Effect of hydrothermal treatment temperature on the properties of sewage sludge derived solid fuel

Abstract

High moisture content along with poor dewaterability are the main challenges for sewage sludge treatment and utilization. In this study, the effect of hydrothermal treatment at various temperature (120-200 ˚C) on the properties of sewage sludge derived solid fuel was investigated in the terms of mechanical dewatering character, drying character, calorific value and heavy metal distribution. Hydrothermal treatment (HT) followed by dewatering process significantly reduced moisture content and improved calorific value of sewage sludge with the optimum condition obtained at 140˚C. No significant alteration of drying characteristic was produced by HT. Heavy metal enrichment in solid particle was found after HT that highlighted the importance of further study regarding heavy metal behavior during combustion. However, it also implied the potential application of HT on sewage sludge for heavy metal removal from wastewater.

Producing sludge for agricultural applications

“…They observed no removal during the investigated processes (thermal treatment and sonication), and because of the mass loss during the treatments, the effective heavy metal concentration increased at the end. In the study of Yan et al (2015), the effect of hydrothermal treatment at various temperatures (120-200 o C) on the properties of sewage sludge derived solid fuel was investigated. Similar heavy metal enrichment in solid particles was found after hydrothermal treatment.…”

The Migration and Transformation of Heavy Metals in Sewage Sludge during Hydrothermal Carbonization Combined with Combustion

“…The dehydration process requires substantial amounts of heat, thereby increasing the economic burden. Hydrothermal carbonization (HTC) is a process whereby sludge can be converted into high-density solid fuel under mild temperatures and pressures [ 8 – 10 ]. In addition, waste heat from the HTC process can be used to preheat the raw materials and improve the recovery of energy [ 11 , 12 ].…”