A novel carbon absorption material is described which is formed from anaerobic digestate. The material has a hollow tubular structure and is particularly advantageous in converting hydrogen sulfide in biogas and in absorbing the converted sulfur and sulfur compounds from biogas into its structure. The material after use as a hydrogen sulfide absorbent has value as a horticultural or agricultural product or as a sulfur impregnated activated carbon. The process for producing this novel carbon absorption material is described. In an embodiment, the process described uses in particular, a humidified inert gas over a temperature range of between about 500° C. to 900° C. to convert anaerobic digestate to an active carbon absorbent. The thermal treatment is relatively mild and retains the fibrous structure of the source material while removing cellulosic and hemicellulosic components from the anaerobic digestate.