Carbon Dioxide Sequestration in Alkaline Top Soil Using Alkaline Wastes

Due to growing concern about climate change and global warming, new ways must be developed to reduce CO2 emissions in atmosphere. Incinerator ash produced in municipal treatment facilities and marble-dust produced during marble cutting process are alkaline wastes. This paper examines the carbon mineral sequestration potential of mixing alkaline wastes in two soil samples in accelerated carbonation conditions. Six different percentages of alkaline wastes in 20 g sample were used. Batch reactor conditions were maintained at 40 °C, relative humidity 60-70% and CO2 flow-rate of 10 litres-a-minute. Optimum water content was found by carrying out experiments on a sample with 7 different water-to-solid ratio (0, 0.2, 0.4, 0.6, 0.8, 1 and 1.2). The particle-size effect was gauged by taking soil samples sieved through standard sieve sizes of BSS25 and BSS50. It was concluded that low water-to-solids ratio is better for carbonation, although some minimum amount of water is necessary for reaction. The optimum water-to-solids ratio for incinerator ash comes to be 0.4. Marble dust was found to be inefficient to capture CO2 due to lower pH and due to lump formation. As expected, carbonation was higher for samples with less particle size and higher surface area.