Paper-ash is used for remediation of heavily contaminated soils with metals, but remediation efficiency after longer periods has not been reported. To gain insights into the mechanisms of immobilization of cadmium (Cd), lead (Pb), and znic (Zn), a study was performed in the laboratory experiment in uncontaminated, artificially contaminated, and remediated soils, and these soils treated with sulfate, to mimic conditions in contaminated soil from zinc smelter site. Remediation was performed by mixing contaminated soil with paper-ash to immobilize Cd, Pb, and Zn in the geotechnical composite. Partitioning of Cd, Pb, and Zn was studied over one year in seven-time intervals applying the sequential extraction procedure and complementary X-ray diffraction analyses. This methodological approach enabled us to follow the redistribution of Cd, Pb, and Zn over time, thus, to studying immobilization mechanisms and assessing the remediation efficiency and stability of newly formed mineral phases. Cd, Pb, and Zn were effectively immobilized by precipitation of insoluble hydroxides after the addition of paper-ash and by the carbonization process in insoluble carbonate minerals. After remediation, Cd, Pb, and Zn concentrations in the water-soluble fraction were well below the limiting values for inertness: Cd by 100 times, Pb by 125 times, and Zn by 10 times. Sulfate treatment did not influence the remediation efficiency. Experimental data confirmed the high remediation efficiency and stability of insoluble Cd, Pb, and Zn mineral phases in geotechnical composites.

A sampling device was developed for collecting and size-fractionating airborne particulate matter (PM). A low-volume cascade system with polytetrafluoroethylene membrane filters (PM₁₀, PM_2.5, and PM_0.1) connected to an ultrapure-water trap was used to retain the PM_<0.1 fraction that passed through the filters. In the collected samples, metal(oid)s and platinum group elements (PGEs) were determined by inductively coupled plasma mass spectrometry after microwave-assisted digestion using a mixture of acids. Polycyclic aromatic hydrocarbons (PAHs) were extracted with a solvent mixture of acetone and petroleum ether, assisted by mechanical shaking and determined by gas chromatography mass spectrometry. The analytical methods were optimised and validated using the urban PM Standard Reference Material 1648a. Measurement repeatability and accuracy were 6% and 2% for metal(oid)s and PGEs, and 3% and 6% for PAHs, respectively. Field emission scanning electron microscopy analysis confirmed that the sampling device efficiently fractionated airborne PM to nano-sized particles. The sampling device was successfully applied to collect PM, enabling effective air pollution monitoring in urban areas. Analysis revealed that metal(oid)s were most abundant in PM₁₀, while those originating from traffic were also elevated in PM_<0.1. High-molecular-weight PAHs were distributed between PM₁₀ and PM_2.5 fractions. The sampling device provides valuable insights into the chemical composition of (ultra)fine particles, overcoming the limitations of filter-based PM fractionation and providing improved air pollution control for nanoparticle-bound pollutants.

The environmental properties of three geotechnical composites made by recycling wastes were investigated on a laboratory scale and in the field with the use of lysimeters designated for the revitalization of degraded mining sites. Composites were prepared by combining the mine waste with paper-mill sludge and foundry sand (Composite 1), with digestate from municipal waste and paper ash (Composite 2), and with coal ash, foundry slag and waste incineration bottom ash (Composite 3). The results of laboratory leaching tests proved that Composites 1 and 3 are environmentally acceptable, according to the legislative limits, as the potentially hazardous substances were immobilized, while in Composite 2, the legislative limits were exceeded. In the field lysimeters, the lowest rate of leaching was determined for optimally compacted Composites 1 and 3, while for Composite 2 the leaching of Cu was high. This study proved that optimally installed Composites 1 and 3 are environmentally acceptable for use in construction as an alternative to virgin materials, for the revitalization of degraded mining sites or, along with Composite 2, for closure operations with landfills. In this way, locally available waste streams are valorised and channelized into a beneficial and sustainable recycling practice.

The environmental properties of three geotechnical composites made by recycling selected wastes were investigated on a laboratory scale and later in the field with the use of lysimeters, which were large enough to reflect the conditions in earth-structures designated for the revitalization of degraded mining sites. Composites were prepared by combining the mine waste with paper-mill sludge and foundry sand (Composite 1), with digestate from municipal waste and paper ash (Composite 2), and with coal ash, foundry slag and waste incineration bottom ash (Composite 3). The results of standardised laboratory leaching tests proved that Composites 1 and 3 are environmentally acceptable, according to the legislative limits, as the potentially hazardous substances were successfully immobilized. In Composite 2 the legislative limits were exceeded and therefore its use is limited to closure operations for non-hazardous landfills. In the field lysimeters the lowest rate of leaching was determined for optimally compacted Composites 1 and 3, while for Composite 2 the leaching of Cu was high, similar to the laboratory tests. A higher degree of compaction after installation had a beneficial effect on the immobilization of hazardous substances in Composites 1 and 3. This effect was not observed for Composite 2, mobilization of hazardous substances in Composite 2 is related to soluble organic matter contained in the composite. This study proved that optimally installed Composites 1 and 3 are environmentally acceptable for use in construction as an alternative to virgin materials, for the revitalization of degraded mining sites or, along with Composite 2, for closure operations with landfills. In this way locally available waste streams are valorised and channelized into a beneficial and sustainable recycling practice.