Anaerobic batch digestion of solid potato waste alone and in combination with sugar beet leaves

The objective of this study was to characterise anaerobic batch biodegradation of potato waste alone and when co-digested with sugar beet leaves. The effects of increasing concentration of potato waste expressed as percentage of total solids (TS) and the initial inoculum-to-substrate ratio (ISR) on methane yield and productivity were investigated. The ISRs studied were in the range 9.0-0.25 and increasing proportions of potato waste from 10% to 80% of TS. A maximum methane yield of 0.32 1 CH4/g VSdegraded was obtained at 40% of TS and an ISR of 1.5. A methane content of up to 84% was obtained at this proportion of potato waste and ISR. Higher ISRs led to faster onset of biogas production and higher methane productivity. Furthermore, co-digestion of potato waste and sugar beet leaves in varying proportions was investigated at constant TS. Co-digestion improved the accumulated methane production and improved the methane yield by 31-62% compared with digestion of potato waste alone. (C) 2003 Elsevier Ltd. All rights reserved.