Performances of anaerobic co-digestion of fruit & vegetable waste (FVW) and food waste (FW): Single-phase vs. two-phase

Abstract

The co-digestion of fruit & vegetable waste (FVW) and food waste (FW) was performed at various organic loading ratios (OLRs) in single-phase and two-phase system, respectively. The results showed that the ethanol-type fermentation dominated in both digestion processes when OLR was at low levels (<2.0g(VS)L-1d-1). The propionic acid was rapidly accumulated as OLR was increased to higher levels (>2.0g(VS)L-1d-1), which could cause unstable anaerobic digestion. Single-phase digestion was better than two-phase digestion in term of 4.1% increase in CH4 production at lower OLRs (<2.0g(VS)L-1d-1). However, at higher level of OLR (≥2.0g(VS)L-1d-1), two-phase digestion achieved higher CH4 production of 0.351-0.455L(gVS)-1d-1, which were 7.0-15.8% more than that of single-phase. Additionally, two-phase digestion presented more stable operation, and higher OLR treatment capacity. Furthermore, comparison of these two systems with bioenergy recovery revealed that two-phase system overall presented higher bioenergy yield than single-phase. © 2013 Elsevier Ltd.