Pretreatment of robusta coffee hulls and co-digestion with cow-dung for enhanced anaerobic digestion
Section
Biological Sciences
Abstract
The effect of alkali pre-treatment on anaerobic digestion of Robusta coffee hulls with a lignin content of 29% was studied in batch culture at 55˚C. In order to investigate the effect of cow dung in minimising the effect of coffee-based inhibitory compounds, digestion experiments were performed with blends of pre-treated and non-treated coffee hulls and cow dung with 0,5,10,20,30,50,75 and 100% coffee hulls at a total volatile solids concentration of 1.8g/l fermentation volume. Methane production increased with increase in coffee hulls concentration up to 30% for both substrates. The lowest production was observed at 100% non-treated coffee hulls. Methane production was significantly higher (13-164%) for the pre-treated substrates compared to the non treated one. The highest increase was obtained at 100% coffee hulls. Degradation of volatile solids decreased with increase in coffee hulls concentration for both substrates. The extent of degradation of the pre-treated substrate (59-94%) was significantly higher than that obtained for the non-treated substrate (30-91%). The lowest extent of degradation was measured for the non-treated hulls at 100%. It is possible that there was an inhibition of methanogenesis by coffee based compounds with increase in the coffee hulls concentration in the digestion mixture.
Recommended Citation
Kivaisi, A. K.
(2002)
"Pretreatment of robusta coffee hulls and co-digestion with cow-dung for enhanced anaerobic digestion,"
Tanzania Journal of Science: Vol. 28:
Iss.
2, Article 1.
Available at:https://doi.org/10.65085/2507-7961.2077