Recycling of municipal sewage sludge incineration fly ash based on (NH4) 2SO4 roasting-acid leaching and filling PP matrix process.

Abstract

Sludge incineration is one of the most efficient sludge treatment methods. The fly ash produced by incineration must be handled further since it has a significant number of heavy metals. In this study, the chemical composition of sewage sludge incineration fly ash (SSA) generated from Zhejiang in various months was identified by XRD, X-ray fluorescence spectrometer (XRF), and SEM analyzes. The SSA were treated by a (NH4)2SO4 roasting-acid leaching process to determine its effect on the elimination performance of heavy metals. The SSA content on the mechanical properties and heavy metal leaching of modified SSA-filled PP composite were also studied. Results show (NH4)2SO4 roasting-acid leaching process has a good effect of eliminating heavy metals, with the highest leaching of Zn of 86.4%. The presence of sodium stearate modifier increases activation index of SSA and then improves the compatibility of SSA particles in PP, resulting for the composites have relatively excellent mechanical properties. For the toxicity characteristic leaching procedure (TCLP) test, modified SSA particles can be effectively encapsulated with PP resins, which have a considerable inhibitory effect on heavy metal leaching. This process from this study provides a reference for sewage sludge treatment by using modified SSA as a polymer filler to achieve the immobilization of heavy metals and the resource recycling.