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Chapter 3 Methodology The research work of this dissertation consists of three phases as shown below in Figure 3.1. In the beginning, gas formation potential of simulated OFMSW was investigated in lab-scale set-up. The Phase I and II of this research work, consisting of two separate pilotscale experiments, mainly focused on optimization of dry anaerobic digestion in terms of C/N ratio and organic loading rates respectively. Various operational parameters of digestion (pH, alkalinity, VFA, ammonia) were continuously analyzed to run the digestion process smoothly and their effect on methane production and VS removal were noticed. Similarly, characteristics of digestate from the reactor were also determined continuously. Moreover, in Phase III, various options of digestate management were analyzed from perspective of GHG emissions. Phase I AD Optimization – C/N ratio •Testing simulated substrates with different C/N ratio •Investigation of AD operational parameters •Characterization of digestate (TS, VS, C, N) Gas formation potential test Phase III Digestate Management and GHG Emissions Figure 3.1 Phases of overall research study 44 Phase II AD Optimization – OLR •Testing OLRs of feed of selected C/N ratio •Investigation of AD operational parameters •Characterization of digestate (TS, VS, C) •GHG emission potential of AD feed, raw digestate, stored digestate and cured digestate •GHG emission reduction options for a better digestate management
3.1 Inoculum and Simulations of Waste 3.1.1 Inoculum for anaerobic digestion experiments Inoculum for gas formation potential test was brewery sludge from up-flow anaerobic sludge blanket reactor (UASB), Singha beer factory, Thailand. Inoculum for start -up of Phase I experiment was prepared by blending 50, 25 and 25% (w/w) of cow dung, anaerobically digested food waste and anaerobic brewery sludge from the same UASB as mentioned above. Thailand. Mixed inoculum was characterized with the TS and VS content of 13% and 65 %TS, respectively. Inoculum for start-up of Phase II experiment was prepared by blending 25, 69 and 6% (w/w) of cow dung, anaerobically digested OFMSW and anaerobic brewery sludge from the same UASB. Mixed inoculums had TS and VS content of 9.67% and 67.48 %TS respectively. 3.1.2 Simulations of waste The OFMSW was simulated using food waste, vegetable and fruit waste, leaf waste and office papers collected from their respective sources. The components were individually size reduced up to 25mm using mechanical shredder before mixing. Three feedstocks were prepared with different composition. Feedstock 1 and 2 were used for Phase I experiment while Feedstock 3 was used for Phase II experiment. Mixing composition was varied to achieve the C/N ratio of 27 and 32 for the study purpose. The composition and characteristics of three feedstocks are given in Table 3.1. Table 3.1 Composition and Characteristics of Simulated Feedstock Detail Unit Feedstock 1 Feedstock 2 Feedstock 3 Composition Food waste % FW a 42 40 45 Vegetable waste % FW 45 27 33 Fruit waste % FW 5 20 15 Leaf waste % FW 5 8 - Paper waste % FW 3 5 7 Characteristics Moisture % 79-84 75-85 81-86 TS (range) % 16-21 15-25 14-19 VS (range) %TS 79-90 80-90 84-88 C (avg.) %TS 51.30 52.10 51.20 TKN (avg.) %TS 1.92 1.63 1.61 C/N (avg.) - 26.72 31.96 31.80 a Percentage based on fresh weight. In Feedstock 3, composition was set to achieve C/N ratio of 32 but without the use of leaf waste. Leaf waste was not used in Feedstock 3 to reduce feed TS and to avoid the observed blockage of pump. To ensure the homogenous feedstock supply for anaerobic digestion system, it was prepared in bulk quantities and stored at 5 o C. Every day, required amount of 45
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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: amount of anaerobic fermentation re
Page 57 and 58: ed pump, water circulating jacket,
Page 59 and 60: the reactor was increased from 35°
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
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References Abdullahi, Y. A., Akunna
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Cengel, Y.A. (2003). Heat Transfer
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Forster-Carneiro, T., Pérez, M., R
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Kaparaju, P., Buendia, I., Ellegaar
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Liu, C., Yuan, X., Zeng, G., Li, W.
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Paavola, T. and Rintala, J. (2008).
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Stroot, P. G., McMahon, K. D., Mack
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Zeshan, Karthikeyan, O. P. and Visv
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Fruit and vegetable Waste Closer to
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Figure A-5 Sand drying bed for dewa
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Assumptions Size of the community:
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The flow rate of 0.569 m 3 biogas/h
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Area for 910 kg dry solids = 910 (k
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= 280 m 3 /d x 0.000717 tons/m 3 (D
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Table C-1 Operational Parameters of
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Run Time GPR % CO2 % CH4 Methane Yi
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Appendix D Data of Phase II Pilot E
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Table D-3 Characteristics of Feed a
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Methodology Methodology for for Ene
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Q = Heat transfer rate or heat loss
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Calculation of GHG Emission Potenti
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