Evaluation of shredded tyre chips as sorption media for passive treatment walls

The potential of shredded tyre chips, either on their own or mixed with gra vel, to act as a permeable reactive barrier has been examined by carrying o ut tests for assessing sorption characteristics and establishing their mech anical properties. Sorption-desorption tests have been carried out using fr ee product petrol and paraffin and aqueous phase phenol and cresols. Compaction and compressibility tests have been carried our to establish opt imum tyre-chip mixes in order to optimise the mix in terms of compressibili ty behaviour. The results demonstrate that tyre chips show significant prom ise for incorporation in a permeable reactive barrier. The evidence indicat es that they would be particularly effective for the retardation of aqueous phase hydrophobic organic contaminants and residual free product. Optimum mixes of 2-6 mm tyre chips and 20 mm gravel, in terms of mechanical stabili ty, will contain just under 10% of tyre chips. (C) 2001 Elsevier Science B. V. All rights reserved.