Above ground part of common reed to enhance anaerobic co-digestion of farm biomasses: Potential, monitoring and efficiency

• We performed anaerobic co-digestion trials with an experimental reactor.
• A new feeding ratio of cattle slurry, cheese whey and aerial part of Phragmites australis was used.
• No chemicals were used to pH control.
• Stable biogas production conditions were reached at 10% of Phragmites australis in the mix.
• After the feed test a digestate methane yield test was performed.

This paper shows that common reeds used in phytoremediation plants can be successfully disposed of in anaerobic digestion reactors. At mesophilic condition the following were investigated: biogas yield resulting from an anaerobic co-digestion campaign of mixtures of cattle slurry, cheese whey and aboveground biomass of Phragmites australis, rates of production of methane, removal efficiencies of chemical oxygen demand (COD) and bio-methane yield (BMY). The resulting concentration of methane in the biogas was between 53 and 56%. Maximum removal efficiencies for COD was 70%. The mixture of 50% cattle slurry, 40% cheese whey and 10% of aboveground parts of P. australis achieved an organic loading rate (OLR) of 3.3 g-VS/l-d with a methane yield of 241 l-CH4/kg-VS. A high digestate methane potential with a high OLR in the feed was also tested, with a result of 219 l-CH4/kg-VS.