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    Assessment and classification of different ashes from waste incinerators in Thailand
    (2024-12-01)
    Muthuraja, Raji
    ;
    Pombhejara, Chatpong Na
    ;
    Ganesan, Sunantha
    ;
    Attaphong, Chodchanok
    ;
    Morawan, Nattaya
    Rapid urbanisation and a growing population have led to a huge production of solid waste worldwide. To mitigate solid wastes, Thailand adapts incineration. As a consequence, a variety of fly ashes being produced in large quantities. Fly ash management is therefore a risk for the future. A comparison of the chemical and physical properties of five sources of ashes from the waste incinerators in three regions in Thailand, namely MFA1, MFA2, IFA, and fly ash that used in a ready-mixed concrete plant, CFA1 and CFA2 was conducted. Additionally, bottom ashes, MBA1, MBA2 and IBA were also characterized similarly. The analysis showed that coal fly ash from ready mixed concrete plant of CFA1 and CFA2 were classified under class F and C, respectively. The heavy metal analysis showed that fly ash from MFA1 and IFA has high amount of Zn (7,523 mg/kg and 28,315 mg/kg), followed by MFA1 has high amount of cadmium (127 mg/kg) and MFA1 and IFA showed high concentration of lead (1,955 mg/kg and 1,425 mg/kg). The present study show that fly ash often contains heavy metals, dioxins, and other hazardous substances, highlighting the need for detailed analysis to determine proper handling and disposal methods. Advanced classification systems, which may include parameters such as leaching behavior, particle size distribution, and contaminant concentrations, are essential for categorizing fly ash into appropriate management pathways, such as landfilling, resource recovery, or reuse in construction materials.
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    Reduction of heavy metal movement in soil contaminated with diesel using Corncob-Biochar
    (2021-01-01)
    Chaiyaraksa, Chompoonut
    ;
    Phumcharoen, Ketklao
    This research aimed to study the effect of biochar on the stability of Mn, Cd, and Pb in soil contaminated with diesel. The clay with pH 6.80, medium in organic matter (OM), high in cation exchange capacity (CEC), low in phosphate and salinity was from Bang Rong Subdistrict, Klong Khuen District, Chachoengsao Province (N13˚50’32.1252” E101˚ 9’5.6808”). The metal content is in the standard for use in agriculture. The soil sample was prepared to contain Mn, Pb, and Cd at 2,000 mg/kg, 550 mg/kg, and 50 mg/kg, respectively. The biochar from corncob was neutral, low in CEC, high in conductivity and OM. The surface area, pore-volume, pore radius, acid neutralization capability, and the pH at the point of zero charges (pHPZC) were 61.189 sq. m/g, 0.088 mL/g, 13.664 Angstrom, 1,000 meq/kg, and 6.80, respectively. Five percent of biochar was mixed to the soil containing 2% and 5% of diesel at room temperature for 2, 4, and 8 weeks before extraction with diethylenetriaminepentaacetic acid (DTPA) and sequential extraction. The results indicated that the higher the amount of diesel in soil, the slower the metal movement. Biochar could retard the mobility of Mn, Pb, and Cd in the soil sample. Five percent of biochar was not enough to decrease the metal mobility in soil contaminated with diesel 5%. The amount of extracted heavy metals increased with the more extended mixing period. The addition of biochar to the soil sample could change metals from unstable to stable forms.
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    Mobility retardation of Cd, Pb and Mn in acid soil using phosphate fertilizers
    (2019-05-01)
    Chaiyaraksa, Chompoonut
    ;
    Rodsa, Natthanan
    Contamination of heavy metals in soil is a major problem that causes damage to the environments. The aim of this research was to observe the efficiency of phosphate fertilizer, including phosphate rock, di-ammonium phosphate, and monopotassium phosphate in stabilizing lead, cadmium, and manganese in contaminated soil. The sampling soil was an acid sandy clay loam soil from Rayong Province which is one of the most industrialized provinces in Thailand. After applying fertilizers to the soil, the determination was on soil pH, the total concentration of heavy metals, heavy metal forms in soil and potential of heavy metals to enter the biological system. The results showed that phosphate rock, diammonium phosphate, and monopotassium phosphate increased the soil pH from 3.60 to 6.5, 7.0 and 5.2, respectively. Phosphate fertilizers could change an unstable form to a more stable form of heavy metals. Phosphate rock (7.5 g/kg<inf>soil</inf>) has the highest potential for reducing the mobility of all three metals (about 80% for manganese, 60% for cadmium, and 50% for lead), followed by monopotassium phosphate. The results obtained from the extraction with DTPA and CaCl<inf>2</inf> were closely related to the results obtained from the sequential extraction method. Phosphate rock was the best to reduce potentially toxic metals phytoavailability. Soil improvement with phosphate fertilizer was considered a good alternative for stabilizing soils contaminated with cadmium, lead, and manganese.
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    Acid soil amendment by zeolite, sepiolite and diatomite
    (2019-01-01)
    Chaiyaraksa, Chompoonut
    ;
    Tumtong, Mintra
    The aim of this research was to reduce the heavy metal movement to the biosystem using clay minerals including zeolite, sepiolite, and diatomite. The clay soil and sandy loam soil were made contaminated with 200, 350, 700, and 250 mg of Zn, Cu, Cr, and Ni per kg of soil, respectively. The ratio of clay minerals added to soils was 2.5%, 5%, and 7.5%. The determination of various forms of heavy metals bound to soil mixed with clay minerals and left for a period of 30 and 60 days was carried out using the sequential extraction method. The results indicated that Ni and Zn were mostly in an exchangeable form, while Cu and Cr were mostly in an oxide bound form and an organically bound form. The pH of the soils increased after adding clay minerals. Diatomite caused the smallest change in the pH value. Chromium had the best adsorption capacity by bonding with various elements in the soil, followed by Cu, Zn, and Ni, respectively. The addition of sepiolite caused more heavy metals in a stable form than adding zeolite and diatomite. When adding clay minerals to both types of soil, the highest impact was on Ni, followed by Zn, Cu, and Cr, respectively. The bioavailable index (BI) value was the least when adding sepiolite. The risk of heavy metals moving to the biosystem was lower when increasing the incubation time. Without adding any clay mineral, the BI value of metals in the sandy clay loam soil was higher than that in the clay soil.
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    Evaluation of phosphate fertilizers for the stabilization of cadmium in highly contaminated soils
    (2009-06-15)
    Thawornchaisit, Usarat
    ;
    Polprasert, Chongrak
    The efficiency of three phosphate fertilizers including triple superphosphate (TSP), diammonium phosphate (DAP), and phosphate rock (PR) as stabilizing agents of cadmium-contaminated soils has been assessed in this study. Two types of assessment criteria, (a) the reduction of leachable cadmium concentration; and (b) the changes in Cd association with specific operational soil fraction based on the sequential extraction data, are used in the evaluation of stabilization performance of each fertilizer. Results of the study showed that after the 60-day stabilization, the leachable concentrations of Cd in PR-, DAP- and TSP- treated soils reduced from 306 mg/kg (the control) to 140, 34, and 12 mg/kg with the stabilization efficiency as TSP>DAP>PR. Results from the assessment of Cd speciation via sequential extraction procedure revealed that the soluble-exchangeable fraction and the surface adsorption fraction of Cd in the soils treated with PO<inf>4</inf> fertilizers, especially with TSP, have been reduced considerably. In addition, it is found that the reduction was correspondingly related with the increase of more stable forms of cadmium: the metal bound to manganese oxides and the metal bound to crystalline iron oxides. Treatment efficiency increased as the phosphate dose (based on the molar ratio of PO<inf>4</inf>/Cd) increased. In addition, it was observed that stabilization was most effective when using the molar ratio of PO<inf>4</inf>/Cd at 2:1 and at least 21-day and 28-day stabilization time for TSP and DAP, respectively. © 2008.