Consequential life-cycle assessment of treatment options for repulping reject from liquid packaging board waste treatment.

Liquid packaging board is one of the highly demanded packaging mediums for liquid food and beverages, generating substantial waste each year. Even though the fibre part of the liquid packaging board is recycled through a repulping process, the plastic and aluminium are usually used for energy recovery and as alternative raw materials in cement factories. This practice reduces the life span and economic value of plastic and aluminium, which does not fit within a circular economy. The plastic and aluminium from liquid packaging board waste can be recycled mechanically and chemically. This study used the consequential life-cycle assessment method to compare the environmental impact of the recovery options of rejected materials from liquid packaging board waste treatment. Four scenarios were established: (1) energy recovery by waste incineration, (2) composite pallet production by mechanical recycling, (3) plastic pallet production by mechanical recycling, and (4) plastic pallet production by chemical recycling. The study showed that when the consumed energy was supplied from renewable sources, plastic pallet production by mechanical recycling process had the lowest environmental impact, and energy recovery by waste incineration had the highest impact. A sensitivity analysis revealed that composite pallet production by mechanical recycling process showed the best impact if the energy was sourced from the average production mix, and plastic pallet production by chemical recycling had the lowest impact when mechanically recycled plastic substituted for 0%, 30%, and 50% of virgin plastic. These results should be of interest to liquid packaging board manufacturers and other related stakeholders.