基于 LCA 的废弃 PET 酶法解聚和碱性水解过程环境影响对比分析

The massive production and improper disposal of waste plastics caused severe environmental pollution issues. The recycling and utilization of waste polyethylene terephthalate (PET) have received broad attention. In recent years, significant progress has been made in enzymatic depolymerization technology for waste PET, which shows potential for scaled industrial application. However, the environmental friendliness of enzymatic depolymerization compared with other recycling methods is still unclear. In this study, the environmental impact and process contribution of PET enzymatic depolymerization and alkaline hydrolysis were quantified through LCA, and the sensitivity analysis of the PET enzymatic depolymerization was constructed. The results show that the various environmental impacts of PET enzymatic depolymerization are higher than those of alkaline hydrolysis, and eight of the ten environmental indicators are more than 30% higher. Raw material pretreatment, enzyme production, and the NaOH usage in the depolymerization process are the main contributors to the environmental impact of the PET enzymatic depolymerization process. The high impact factors of alkaline hydrolysis are mainly the use of electricity and NaOH during the depolymerization process. The sensitivity analysis shows that enzyme loading rate, enzyme production, and electricity structure significantly affect the environmental benefits of enzymatic depolymerization, while the impact of solid loading rate is relatively small. Under the scenario where enzyme loading rate, enzyme production, and electricity structure are simultaneously improved, the various environmental impact indicators of PET enzymatic depolymerization are lower than or close to alkaline hydrolysis, indicating that the PET enzymatic depolymerization technology has great development potential.