Quantitative sustainability assessment of plant layouts for mechano-chemical remanufacturing of waste tires into rubber sheets with integrated pyrolysis-distillation

Abstract

Waste tires are a major contributor to the solid waste stream globally. However, waste tires can be recovered and remanufactured into valuable products, such as rubber sheet, steel, and nylon. This study proposes a novel strategy of incorporating pyrolysis–distillation (P–R) lines into remanufacturing plant layouts for the mechano-chemical remanufacturing of waste tires into sheet rubber to add energy products as an additional output to diversify the profitable product range. A quantitative sustainability assessment was performed to evaluate batch, semi-continuous, and fully continuous P–R reactors with capacities of 5–50 t/day for pyrolysis and 5–20 t/day for distillation, which are integrated to develop 99 pre-design options to remanufacture 15–50 t/day of waste tires into energy products. The pre-designs were optimized quantitatively and reduced into eight alternatives for introduction at specific positions in the plant layouts to increase the capacity of the plant by approximately 40% (to process an extra 180 t/day of waste tires) based on European Union experience in producing energy products from waste tires. Accordingly, yields of energy products of 84,768 L/day of diesel, 63 t/day of charcoal, 27 t/day of waste steel, and 8.1 t/day of raw asphalt.can be obtained, thereby yielding 13.734–34.219 million USD/year profit. Furthermore, a high technical feasibility index of 0.82, very high economic sustainability satisfaction factor of 0.98, very high environmental sustainability satisfaction factor of 0.97, and very high social sustainability satisfaction factor of 0.91 indicate that the proposed remanufacturing process is viable as a quadilateral-bottom-line sustainability strategy.