Evaluating the effect of biochar addition on the anaerobic digestion of swine manure: application of Py-GC/MS

Swine manure mono-digestion results in relatively low methane productivity due to the low degradation rate of its solid fraction (manure fibers), and due to the high ammonia and water content. The aqueous ammonia soaking (AAS) pretreatment of manure fibers has been proposed for overcoming these limitations. In this study, continuous anaerobic digestion (AD) of manure mixed with optimally AAS-treated manure fibers was compared to the AD of manure mixed with untreated manure fibers. Due to lab-scale pumping restrictions, the ratio of AAS-optimally treated manure fibers to manure was only 1/3 on a total solids (TS) basis. However, the biogas productivity and methane yield were improved by 17% and 38%, respectively, also confirming the predictions from a simplified 1st order hydrolysis model based on batch experiments. Furthermore, an improved reduction efficiency of major organic components was observed for the digester processing AAS-treated manure fibers compared to the non-treated one (e.g., 42% increased reduction for cellulose fraction). A preliminary techno-economic analysis of the proposed process showed that mixing raw manure with AAS manure fibers in large-scale digesters could result in a 72% increase of revenue compared to the AD of manure mixed with untreated fibers and 135% increase compared to that of solely manure.

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Crop Yield and Nitrous Oxide Emissions following Swine Manure Application: A Meta‐Analysis

ael ◽

10.2134/ael2019.07.0024 ◽

2019 ◽

Vol 4 (1) ◽

pp. 190024 ◽

Cited By ~ 1

Author(s):

Weiquan Luo ◽

Peter L. O'Brien ◽

Jerry L. Hatfield

Keyword(s):

Nitrous Oxide ◽

Crop Yield ◽

Meta Analysis ◽

Swine Manure ◽

Nitrous Oxide Emissions ◽

Manure Application

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

C – Journal of Carbon Research ◽

10.3390/c6020043 ◽

2020 ◽

Vol 6 (2) ◽

pp. 43 ◽

Cited By ~ 1

Author(s):

Rubén González ◽

Judith González ◽

José G. Rosas ◽

Richard Smith ◽

Xiomar Gómez

Keyword(s):

Anaerobic Digestion ◽

Waste Treatment ◽

Wide Spectrum ◽

Swine Manure ◽

Solid Content ◽

Electricity Production ◽

Plant Design ◽

Heating Value ◽

High Heating Value ◽

Bio Oil

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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