Soil Washing of Fluorine Contaminated Soil Using Various Washing Solutions

Bench-scale soil washing experiments were conducted to remove fluoride from contaminated soils. Five washing solutions including hydrochloric acid (HCl), nitric acid (HNO3), sodium hydroxide (NaOH), sulfuric acid (H2SO4) and tartaric acid (C4H6O6) were tested. The concentration of the washing solutions used ranged from 0.1 M to 3 M with a liquid to solid ratio of 10. The soil washing results showed that the most effective washing solution for the removal of fluoride from contaminated soils was HCl. The highest fluoride removal results of approximately 97% from the contaminated soil were obtained using 3M HCl. The fluoride removal efficiency of the washing solution increases in the following order: C4H6O

Remediation of Petroleum-Contaminated Gas Station Soil Using High-Pressure Soil Washing Technology

Objectives In this study, high-pressure soil washing was performed on in-situ gas station soils for the remediation of petroleum-contaminated gas station sites. Methods On-site gas station soils (GSS) collected from four different locations were subjected to high-pressure soil washing to analyze the amount of fine soil removal and TPH concentration after washing according to the cut-off size (0.075, 0.105 mm). In addition, the four GSS were evaluated for the relationship between the organic matter content of each soil and TPH removal efficiency. Furthermore, to evaluate the disintegration force of high-pressure soil washing technology to disperse soil aggregates, the particle size distribution of the soil before and after washing was evaluated and XRD analysis was performed. Results and Discussion As the cut-off size increased (0.075 mm → 0.105 mm), the removal rate of fine soil in the GSS increased, and the TPH concentration tended to decrease. With respect to the TPH Soil Contamination Warning Standard for Region 2 (800 mg/kg), only the GSS 3 was in compliance with the standard (630 mg/kg). There were no significant differences in fine soil removal rates among the soils, which was expected since all the soils tested represented the same sandy loam. Washing efficiencies by soil were relatively low for soils with relatively high organic matter content. The particle size distribution showed the largest particle reduction was in the 2-0.850 mm range after remediation, while soil particles increased in the 0.105-0.075 mm and <0.075 mm range. In addition, XRD analysis showed an increase in the peak intensity of Quartz and the removal of clay mineral after washing, confirming the effective breakdown of soil aggregates and removal of fine soil by cavitation. Conclusion If an optimal cut-off size is established, considering the soil texture and economics of the contaminated site after identifying the initial organic content level in the soil prior to washing, it is anticipated that high-pressure soil washing technology will be effectively applied for the remediation of petroleum-contaminated gas station sites

Stabilization of Lead (Pb) and Zinc (Zn) in Contaminated Rice Paddy Soil Using Starfish: A Preliminary Study

Lead (Pb) and zinc (Zn) contaminated rice paddy soil was stabilized using natural (NSF) and calcined starfish (CSF). Contaminated soil was treated with NSF in the range of 0-10 wt.% and CSF in the range of 0-5 wt.% and cured for 28 days. Toxicity characteristic leaching procedure (TCLP) test was used to evaluate effectiveness of starfish treatment. Scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX) analyses were conducted to investigate the mechanism responsible for effective immobilization of Pb and Zn. Experimental results suggest that NSF and CSF treatments effectively immobilize Pb and Zn in treated rice paddy soil. TCLP levels for Pb and Zn were reduced with increasing NSF and CSF dosage. Comparison of the two treatment methods reveals that CSF treatment is more effective than NSF treatment. Leachability of the two metals is reduced approximately 58% for Pb and 51% for Zn, upon 10 wt.% NSF treatment. More pronounced leachability reductions, 93% for Pb and 76% for Zn, are achieved upon treatment with 5 wt.% CSF. Sequential extraction results reveal that NSF and CSF treatments of contaminated soil generated decrease in exchangeable/weak acid Pb and Zn soluble fractions, and increase of residual Pb and Zn fractions. Results for the SEM-EDX sample treated with 5 wt.% CSF indicate that effective Pb and Zn immobilization is most probably associated with calcium silicate hydrates (CSHs) and calcium aluminum hydrates (CAHs)

Quality Improvement of Acidic Soils by Biochar Derived from Renewable Materials

Biochar derived from waste plant materials and agricultural residues was used to improve the quality of an acidic soil. The acidic soil was treated for 1 month with both soy bean stover-derived biochar and oak-derived biochar in the range of 1 to 5 wt% for pH improvement and exchangeable cation enhancement. Following 1 month of treatment, the soil pH was monitored and exchangeable cations were measured. Moreover, a maize growth experiment was performed for 14 days with selected treated soil samples to confirm the effectiveness of the treatment. The results showed that the pH of the treated acidic soil increased by more than 2 units, and the exchangeable cation values were greatly enhanced upon treatment with 5 wt% of both biochars, after 1 month of curing. Maize growth was superior in the 3 wt% biochar-treated samples compared to the control sample. The presented results demonstrate the effective use of biochar derived from renewable materials such as waste plant materials and agricultural residues for quality improvement of acidic soils

Enhanced Electrokinetic Transport of Sulfate in Saline Soil

The electrokinetic transport of sulfate was investigated as a means of treating and restoring a sulfate-accumulating saline soil. The electrokinetic treatment decreased the electrical conductivity of the soil, an indicator of soil salinity, to 58.6%, 73.1%, and 83.5% for 7, 14 and 21 days, respectively. More than 96% of the chloride and nitrate were removed within 7 days. However, the removal of sulfate was highly influenced by the anode material. An iron anode removed sulfate effectively, whereas, sulfate was hyper-accumulated in the anodic region when an inert anode was used. The iron anode was oxidized in a sacrificial anodic reaction, which competed with the electrolysis reaction of water at the anode, and finally the reaction prevented the severe acidification of the soil in the anodic region. However, the competing reactions produced hydrogen ions at the anode, and the ions were transported toward the cathode, which, in turn, acidified the soil, especially, in the anodic region. The acidification switched the surface charge of the soil from negative to positive, increasing the interaction between the soil surface and sulfate, and thus inhibiting the transport of sulfate under the electric field. The zeta potential analysis of the soil provided an explanation. The results indicate that preventing severe acidification is an important factor which influences the transport of anions and iron anode for the enhanced removal of anionic pollutants by electrokinetic remediation

Assessment of Soil Washing for Simultaneous Removal of Heavy Metals and Low-Level Petroleum Hydrocarbons Using Various Washing Solutions

Bench-scale soil washing experiments were conducted for simultaneous removal of heavy metals (Pb, Cu, Zn) and low-level petroleum hydrocarbon contaminants from soils. Various washing solutions including hydrochloric acid (HCl), nitric acid (HNO3), sulfuric acid (H2SO4), tartaric acid (C4H6O6) and ethylenediaminetetraacetic acid (C10H16N2O8, EDTA) were used. The concentration of the washing solutions ranged from 0.1 to 3M with a liquid-to-solid ratio of 10. The soil washing results showed that hydrochloric acid (HCl) was the best washing solution at 3M for heavy metal removal. Other washing solutions also showed a significant removal of heavy metals, except for sulfuric acid (H2SO4). Sulfuric acid (H2SO4) exhibited the worst performance among all washing solutions used with respect to Pb removal. 1M HCl and HNO3were sufficient for effective Pb and Cu removal, and all of the tested washing solutions at a concentration of 0.1M produced results compliant with the Korean warning standard for Zn removal. In the case of total petroleum hydrocarbons (TPH), tartaric acid (C4H6O6) produced the highest removals at all concentration levels compared with other washing solutions. More specifically, TPH removal efficiencies exceeded 33 and 82 % at the lowest (0.1M) and highest (3M) tartaric acid (TA) concentrations, respectively. Overall, TA could be a viable washing solution for the removal of both heavy metals (Pb, Cu, Zn) and TPH from contaminated soils

Immobilization of Lead in Contaminated Firing Range Soil Using Biochar

Soybean stover-derived biochar was used to immobilize lead (Pb) in military firing range soil at a mass application rate of 0 to 20 wt.% and a curing period of 7 days. The toxicity characteristic leaching procedure (TCLP) was performed to evaluate the effectiveness of the treatment. The mechanism responsible for Pb immobilization in military firing range soil was evaluated by scanning electron microscopy-energy dispersive x-ray spectroscopy (SEM-EDX) and x-ray absorption fine structure (XAFS) spectroscopy analyses. The treatment results showed that TCLP Pb leachability decreased with increasing biochar content. A reduction of over 90 % in Pb leachability was achieved upon treatment with 20 wt.% soybean stover-derived biochar. SEM-EDX, elemental dot mapping and XAFS results in conjunction with TCLP leachability revealed that effective Pb immobilization was probably associated with the pozzolanic reaction products, chloropyromorphite and Pb-phosphate. The results of this study demonstrated that soybean stover-derived biochar was effective in immobilizing Pb in contaminated firing range soil

Aortic Dissection and Rupture in a Child

After developing sudden severe chest pain, an 11-year-old boy presented to the emergency room with chest pain and palpitations and was unable to stand up. The sudden onset of chest pain was first reported while swimming at school about 30 minutes prior to presentation. Arterial blood pressure (BP) was 150/90 mmHg, heart rate was 120/minute, and the chest pain was combined with shortness of breath and diaphoresis. During the evaluation in the emergency room, the chest pain worsened and abdominal pain developed. An aortic dissection was suspected and a chest and abdomen CT was obtained. The diagnosis of aortic dissection type B was established by CT imaging. The patient went to surgery immediately with BP control. He died prior to surgery due to aortic rupture. Here we present this rare case of aortic dissection type B with rupture, reported in an 11-year-old Korean child

Endoscopic Management of Acute Cholecystitis and Cholangitis Caused by Limy Bile

Limy bile is a relatively rare condition in which a radiopaque material is visible in the gallbladder, extending rarely into the bile duct, on plain radiography. Acute cholangitis or cholecystitis caused by limy bile is a very rare condition. There are no definite treatment guidelines for limy bile, but in most cases with cholangitis or cholecystitis, laparoscopic cholecystectomy has been the preferred treatment. We report a case of limy bile with biliary symptoms that was treated only with an endoscopic procedure