The biodegradability and first-order hydrolysis coefficient of maize silage have been assessed from batch experiments using different types of inoculum and substrate to inocula (S/I) ratios, and from CSTRs working at different hydraulic retention times (HRTs). In the batch experiments, the assessed maximum biodegradability of the maize silage was 68 (±2.7)% and 73(±2.9)% while the first order hydrolysis was 0.26 (±0.01) and 0.27(±0.02) d−1, using granular and a mixture of granular and suspended inoculum, respectively. In the CSTR experiment biodegradability ranged from 41–65% depending on the HRT applied whereas the calculated first order hydrolysis coefficient was 0.32 d−1. It is concluded that batch experiments can be used to assess first order hydrolysis constants and biodegradability provided that a well balanced inoculum is guaranteed. Further, it is shown that CSTR reactors digesting maize silage and operating at HRTs as low as 20 days can attain 88% of maximum biodegradability as long as pH fluctuations are minimized. 2 mmol NaHCO3 per gram maize silage was calculated to suffice for the purpose.
Implications of reactor type and conditions on first-order hydrolysis rate assessment of maize silage
C. P. Pabón Pereira, G. Zeeman, J. Zhao, B. Ekmekci, J. B. van Lier; Implications of reactor type and conditions on first-order hydrolysis rate assessment of maize silage. Water Sci Technol 1 October 2009; 60 (7): 1829–1836. doi: https://doi.org/10.2166/wst.2009.549
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