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In this study, municipal solid waste incineration (MSWI) fly ash was subjected to mineral carbonation with the aim of investigating CO2 sequestration in waste material. The conducted study follows the trend of searching for alternatives to natural mineral materials with the ability to sequestrate CO2. The mineral carbonation of MSWI fly ash allowed for the storage of up to 0.25 mmol CO2 g−1. Next, both carbonated and uncarbonated MSWI fly ashes were activated using an alkaline activation method by means of two different activation agents, namely potassium hydroxide and potassium silicate or sodium hydroxide and sodium silicate. Mineral carbonation caused a drop in the compressive strength of alkali-activated materials, probably due to the formation of sodium and/or potassium carbonates. The maximum compressive strength obtained was 3.93 MPa after 28 days for uncarbonated fly ash activated using 8 mol dm−3 KOH and potassium hydroxide (ratio 3:1). The relative ratio of hydroxide:silicate also influenced the mechanical properties of the materials. Both carbonated and uncarbonated fly ashes, as well as their alkali-activated derivatives, were characterized in detail by means of XRD, XRF, and FTIR. Both uncarbonated and carbonated fly ashes were subjected to TG analysis. The obtained results have proved the importance of further research in terms of high-calcium fly ash (HCFA) utilization. [ABSTRACT FROM AUTHOR]

The impact of lignite and leonardite combined with a NaX-C composite on the abundance of selected groups of culturable micro-organisms in soil contaminated with Pb, Cd and Zn was tested. For this purpose, a 7-month incubation experiment and two-year pot experiments were conducted. The pattern of both experiments was analogous and included: soil without fertilization (C); soil fertilized with NPK mineral fertilizers (MF); soil with NPK + 3 or 6% lignite (MF+CW3%, MF+CW6%) and 3% zeolite-carbon composite (NaX-C); soil with NPK + 3 or 6% leonardite (MF+CL3%, MF+CL6%) and 3% zeolite-carbon composite (NaX-C). The test plant in the pot experiment was the Kosynier variety of maize. The soil material was used to estimate the abundance of general bacteria, mold fungi, actinomycetes (actinomycetales), ammonification bacteria and bacteria from the Azotobacter genus. The study found that the application of lignite and leonardite combined with a NaXC composite had generally contributed to a significant increase in the total nitrogen content and a decrease in the total carbon content in soil in the pot experiment. In general, the mineral-organic mixtures had a stimulating effect on the analyzed groups of soil microorganisms in both experiments, but the dominant groups in the pot experiment were total bacteria and ammonifying bacteria, while in the incubation experiment, fungi and actinomycetes were the prevalent groups. An RDA analysis indicated that mold fungi, bacteria, actinomycetes and amminofers were positively correlated with the EC, total nitrogen and carbon. [ABSTRACT FROM AUTHOR]