Is the biochar produced from sewage sludge a good quality solid fuel?

• Published in: Archives of environmental protection 2016-12, Vol.42 (4), p.125-134
• Main Authors: Pulka, Jakub, Wiśniewski, Dariusz, Gołaszewski, Janusz, Białowiec, Andrzej
• Format: Article
• Language: English
• Subjects: Alternative energy sources; ash; biochar; Biomass energy; calorific value; Carbon; Decomposition; Life sciences; Lignocellulose; Renewable resources; sewage sludge; Sludge; solid fuel; Sulfur content; Temperature; torrefaction; Water treatment
• ISSN: 2083-4810; 2083-4772; 2083-4810
• DOI: 10.1515/aep-2016-0043

The influence of sewage sludge torrefaction temperature on fuel properties was investigated. Non-lignocellulosic waste thermal treatment experiment was conducted within 1 h residence time, under the following temperatures: 200, 220, 240, 260, 280 and 300°C. Sawdust was used as lignocellulosic reference material. The following parameters of biochar have been measured: moisture, higher heating value, ash content, volatile compounds and sulfur content. Sawdust biochar has been confirmed to be a good quality solid fuel. High ash and sulfur content may be an obstacle for biochar energy reuse. The best temperature profile for sawdust torrefaction and fuel production for 1 h residence time was 220°C. At this temperature the product contained 84% of initial energy while decreased the mass by 25%. The best temperature profile for sewage sludge was 240°C. The energy residue was 91% and the mass residue was 85%. Higher temperatures in both cases caused excessive mass and energy losses.