Electrolysis-enhanced co-digestion of switchgrass and cow manure

BACKGROUND Anaerobic digestion of agricultural wastes is a cost effective way for combining resource recovery and methane production. This paper evaluates the co-digestion of cow manure and switchgrass in a completely stirred tank reactor (CSTR) by the electrolysis-enhanced anaerobic digestion (eAD) process. RESULTS The electrodes for water electrolysis were installed directly in an anaerobic digester and were used to create micro-aerobic conditions. Significant gains in process performance and biogas quality were obtained at current densities of 20–25 mA (per digester volume) with a corresponding volumetric energy consumption of 0.07–0.08 Wh . In particular, the COD removal rate was increased from 0.6 to 0.9 g COD d-1, methane production increased by 26%, and H2S content in the biogas declined from 2500–3000 ppm to less than 10 ppm. CONCLUSIONS The improved performance was achieved due to methane production from hydrolytic H2 and possibly due to the enhanced hydrolysis of organic matter. © 2013 Her Majesty the Queen in Right of Canada Journal of Chemical Technology & Biotechnology © 2013 Society of Chemical Industry