Comparative Analysis of Bacterial and Archaeal Community Structure in Microwave Pretreated Thermophilic and Mesophilic Anaerobic Digesters Utilizing Mixed Sludge under Organic Overloading
Abstract
:1. Introduction
2. Materials and Methods
2.1. Sludge Sample Collection
2.2. Experimental Approach
2.3. Analytical Procedures
2.4. Microbial Community Analysis
2.5. Statistical Analysis
3. Results and Discussion
3.1. Sludge Solubilization by Microwave Pretreatment
3.2. Performance of Bench-Scale Anaerobic Digesters by Microwave Pretreatment
3.2.1. The Relationship between Process Stability and Volatile Fatty Acids Accumulation
3.2.2. The Relationship between Process Stability and Microbial Community Structure
4. Conclusions
Author Contributions
Funding
Acknowledgments
Conflicts of Interest
References
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Parameters | Mixed Sludge Digester Feed (1FPS:TWAS = 33:67% by Volume) | ||
---|---|---|---|
Non-irradiated | 2MW-irradiated | ||
Control (Raw Sludge) | MW 1—80 °C | MW 2—160 °C | |
3TS (% by wt.) | 43.94 ± 0.24 (16) | 3.40 ± 0.35 (16) | 3.37 ± 0.25 (16) |
5VS (% by wt.) | 3.38 ± 0.20 (16) | 2.90 ± 0.33 (16) | 2.87 ± 0.24 (16) |
6Ammonia (mg N/L/%VS by wt.) | 207 ± 51 (3) | 259 ± 54 (3) | 219 ± 18 (3) |
pH (-) | 5.63 ± 0.13 (5) | 5.64 ± 0.05 (5) | 5.52 ± 0.20 (5) |
6Alkalinity (mg as CaCO3/L/%VS by wt.) | 502 ± 116 (3) | 590 ± 38 (3) | 531 ± 106 (3) |
Volatile Fatty Acids (VFAs) | |||
6,7Acetic acid (mg/L/%VS by wt.) | 316 ± 79 (3) | 415 ± 104 (3) | 451 ± 104 (3) |
6,7Propionic acid (mg/L/%VS by wt.) | 241 ± 80 (3) | 337 ± 103 (3) | 322 ± 93 (3) |
6,7Butyric acid (mg/L/%VS by wt.) | 174 ± 64 (3) | 208 ± 86 (3) | 203 ± 66 (3) |
6,7Total VFAs (mg/L/%VS by wt.) | 731 ± 223 (3) | 960 ± 293 (3) | 976 ± 264 (3) |
1MW Pretreatment Conditions | Anaerobic Digester Conditions | ||||
---|---|---|---|---|---|
2Final Temp. (°C) | Holding Time (min) | Mixed Sludge Feed | Digester | Temperature (°C) | 3SRT (days) |
- | - | Control(non-irradiated) | 4T1—Control 5M1—Control | 55 ± 1 35 ± 1 | 6 |
80 | 30 | MW 1—80 °C | T2—80 °C M2—80 °C | 55 ± 1 35 ± 1 | 6 |
160 | 30 | MW 2—160 °C | T3—160 °C M3—160 °C | 55 ± 1 35 ± 1 | 6 |
Sample | Parameter | Frequency |
---|---|---|
Digester influent | ||
Mixed sludge feed | 1TS, 2VS, total & soluble 3COD, pH, alkalinity, ammonia, and total 4VFAs | Upon preparation of feed with fresh substrates (bi-weekly) |
Biopolymers (protein, humic acids, and sugar) | 5Minimum three sets of data | |
Digester Effluent | ||
Digestate | pH | Daily |
TS, VS and total & soluble COD | Every three days | |
Alkalinity, ammonia, and total VFAs | Once a week | |
Biopolymers (protein, humic acids, and sugar) | 5Minimum three sets of data | |
Digester biogas | Biogas volume | Daily |
Biogas composition | Once a week |
Parameters | Mixed Sludge Digester Feed | ||
---|---|---|---|
Non-irradiated | 1MW-irradiated | ||
Control(Raw Sludge) | MW1—80 °C | MW2—160 °C | |
2COD: | |||
CODsoluble (mg/L/%3VS by wt.) | 42107 ± 444 (9) | 2917 ± 349 (9) | 4028 ± 688 (9) |
5The solubilization ratio (%) | 13 ± 0.4 (9) | 19 ± 1.3 (9) | 27 ± 0.8 (9) |
6The fold increase in solubilization (-) | - | 1.5 | 2.1 |
Protein: | |||
Proteinsoluble (mg/L/%VS by wt.) | 30 ± 0.41 (2) | 94 ± 2.1 (2) | 199 ± 1.9 (2) |
The solubilization ratio (%) | 4 ± 0.1 (2) | 20 ± 1.1 (2) | 39 ± 0.1 (2) |
The fold increase in solubilization (-) | - | 4.8 | 9.4 |
Humic acids: | |||
Humic acidssoluble (mg/L/%VS by wt.) | 61 ± 1.3 (2) | 131 ± 8.5 (2) | 276 ± 9.6 (2) |
The solubilization ratio (%) | 8 ± 0.2 (2) | 23 ± 1.2 (2) | 51 ± 1.7 (2) |
The fold increase in solubilization (-) | - | 2.8 | 6.2 |
Sugar: | |||
Sugarsoluble (mg/L/%VS by wt.) | 4.6 ± 0.2 (2) | 8.4 ± 0.6 (2) | 38.4 ± 1.3 (2) |
The solubilization ratio (%) | 0.9 ± 0.1 (2) | 2.1 ± 0.1 (2) | 9.2 ± 0.8 (2) |
The fold increase in solubilization (-) | - | 2.2 | 10.4 |
Parameters | Thermophilic | Mesophilic | ||||
---|---|---|---|---|---|---|
1T1 Control | T2 80 °C | T3 160 °C | 2M1 Control | M2 80 °C | M3 160 °C | |
Retention Time and Loading Conditions | ||||||
3SRT (days) | 6 | 6 | 6 | 6 | 6 | 6 |
4OLR (g 5VS/L/d) | 5.72 ± 0.32 (5)b | 5.12 ± 0.15 (5) | 4.91 ± 0.28 (5) | 5.72 ± 0.32 (5) | 5.12 ± 0.15 (5) | 4.91 ± 0.28 (5) |
OLR (g 6COD/L/d) | 8.71 ± 1.28 (3) | 7.81 ± 0.48 (3) | 7.56 ± 0.33 (3) | 8.71 ± 1.28 (3) | 7.81 ± 0.48 (3) | 7.56 ± 0.33 (3) |
Removal Efficiencies | ||||||
3TS (% by wt.) | 445 ± 2.5 (9) | 44 ± 2 (9) | 46 ± 4 (9) | 38 ± 3.7 (9) | 40 ± 2.1 (9) | 45 ± 2.4 (9) |
5VS (% by wt.) | 52 ± 3.0 (9) | 52 ± 2.4 (9) | 54 ± 3.8 (9) | 45 ± 3.6 (9) | 47 ± 1.8 (9) | 53 ± 2.4 (9) |
Methane Production | ||||||
6Daily specific methane yield (mL CH4/g VSfed) | 319 ± 17 (32) | 317 ± 16 (32) | 318 ± 17 (32) | 346 ± 18 (32) | 369 ± 16 (32) | 384 ± 25 (32) |
CH4 content in the biogas (%) | 65.3 ± 0.8 (4) | 65.4 ± 1.1 (4) | 64.9 ± 0.7 (4) | 65.8 ± 0.3 (4) | 66.9 ± 0.4 (4) | 65.1 ± 1.0 (4) |
Digestate (Effluent) Characteristics | ||||||
pH (-) | 8.0 ± 0.04 (32) | 7.8 ± 0.03 (32) | 7.7 ± 0.07 (32) | 7.4 ± 0.02 (32) | 7.3 ± 0.03 (32) | 7.4 ± 0.04 (32) |
VS (% by wt.) | 1.64 ± 0.1 (9) | 1.46 ± 0.1 (9) | 1.37 ± 0.1 (9) | 1.87 ± 0.1 (9) | 1.63 ± 0.1 (9) | 1.45 ± 0.1 (9) |
Digestate Supernatant Characteristics | ||||||
Alkalinity (mg/L/% VS by wt. as CaCO3) | 2888 ± 109 (3) | 2440 ± 192 (3) | 2589 ± 392 (3) | 1990 ± 164 (3) | 1850 ± 84 (3) | 2220 ± 275 (3) |
Ammonia (mg N/L/% VS by wt.) | 781 ± 32 (3) | 709 ± 107 (3) | 798 ± 158 (3) | 538 ± 2.3 (3) | 504 ± 44 (3) | 636 ± 85 (3) |
7CODsoluble (mg/L/% VS by wt.) | 2474 ± 263 (5) | 2906 ± 175 (5) | 4535 ± 687 (5) | 515 ± 74 (5) | 488 ± 50 (5) | 1452 ± 179 (5) |
8Total 9VFAs (mg/L/%VS by wt.) | 607 ± 219 (5) | 1031 ± 253 (5) | 1341 ± 297 (5) | 27 ± 4 (5) | 25 ± 3 (5) | 104 ± 13 (5) |
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Kor-Bicakci, G.; Ubay-Cokgor, E.; Eskicioglu, C. Comparative Analysis of Bacterial and Archaeal Community Structure in Microwave Pretreated Thermophilic and Mesophilic Anaerobic Digesters Utilizing Mixed Sludge under Organic Overloading. Water 2020, 12, 887. https://doi.org/10.3390/w12030887
Kor-Bicakci G, Ubay-Cokgor E, Eskicioglu C. Comparative Analysis of Bacterial and Archaeal Community Structure in Microwave Pretreated Thermophilic and Mesophilic Anaerobic Digesters Utilizing Mixed Sludge under Organic Overloading. Water. 2020; 12(3):887. https://doi.org/10.3390/w12030887
Chicago/Turabian StyleKor-Bicakci, Gokce, Emine Ubay-Cokgor, and Cigdem Eskicioglu. 2020. "Comparative Analysis of Bacterial and Archaeal Community Structure in Microwave Pretreated Thermophilic and Mesophilic Anaerobic Digesters Utilizing Mixed Sludge under Organic Overloading" Water 12, no. 3: 887. https://doi.org/10.3390/w12030887