African Journal of
Environmental Science and Technology

  • Abbreviation: Afr. J. Environ. Sci. Technol.
  • Language: English
  • ISSN: 1996-0786
  • DOI: 10.5897/AJEST
  • Start Year: 2007
  • Published Articles: 1047

Full Length Research Paper

Use of effective microorganisms to enhance cost-effective biogas purification at the household level

Selele Minza
  • Selele Minza
  • Department of Environmental Science and Management, School of Environmental Science and Technology (SEST), Ardhi University, P. O. Box 35176, Dar es Salaam, Tanzania.
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Mgana M. Shaaban
  • Mgana M. Shaaban
  • Department of Environmental Engineering, School of Environmental Science and Technology (SEST), Ardhi University, Dar es Salaam, Tanzania.
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Mbuligwe E. Stephen
  • Mbuligwe E. Stephen
  • Department of Environmental Engineering, School of Environmental Science and Technology (SEST), Ardhi University, Dar es Salaam, Tanzania.
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  •  Received: 23 October 2020
  •  Accepted: 15 September 2021
  •  Published: 30 November 2021

Abstract

This study investigated the use of effective microorganisms (EM) to enhance cost-effective biogas purification at household-level application. It involved experimental setups for biogas purification in two different runs: 4 L activated EM and 1 L dormant EM by bubbling biogas through EM purification units. Biogas composition was analyzed using an industry-standard biogas analyzer. The results indicated that EM has the potential for biogas purification through a biological process, to remove H2S and CO2 by involving photosynthetic bacteria (Rhodopseudomonas palustris) in the presence of light. The raw biogas average composition was 62.2% CH4, 37.4% CO2 and 1359.3 ppm H2S. The 4L activated EM batch solution purified the raw biogas to 80.2% CH4, 19.5% CO2 and 786.1 ppm H2S. The corresponding purification efficiencies are 60% for CO2 and 49% for H2S. Purified biogas could be used by the household to cook for 1.82 h (85%) while raw biogas could cover only 55%. The designed biogas purification system can cost only Tshs 91,010/= and purify about 15,000 L of biogas at EM cost of Tshs 9,100/month.

 

Key words: Biogas composition, photosynthetic bacteria, anaerobic digestion, biochemical processes, Rhodopseudomonas palustris, biological desulphurization.