Pilot scale fermentation coupled with anaerobic digestion of food waste - Effect of dynamic digestate recirculation

Gottardo, Marco; Mıcoluccı, Federico; Bolzonella, David; Uellendahl, Hinrich; Pavan, Paolo

doi:10.1016/j.renene.2017.07.047

Cited by 66 publications

(42 citation statements)

References 26 publications

(25 reference statements)

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“…A pH value between 5.0 and 6.0 is seen optimal for most substrates, which also correlates with the optimal pH for hydrogen production at 5.5. For the digestion of liquid residues like sludge, alkaline pH between 8.0-11.0 is more suitable as it enhances hydrolysis and inhibits methanogens [32,54]. Some groups also found higher product yields during acidogenesis at pH 10.0 with FW and OFMSW, as presented in Table 2 [55,56].…”

Section: Comparison Of Process Conditions For Hydrolysismentioning

confidence: 98%

“…Butyric type fermentation with high production of acetic acid, butyric acid and hydrogen with dominance of Clostridium is considered best for two-stage AD and can be influenced by process parameters as pH, organic loading rate (OLR), oxidation-reduction potential [29] and hydraulic retention time (HRT) [30,31]. The influence of OLR seems to vary with the substrate, but various groups found that pH > 5.0 favors butyric type fermentation, whereas a lower pH leads to dominance of Lactobacilli producing lactic acid or ethanol metabolism [27,29,32]. Ethanol-type fermentation is observed mostly at pH 4.0-4.5 and may feature high gas production [27,33].…”

Section: Microbial Consortia and The Main Products In A Microbial Hydmentioning

confidence: 99%

“…An effluent tank can be installed between the stages in order to control process conditions, namely, the recirculation ratio and the flow to the second stage. The utilization of effluent instead of chemicals for pH control is a benefit for costs and sustainability [32,73].…”

Section: Recirculation Systemsmentioning

confidence: 99%

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Role of Microbial Hydrolysis in Anaerobic Digestion

2020

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There is a growing need of substrate flexibility for biobased production of energy and value-added products that allows the application of variable biodegradable residues within a circular economy. It can be used to balance fluctuating energy provision of other renewable sources. Hydrolysis presents one of the biggest limitations during anaerobic digestion. Methods to improve it will result in broader process applicability and improved integration into regional material cycles. Recently, one focus of anaerobic digestion research has been directed to systems with a separate hydrolysis–acidogenesis stage as it might be promised to improve process performance. Conditions can be adjusted to each class of microorganisms individually without harming methanogenic microorganisms. Extensive research of separate biomass pretreatment via biological, chemical, physical or mixed methods has been conducted. Nevertheless, several methods lack economic efficiency, have a high environmental impact or focus on specific substrates. Pretreatment via a separate hydrolysis stage as cell-driven biotransformation in a suspension might be an alternative that enables high yields, flexible feeding and production, and a better process control. In this review, we summarize existing technologies for microbial hydrolytic biotransformation in a separate reactor stage and the impacts of substrate, operational parameters, combined methods and process design as well as remaining challenges.

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Section: Comparison Of Process Conditions For Hydrolysismentioning

confidence: 98%

Section: Microbial Consortia and The Main Products In A Microbial Hydmentioning

confidence: 99%

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Role of Microbial Hydrolysis in Anaerobic Digestion

2020

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“…Zuo et al also reported that the effect of recirculation in two‐stage AD of vegetable waste is more pronounce when the system runs at a high OLR (above 2.6 g VS L −1 day −1 ). Digestate recirculation has also been applied at pilot scale, and the results proved that recirculation could stabilize the first‐stage process …”

Section: High‐rate Second‐stage Processmentioning

confidence: 95%

Rapid anaerobic digestion of organic solid residuals for biogas production using flocculating bacteria and membrane bioreactors – a critical review

Wikandari

Taherzadeh

2019

Biofuels Bioprod Bioref

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Anaerobic digestion (AD) is an attractive and sustainable alternative for stabilizing solid organic waste and producing biogas or biomethane. However, it is carried out by slow‐growing bacteria and archaea and it normally demands a hydraulic retention time (HRT) of 20–60 days in the bioreactor. Although high‐rate AD methods and technologies have been developed, they are normally applied to liquid wastes such as wastewater. In this work, the theory and latest developments in high‐rate digestion of organic solid wastes are reviewed. The process is accomplished by running the AD in a two‐stage operation. The first stage involves dissolving the solid materials in water, using robust hydrolytic bacteria. The effluent is then filtered to remove any undigested material, which in some cases contains inhibitory compounds. The filtrate is then fed to bioreactors containing high cell density ADs such as flocculating bacteria (granules) or membrane bioreactors (MBR) to protect the sensitive and very slow‐growing methanogen. Different approaches to overcoming problems faced in the first stage of digestion are proposed in this review. These problems include slow digestion of lignocellulosic biomass or failure of digestion due to inhibition problems for feedstocks containing toxic compounds, and rapid acidification for easily degradable substrates. The principle, technology, benefits and drawbacks, and factors affecting the efficacy of each type of high cell‐density reactor are presented. © 2019 Society of Chemical Industry and John Wiley & Sons, Ltd.

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“…Recently, some authors from dry and semi‐dry AD studies proposed a strategy for pH control, coupling in series the first fermentation process with a second AD process and using the recirculation of the AD effluent, rich in buffer agents, to control the pH in the first stage. Buffering capacity is connected to alkalinity of the anaerobic digestate, which is the equilibrium of carbon dioxide and bicarbonate ions; a recirculation‐controlled approach is necessary indeed.…”

Section: Introductionmentioning

confidence: 99%

Two‐Stage Dry Anaerobic Digestion Process Control of Biowaste for Hydrolysis and Biogas Optimization

Mıcoluccı

Uellendhal

2018

Chem Eng & Technol

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An advanced management system is offered which adapts to most of the two‐stage anaerobic dry treatment plants that do not benefit from a local expert in biowaste treatment. This approach takes advantage of pH sensors to control the process within the optimal range to enhance the hydrolysis and to stabilize and increase the biogas production. By applying automatic pH control in the operational regime by a shift between direct recirculation in the first stage or using digestate of the second stage for percolation, the pH in the first stage could be kept low at pH 5.2 ± 0.2 over the whole operation period. The results demonstrate that the energy efficiency of the two‐stage dry anaerobic digestion process can be significantly increased by controlling the pH in the first stage.

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Pilot scale fermentation coupled with anaerobic digestion of food waste - Effect of dynamic digestate recirculation

Cited by 66 publications

References 26 publications

Role of Microbial Hydrolysis in Anaerobic Digestion

Role of Microbial Hydrolysis in Anaerobic Digestion

Rapid anaerobic digestion of organic solid residuals for biogas production using flocculating bacteria and membrane bioreactors – a critical review

Two‐Stage Dry Anaerobic Digestion Process Control of Biowaste for Hydrolysis and Biogas Optimization

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