Effect of Mixing Regimes on Cow Manure Digestion in Impeller Mixed, Unmixed and Chinese Dome Digesters

Abiodun O. Jegede, Grietje Zeeman and Harry Bruning
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Abiodun O. Jegede: Centre for Energy Research and Development, Obafemi Awolowo University, 220282 Ile-ife, Nigeria
Grietje Zeeman: sub-Department Environmental Technology, Wageningen University and Research, 6708 WG Wageningen, The Netherlands
Harry Bruning: sub-Department Environmental Technology, Wageningen University and Research, 6708 WG Wageningen, The Netherlands

Energies, 2019, vol. 12, issue 13, 1-14

Abstract: This study examines the effect of mixing on the performance of anaerobic digestion of cow manure in Chinese dome digesters (CDDs) at ambient temperatures (27–32 °C) in comparison with impeller mixed digesters (STRs) and unmixed digesters (UMDs) at the laboratory scale. The CDD is a type of household digester used in rural and pre-urban areas of developing countries for cooking. They are mixed by hydraulic variation during gas production and gas use. Six digesters (two of each type) were operated at two different influent total solids (TS) concentration, at a hydraulic retention time (HRT) of 30 days for 319 days. The STRs were mixed at 55 rpm, 10 min/hour; the unmixed digesters were not mixed, and the Chinese dome digesters were mixed once a day releasing the stored biogas under pressure. The reactors exhibited different specific biogas production and treatment efficiencies at steady state conditions. The STR 1 exhibited the highest methane (CH 4 ) production and treatment efficiency (volatile solid (VS) reduction), followed by STR 2. The CDDs performed better (10% more methane) than the UMDs, but less (approx. 8%) compared to STRs. The mixing regime via hydraulic variation in the CDD was limited despite a higher volumetric biogas rate and therefore requires optimization.

Keywords: mixing; Chinese dome digester; impeller mixed digester; unstirred digester; hydraulically mixed; total solids (TS) concentration (search for similar items in EconPapers)
JEL-codes: Q Q0 Q4 Q40 Q41 Q42 Q43 Q47 Q48 Q49 (search for similar items in EconPapers)
Date: 2019
References: View references in EconPapers View complete reference list from CitEc
Citations: View citations in EconPapers (2)

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