Evaluation of Possible Recycling of Used Tires Using Microorganisms

In this paper, devulcanization of used tires using microorganisms was investigated in order to remove sulfur from the polymeric network of the vulcanized tires. For this purpose, a kind of used tire powder in three different mesh sizes (16-45, 60-100 and >80) and a kind of reclaimed rubber were examined by different mixed cultures and pure cultures. The microorganisms were four microbial consortia prepared from petroleum polluted sites, two species of Acidothiobacillus ferrooxidans (PTCC 1646 & PTCC 1647), Pseudomonas putida (DSMZ 298) and Rhodococcus Erythropolis IGTS8 (ATCC 53968). After five weeks of contact between tires and microorganisms at 30 ºC and 140 rpm, the amounts of sulfate in the culture media were measured indicating the reduction of sulfur from the tire matrix. The results showed that both species of Acidothiobacillus ferrooxidans were best able to increase the amount of sulfate in the culture medium up to 12%.