Effect of Mechanical Pre-Treatment of the Agricultural Substrates on Yield of Biogas and Kinetics of Anaerobic Digestion
Abstract
:1. Introduction
2. Materials and Methodology
2.1. Substrates
2.2. Laboratory Measurements
2.3. The Method of Anaerobic Digestion
2.4. Cumulative Biogas Production
- Vo—normal volume of biogas, Nml;
- V—read out biogas volume, ml;
- pl—air pressure at the time of reading, hPa;
- pw—pressure of water vapor in the ambient temperature, hPa;
- To—the normal temperature To = 273 K;
- po—normal pressure po = 1013 hPa;
- T—ambient temperature, K.
- Vis—the volume of biogas produced from the inoculum, Nml;
- ΣVis—the total volume of biogas produced from the inoculum, Nml;
- mis—inoculum mass, g;
- mm—weight of inoculum in the control sample, g;
- Vn—net volume of biogas, Nml.
- Vs—unit biogas produced during the experiment;
- M—substrate mass, g;
- TS—total solid, %
- VS—volatile solid, % TS.
2.5. Kinetic Model of Biogas Production
- QB is the cumulative biogas production (Nm3/Mg VS) at time t (day), t is the time (day) over the digestion period, Hmax is biogas production potential (Nm3/Mg VS), Rmax is maximum rate of biogas production (Nm3/Mg VS day) while λ is the lag phase (day) or minimum time between the inoculation and biogas appearance). Kinetic constants Hmax, Rmax, λ and R2 were determined using the non-linear regression and the root mean square error (RMSE) error was estimated. The use of the Gompertz model to describe the test results gave good results at work [15], where the model was characterized by a good fit to the test results. First, the use of the model was dictated by the need to demonstrate the effect of the degree of fragmentation of substrates on fermentation kinetics.
2.6. Measurement Error Analysis and Statistical Analysis
2.7. Data Analysis
3. Results and Discussion
3.1. Substrate Characteristics
3.2. Batch Anaerobic Digestion
3.3. Kinetics of Anaerobic Digestion
4. Discusion
5. Conclusions
Author Contributions
Funding
Conflicts of Interest
References
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Parameter | Inoculum | Maize Cannavaro Silage | Maize Atletico Silage | Sorghum Silage | Beet Silage | Topinambur Silage | Rye Progas Silage | Rye Palazzo Silage | Grass Silage | Tall Wheatgrass Silage |
---|---|---|---|---|---|---|---|---|---|---|
Total solid (TS, %) | 5.9 ± 0.1 | 40.63 ± 4.20 | 37.32 ± 3.51 | 25.81 ± 3.32 | 18.74 ± 2.32 | 21.84 ± 3.33 | 58.20 ± 4.12 | 54.54 ± 4.21 | 17.92 ± 2.34 | 22.25 ± 0.23 |
Volatile solid (VS, % TS) | 76.9 ± 0.12 | 96.92 ± 2.25 | 96.22 ± 2.23 | 93.53 ± 2.43 | 91.41 ± 3.21 | 81.94 ± 2.20 | 86.75 ± 4.21 | 82.11 ± 4.12 | 74.36 ± 2.11 | 87.41 ± 4.21 |
Ash (%) | 1.37 ± 0.10 | 1.28 ± 0.13 | 1.41 ± 0.23 | 1.69 ± 016 | 1.61 ± 052 | 3.94 ± 1.12 | 7.86 ± 0.87 | 9.70 ± 0.32 | 4.59 ± 0.38 | 2.79 ± 0.43 |
pH | 8,8 | 4.4 | 4.3 | 4.4 | 4.0 | 5.3 | 5.2 | 4.9 | 5.6 | 4.8 |
N (% TS) | 7,84 ± 0.11 | 1.59 ± 0.12 | 1.55 ± 0.11 | 1.54 ± 0.09 | 0.98 ± 0.07 | 1.51 ± 0.14 | 1.15 ± 015 | 1.32 ± 0.19 | 2.92 ± 0.21 | 2.14 ± 0.23 |
C (% TS) | 46.3 ± 014 | 45.66 ± 3.21 | 46.25 ± 2.18 | 44.70 ± 1.98 | 40.95 ± 1.98 | 41.00 ± 2.08 | 36.92 ± 2.12 | 29.63 ± 2.17 | 40.46 ± 2.17 | 45.66 ± 2.19 |
C/N | 5.9 | 28.7 | 29.8 | 29.0 | 41.7 | 27.2 | 32.1 | 22.4 | 13.8 | 21.3 |
QB (Nm3/Mg VS) | 212.84 ± 15.2 | 515.61 ± 12.36 | 601.20 ± 22.50 | 586.62 ± 21.14 | 726.14 ± 33.31 | 418.70 ± 25.54 | 473.87 ± 23.16 | 559.18 ± 33.17 | 508.32 ± 32.87 | 667.47 ± 43.12 |
P (g/kg TS) | 9.3 | 3.21 | 1.46 | 1.84 | 1.29 | 2.37 | 1.27 | 1.06 | 2.27 | 1.8 |
P-PO4 (g/kg TS) | 1.8 | 1.34 | 1.24 | 1.28 | 1.26 | 1.35 | 0.37 | 0.51 | 1.29 | 1.67 |
K (g/kg TS) | 94.6 | 7.69 | 6.49 | 12.17 | 11.73 | 25.9 | 8.05 | 8.15 | 31.63 | 20.96 |
Ca (g/kg TS) | 93.6 | 1.56 | 1.76 | 5.26 | 3.94 | 27.69 | 1.62 | 15.8 | 29.95 | 8.44 |
Na (g/kg TS) | 9.9 | 0.4 | 0.55 | 0.91 | 1.71 | 1.26 | 0.87 | 0.75 | 1.23 | 1.14 |
N-NH4 (g/kg TS) | 40.4 | 1.01 | 1.28 | 1.49 | 0.42 | 0.05 | 1.03 | 1.47 | 0.24 | 2.19 |
Hg (mg/kg TS) | 0.0130 | 0.0048 | 0.0050 | 0.0136 | 0.0175 | 0.0528 | 0.0248 | 0.0250 | 0.0580 | 0.0253 |
Zn (mg/kg TS) | 832 | 29.0 | 35.0 | 50.3 | 25.0 | 42.7 | 41.5 | 47.2 | 51.0 | 36.0 |
Pb (mg/kg TS) | 5.54 | 1.38 | 2.09 | 2.12 | 2.43 | 8.26 | 6.94 | 6.74 | 11.6 | 5.26 |
Cd (mg/kg TS) | <0.900 | <0.100 | <0.100 | 0.479 | 0.178 | 0.391 | 0.283 | 0.277 | 0.416 | 0.119 |
Cr (mg/kg TS) | 21.7 | 15.6 | 9.10 | 20.2 | 21.7 | 7.95 | 12.41 | 9.24 | 7.76 | 26.31 |
Cu (mg/kg TS) | 295 | 5.37 | 6.04 | 7.72 | 9.79 | 16.82 | 13.54 | 13.81 | 22.83 | 10.32 |
Ni (mg/kg TS) | 18.5 | 10.70 | 6.45 | 7.11 | 18.6 | 5.01 | 52.3 | 45.92 | 4.74 | 11.90 |
S (g/kg TS) | 5.98 | 1.10 | 1.04 | 1.40 | 1.18 | 1.77 | 1.47 | 1.60 | 2.47 | 2.63 |
Mg (g/kg TS) | 3.46 | 1.39 | 1.53 | 2.05 | 2.24 | 4.86 | 0.801 | 0.825 | 6.42 | 4.24 |
Fe (g/kg TS) | 2.58 | 0.213 | 0.167 | 0.266 | 2.56 | 0.394 | 2.82 | 3.52 | 0.541 | 0.781 |
P (g/kg TS) | 11.4 | 2.68 | 2.66 | 2.25 | 2.23 | 1.61 | 1.24 | 1.47 | 2.35 | 3.26 |
K (g/kg TS) | 45.2 | 8.24 | 7.84 | 17.0 | 16.1 | 39.0 | 10.7 | 10.5 | 3.62 | 29.1 |
Co (g/kg TS) | <0.250 | <0.100 | <0.100 | <0.100 | <0.100 | <0.100 | 0.269 | 0.280 | <0.100 | <0.100 |
Mo (g/kg TS) | <0.480 | 0.705 | 0.557 | 0.579 | 0.958 | 0.629 | 2.01 | 1.12 | 0.801 | 1.93 |
Mn (g/kg TS) | 15.6 | 16.6 | 19.6 | 44.8 | 42.9 | 71.4 | 160 | 164 | 90.3 | 45.3 |
Silages from Substrates | Degree of Fragmenta -tion (mm) | TS (%) | VS (% TS) | Cumulative Biogas Yield QB (Nm3/Mg VS) | Methane Yield (Nm3/Mg VS) | CO2 (%) | CH4/CO2 | VS Removal (%) | pH Initial | pH Final |
---|---|---|---|---|---|---|---|---|---|---|
1.5 | 18.00 | 74.36 | 98.02 ± 32.17 | 46.86 ± 11.2 | 34.02 | 1.68 | 51.2 | 7.12 | 6.06 | |
Grass | 5 | 17.92 | 74.36 | 131.23 ± 31.19 | 63.99 ± 10.02 | 25.30 | 1.87 | 51.7 | 7.21 | 6.12 |
10 | 17.92 | 74.36 | 508.34 ± 32.87 | 298.18 ± 7.02 | 24.68 | 1.92 | 51.9 | 7.27 | 6.13 | |
1.5 | 58.23 | 86.75 | 414.82 ± 21.87 | 206.38 ± 11.73 | 36.48 | 1.52 | 51.5 | 7.18 | 6.14 | |
Rye Progas | 5 | 58.20 | 86.75 | 287.65 ± 22.25 | 148.65 ± 6.24 | 43.75 | 1.14 | 51.9 | 7.25 | 6.19 |
10 | 58.20 | 86.75 | 473.78 ± 23.16 | 259.77 ± 6.75 | 34.30 | 1.67 | 51.9 | 7.22 | 6.12 | |
1.5 | 54.54 | 82.11 | 213.46 ± 31.19 | 111.51 ± 6.78 | 38.84 | 1.32 | 51.3 | 7.14 | 6.12 | |
Rye Palazzo | 5 | 54.54 | 82.11 | 421.49 ± 32.19 | 209.86 ± 11.01 | 37.83 | 1.36 | 51.3 | 7.23 | 6.13 |
10 | 54.54 | 82.11 | 559.11 ± 33.17 | 295.51 ± 9.51 | 35.31 | 1.48 | 51.8 | 7.32 | 6.14 | |
1.5 | 25.81 | 93.53 | 482.96 ± 22.09 | 284.85 ± 6.90 | 39.72 | 1.29 | 51.5 | 7.13 | 6.12 | |
Sorghum | 5 | 25.81 | 93.53 | 649.80 ± 20.98 | 334.22 ± 8.67 | 34.99 | 1.36 | 51.8 | 7.22 | 6.12 |
10 | 25.81 | 93.53 | 586.59 ± 21.14 | 319.88 ± 6.42 | 37.62 | 1.23 | 51.2 | 7.22 | 6.12 | |
1.5 | 22.25 | 87.41 | 501.54 ± 40.25 | 287.03 ± 12.48 | 36.04 | 1.59 | 51.1 | 7.23 | 6.13 | |
Tall Wheatgrass | 5 | 22.25 | 87.41 | 544.06 ± 39.18 | 297.95 ± 12.99 | 35.03 | 1.52 | 51.3 | 7.19 | 6.13 |
10 | 22.25 | 87.41 | 667.36 ± 43.12 | 403.15 ± 13.20 | 34.49 | 1.75 | 51.9 | 7.13 | 6.14 | |
1.5 | 18.74 | 91.41 | 549.66 ± 32.87 | 349.88 ± 9.63 | 35.02 | 1.82 | 52.4 | 7.23 | 6.93 | |
Beet | 5 | 18.74 | 91.41 | 612.37 ± 32.98 | 388.57 ± 10.53 | 34.87 | 1.99 | 52.7 | 7.32 | 6.95 |
10 | 18.74 | 91.41 | 726.12 ± 33.31 | 461.80 ± 9.93 | 34.12 | 2.08 | 52.9 | 7.13 | 6.98 | |
1.5 | 37.32 | 96.22 | 629.35 ± 21.98 | 383.30 ± 6.06 | 36.57 | 1.67 | 51.9 | 7.22 | 6.72 | |
Maize Atletico | 5 | 37.32 | 96.22 | 735.59 ± 21.87 | 413.93 ± 6.75 | 35.97 | 1.76 | 52.7 | 7.22 | 6.83 |
10 | 37.32 | 96.22 | 601.20 ± 22.50 | 362.80 ± 7.50 | 36.54 | 1.61 | 51.8 | 7.23 | 6.72 | |
1.5 | 40.63 | 96.92 | 643.79 ± 11.87 | 392.49 ± 9.60 | 34.98 | 1.60 | 51.9 | 7.13 | 6.62 | |
Maize Cannavaro | 5 | 40.63 | 96.92 | 671.83 ± 13.02 | 356.80 ± 3.36 | 35.89 | 1.51 | 52.6 | 7.32 | 6.68 |
10 | 40.63 | 96.92 | 515.61 ± 12.36 | 313.05 ± 5.55 | 35.44 | 1.58 | 51.7 | 7.22 | 6.62 | |
1.5 | 21.84 | 81.94 | 553.67 ± 26.15 | 291.48 ± 8.97 | 38.07 | 1.38 | 51.8 | 7.23 | 6.13 | |
Topinambur | 5 | 21.84 | 81.94 | 510.43 ± 24.18 | 260.63 ± 7.86 | 35.27 | 1.44 | 51.3 | 7.13 | 6.12 |
10 | 21.84 | 81.94 | 418.70 ± 25.54 | 240.39 ± 8.04 | 40.10 | 1.34 | 52.2 | 7.17 | 6.12 |
Parameters | Correlation Significant for N = 28, p < 0.05 | ||||||
---|---|---|---|---|---|---|---|
Average | Standard Deviation | Degree of Fragmentation | Substrate | Volatile Solid | Biogas Yield | Methane Yield | |
Degree of fragmentation | 8.9107 | 18.3818 | 1.000000 | 0.972036 | 0.326022 | -−0.374277 | 0.878026 |
Substrate | 8.4286 | 18.3251 | 0.972036 | 1.000000 | 0.399170 | −0.349097 | 0.896007 |
Volatile solid | 88.3196 | 7.4841 | 0.326022 | 0.399170 | 1.000000 | 0.462835 | 0.545469 |
Biogas yield | 493.1985 | 179.4309 | −0.374277 | −0.349097 | 0.462835 | 1.000000 | −0.105449 |
Methane yield | 57.4587 | 9.7675 | 0.878026 | 0.896007 | 0.545469 | −0.105449 | 1.000000 |
Substrate | Biogas Prod. Potential Hmax (Nm3/Mg VS) | Max. Rate of Biogas Prod. Rmax (Nm3/Mg VS day) | The Lag Phase λ (day) | Coefficient of Determination R2 | Root Mean Squared Error RMSE |
---|---|---|---|---|---|
Topinambour silage 1.5 mm | 545.84 | 55.60 | 6.93 | 0.998 | 11.78 |
Topinambour silage 5 mm | 497.13 | 54.55 | 6.28 | 0.999 | 12.41 |
Topinambour silage 10 mm | 396.99 | 65.83 | 4.78 | 0.987 | 15.42 |
Rye Progas silage 1.5 mm | 420.81 | 30.97 | 10.21 | 0.999 | 4.74 |
Rye Progas silage 5 mm | 313.82 | 17.28 | 12.19 | 0.999 | 6.04 |
Rye Progas silage 10 mm | 459.79 | 45.36 | 6.95 | 0.989 | 17.91 |
Maize Cannavaro silage 1.5 mm | 639.41 | 83.66 | 5.21 | 0.999 | 7.82 |
Maize Cannavaro silage 5 mm | 647.94 | 102.52 | 4.34 | 0.998 | 18.85 |
Maize Cannavaro silage 10 mm | 485.21 | 59.90 | 6.26 | 0.997 | 15.85 |
Beet silage 1.5 mm | 539.85 | 194.58 | 2.55 | 0.998 | 9.48 |
Beet silage 5 mm | 601.15 | 200.72 | 2.33 | 0.998 | 11.81 |
Beet silage 10 mm | 718.16 | 131.98 | 4.75 | 0.999 | 17.82 |
Grass silage 1.5 mm | 96.70 | 9.26 | 8.38 | 0.999 | 1.18 |
Grass silage 5 mm | 129.79 | 12.29 | 8.60 | 0.997 | 3.06 |
Grass silage 10 mm | 486.63 | 77.08 | 5.46 | 0.998 | 14.05 |
Sorghum silage 1.5 mm | 478.67 | 56.22 | 5.73 | 0.996 | 15.21 |
Sorghum silage 5 mm | 636.28 | 73.79 | 6.42 | 0.999 | 13.52 |
Sorghum silage 10 mm | 567.51 | 71.75 | 5.70 | 0.999 | 20.23 |
Rye palazzo silage 1.5 mm | 216.10 | 20.38 | 7.37 | 0.999 | 4.13 |
Rye palazzo silage 5 mm | 451.32 | 27.39 | 10.68 | 0.998 | 12.50 |
Rye palazzo silage 10 mm | 545.44 | 47.02 | 8.22 | 0.998 | 16.93 |
Tall wheatgrass silage 1.5 mm | 490.73 | 81.66 | 4.44 | 0.999 | 15.62 |
Tall wheatgrass silage 5 mm | 533.11 | 95.25 | 3.97 | 0.998 | 10.62 |
Tall wheatgrass silage 10 mm | 650.83 | 144.29 | 3.62 | 0.999 | 11.72 |
Atletico maize silage 1.5 mm | 625.65 | 88.05 | 5.67 | 0.999 | 9.66 |
Atletico maize silage 5 mm | 715.82 | 114.19 | 4.54 | 0.998 | 15.38 |
Atletico maize silage 10 mm | 579.66 | 77.75 | 6.39 | 0.999 | 13.35 |
Parameters | Kinetic Constants of Biogas Production, N = 28 Correlation Significant for p < 0.05 | ||||||
---|---|---|---|---|---|---|---|
Average | Standard Deviation | Substrate | Degree of Fragmen-tation | Hmax (Nm3/Mg VS) | Rmax (Nm3/Mg VS day) | Lambda, λ | |
Substrate | 8.4286 | 18.3251 | 1.000000 | 0.972036 | −0.405666 | 0.117710 | 0.978675 |
Degree of fragmentation | 8.9107 | 18.3818 | 0.972036 | 1.000000 | −0.385217 | 0.114477 | 0.971377 |
Hmax (Nm3/Mg VS) | 484.6907 | 173.2062 | −0.405666 | −0.385217 | 1.000000 | 0.567290 | −0.497057 |
Rmax (Nm3/Mg VS day) | 76.4400 | 48.5657 | 0.117710 | 0.114477 | 0.567290 | 1.000000 | −0.008957 |
Lambda, λ | 9.6061 | 18.0606 | 0.978675 | 0.971377 | 0.497057 | −0.008957 | 1.000000 |
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Szlachta, J.; Prask, H.; Fugol, M.; Luberański, A. Effect of Mechanical Pre-Treatment of the Agricultural Substrates on Yield of Biogas and Kinetics of Anaerobic Digestion. Sustainability 2018, 10, 3669. https://doi.org/10.3390/su10103669
Szlachta J, Prask H, Fugol M, Luberański A. Effect of Mechanical Pre-Treatment of the Agricultural Substrates on Yield of Biogas and Kinetics of Anaerobic Digestion. Sustainability. 2018; 10(10):3669. https://doi.org/10.3390/su10103669
Chicago/Turabian StyleSzlachta, Józef, Hubert Prask, Małgorzata Fugol, and Adam Luberański. 2018. "Effect of Mechanical Pre-Treatment of the Agricultural Substrates on Yield of Biogas and Kinetics of Anaerobic Digestion" Sustainability 10, no. 10: 3669. https://doi.org/10.3390/su10103669