Stable operation during pilot-scale anaerobic digestion of nutrient-supplemented maize/sugar beet silage.
Biogas production from maize/sugar beet silage was studied under mesophilic conditions in a continuous stirred tank reactor pilot-scale process. While energy crop mono-digestion is often performed with very long hydraulic retention times (HRTs), the present study demonstrated an efficient process operating with a 50-day HRT and a corrected total solids (TS(corr)) based organic loading rate of 3.4 kg/m(3)d. The good performance was attributed to supplementation with both macro- and micronutrients and was evidenced by good methane yields (318 m(3)/ton TS(corr)), which were comparable to laboratory maximum expected yields, plus low total volatile fatty acid concentrations (<0.8 g/L). A viscoplastic and thixotropic digester fluid behaviour was observed, and the viscosity problems common in crop mono-digestion were not seen in this study. The effluent also complied with Swedish certification standards for bio-fertilizer for farmland application. Nutrient addition thus rendered a stable biogas process, while the effluent was a good quality bio-fertilizer.
Department of Biotechnology, Lund University, P.O. Box 124, SE-221 00 Lund, Sweden. Nges.Ivo_Achu@biotek.lu.se
Ivo Achu
IA
Nges
Annika
A
Björn
Lovisa
L
Björnsson
D000693:Anaerobiosis; D027461:Beta vulgaris / Q000737:chemistry*; D001709:Biotechnology / Q000295:instrumentation / Q000379:methods*; D018556:Crops, Agricultural / Q000378:metabolism; D005232:Fatty Acids, Volatile / Q000032:analysis; D005308:Fertilizers; D005502:Food; D006863:Hydrogen-Ion Concentration; D008697:Methane / Q000378:metabolism; D010100:Oxygen / Q000032:analysis; D010865:Pilot Projects; D012212:Rheology; D012820:Silage / Q000032:analysis*; D014783:Viscosity; D014835:Volatilization; D003313:Zea mays / Q000737:chemistry*
D005232:Fatty Acids, Volatile; D005308:Fertilizers; D008697:Methane; D010100:Oxygen