Volume 35 (2004-2005) Issue 2 Pages 75-82
The operational performances of continuous stirred tank reactors (CSTRs), using biogas reactor of conventional immobilized carrier and novel entrapped carriers containing inorganic, trace metals and vitamin B groups were compared. These reactors were operated at 25, 15 and 5°C, and innoculated with psychrophilic methanogens acclimated for 6 months from mesophilic one which was transferred from mesophilic digested reactor in a sewage plant. The novel entrapped carriers were developed and experimented for the psychrophilic biogas reactors. The novel entrapped carriers contained 100, 1, 000, 5, 000 and 10, 000 times of the conventional inorganics, trace metals and vitamin B groups concentrations in the glucomannan-gel, and these were entrapped the outlayer of the glucomannan by PVA-gel. The outer diameter of carriers were about 4-5mm. Operational conditions of these experiments were set at 1-4kg-VAm-3d-1 of loading organic acid, 5, 10 and 20% packing ratio of the working volume and 20 days of constant hydraulic retention time (HRT). The following optimal conditions were obtained by comparison to CSTR; 1, 000 times of the contained inorganics, trace elements and vitamin B groups, 3.5-4kg-VAm-3d-1 of organic acid and 10% packing ratio. From the aspect of evaluation of methanogenic activity (as shown with unit of CH4-mLd-1g-VSS-1), the operation temperatures for the psychrophilic biogas reactor should be selected in the range of 15-25°C.