Friday, 13 November 2020 12:13

Co-digesting Pretreated Chicken - Goat and Untreated Cow Manure on Biogas Production in Fixed Dome Laboratory Digester

Written by C. S. Waswa1*, P. A. Kabok2 and D. M. Nyaanga1
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C. S. Waswa1*, P. A. Kabok2 and D. M. Nyaanga1

1Agricultural Engineering Department, Egerton University,

P.O. Box 536 – 20115, Egerton, Kenya.

2School of Engineering, Jaramogi Oginga Odinga University,

P.O. Box 210-40601, Bondo, Kenya.

*Corresponding Author:

Generation of biogas can greatly be influenced by feed stock pretreatment. The effect of hydro, mechanical and thermal pretreatment of chicken and goat manure on biogas production was done using a 0.15m3 laboratory scale batch digester. The feed stocks were subjected to 6, 12 and 18 hours of soaking, 2 mm, 3 mm and 4 mm of mechanical mincing, and 60˚C, 80˚C and 100˚C of heating. Pretreated feed stocks were co-digested with untreated cow manure from an extensive dairy rearing system. Experiments were done at 8 % substrate total solids and a constant temperature of 35°C. Averagely, mechanical pretreatment resulted in the highest increase in mean biogas production rate with 11.11%, over the co-digestion control (0.54 m3/m3d), followed by thermal and hydro by 5.56% and1.85%. Maximal increase in production for each pretreatment was at 6 hour soaking time (9.30%), 3 mm effective feed stock particle sizes (18.52%) and 80˚C of heating (14.81%). Co-digestion increased mean biogas production rate over mono-digestion by 68.97% (chicken), 81.84% (goat) and 8.8% (cow manure). Superior outer cell wall and cover disruption of feed stocks for easy hydrolysis advantaged mechanical pretreatment.

Keywords: Pretreatment, Chicken-goat-cow manure, Biogas production, Fixed dome, Laboratory digester

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