Experimental research of efficiency of semi-continuous and periodic biogas production processes by using chicken manure bioloadings

Abstract

Semi‐continuous and periodic biogas production processes were investigated. Dry chicken manure containing 40.0 ± 0.5% volatile solids (VS) was used for the production of bioloading. Semi‐continuous operation bioreactor and periodic bioreactor were used to implement research. Bioloading was additionally supplemented with newly prepared parts by removing 10% of decomposed mass and by adding the same amount of preheated mass every 7 days (semi‐continuous process). The process was periodic when the mass was completely decomposed (after 45 days of the experiment) and fully removed (bioreactor was loaded with a new portion of raw material to 100% of the working volume again). Total duration of both experiments was 90 days. The results show that biogas production by semi‐continuous process is more effective than periodic process due to higher total biogas yield (up to 39.7%) and higher methane yield (up to 33.5%). The maximum concentration of CH4 was determined during the periodic biogas production process, but the difference was only up to 2.1% (68.9% and 66.8%, respectively). Since the produced biogas had quite high average CO2 and H2S concentrations (<40.0% and 2.1 g/m3, respectively), it is recommended to use filter–adsorbers or biofilters. According to the results, semi‐continuous type bioreactor is more effective than periodic.