TY - JOUR
T1 - Meta-analysis of anaerobic co-digestion of livestock manure in last decade
T2 - Identification of synergistic effect and optimization synergy range
AU - Zhou, Jialiang
AU - Zhang, Yuanhui
AU - Khoshnevisan, Benyamin
AU - Duan, Na
N1 - Funding Information:
This work was supported by the National Natural Science Foundation of China (51861125103) and National Key Research and Development Program (2018YFD0800803).
PY - 2021/1/15
Y1 - 2021/1/15
N2 - The anaerobic co-digestion (AcoD) of organic substrates has reportedly shown synergistic effects, but the current indices used to evaluate the magnitude of such effects cannot well support the findings and in some cases bring about confusion. In this paper, meta-analysis was performed through a database compiled from 124 peer-reviewed articles focused on the AcoD of livestock manure. Six commonly used indices for evaluating synergistic effects were statistically analyzed in order to obtain a representative evaluation index. Moreover, the synergy intervals of substrate mixing were preliminarily analyzed on element and molecular levels using the optimized index. The results indicated that the ratio of experimental values to weighted values is a relatively optimized evaluation index. Methane production and organic degradation were found to be two independent indices, thus both of them should be considered simultaneously when AcoD process is under consideration. From a statistical standpoint, the recommended synergy interval of carbon-nitrogen ratio is 20–27. A higher probability of synergy can be achieved when the lipid/carbohydrate ratio is higher than 0.13, as well as the protein/carbohydrate ratio is greater than 0.26. Moreover, a relatively complete execution strategy of AcoD has been preliminarily proposed in terms of selection of co-substrate, mixing ratio, and synergy evaluation. The results achieved herein would have some biases and uncertainties due to the fact that only few studies explicitly demonstrated carbohydrate forms, especially lignin. Therefore, the evaluated indices should be further verified and improved by including more details about carbohydrate forms.
AB - The anaerobic co-digestion (AcoD) of organic substrates has reportedly shown synergistic effects, but the current indices used to evaluate the magnitude of such effects cannot well support the findings and in some cases bring about confusion. In this paper, meta-analysis was performed through a database compiled from 124 peer-reviewed articles focused on the AcoD of livestock manure. Six commonly used indices for evaluating synergistic effects were statistically analyzed in order to obtain a representative evaluation index. Moreover, the synergy intervals of substrate mixing were preliminarily analyzed on element and molecular levels using the optimized index. The results indicated that the ratio of experimental values to weighted values is a relatively optimized evaluation index. Methane production and organic degradation were found to be two independent indices, thus both of them should be considered simultaneously when AcoD process is under consideration. From a statistical standpoint, the recommended synergy interval of carbon-nitrogen ratio is 20–27. A higher probability of synergy can be achieved when the lipid/carbohydrate ratio is higher than 0.13, as well as the protein/carbohydrate ratio is greater than 0.26. Moreover, a relatively complete execution strategy of AcoD has been preliminarily proposed in terms of selection of co-substrate, mixing ratio, and synergy evaluation. The results achieved herein would have some biases and uncertainties due to the fact that only few studies explicitly demonstrated carbohydrate forms, especially lignin. Therefore, the evaluated indices should be further verified and improved by including more details about carbohydrate forms.
KW - Anaerobic co-digestion
KW - Livestock manure
KW - Meta-analysis
KW - Synergistic effect
U2 - 10.1016/j.apenergy.2020.116128
DO - 10.1016/j.apenergy.2020.116128
M3 - Journal article
AN - SCOPUS:85095955621
SN - 0306-2619
VL - 282
JO - Applied Energy
JF - Applied Energy
IS - pt. A
M1 - 116128
ER -