Implications of reactor type and conditions on first-order hydrolysis rate assessment of maize silage.
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.
Pabón Pereira
C P
CP
Department of Agrotechnology and Food Sciences, Wageningen University, P.O. Box 8129, 6700 EV, Wageningen, The Netherlands. Claudia.Pabon@wur.nl
Zeeman
G
G
Zhao
J
J
Ekmekci
B
B
van Lier
J B
JB
D001673:Biodegradation, Environmental; D006868:Hydrolysis; D007700:Kinetics; D012820:Silage / Q000032:analysis*; D003313:Zea mays / Q000737:chemistry*