Enhancing circular plastic waste management: Reducing GHG emissions and increasing economic value in Rayong province, Thailand.

This study evaluates the greenhouse gas (GHG) emissions and economic value creation of plastic waste (PW) management in Rayong, Thailand, a city on the eastern Gulf Coast with a significant amount of generated and leaked PW. By analyzing current practices, and developing and evaluating improvement scenarios, the study explores strategies for reducing GHG and enhancing economic benefits across the PW management chain. Four primary routes with varying capacities handle approximately 5,445.55 tonnes of PW via source separation recycling (5.18 %), post-sorting recycling (9.30 %), energy recovery (54.86 %), and landfills or opened dump disposal (30.66 %). About 83.21 % of the 16 ± 6.9 % PW in municipal solid waste (MSW) is recyclable, primarily consisting of high-density polyethylene (HDPE), polypropylene (PP), low-density polyethylene (LDPE), linear low-density polyethylene (LLDPE), and polyethylene terephthalate (PET). The current management practice generates an economic benefit of approximately 1.68 million USD/yr or 310 USD/t of PW, compared to the proposed scenarios, which enhances recycling efficiency and reduces landfill and energy recovery waste, yielding 2.27-6.48 million USD/yr or 420.64-1200.33 USD/t of PW. The practice emits about 7,028.47 tCOe annually, while improved source and post-sorting efficiencies reduce GHG emissions by 2.86-3.17 times or -2.83 to -2.42 tCOe/t of PW or a total of over 13,078.60-15,268.44 tCOe. Burning PW increases approximately 1.6 times or 11,841.36 tCOe/yr. Enhancing recycling efficiency, particularly through source separation, is key to promoting more productive and valuable PW separation, increasing economic value and GHG mitigation by approximately 3.87 and 3.17 times, respectively. These findings provide valuable insights for local authorities and policymakers to develop strategic interventions and policies that align with the improved scenario by enhancing source separation and recycling. The results demonstrate that improving the efficiency of separation at the source is critical for transitioning from a linear PW management strategy to a circular economy, significantly reducing landfill waste and mitigating environmental threats.