International Journal of
Physical Sciences

  • Abbreviation: Int. J. Phys. Sci.
  • Language: English
  • ISSN: 1992-1950
  • DOI: 10.5897/IJPS
  • Start Year: 2006
  • Published Articles: 2572

Full Length Research Paper

Comparative study of the effect of different pretreatment methods on biogas yield from water Hyacinth (Eichhornia Crassipes)

A. U. Ofoefule1, E. O. Uzodinma1 and O. D. Onukwuli2
1Biomass Unit, National center for Energy Research and Development, Nsukka, University of Nigeria. 2Department of Chemical Engineering, Nnamdi Azikiwe University, Awka, Anambra State, Nigeria.
Email: [email protected]

  •  Accepted: 08 July 2009
  •  Published: 30 September 2009


A comparative study of the effect of different pre-treatment methods on the biogas yield from Water Hyacinth (WH) was carried out. The WH  charged into metallic prototype digesters of 121 L capacity were pre-treated as: dried and chopped alone (WH-A), dried and treated with KOH (WH-T), dried and combined with cow dung (WH-C), while the fresh water Hyacinth (WH-F) served as control. They were all subjected to anaerobic digestion to produce biogas for a 32 day retention period within a mesophilic temperature range of 25 to 36°C. The results of the study showed highest cumulative biogas yield from the WH-C with yield of 356.3 L/Total mass of slurry (TMS) while the WH-T had the shortest onset of gas flammability of 6 days. The mean biogas yield of the fresh Water Hyacinth (WH-F) was 8.48 ± 3.77 L/TMS. When the water Hyacinth was dried and chopped alone (WH-A), dried and treated with KOH (50% w/v) (WH-T) and dried and combined with cow dung (WH-C), the mean biogas yield increased to 9.75 ± 3.40 L/TMS, 9.51 ± 5.01 L/TMS and 11.88 ± L/TMS respectively. Flammable biogas was produced by the WH-F from the 10th day of the digestion period whereas the WH-A, WH-T and WH-C commenced flammable gas production from the 9th, 6th and 11th day respectively. Gas analysis from WH-F shows Methane (65.0%), CO(34.94%). WH- A contained Methane (60.0%), CO2 (39.94%). WH-T contained Methane (71.0%), CO2 (28.94%), while WH-C had Methane (64.0%) CO2 (35.94%). The other gases were found in the same levels and in trace amounts in all the systems. The overall results showed that treating water Hyacinth with chemical did not have a significant improvement on the biogas yield. It also indicated that water Hyacinth is a very good biogas producer and the yield can be improved by drying and combining it with Cow dung.


Key words: Water hyacinth, biogas production, pre-treatment, biogas yield, flammable biogas production, biodigester.