Mineralogy and leachability of gasified sewage sludge solid residues

Gasification of sewage sludge produces combustible gases as well as tar and a solid residue as byproducts. This must be taken into account when determining the optimal thermal conditions for the gasification process. In this study, the influence of temperature, heating atmosphere and residence time on the characteristics of the gasified sewage sludge residues is investigated. ICPAES analyses reveal that the major chemical elements in the char residues are phosphorus, calcium, iron and silicon. Heavy metals such as copper, zinc, chromium, nickel and lead are also present at relatively high levels – from 50 to more than 1000 mg/kg of dry matter. The major mineral phases’ identification – before and after heating – as well as their morphology and approximate chemistry (XRD and SEMEDX) demonstrate that a number of transformations take place during gasification. These are influenced by the reactor’s temperature and the oxidative degree of its internal atmosphere. The copper,zinc and chromiumbearing phases are studied using chemometric tools, showing that the distribution of those metals among the mineral phases is considerably different. Finally, batchleaching tests reveal that metals retained in the residue are significantly stabilized after thermal treatment to a higher or lower extent, depending on the thermal conditions applied.

HERNÁNDEZ Ana Belén;  FERRASE Jean-Henry;  CHAURAND Perrine;  SAVEYN Hans;  BORSCHNECKB Daniel;  ROCHE Nicolas; 

2011-12-22

ELSEVIER SCIENCE BV

JRC65392

0304-3894,   

http://www.sciencedirect.com/science/article/pii/S0304389411005085,    https://publications.jrc.ec.europa.eu/repository/handle/JRC65392,   

10.1016/j.jhazmat.2011.04.070,