Novel separation and immobilization of heavy metals in municipal solid waste fly ash by grinding with nano‐Fe/Ca/CaO/[PO₄] mixture

Abstract

This study was conducted to examine the dry synthesis and application of novel nano‐size calcium/iron‐based composite material as a separation/immobilization treatment of heavy metals (As, Cd, Cr, and Pb) in fly ash from municipal solid waste incinerator. After grinding with nano‐Fe/Ca/CaO and with nano‐Fe/Ca/CaO/[PO4], approximately 30 wt % and 25 wt % of magnetic fraction fly ash were separated. The highest amount of entrapped heavy metals was found in the lighter, magnetically‐separated fly ash fraction (i.e. 91% heavy metals in 25% treated fly ash). Immobilization rate of heavy metals in the magnetic or non‐magnetic fly ash fractions were about 98% and 100%, respectively. SEM‐EDS observations indicate that the main fraction of enclosed/bound materials on treated fly ash includes Ca/PO4‐associated crystalline complexes. After nano‐Fe/Ca/CaO/[PO4] treatment, the heavy metal concentrations in the fly ash leachate were much lower than the Japan standard regulatory limit for hazardous waste landfills. The addition of a nano‐Fe/Ca/CaO/PO4 mixture with simple grinding technique is potentially applicable for the remediation and volume reduction of fly ash contaminated by heavy metals. © 2016 American Institute of Chemical Engineers Environ Prog, 35: 1693–1698, 2016

Effects of Surfactants on the Removal of Carbonaceous Matter and Dioxins from Weathered Incineration Fly Ash

“…However, incineration produces a large amount of medical waste incinerator (MWI) fly ash, which is dust-like particles and has high content of chlorine, dioxin and heavy metal. Unburned carbon (UC) is the major source of dioxins in fly ash because of its role in de-novo synthesis and its high adsorption capacity (Huang et al, 2003a;Mallampati et al, 2016). Incineration fly ash has a UC content of approximately 3 wt.% to 10 wt.% (Shibayama et al, 2005).…”

Characteristics and Treatment Methods of Medical Waste Incinerator Fly Ash: A Review

“…MCT is a nonthermal process and nontail gas disposal method. Operation conditions are usually 100-600 rpm and 2-24 h in a fully closed reactor [51,132] (Table 9). In the MCT process, five types of reagents are usually used: Lewis bases (such as CaO, Al 2 O 3 , La 2 O 3 , and Bi 2 O 3 ) which serve as electron donors; neutral substances (such as alumina and SiO 2 ), which can provide free radicals to decontaminate organics [133]; oxidants (such as δ-MnO 2 and S 2 O 8 2− ) which can promote the oxidation of organics; reductants including pure metals which can be used as both electron donor and H donor; in addition, in order to reduce the production of hazardous intermediate substances, organic molecules (such as amides, amines, alcohols, ethers, and glycols) are applied together with pure metals to serve as H donor in reaction process [134,135].…”

“…In the MCT process, five types of reagents are usually used: Lewis bases (such as CaO, Al 2 O 3 , La 2 O 3 , and Bi 2 O 3 ) which serve as electron donors; neutral substances (such as alumina and SiO 2 ), which can provide free radicals to decontaminate organics [133]; oxidants (such as δ-MnO 2 and S 2 O 8 2− ) which can promote the oxidation of organics; reductants including pure metals which can be used as both electron donor and H donor; in addition, in order to reduce the production of hazardous intermediate substances, organic molecules (such as amides, amines, alcohols, ethers, and glycols) are applied together with pure metals to serve as H donor in reaction process [134,135]. With development, Fe-SiO 2 , Fe/Zn-SiO 2 , and Fe/Ni-SiO 2 , and auxiliary materials, such as CaO and quartz sand, are introduced [132,136,137]. The dioxin treatment mechanism by MCT includes the dual paths: destruction and dechlorination.…”

Comparison of arsenic immobilization properties among calcium silicate hydrate, ettringite, and friedel's salt in a slag‐based binder

“…Numerous treatment methods, such as vitrification, acid extraction, adsorption, and solidification/stabilization (S/S), have been developed to prevent arsenic and heavy metal contamination . To date, S/S with ordinary Portland cement is the most common method for arsenic‐containing waste disposal .…”