Integrating anaerobic digestion and slow pyrolysis improves the product portfolio of a cocoa waste biorefinery

Ghysels, Stef; Acosta, Nayaret; Estrada, Adriana Ledezma; Pala, Mehmet; Vrieze, Jo De; Ronsse, Frederik; Rabaey, Korneel

doi:10.1039/d0se00689k

Cited by 39 publications

(18 citation statements)

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“…The integration of different units would allow a complete valorization of resources. This may be the case of integrating digestion and thermal processes, which recently has been subject to extensive research [144][145][146] since the thermal valorization of digested material increases the recovery of energy and valuable products [147,148]. Char obtained from pyrolysis may serve as an adsorbent agent in biogas upgrading [149,150], thus reducing operational costs.…”

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confidence: 99%

Biogas Production from Organic Wastes: Integrating Concepts of Circular Economy

Ellacuriaga

García-Cascallana

Gómez

2021

Fuels

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Anaerobic digestion is traditionally used for treating organic materials. This allows the valorization of biogas and recycling of nutrients thanks to the land application of digestates. However, although this technology offers a multitude of advantages, it is still far from playing a relevant role in the energy market and from having significant participation in decarbonizing the economy. Biogas can be submitted to upgrading processes to reach methane content close to that of natural gas and therefore be compatible with many of its industrial applications. However, the high installation and operating costs of these treatment plants are the main constraints for the application of this technology in many countries. There is an urgent need of increasing reactor productivity, biogas yields, and operating at greater throughput without compromising digestion stability. Working at organic solid contents greater than 20% and enhancing hydrolysis and biogas yields to allow retention times to be around 15 days would lead to a significant decrease in reactor volume and therefore in initial capital investments. Anaerobic digestion should be considered as one of the key components in a new economy model characterized by an increase in the degree of circularity. The present manuscript reviews the digestion process analyzing the main parameters associated with digestion performance. The novelty of this manuscript is based on the link established between operating reactor conditions, optimizing treatment capacity, and reducing operating costs that would lead to unlocking the potential of biogas to promote bioenergy production, sustainable agronomic practices, and the integration of this technology into the energy grid.

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confidence: 99%

Biogas Production from Organic Wastes: Integrating Concepts of Circular Economy

Ellacuriaga

García-Cascallana

Gómez

2021

Fuels

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“…37,39,40,53 Xie et al reported significant quantities of furans and 2-cyclopenten-1-one derivatives, 36 but this was likely due to the holocellulose residues present in lignin. 41 It is also observed that the number of low-molecular-weight ketones decreased in the presence of a catalyst. Light oxygenates, such as esters, carboxylic acids, and alcohols, could be further cracked into NCGs (mainly CO 2 and, to a lesser extent, CH 4 ) through decarboxylation.…”

Section: Resultsmentioning

confidence: 96%

“…For instance, the lignin used by Xie et al presumably contained a significant fraction of residual carbohydrates, 36 evidenced by carbohydrate-derived furans and 2-cyclopenten-1-one in the pyrolysis liquids. 41 Second, the majority of studies performed batch pyrolysis on gram scale. Only one study was found to report catalytic VPU of lignin vapors at lab scale (66−108 g lignin per hour) using H/ZSM-5.…”

Section: Introductionmentioning

confidence: 99%

“…Moreover, some basic characteristics of the used lignin have been omitted. For instance, the lignin used by Xie et al presumably contained a significant fraction of residual carbohydrates, evidenced by carbohydrate-derived furans and 2-cyclopenten-1-one in the pyrolysis liquids . Second, the majority of studies performed batch pyrolysis on gram scale.…”

Section: Introductionmentioning

confidence: 99%

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Ex Situ Catalytic Fast Pyrolysis of Lignin-Rich Digested Stillage over Na/ZSM-5, H/ZSM-5, and Fe/ZSM-5

et al. 2020

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The global increase in lignocellulosic ethanol production goes in tandem with an increase in lignin-rich stillage that remains underutilized to date. Anaerobic digestion could valorize residual (biodegradable) organic fractions into biogas, leaving a lignin-rich digested stillage (LRDS). This LRDS from the lignocellulosic ethanol production has been assessed as a feedstock for slow and fast pyrolysis in earlier studies, with the intention to increase the overall output of useful products or energy carriers from the starting material. While using this lignin-rich feedstock, ex situ catalytic vapor-phase upgrading (VPU) of fast pyrolysis vapors with fractional condensation was conducted over Na/ZSM-5, H/ZSM-5, and Fe/ZSM-5 catalysts. Semicontinuous fast pyrolysis experiments have been carried out at a reaction temperature of 480°C in a mechanically stirred sand bed, which was connected directly to a fixed bed of catalyst particles for ex situ upgrading of the fast pyrolysis vapors. The carbon and mass yields in heavy phase liquids decreased after catalytic VPU (mass: ca. 8−11 wt %; carbon: ca. 11−15 wt %), compared to noncatalytic pyrolysis (mass: ca. 18 wt %; carbon: ca. 23 wt %). However, the yield in specific compounds, that is, alkylphenols and aromatics such as BTX, increased much upon catalytic VPU (especially for Fe/ZSM-5). For Fe/ZSM-5, the concentration in alkylphenols and aromatics was 20.8 wt % on liquid basis and the yield was 1.7 wt % on as-received (a.r.) feedstock basis. For noncatalytic pyrolysis, the concentration in alkylphenols and aromatics was 2.1 wt % (liquid basis) with a yield of 0.4 wt % (a.r. feedstock basis). This study thus demonstrates the potential of (modified) catalysts to upgrade lignin pyrolysis vapors.

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“…This is particularly adequate for centralized treatment plants with no possibility of land digestate disposal. The evaluation of performance under different configurations and types of organic materials has been studied by González-Arias et al [ 156 , 157 ] and Ghysels et al [ 158 ] analyzing the global process performance of digestate pyrolysis and co-pyrolysis with lignocellulosic biomass. Life cycle analysis has also been applied to the integrated approach of digestion and pyrolysis as a treatment option for waste management [ 159 ], indicating a higher conversion rate of the raw material to energy [ 160 ].…”

Section: Technical and Economic Feasibility Of Anaerobic Digestionmentioning

confidence: 99%

Anaerobic Digestion for Producing Renewable Energy—The Evolution of This Technology in a New Uncertain Scenario

Arenas

Pesantes

Carpio

et al. 2021

Entropy

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Anaerobic digestion is a well-known technology with wide application in the treatment of high-strength organic wastes. The economic feasibility of this type of installation is usually attained thanks to the availability of fiscal incentives. In this review, an analysis of the different factors associated with this biological treatment and a description of alternatives available in literature for increasing performance of the process were provided. The possible integration of this process into a biorefinery as a way for producing energy and chemical products from the conversion of wastes and biomass also analyzed. The future outlook of anaerobic digestion will be closely linked to circular economy principles. Therefore, this technology should be properly integrated into any production system where energy can be recovered from organics. Digestion can play a major role in any transformation process where by-products need further stabilization or it can be the central core of any waste treatment process, modifying the current scheme by a concatenation of several activities with the aim of increasing the efficiency of the conversion. Thus, current plants dedicated to the treatment of wastewaters, animal manures, or food wastes can become specialized centers for producing bio-energy and green chemicals. However, high installation costs, feedstock dispersion and market distortions were recognized as the main parameters negatively affecting these alternatives.

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Integrating anaerobic digestion and slow pyrolysis improves the product portfolio of a cocoa waste biorefinery

Abstract: Integrating anaerobic digestion/slow pyrolysis of agricultural residues (cocoa waste) resulted in biogas, biochar and phenolics-rich pyrolysis liquids of superior quality.

Cited by 39 publications

References 62 publications

Biogas Production from Organic Wastes: Integrating Concepts of Circular Economy

Biogas Production from Organic Wastes: Integrating Concepts of Circular Economy

Ex Situ Catalytic Fast Pyrolysis of Lignin-Rich Digested Stillage over Na/ZSM-5, H/ZSM-5, and Fe/ZSM-5

Anaerobic Digestion for Producing Renewable Energy—The Evolution of This Technology in a New Uncertain Scenario

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