about anaerobic digestion
Page 192 and 193: 7.1.1.6 Effect of sludge age on bio
Page 194 and 195: 7.1.2.4 Critical design parameters
Page 196 and 197: 172
Page 198 and 199: Batstone D. J., Keller J., Angelida
Page 200 and 201: Gopala K. G. V. T. (2007). Treatmen
Page 202 and 203: MacLeod F. A., Guiot S. R. and Cost
Page 204 and 205: Sasse L. (1998). Decentralised wast
Page 206 and 207: Wanasen (2003). Upgrading conventio
Page 209 and 210: METTHODS OFF SAMPLINNG AND ANNALYSI
Page 211 and 212: 3.6 Enumeration of total coliforms
Page 213 and 214: that the means are the same, or con
Page 215 and 216: And the significance of the regress
Page 217 and 218: ADDITIONAL RESULTS 193 APPENDIX A3
Page 219 and 220: Table A3. 1 cont. Phase I Phase II
Page 221 and 222: each of the eight compartments were
Page 223 and 224: 3.2 Pathogen indicator organisms A
Page 225 and 226: APPLIED VS. APPARENT HYDRAULIC RETE
Page 227: 19 h apparent HRT 14 h apparent HRT
Page 231 and 232: i.e. the average SRT of an accumula
Page 233: X X = P Inert ⋅ where Xinert is t
Page 236 and 237: iodegradable organic material may b
Page 238 and 239: Substituting Eq. A6- 1 in Eq. A6- 7
Page 240 and 241: 1.5 Implementation of steady-state
Page 242 and 243: X = 7⋅ Y = 7 Z = 7⋅ A = 7⋅ (
Page 244 and 245: Dama, P., Bell J., Naidoo, V., Foxo
Page 246: Lalbahadur T. (2004) Characterisati
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