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Waste cement is a construction and demolition waste produced from old buildings’ demolition and transformation. In recent years, the recycling of recycled concrete is limited to the use of recycled aggregate, and the research on the utilization of waste cement in waste concrete is scarce. This study explored the effective application of waste cement for the adsorption of cadmium (Cd2+) from an aqueous solution and the bioavailability and immobility of Cd2+ in soil. Results showed that the maximum adsorption capacities of ordinary Portland cement(OPC) paste, fly ash cement (FAC) paste, and zeolite cement (ZEC) paste for Cd2+ were calculated to be 10.97, 9.47, 4.63 mg·g−1, respectively. The possible mechanisms for Cd2+ adsorption in the solution by waste cement mainly involve precipitation by forming insoluble Cd2+ compounds in alkaline conditions, and ion exchange for Cd2+ with the exchangeable calcium ions in waste cement, which were confirmed by XRD and SEM. Results from diethylene triaminepentaacetic acid (DTPA) extraction and toxicity characteristic leaching procedure (TCLP) implied reduction of the Cd2+ mobility. DTPA-extractable Cd2+ decreased by 52, 48 and 46%, respectively, by adding 1% OPC, FAC and ZEC. TCLP-extractable Cd2+ decreased by 89.0, 80.3, and 56.0% after 1% OPC, FAC, and ZEC treatment, respectively. BCR analyses indicate that OPC, FAC, and ZEC applications increased the percentage of Cd2+ in residual fraction and induced a high reduction in the acid-soluble Cd2+ proportion. The leaching column test further confirmed a reduction in Cd2+ mobility by waste cement treated under continuous leaching of simulated acid rain (SAR). Therefore, waste cement exhibited a significant enhancement in the immobilization of Cd2+ under simulated acid rain (SAR) leaching. In summary, the application of alkaline waste cement could substantially remove Cd2+ from wastewater and reduce Cd2+ mobility and bioavailability in contaminated soil.
Xiuming Ding; Junfeng Wang; Qing Huang; Shan Hu; Yuejun Wu; Luya Wang. The Effects of Waste Cement on the Bioavailability, Mobility, and Leaching of Cadmium in Soil. International Journal of Environmental Research and Public Health 2021, 18, 8885 .
AMA StyleXiuming Ding, Junfeng Wang, Qing Huang, Shan Hu, Yuejun Wu, Luya Wang. The Effects of Waste Cement on the Bioavailability, Mobility, and Leaching of Cadmium in Soil. International Journal of Environmental Research and Public Health. 2021; 18 (16):8885.
Chicago/Turabian StyleXiuming Ding; Junfeng Wang; Qing Huang; Shan Hu; Yuejun Wu; Luya Wang. 2021. "The Effects of Waste Cement on the Bioavailability, Mobility, and Leaching of Cadmium in Soil." International Journal of Environmental Research and Public Health 18, no. 16: 8885.
Biowaste materials could be considered a renewable source of fertilizer if methods for recovering P from waste can be developed. Over the last few decades, there has been a high level of interest in using biochar to remove contaminants from aqueous solutions. This study was conducted using a range of salts that are commonly found in biogas slurry (ZnCl2, FeCl3, FeCl2, CuCl2, Na2CO3, and NaHCO3). Experiments with a biogas digester and aqueous solution were conducted at pH nine integration with NH4 +, Mg2+, and PO4 3− molar ratios of 1.0, 1.2, and 1.8, respectively. The chemical analysis was measured to find out the composition of the precipitate, and struvite was employed to remove the aqueous solutions. The study found that the most efficient removal of phosphate and ammonium occurred at pH nine in Tongan sludge urban biochar and rice biochar, respectively. Increasing the concentration of phosphate and ammonium increased the phosphate and ammonium content. Moreover, increasing the biochar temperature and increasing the concentration of phosphate and ammonium increased the efficiency of the removal of ammonium and phosphate. The removal efficiency of ammonium and phosphate increased from 15.0% to 71.0% and 18.0% to 99.0%, respectively, by increasing the dose of respective ions K+, Zn2+, Fe3+, Fe2+, Cu2+, and CO3 2.The elements were increased from 58.0 to 71.0 for HCO3 − with the increasing concentration from 30 mg L−1 to 240 mg L−1.This study concluded that phosphate and ammonium can be recovered from mushroom soil biochar and rice biochar, and phosphate can be effectively recovered via the struvite precipitation method.
Aftab Kubar; Qing Huang; Muhammad Sajjad; Chen Yang; Faqin Lian; Junfeng Wang; Kashif Kubar. The Recovery of Phosphate and Ammonium from Biogas Slurry as Value-Added Fertilizer by Biochar and Struvite Co-Precipitation. Sustainability 2021, 13, 3827 .
AMA StyleAftab Kubar, Qing Huang, Muhammad Sajjad, Chen Yang, Faqin Lian, Junfeng Wang, Kashif Kubar. The Recovery of Phosphate and Ammonium from Biogas Slurry as Value-Added Fertilizer by Biochar and Struvite Co-Precipitation. Sustainability. 2021; 13 (7):3827.
Chicago/Turabian StyleAftab Kubar; Qing Huang; Muhammad Sajjad; Chen Yang; Faqin Lian; Junfeng Wang; Kashif Kubar. 2021. "The Recovery of Phosphate and Ammonium from Biogas Slurry as Value-Added Fertilizer by Biochar and Struvite Co-Precipitation." Sustainability 13, no. 7: 3827.