Cost effective in-situ methane enrichment for chicken farm biogas system

Abstract

This study aims to investigate an in-situ methane enrichment in an anaerobic digestion of chicken manure. The process was carried out by desorbing carbon dioxide (CO2) from the effluent and recirculating effluent back to the digester. Laboratory-scale experiments were conducted in a 1100-liter anaerobic channel digester equipped with an external bubble column for the CO2 desorption. The experimental results showed that the CO2 desorption was achieved in a range of 98 to 121 l/day. The efficiency of CO2 desorption depended on a ratio between liquid and gas flow rates (L/G ratio) which the flow rate of liquid ranged between 230% and 430% of the digester volume per day. A higher methane content (65.12–72.68% CH4 by volume) was obtained whereas the methane (CH4) loss was in a range of only 1.15–2.58% which was relatively low. Not only the CO2 can be desorbed, but hydrogen sulfide can also be removed.