Abstract

This second half of our work on ash behavior concentrates on the effects of hydrothermal treatment conditions on paper sludge. Ash composition and solubility were determined based on treatment temperature, reactor solid load and liquid pH using experimental design and univariate regression methods. In addition, ash properties for combustion were evaluated based on recent developments on ash classification. Based on the results, all experimental variables had a statistically significant effect on ash yields. Only reactor solid load was statistically insignificant for char ash content, which increased based on increasing treatment temperature due to the decomposition of organic components. Ash dissolution and ash yield were governed by liquid pH and the generation of acids mainly due to the solubility of calcium carbonate identified as the main mineral species of paper sludge. Dissolution of calcium carbonate however decreased ash fusion temperatures more likely causing problems during char incineration. This indicated that decreasing the ash content of sludge during hydrothermal treatment can actually weaken ash properties for solid fuel applications. (C) 2016 Elsevier Ltd. All rights reserved.

Keywords

Biosolids; Calcium carbonate; Experimental design; Hydrothermal carbonization; Multiple linear regression; Wet torrefaction

Published in

Energy Conversion and Management
2016, Volume: 121, pages: 409-414
Publisher: PERGAMON-ELSEVIER SCIENCE LTD

SLU Authors

• Mäkelä, Mikko

  • Department of Forest Biomaterials and Technology, Swedish University of Agricultural Sciences
    
  • Tokyo Institute of Technology

UKÄ Subject classification

Other Chemistry Topics


Publication identifier

DOI: https://doi.org/10.1016/j.enconman.2016.05.015

Permanent link to this page (URI)

https://res.slu.se/id/publ/77609