Preliminary Study of Anaerobic Digestion Improvement by Bacterial Immobilization Media from Activated Carbon and Natural Zeolite

Abstract

Immobilization on the solid surface of anaerobic microorganism can improve biogas production. A study on the biogas production and the analysis of biogas-producing bacteria in natural zeolite and activated carbon-based media have been carried out. This research was aimed to find out the effect of solid media addition and to identify the bacteria species involved in biogas production under the anaerobic condition. The bacterial culture was carried out in batch anaerobic digesters for a 35-day incubation period. Three different composition of ring-shaped packing consist of natural zeolite (Z), activated carbon (K), and an equal mixture of natural zeolite and activated carbon (C) were added in an anaerobic reactor. Biogas as the product was analyzed with GC-TCD. Each of the bacteria's DNA in the media then isolated, amplified, and also purified to find out the intensity of each DNA band. Sequencing process was conducted for each purified DNA bacteria and the sequence result then translated by BLASTn program in the gene-bank NCBI. The highest methane concentration of 34.32% was obtained from reactor with natural zeolite media, then the mixed media added reactor provided biogas with 26.31% methane and the last reactor with activated carbon media showed the smallest value of 20.77% of methane. Sequencing result shows that Dictyoglomus thermophilum species was dominated on the surface of K-packing, Rhodopseudomonas palustris species was observed on the C-media, and Thermococcus litoralis was living on Z-media. SEM image was taken to confirm the results of DNA identification.