Stabilisation/solidification of APC residues from MSW incineration with hydraulic binders and chemical additives

Abstract

This study focuses on the stabilisation/solidification (S/S) treatment of air pollution control (APC) residues from municipal solid waste (MSW) incineration. Six formulations (T1-T6) were tested based on different cements as binders, for the immobilisation of pollutants and to prevent their entering into the environment at unacceptable rates. Soluble phosphates and silicates were considered in some cases to fix heavy metals. The performance of T1-T6 products was measured in terms of initial and final setting times, mechanical strength, total availability and leaching from S/S products. Two monolithic leaching tests were used to estimate emissions of pollutants over 48h and 64 days. The results showed that the setting time was reduced when soluble phosphates were used. Moreover, although all the treatments have met the threshold of 1MPa for unconfined compressive strength, this parameter was significantly reduced due to matrix dissolution during immersion. After three cycles of leaching, the limit of 10% for solubilisation was exceeded for all treatments with the exception of T5 (with phosphates). This study demonstrated that the S/S treatment used at the industrial level can be improved with respect to toxic heavy metals, by using soluble silicates or phosphates, but not regarding soluble salts.

A comparative study on the heavy metal solidification/stabilization performance of four chemical solidifying agents in municipal solid waste incineration fly ash

“…hydroxide, carbonates [8], H 3 PO 4 [42], phosphates [43], silicates [31,44], geopolymers [10,45]; and organic solidifying agents or chelators [46], such as ethylene diaminetetracetic acid (EDTA) and thiodiglycolic acid (TGA) [47], thiourea [11,15,41,48], sodium diethyldithiocarbamate trihydrate [8], pyrrolidines, imines, carbamates and thiols [49,50] have been used to stabilize such metals. Of the two chemical solidifying agents, organic solidifying agents have received more attention due to their low cost, room temperature hardening, flexibility and capability to immobilize and stabilize hazardous wastes without additional pre-treatment (such as pH control) required [10,51].…”

Prospects of the application of curable decontamination solutions in problems of impact improving of nuclear power plants

“…By the main component of the decontamination solution (suspension) the methods, in varying degrees verified to date, can be divided into the methods of hydraulic binder solutions, clay slurries (with the usual clay and clay with a high content of aluminum oxide); diatomite suspensions, as well as combined solutions [2][3][4].…”

Immobilization and volume reduction of heavy metals in municipal solid waste fly ash using nano-size calcium and iron-dispersed reagent

“…Compared with other solidification and stabilization (S/S) processes that use additive or binder to chemically or physically immobilize the hazardous contents present in waste (Wiles, 1996;Quina et al, 2014), this treatment processes is a simple, short-term, and inexpensive process. Many countries already use the addition of Portland cement for S/S.…”