Impact of anaerobic digestion on organic matter quality in pig slurry

Effects of anaerobic digestion on soil carbon and nitrogen turnover, N emissions, and soil biological activity. A review

“…Regardless of anaerobic digestion, soil C accumulation was similar, although the C org input in the undigested treatment was nearly twice as high as in the anaerobic digestion treatment. These results are in agreement with results reported by Marcato et al (2009) and Sánchez et al (2008). Therefore, it can be concluded that C losses during the anaerobic digestion process are compensated by the lower C degradation after field application of the fertilizer.…”

“…The degree of increase of stable compounds corresponds to the degree of degradation obtained via anaerobic digestion (Asmus et al 1988;Gómez et al 2007a;Thomsen et al 2013) and with the decrease of the biological oxygen demand after field application of the manures Tambone et al 2009;Alburquerque et al 2012a). Characterizations of the C org compounds of digestates by FTIR spectra indicated that anaerobic stabilization of organic matter is mainly due to the buildup of more stable compounds in the dry matter rather than humification processes (Marcato et al 2009). From the available references, it can be concluded that anaerobic digestion has only a minor influence on the total amounts of highly recalcitrant compounds in the organic manures, which basically influences long-term soil organic matter contents and long-term soil fertility.…”

“…During anaerobic digestion, lignin is not degraded, whereas volatile fatty acids (>90 %), cellulose (>50 %), hemicellulose (>80 %), and raw protein are partially degraded (Asmus et al 1988;Molinuevo-Salces et al 2013). Using Fictitious Atomic-Group Separation (FAS) techniques, Marcato et al (2009) reported that the degree of carbon oxidation was lower in undigested pig slurry (0.829) than in digested pig slurry (0.216). The higher oxidation degree of digestate is surprising since they came from a reduced environment (−300 mV).…”

“…−15 % absolute) and an enrichment in thermostable compounds in the range of 32 to 625 %, an increase of the degree of aromaticity (e.g., aromatic lignin by approx. 30-60 %), and an accumulation of long-chain aliphatic components due to the inability of the organisms involved in the digestion process to degrade these kind of materials under anoxic conditions (Table 1), indicating a relative increase of the biological recalcitrance in the digestates compared to the input materials (Cuetos et al 2009;Gómez et al 2005Gómez et al , 2007aGómez et al , b, 2011Marcato et al 2009;Pognani et al 2009;Tambone et al 2009Tambone et al , 2013 by unilateral decomposition of the easier decomposable C compounds. Similar conclusions have been drawn in many other reports by application of soil incubation approaches (e.g., Reinhold et al 1991;Sánchez et al 2008;Thomsen et al 2013).…”

Centrifugation of Digestate: The Effect of Chitosan on Separation Efficiency

“…The energy potential of anaerobic digestion (AD) is of particular importance to those European countries that derive it from the treatment of agricultural by-products, such as food and food processing waste [1], cattle and pig manures, and other biomasses [2]. The residual product of AD (digestate/co-digestate) is either applied directly as fertilizer or treated further by drying, membrane filtration (ultrafiltration and reverse osmosis), or evaporation [3].…”