Drying of biogas digestate: A review with a focus on available drying techniques, drying kinetics, and gaseous emission behavior

Salamat, Razieh; Scaar, Holger; Weigler, Fabian; Berg, Werner; Mellmann, Jochen

doi:10.1080/07373937.2020.1781879

Cited by 29 publications

(9 citation statements)

References 86 publications

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“…It is well known that drying can substantially alter the quality and physicochemical characteristics of DOC, e.g. , in soil and aquatic sediment samples 26 , 27 , but information regarding the drying effect on anaerobic sludge is limited to a few studies 28 – 30 , with no study evaluating the drying effect on DOC in terms of microbes. Nevertheless, Knoop et al (2018) observed a decrease in DOC during drying in anaerobic digesters operating with municipal organic waste.…”

Section: Resultsmentioning

confidence: 99%

Absence of oxygen effect on microbial structure and methane production during drying and rewetting events

Liu

Yekta

et al. 2022

Sci Rep

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Natural environments with frequent drainage experience drying and rewetting events that impose fluctuations in water availability and oxygen exposure. These relatively dramatic cycles profoundly impact microbial activity in the environment and subsequent emissions of methane and carbon dioxide. In this study, we mimicked drying and rewetting events by submitting methanogenic communities from strictly anaerobic environments (anaerobic digestors) with different phylogenetic structures to consecutive desiccation events under aerobic (air) and anaerobic (nitrogen) conditions followed by rewetting. We showed that methane production quickly recovered after each rewetting, and surprisingly, no significant difference was observed between the effects of the aerobic or anaerobic desiccation events. There was a slight change in the microbial community structure and a decrease in methane production rates after consecutive drying and rewetting, which can be attributed to a depletion of the pool of available organic matter or the inhibition of the methanogenic communities. These observations indicate that in comparison to the drying and rewetting events or oxygen exposure, the initial phylogenetic structure and the organic matter quantity and quality exhibited a stronger influence on the methanogenic communities and overall microbial community responses. These results change the current paradigm of the sensitivity of strict anaerobic microorganisms to oxygen exposure.

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Section: Resultsmentioning

confidence: 99%

Absence of oxygen effect on microbial structure and methane production during drying and rewetting events

Liu

Yekta

et al. 2022

Sci Rep

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“…Strict regulations imposed by the European Union (EU) with the target of reducing greenhouse gas (GHG) emissions oblige the biogas plant operators to manage digestate more properly. [8] The relative commitment can be achieved as obtaining an efficient drying process with regards to both energy consumption and emission is not possible. The important step needs to be taken along with efforts to the introduction of efficient drying process-digestate marketability as operators lose the desire to pay for digestate treatment due to lack of potential market for digestate.…”

Section: Drying Of Biogas Digestatementioning

confidence: 99%

Critical reviews for facilitating innovations and advances in drying science and technology

Shirkole¹,

Thorat²,

Mujumdar³

2021

Drying Technology

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“…The studies reported that thermal digestion offering quick removal of moisture, eliminating the pathogens and converting organics to produce nutrient-rich end product, could prove to be a viable technique for the rapid conversion of FW into value-added fertiliser (O’Connor et al, 2022; Saha et al, 2021; Salamat et al, 2022). However, being a novel concept, the thermal digestion process was not explored earlier wherein the optimisation of its process parameters is extremely important to save time and energy required for efficient digestion of FW.…”

Section: Introductionmentioning

confidence: 99%

Optimisation of process parameters of a thermal digester for the rapid conversion of food waste into value-added soil conditioner

Kumar

Gupta

Yadav³

2023

Waste Manag Res

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A novel thermal digester for converting food waste (FW) into nutrient-rich soil conditioner was designed and explored. The process variables, that is, temperature, the volume of the digestion chamber and the rotational speed of the digester were optimised using response surface methodology (RSM). The study revealed that the digester temperature of 150°C and rotational speed of 40 RPM required minimum time (180 minutes) for attaining the equilibrium moisture with a minimum energy consumption of 0.218 kWh kg−1. The process resulted in 80 ± 2.5% reduction in total volume of the FW. Detailed characterisation revealed that the end product was comparable to the organic fertiliser as per the Fertiliser Association of India norms. The digestion helps in breakdown of cellulose content of FW into hemicellulose which supports formation of primary and secondary walls, seed storage carbohydrates, and facilitates plant growth. 1H-Nuclear magnetic resonance (1H-NMR) spectra of the end product revealed mineralisation of organics during digestion. Decrease in ultraviolet (UV) absorbance value at 280 nm also revealed the humification of the end product. X-ray diffraction (XRD) analysis disclosed extremely low crystallinity and non-recalcitrant nature of the end product. A low humification index value (HI-3.43), high fertilising index (FI-4.8), and clean index (CI-5.0) revealed that the end product could safely be utilised as an organic fertiliser. The cost–benefit analysis revealed that thermal digestion technique is profitable and economically viable with benefit–cost ratio (BCR) of 1.35. The study offers a unique approach for the rapid and hassle-free production of value-added soil conditioner from FW.

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Drying of biogas digestate: A review with a focus on available drying techniques, drying kinetics, and gaseous emission behavior

Cited by 29 publications

References 86 publications

Absence of oxygen effect on microbial structure and methane production during drying and rewetting events

Absence of oxygen effect on microbial structure and methane production during drying and rewetting events

Critical reviews for facilitating innovations and advances in drying science and technology

Optimisation of process parameters of a thermal digester for the rapid conversion of food waste into value-added soil conditioner

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