## 1 Introduction  
Solid waste generation is increasing across the world, and this trend is growing as the population grows [1]. Due to reasons like cost and poor quality of material, much of these wastes cannot be feasibly recycled and are instead landfilled [2]. For instance, the United States alone landfilled 139 million tons of municipal solid waste in the year 2017 [3]. The practice of landfilling is known to cause significant environmental damage and negative health impact [4, 5]. Moreover, landfilling is economically destructive by wasting a precious, energy-intensive resource. Closely following population and economic growth, global energy demand is expected to increase by 48% from 2012 to 2040 [6], requiring investment into safe, low cost, and clean energy sources. Furthermore, in a highly competitive and increasingly regulated sector, existing coal power plants are facing more stringent regulations [7]. These issues can be reconciled by utilizing a thermal treatment process to convert solid waste into a low-cost and clean fuel source. Torrefaction is a thermochemical treatment process with the purpose of improving the feedstock characteristics for later use in pyrolysis, gasification, or combustion. It has long been studied as a key to develop the use of woody biomass, a renewable energy source, to help replace fossil fuels [8]. Although the technology is well established, biomass has not yet taken off as a major energy source on the market, contributing to just 1.4% of U.S. energy production [9]. Among many obstructions to the commercialization of technology for biomass torrefraction [10], the prohibitive high cost is the most prominent [11; 12]. Solid waste has been recently proposed as a feedstock for the torrefraction process to produce fuels for power applications [8]. It solves many of the challenges associated with woody biomass [10], but most importantly, the source is ubiquitous and readily available. With waste disposal tipping fees, the waste feedstock often has a negative price, helping the economic issues associated with biomass feedstocks. Solid waste has already been considered as a feedstock for waste to energy (WTE) plants, and 12.7% of U.S. municipal solid waste (MSW) was combusted with energy recovery in the year 2017 [3]. A major reason this idea has failed to take hold is the poor properties of the untreated mixed solid wastes such as energy density, moisture content, and the high costs associated with the high chlorine in the flue gas treatment [10]. However, a simple torrefraction process of solid waste is being increasingly studied and shown to be an inexpensive and reliable method for improving the feedstock quality [13]. Additionally, using heat-treated MSW has been shown to be carbon-neutral due to the reduction in methane and CO\({}_{2}\) emissions from landfills [14]. [PERSON] et al., 2018 previously showed that torrefied solid waste has similar characteristics to the common Powder River Basin (PRB) coal and can be used to replace it in existing plants [10]. Using heat-treated solid waste in existing coal-fired plants, the full economic advantage of the available resources can be taken, while simultaneously curbing the use of heavily polluting coal and reducing the accumulation of waste. The same team also studied the characteristics of extruded wastes produced by the same feedstock, which addressed multiple properties including densification, grindability, water resistance, durability, heat content, and combustion behaviors [13]. A major hurdle solid waste faces as a potential solid fuel is the chlorine released from PVC waste during combustion. This chlorine is known to cause corrosion and emission issues [15]. [PERSON] et al., 2000 found that the higher the chlorine level of the waste, the more the emission of polychlorinated dibenzo-p-dioxins and dibenzofurans (PCDD/Fs) will be produced [16]. [PERSON] et al., 1990 also studied the effect of PVC content on PCDD emissions during MSW combustion.