carbon granules were used. The activated carbon was produced
from coconut shells, having approximate particle size of 2 mm
and the measured total surface area and HHV of about 700 m2/g
and 33,600 kJ/kg (8000 kcal/kg), respectively. The activated carbon
was impregnated with 2% KI.
The H2S removal unit, constructed in this study, was connected
to the existing biogas line as shown in Fig. 2. It consisted of two
adsorption columns (PVC, 3 in. ID), each of which was packed with
2 kg of prepared adsorbent. The two columns were alternately
operated for continuous adsorption to keep H2S concentration of
treated biogas below 50 ppm, which is well below the maximum
concentration of H2S acceptable for running in internal combustion
engines [5].