Relation between thermal drying process and sludge characteristics of drinking water treatment sludge (DWTS)

Recently, drinking water treatment sludge (DWTS) has garnered increasing attention due to its environmental and management challenges. Thermal drying, a widely adopted sludge treatment method, is essential for various recycling categories of DWTS. However, little research has been done on the thermal drying process of DWTS especially quantitative analysis between drying properties and sludge characteristics. In this study, the mathematical drying model and physico-chemical characteristics of DWTS were comprehensively investigated. Results show that the average and maximum drying rates of DWTS were significantly positively correlated with the pore area, initial moisture content, and soluble chemical oxygen demand, while they exhibited a significant negative correlation with the inorganic matter mass fraction (p < 0.05). This was likely due to the fact that the increased initial moisture content and pore area promoted moisture evaporation. Meanwhile, the inorganic matter hindered evaporation. This exploration deepened the knowledge of the DWTS drying process and provided novel insights into its relation with sludge characteristics, which was conducive to the recycling of DWTS.