Product regulation in co-pyrolysis of multi-source wastes and analysis of environmental and economic potential

With the continuous increase in global solid waste generation, conventional disposal technologies have increasingly shown limitations in environmental performance, resource utilization, and economic efficiency. In this study, the co-pyrolysis of four representative multi-source wastes, namely medical protective clothing (MPC), agricultural plastic film mainly composed of low-density polyethylene (LDPE), municipal sludge (SS), and municipal solid waste (MSW), was investigated. An Aspen Plus-based comparative model was established to examine eight co-pyrolysis scenarios, with emphasis on the effects of temperature and blending-ratio redistribution on product distribution and major pollutant output. At 500 °C, increasing the total fraction of SS and MSW from 20.0 to 80.0 wt% increased the yields of pyrolysis gas and pyrolysis oil by 6.5 wt% and 5.1 wt%, respectively, while the yield of char decreased by 11.6 wt%. Among the evaluated co-pyrolysis pathways, the condition with MPC: LDPE: SS: MSW = 40:40:10:10 showed the lowest CO₂ emission of 425.01 kg and the lowest SO₂ emission of 2.0 kg during the production of 1 t of char, and it also exhibited favorable combined environmental and economic performance within the present comparative framework. Under the adopted screening-level economic assumptions, the cumulative cash flow of this pathway became positive from the fourth quarter. In addition, a conceptual waste-pyrolysis/coal-fired-boiler coupling route was outlined as a possible downstream application scenario. Overall, this study clarified product-regulation behavior in multi-source waste co-pyrolysis and provided process-level support for comparative pathway screening under a unified modelling framework.