Thermal Conversion of Municipal Biowaste Anaerobic Digestate to Valuable Char

Nisticò, Roberto; Guerretta, Federico; Benzi, Paola; Magnacca, Giuliana; Mainero, Davide; Montoneri, Enzo

doi:10.3390/resources8010024

Cited by 8 publications

(3 citation statements)

References 29 publications

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“…The authors [30] claim that nitrogen heteroatoms in the process of ELT pyrolysis pass mainly into pyrolytic carbon. The municipal biowaste anaerobic digestate of a typical waste treatment plant is pyrolyzed under a mild condition (i.e., 540 • C) to directly yield N-doped biochar without performing any subsequent functionalization process.…”

Section: Discussionmentioning

confidence: 99%

End of Life Tires as a Possible Source of Toxic Substances Emission in the Process of Combustion

et al. 2019

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Several million tons of end of life tires (ELTs) are piled annually as a result of human activities. Various methods have been proposed for the extraction and recycling of the resource potential of ELTs. The chemical composition of ELTs seems to enable their usage as a fuel after mechanical separation of a steel cord. Indeed, in the rubber of ELTs, up to 90 mass% accounts for carbon and hydrogen. Currently, it is by incineration that a significant proportion of ELTs is utilized. However, ELTs contain not only sulfur, which is used for vulcanization, but also nitrogen-containing additives. The behavior of these heteroatoms during oxidation is poorly investigated. It has been shown that the pyrolysis liquid fuel obtained from ELTs contains such sulfur compounds as mercaptans and nitrogen in the form of hydrocyanic acid and cyanogen. Deep oxidation of ELTs results in the oxidation of sulfur compounds to dioxide, but the oxidation products have been found to contain traces of cyanogen. Taking this into account, one should pay attention to the ways of transforming heteroatoms during the process of ELT oxidation and the products of ELT pyrolysis as potential sources of highly toxic gas emissions.

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Section: Discussionmentioning

confidence: 99%

End of Life Tires as a Possible Source of Toxic Substances Emission in the Process of Combustion

et al. 2019

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“…Amongst these valorization options are the recovery of nutrients from digestates by using this liquid effluent as nutrient media for microalgae cultivation or as culture media for plant growth-promoting microorganisms [18][19][20]. Another promising alternative that is less well established is the thermal post-treatment of the solid fraction for producing charred materials [21,22].…”

Section: Introductionmentioning

confidence: 99%

Biochar and Energy Production: Valorizing Swine Manure through Coupling Co-Digestion and Pyrolysis

González

Rosas

et al. 2020

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Anaerobic digestion is an established technological option for the treatment of agricultural residues and livestock wastes beneficially producing renewable energy and digestate as biofertilizer. This technology also has significant potential for becoming an essential component of biorefineries for valorizing lignocellulosic biomass due to its great versatility in assimilating a wide spectrum of carbonaceous materials. The integration of anaerobic digestion and pyrolysis of its digestates for enhanced waste treatment was studied. A theoretical analysis was performed for three scenarios based on the thermal needs of the process: The treatment of swine manure (scenario 1), co-digestion with crop wastes (scenario 2), and addition of residual glycerine (scenario 3). The selected plant design basis was to produce biochar and electricity via combined heat and power units. For electricity production, the best performing scenario was scenario 3 (producing three times more electricity than scenario 1), with scenario 2 resulting in the highest production of biochar (double the biochar production and 1.7 times more electricity than scenario 1), but being highly penalized by the great thermal demand associated with digestate dewatering. Sensitivity analysis was performed using a central composite design, predominantly to evaluate the bio-oil yield and its high heating value, as well as digestate dewatering. Results demonstrated the effect of these parameters on electricity production and on the global thermal demand of the plant. The main significant factor was the solid content attained in the dewatering process, which excessively penalized the global process for values lower than 25% TS.

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“…Even within the material, hemicellulosic, cellulose, lignin, and different grain sizes affect the process of pyrolysis. Concerning this, high heating speed is not necessarily the same as high reaction speed, but there is a complex relation between thermal hysteresis and the propelling from various heating speeds [19,37]. Within slow heating systems, decreasing grain size increases activation energy, which can be attributed to the shape of the molecules [38].…”

Section: Introductionmentioning

confidence: 99%

Modeling of Some Operating Parameters Required for the Development of Fixed Bed Small Scale Pyrolysis Plant

Bacskai

Madar²,

Fogarassy

et al. 2019

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In recent years, we have read a lot of research aimed at creating a small, easy-to-mobilize pyrolysis unit. But these devices were not efficiently designed. According to literature data, small equipment (5.0–50 kW) has to be considered differently on the combustion aspects, compared to a larger pyrolysis unit. The main purpose of our research is to determine the operating characteristics of a small fixed bedding CHP (combined heat and power) pyrolysis power plant. At the design stage, it is also critical to know the properties of the biomass (usually different biological wastes) used on the input side. The use of a wide diversity of biomass waste may result in the volume of material remains and the energy produced is not usable in the right form. To obtain a clear picture of the combustion conditions, a fixed bedding pilot pyrolysis device was made. With the measurements in the experimental apparatus, we have a clearer picture of the changes in some of combustion parameters. We have examined exactly how the size and hardness of biomass materials affect the efficiency of pyrolysis. By modelling the “mass change”—with the knowledge of the material content, physical characteristics, and the parameters of the pyrolysis equipment—the amount of the expected material remains, and combustion conditions can be predicted with a mathematical function. We have found an appropriate mathematical model (R2 = 0.8758) to describe the relationship between gas production and material structure for a given period.

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Thermal Conversion of Municipal Biowaste Anaerobic Digestate to Valuable Char

Cited by 8 publications

References 29 publications

End of Life Tires as a Possible Source of Toxic Substances Emission in the Process of Combustion

End of Life Tires as a Possible Source of Toxic Substances Emission in the Process of Combustion

Biochar and Energy Production: Valorizing Swine Manure through Coupling Co-Digestion and Pyrolysis

Modeling of Some Operating Parameters Required for the Development of Fixed Bed Small Scale Pyrolysis Plant

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