Energy-efficient enrichment of bioslurry and methane content of biogas from wheat flour in a bio-electrochemical anaerobic digester

The methane-rich biogas resulting from an anaerobic digester (AD) was utilized as a potential source of energy, whereas the bioslurry, due to its rich nutrients content, was explored as a fertilizer.The effect of a bio-electrochemical system (BES) integrated with a conventional anaerobic digester (AD) for biogas enrichment is widely reported.This paper presents a comparative study of the characteristics of bioslurry resulting from two different digestors, i.e., only-AD and AD-BES.In contrast to only-AD, AD-BES-derived bioslurry showed a significant increase in nitrogen, phosphorus and potassium content to the tune of 14.29%, 37.04% and 19.26%, respectively.Moreover, it showed an increment in pH and reduction of total solid, volatile solid, C:N ratio.This paper also includes a comparison of two different methods for analyzing methane and carbon dioxide concentration in the biogas, i.e., statistical analysis-based method using ORSAT apparatus and gas chromatographic (GC) method.The comparison showed little difference in methane and carbon dioxide concentrations between the two methods (1.66 % and 2.79%, respectively).The comparison of the energy requirement (kWh) of AD-BES and of other methane-enriching conventional methods demonstrated a noteworthy reduction in energy requirement of AD-BES (43-90%).The results showed that AD-BES provides significantly enriched nutrients of bioslurry, and increased the concentration of methane in the biogas at lower energy requirement.