Abstract
This study is aimed to promote efficiency of methane fermentation by using the sub-critical water hydrolyzed solution. To attain this, support materials, which can immobilize methanogens and adsorb substrate such as acetic acid, are very important. Four different support materials were used: bamboo charcoal, activated carbon, activated carbon with cellulose, and super absorbent polymer. The saturation capacity for adsorption of acetic acid on the activated carbon was 3.89 mol/kg. In the immobilization experiment, sludge from digester (operating at Yagi bio-ecology center) was acclimatized for 4 days with 0.1 M acetic acid and support materials. After support materials were taken out, they were washed to remove residues and then resuspended with 0.01 M acetic acid to measure methane production. Sequentially, methane production from immobilized aceticlastic methanogens on the support materials were measured. The amount of immobilized methanogens was shown by methane production from methanogens immobilized on support materials. From the experimental results, bamboo charcoal and activated carbon immobilized 40% of aceticlastic methanogens from the sludge. Activated carbon with cellulose immobilized 20%. Super absorbent polymers did not immobilize methanogens. Activated carbon with cellulose may contain utilizable organic carbon such as sugars. Thus, activated carbon with cellulose was difficult to be used as support materials for a long term. Bamboo charcoal and activated carbon may not contain such utilizable organic carbon. Therefore, bamboo charcoal and activated carbon can be used as support materials for a long term.
