Assessment of char quality produced through pyrolysis of commingled municipal solid waste at varying temperatures and its prospective utilization

The mixed municipal solid waste (MSW) segregation is usually necessary for processes such as composting, recycling, or incineration. However, pyrolysis offers an alternative approach for treating commingled MSW without requiring prior waste segregation. In this study, char was produced through commingled MSW pyrolysis at 250, 350, 450, and 550 °C, employing a fixed bed reactor at holding time and rate of heat of 180 min and 10 °C/min, respectively. MSW char, derived from pyrolysis at 250 to 550 °C, peaked at 72.66% yield at 250 °C. As the temperature increased, moisture (0.68%), volatile matter (6.90%), and fixed carbon (61.51%) decreased, while ash content increased (30.91%), providing 250 °C char showing the most potential as a combustible material. A higher H/C ratio (2.17) at 250 °C indicated aromatic organic matter, while the O/C ratio was 0.74. With the rising temperature, there was a decrease in heating value by 83%, bulk density by 4.5%, iodine number by 58%, and 43% of specific surface area. In comparison, pH (7.44 to 7.85) and crystallinity index increased by 5.2% and 53.36%, respectively. Heavy metals remained within permissible limits. Total Kjeldahl Nitrogen (TKN) and C/N ratios were 0.67% and 5.07, respectively. Moreover, from the analysis, it was found that there was no trace of microplastic in the char. The heterogeneous MSW char, rich in physicochemical parameters and nutrients, is a valuable nutrient source in soil, akin to biochar’s versatile adsorption and soil enhancement properties.