Leaching of Chlorides, Sulphates, and Phosphates from Ashes Formed as a Result of Burning Conventional Fuels, Alternative Fuels, and Municipal Waste in Household Furnaces

Abstract

The aim of the study was to assess leaching of Cl−, SO42−, and PO43− from ashes formed in household furnaces. The ashes were obtained following the combustion of conventional fuels, namely wood and hard coal, and alternative fuels with various fractions of municipal waste in a household boiler. Aqueous leachates of the ashes were used to determine concentrations of chlorides by titration (Mohr’s method) (21.3–3049.6 mg/dm3), sulphates by the gravimetric method (12.2–244.1 mg/dm3), and phosphates by spectrophotometry (0.01–67.2 mg/dm3). It was found that co-combustion of municipal waste with plastic-coated paper cartons, diapers, or a mixed waste fraction leaves the greatest amount of ashes on the furnace grate. The highest amounts of Cl−, SO42−, and PO43− were leached from ashes generated from burning a mix of wood and coals, or wood alone (different species). The addition of municipal waste to the process of burning the conventional and alternative fuels studied did not significantly increase Cl−, SO42−, and PO43− content in aqueous extracts of ashes, the exception being diapers and plywood. In light of the study results, it was concluded that all the ashes could be reused (as an additive to concrete) except for the ash generated from the combustion of a mixed municipal waste fraction and coal (due to the content of Cl−) and diapers (due to the content of PO43−). It was demonstrated that Cl−, SO42−, and PO43− content in the entire set of samples and in individual ash groups is highly heterogeneous and variable.

Ecological Risk Assessment Related to the Presence and Toxicity of Potentially Toxic Elements in Ashes from Household Furnaces

“…As demonstrated in previous studies, the sand and silt fractions are of major importance, as they determine the dustiness and filtrating properties of ashes [20,28,29]. Another important property of ashes is their solubility and high susceptibility of their components, especially the toxic ones, to leaching [11,15,27,30,31]. The latter contain potentially toxic elements (PTEs), which mainly include heavy metals (i.e., Al, Cd, Cr, Fe, Ni, Pb, and Zn) and metalloids (As).…”

“…The hearth and ash collector were thoroughly cleaned after combusting each portion of the material. The exact procedure of obtaining ash samples has been described previously [31].…”

“…The exact procedure of ash sample preparation has been described by Kici ńska and Caba [31]. The fuels were incinerated according to the following steps: − a portion of the primary material was placed in the furnace chamber; − the material underwent incomplete combustion, initiated with a gas burner; − the furnace and ash were cooled down; − the ash was collected into a container; − the coarse fraction was separated using a sieve; − a sample of the ash was collected and placed in a tightly sealed plastic bag; − the chamber and bottom hopper were cleaned mechanically and with compressed air before the incineration of the next portion of fuel.…”

Strontium leaching from municipal waste subjected to incineration

“…1 ). A morphological description of the ashes obtained has been described in a paper by Kicińska and Caba ( 2021 ).

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Comparison of Pyrolysis and Combustion Processes of Vinyl Floor Panels Using Thermogravimetric Analysis (TG-FTIR) in Terms of the Circular Economy

“…Waste of vinyl panels was treated in terms of secondary raw material, which, in the light of the circular economy, may constitute potential energy or chemical resource. To a large extent, the circular economy in waste management is currently focused on resource recovery, rational management of non-renewable resources, and prevention of negative environmental impact [17][18][19][20][21].…”