Simultaneous removal of siloxanes and H₂S from biogas using an aerobic biotrickling filter

The feasibility of simultaneous removal of siloxane and H₂S from biogas was investigated using an aerobic biotrickling filter (BTF). The biodegradation of H₂S in the BTF followed a first-order kinetic model and more than 95 % H₂S was eliminated within a residence time of 0.3 min. The removal of decamethylcyclopentasiloxane (D5) increased with longer empty bed residence time (EBRT). The partition test and microbial community analysis further reveals that up to 52 % removal of D5 was reached mainly by the chemical-absorption in acid recycling liquid. Finally, D5 was converted into mixtures of dimethylsilanediol (DMSD) and hexamethyldisiloxane (L2) via ring-opening hydrolysis in acid liquid and ring-shrinking polyreaction using CH₄ derived from biogas. These operational characteristics demonstrate that the abiotic removal of D5, in addition to biological removal of H₂S in an aerobic BTF can significantly decrease the siloxane loading to the downstream siloxane removing units.