Enhancing municipal solid waste efficiency through Refuse Derived Fuel pellets: Additive analysis, die retention time, and temperature impact

Abstract

Nowadays, a significant amount of non-recyclable solid waste is buried, causing numerous environmental issues. In addition, today’s developing world has increased energy demand. The production of fuel from waste, also known as Refuse Derived Fuel (RDF), is the optimal solution for both issues mentioned. This study aims to produce usable RDF pellets from the residual waste of the Tehran Kahrizak waste center and examines the effect of variables including die temperature, retention time, and three additives with specified weight percentages (0.03% bentonite, 0.04% diatomite, and 0.03% zeolite) on pellets characteristics. The results indicated that temperature and retention time effects, and additives combination was significant at the 0.01% level for all factors. In general, greater temperatures and longer retention durations result in more reliable, higher-quality pellets, but they also cost more energy to create. Scanning electron microscopy (SEM) analysis revealed that pellets containing zeolite contained the greatest number of adhesion bridges. Furthermore, the addition of zeolite and bentonite increased the pellet density. For volume expansion, the synergistic effects of temperature and retention time duration were substantial. The rate decreased by 22.5% after the addition of diatomaceous. The pellets made at 110 °C resisted more than 150 min in water. At high temperatures, pellets containing diatomite additive became brittle, whereas zeolite additive had the highest toughness at all temperatures. All additives were moisture absorbers that increased the pellets’ moisture content. Among the additives, bentonite is the most absorptive of moisture. Additionally, bentonite increased the amount of ash by 17.1% and decreased the amount of volatile matter, whereas diatomite induced ash reduction. The addition of zeolite increased the fixed carbon content. The thermal value of pellets made from bentonite increased by 39.5% due to agglomeration processing. All additives decreased the pellet manufacturing process’ energy consumption. Zeolite had the most significant effect. In addition, the Technique for Order of Preference by Similarity to Ideal Solution (TOPSIS) method was used to select the optimal scenario in the current investigation. It was observed that zeolite and diatomite additives positively impacted the pellet, whereas bentonite had a negative effect.