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mixed with it. Three replications of this batch test were run with a blank or control run to accomplish the experiment. A reference set-up was also run using cellulose as substrate to check the inoculums activity. The sequential procedure of conducting GP21 test has been described in the Figure 3.4. Figure 3.4 Method teps for gas formation potential test Based on this method (Heerenklage and Stegmann, 2005) and the characteristics of substrates and inoculum (Table 3.2), the substrate to inoculums ratio (S/I ratio) on kg VS basis achieved in the GP21 reactors was 5.55 and 8.10 for feedstock 1 and 2 respectively. Table 3.2 Characteristics of Substrate and Inoculum Used in Gas Formation Potential Test Characteristics Feedstock 1 Inoculum Feedstock 2 Inoculum TS (%) 15.84 5.25 25.11 5.36 VS (%TS) 81.94 44.70 79.31 45.79 3.3.2 Experimental conditions for Phase I pilot experiment In this experiment, the effect of C/N ratio and ammonia-N accumulation was studied on dry anaerobic digestion of OFMSW. Two simulations of OFMSW with different C/N ratio (i.e. feedstock 1 and 2) were used in pilot-scale ITDAR for this experiment. The detail of experimental conditions is given in the following subsections. a) Start-up operation Add 50 g of sample (WM) + 50 mL anaerobic sludge + 200 mL water to all reaction vessels Flush the reaction vessels with N2 gas after connecting with eudiometer filled with barrier solution Incubate the reaction vessels at 35 ºC for 21 days after lag phase Shake the reaction vessels occasionally and take reading of biogas for 21 days regularly The ITDAR was initially loaded with the 410 kg of feedstock 1 and 180 kg of inoculum source i.e., 70 and 30 % (w/w), respectively, to its working volume. With this composition, the S/I ratio (i.e. substrate to inoculums ratio) was 5.2 on kg-VS basis. The temperature of 48
the reactor was increased from 35°C to 55°C with a gradual increment of 2°C per day to avoid reactor upset and was maintained at 55°C throughout the study. The system was operated in a batch mode, without loading any additional feedstock, for first 14 days and denoted as start-up phase. During the initial start-up phase, the system pH was neutralized using commercial caustic soda (NaOH) for quick onset of methanogenesis in ITDAR. The amount of NaOH required for the pH adjustment was calculated based on the simple laboratory tests using 100 mL of digestate from the ITDAR and pH meter. The reactor contents were mixed at the rate of about 1 Ldig/Lreactor vol.d (one liter digestate recirculated per liter reactor volume per day. So Digrr = 1 means that whole contents in reactor is recirculated for one time in a day) to mix up for homogenous distribution of reactor contents in these periods. From day 15 onwards, ITDAR was operated in a continuous mode by loading with the designed feedstocks under different organic loading rate (OLR) as detailed in below sections. Table 3.3 provides the details of OLR, solid retention time (SRT) and digestate recirculation rate (Dig rr) during continuous operation of ITDAR. As the reactor volume was fixed, the increase in waste loading rate i.e., the OLR, in subsequent runs thus decreased the SRT. During these periods, the system was continuously monitored for the fluctuations in process parameters such as biogas, methane, ammonia-N, volatile fatty acids (VFA), alkalinity and pH as well as other digestate parameters (TS, VS, C and N). Table 3.3 Operating Conditions of ITDAR for Phase I Pilot Experiment Run Duration (d) OLR (kg VS/m 3 .d) Solid retention time (d) Digrr (Ldig/Lreactor vol.d) Feedstock 1 (avg. C/N ratio 27) Start-up 1-14 - 14 1.00 1 15-38 0.65 a 153 0.05 2 39-67 1.60 89 0.10 3 68-99 2.60 54 0.19 Feedstock 2 (avg. C/N ratio 32) 4 100-148 4.00 45 0.34 5 149-170 10.65 13 2.12 6 171-215 4.35 29 2.40 7 216-245 7.70 21 2.90 8 246-280 7.30 19 2.96 a Table gives average values of OLR, retention time and recirculation rate for each run. b) Continuous operation with feedstock 1 (C/N ratio of 27) - Run 1 to 3 As detailed in Table 3.3, the feedstock 1 with the C/N ratio of 27 was loaded into ITDAR under different OLR of 0.65 to 2.60 kg VS/m 3 .d in three consecutive runs (1 to 3). Each run was preceded until the biogas yield attained to its steady state, with no further increment, in ITDAR. The SRT of 153 days was given during run 1 to avoid the reactor upset with lower Digrr. In subsequent runs the step-up increase in OLR was studied with decreasing SRT and increasing Digrr. Every time, one part of the fresh feedstock was mixed up with the two parts (wt/wt basis) of digestate collected from the ITDAR before loading. Based on mass balance calculation, specified amount of digestate was removed from the ITDAR. Feeding and digestate withdrawal was done once a day. To balance the moisture loss due to evapo- 49
Page 1 and 2:
DRY ANAEROBIC DIGESTION OF MUNICIPA
Page 3 and 4:
Abstract Global solid waste generat
Page 5 and 6:
2.9 Characteristics of Digestates 3
Page 7 and 8: List of Tables Table Title Page 2.1
Page 9 and 10: 4.20 Layout of conceptual decentral
Page 11 and 12: 1.1 Background Chapter 1 Introducti
Page 13 and 14: The specific objectives of this res
Page 15 and 16: scale plants of the two processes i
Page 17 and 18: acetogens play their part to run th
Page 19 and 20: In dry anaerobic digestion, recycli
Page 21 and 22: process is inhibited and at that po
Page 23 and 24: eported, which increased with time,
Page 25 and 26: acids and increased downfall of pat
Page 27 and 28: performance of a poorly mixed (1 rp
Page 29 and 30: conventional low-solid system at th
Page 31 and 32: supply of the nutrients missing in
Page 33 and 34: 2.6.2 Single-stage continuous syste
Page 35 and 36: single stage systems are DRANCO, Va
Page 37 and 38: of the solid content around 23% TS
Page 39 and 40: Substrate Feed TS (%) Reactor Type
Page 41 and 42: Second is that it has a high water
Page 43 and 44: 2.9 Characteristics of Digestates D
Page 45 and 46: For instance, Mumme et al., (2010)
Page 47 and 48: Comparison of liquid and solid dige
Page 49 and 50: 2.10 Management Aspects of Anaerobi
Page 51 and 52: Figure 2.11 Changing parameters dur
Page 53 and 54: amount of anaerobic fermentation re
Page 55 and 56: 3.1 Inoculum and Simulations of Was
Page 57: ed pump, water circulating jacket,
Page 61 and 62: parts (wt/wt bas is) of digestate c
Page 63 and 64: Sand drying bed (SDB) is simple, ea
Page 65 and 66: 3.4.4 Estimation of GHG emissions i
Page 67 and 68: d) Calculation methods i) CH4 emiss
Page 69 and 70: Table 3.5 Analytical Methods for Va
Page 71 and 72: Biogas production 100X (NmL) Specif
Page 73 and 74: (i.e. 5.2 and 3.04 respectively, pl
Page 75 and 76: getting affected with the presence
Page 77 and 78: feedstock 2 is considered as a sudd
Page 79 and 80: 8.0) at most of the above said time
Page 81 and 82: Table 4.2 Surplus Energy of ITDAR D
Page 83 and 84: VFA 100 X (mg/L) VFA/Alk ratio 200
Page 85 and 86: the VFA concentration increased to
Page 87 and 88: The increase in GPR was almost line
Page 89 and 90: Based on our results, the best oper
Page 91 and 92: Based on this property of digestate
Page 93 and 94: Table 4.5. With curing of digestate
Page 95 and 96: application (after curing) in CH 4
Page 97 and 98: digestion, etc. Moreover, mixing of
Page 99 and 100: Figure 4.20 Layout of conceptual de
Page 101 and 102: Chapter 5 Conclusions and Recommend
Page 103 and 104: 5.2 Recommendations Following are t
Page 105 and 106: References Abdullahi, Y. A., Akunna
Page 107 and 108: Cengel, Y.A. (2003). Heat Transfer
Page 109 and 110:
Forster-Carneiro, T., Pérez, M., R
Page 111 and 112:
Kaparaju, P., Buendia, I., Ellegaar
Page 113 and 114:
Liu, C., Yuan, X., Zeng, G., Li, W.
Page 115 and 116:
Paavola, T. and Rintala, J. (2008).
Page 117 and 118:
Stroot, P. G., McMahon, K. D., Mack
Page 119 and 120:
Zeshan, Karthikeyan, O. P. and Visv
Page 121 and 122:
Fruit and vegetable Waste Closer to
Page 123 and 124:
Figure A-5 Sand drying bed for dewa
Page 125 and 126:
Assumptions Size of the community:
Page 127 and 128:
The flow rate of 0.569 m 3 biogas/h
Page 129 and 130:
Area for 910 kg dry solids = 910 (k
Page 131 and 132:
= 280 m 3 /d x 0.000717 tons/m 3 (D
Page 133 and 134:
Table C-1 Operational Parameters of
Page 135 and 136:
Run Time GPR % CO2 % CH4 Methane Yi
Page 137 and 138:
Appendix D Data of Phase II Pilot E
Page 139 and 140:
Table D-3 Characteristics of Feed a
Page 141 and 142:
Methodology Methodology for for Ene
Page 143 and 144:
Q = Heat transfer rate or heat loss
Page 145:
Calculation of GHG Emission Potenti
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