Chemolithiotrophic bacteria

In addition to these three properties, the other property of the crosslinks in sulfur-cured rubbers that has been successfully exploited to achieve devulcanisation is the greater susceptibility of the sulfur atoms within them to biological attack by certain bacteria (i.e., chemolithiotrophic bacteria). 

In this process, which has been in existence as a concept for at least 30 years and is often referred to as a microbial process, chemolithiotrophic bacteria in aqueous suspensions in the presence of oxygen can be nsed to selectively attack the sulfur crosslinks in the snrface of waste rnbber crumb particles. The process can also be regarded as a type of biodegradation process, the by-prodncts of which can inclnde elemental sulfur, sulfates, sulfides and snlfnric acid. Specific examples of the bacteria that have been used to devulcanise rubber in this way inclnde species of Thiobacillus, e.g., T. thiooxidans. 

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