Leaching of acid generating materials and elements from coarse- and fine-grained acid sulfate soil materials

Applying Industrial Side Streams in the Neutralization of Acid Generating Sulfide-Rich Sediments – the Impact on Ph and Leaching of Harmful Elements

“…Although the percentual leaching of Al was low, the amount leached out was reasonably high since the total concentration was high in the soil materials. The leaching of Cu, Ba, and Se was higher in Soil B (Åström and Björklund, 1995;Åström, 1998;Peltola and Åström, 2002;Sohlenius and Öborn, 2004;Fältmarsch et al, 2008;Mattbäck et al, 2022). These metals are all known to be abundantly leached from acid sulfate soils ( Österholm and Åström, 2004;Nordmyr et al, 2008).…”

“…The effect of the neutralizing agents on the solubility of metals and metalloids was measured after the incubation period. The solubility measurements were carried out using a modified method based on the SFS-EN 12457-2 standard (Mattbäck et al, 2022). The incubated samples were mixed, and the pH was measured as triplicates.…”

“…The dried sample was mixed well, and two parallel samples were taken for the solubility measurement. The leaching method presented in Mattbäck et al, 2022 was specifically developed and tested to be used on large sample series where there is a low amount of available sample material, and was based on similar methods presented in Åström and Björklund (1997) and Fang and Wong (1999); but further modified to bear more resemblance to the standard one-step 10:1 liquid-solid leaching method EN 12457-2 which consist of the same extraction methodology as the two-step EN 12457-3. The procedure consisted of weighing in approximately 4 g (dry weight) of sample material and adding deionized water to a liquid-solid ratio of 10:1.…”

“…The test tubes were placed in a flat shaker for 24 ± 1 h, after which the samples were centrifuged for 15 min at a speed of 4000 g. After the extraction, the liquid was filtered through a 0.2 μm pore size filter. A pore size of 0.2 μm (instead of 0.45 μm) was used to minimize potential clay colloids passing through the filter, causing an overestimation of metal concentrations (Mattbäck et al, 2022;c.f. Nystrand and Österholm, 2013).…”

Removal and Potential Recovery of Dissolved Metals from Acid Sulfate Soil Drainage by Spent Coffee-Grounds and Dissolved Organic Carbon

“…The main sulfidic components in these materials are iron sulfides (Boman et al 2008). Under reduced conditions (e.g., below the groundwater table), these materials are harmless (Mattbäck et al 2022). However, post-glacial uplifts, common in Northern Europe, causes relative sea levels to fall and exposes sulfidic sediments to oxygen into the vadose zone, leading to oxidation of iron sulfides and formation of sulfuric acid (Boman et al 2008;Shahabi-Ghahfarokhi et al 2022).…”