Co combustion of sewage sludge and Turkish lignite: the effect of blending on combustion characteristics

Abstract

Sewage sludge is an unwanted by-product of municipal wastewater treatment processes but could also be a source of energy, nutrient, and material recovery. Although sewage sludge composition varies by location, influent wastewater composition, the wastewater treatment method used, and season, the composition of sludge comprises organic matter, microorganisms, nutrients such as N and P, minerals besides hazardous contaminants such as heavy metals, pesticides, organic contaminants such as endocrine disrupters, pharmaceuticals residues, polychlorinated biphenyls (PCBs), polycyclic aromatic hydrocarbons (PAHs), and pathogens like viruses, bacteria, and parasites [1][2][3]. Therefore, sewage sludge must be treated and disposed of properly in order to reduce its adverse effects on the environment and human health. The investment and operating costs of municipal sewage sludge processing and disposal comprise up to 50% of the total expenditures of a typical wastewater treatment plant [2][3][4].The use of traditional sewage sludge disposal methods such as composting, landfill, and ocean discharge is losing its popularity due to more stringent restrictions by governments, increasing public concern for the environment and human health, and increased interest in energy and material recovery. Consequently, thermal treatment methods such as combustion, pyrolysis, and gasification become prominent as promising treatment and utilization technologies for municipal sewage sludge [5][6][7][8]. The advantages of thermal treatments include waste reduction, energy recovery, and the destruction of organic pollutants and pathogens.