| Title |
Energetic Valorization of Cereal and Exhausted Coffee Wastes Through Anaerobic Co-digestion With Pig Slurry |
| ID_Doc |
15004 |
| Authors |
Sousa, S; Duarte, E; Mesquita, M; Saraiva, S |
| Title |
Energetic Valorization of Cereal and Exhausted Coffee Wastes Through Anaerobic Co-digestion With Pig Slurry |
| Year |
2021 |
| Published |
|
| DOI |
10.3389/fsufs.2021.642244 |
| Abstract |
In the past years, there has been steady growth in work relating to improve resource efficiency through waste minimization and bioenergy recovery to mitigate climate change. Agro-food industries produce large amounts of bio-waste, challenging innovative energetic valorization strategies in the framework of circular economy principles. Anaerobic digestion (AD) technology is an interesting route to stabilize organic matter and produce biogas as a renewable energy source. This study involves continuous co-digestion of pig slurry (PS), cereal and exhausted coffee wastes (CECW) performed in a continuously stirred tank reactor, with a hydraulic retention time (HRT) of 16 days under at mesophilic conditions (36.9 +/- 0.3 degrees C). The experimental trials, were designed to include different cereal and exhausted coffee liquor (CECL) shares in the feeding mixture, corresponding to different PS to CECL ratios (PS:CECL), respectively: 100:0 (T0), 90:10 (T1), 80:20 (T2), and 70:30 (T3), in terms of percentage of inlet feeding rate (v:v). The results obtained for the feeding rate (70:30) yield to the highest specific methane production (SMP = 341 ml.gVS(-1)) led to a 3.5-fold improvement in comparison with the reference scenario. The synergetic effect between the microbial consortia of PS and the high carbon to nitrogen ratio (C/N) of CECL explain the improvements achieved. The maximum soluble chemical oxygen demand (SCOD) reduction (84.0%) due to the high content and soluble chemical oxygen demand to total chemical oxygen demand ratio (SCOD/TCOD) corroborate the results achieved. The digester stability, evaluated by specific energetic loading rate, was below the limit (0.4 d(-1)). Results from ANOVA showed a significant effect of CECL on the resulting GPR and SMP values. Additionally, Tukey's "Honest Significant Difference" method, confirmed statistically significant differences between the trials T3-T0, T3-T1, T3-T2, and T2-T0. Thus, co-digestion of PS and of CECL seems to be a promising approach for bioenergy recovery and promoting biowastes circularity. |
| Author Keywords |
anaerobic co-digestion; cereal and exhausted coffee wastes; pig slurry; biogas production; waste management; biowastes circularity |
| Index Keywords |
Index Keywords |
| Document Type |
Other |
| Open Access |
Open Access |
| Source |
Science Citation Index Expanded (SCI-EXPANDED) |
| EID |
WOS:000639813300001 |
| WoS Category |
Food Science & Technology |
| Research Area |
Food Science & Technology |
| PDF |
https://www.frontiersin.org/articles/10.3389/fsufs.2021.642244/pdf
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