A comprehensive guide of remediation technologies for oil contaminated soil — Present works and future directions

A laboratory-prepared contaminated soil was partitioned into four fractions, namely carbonate, Fe/Mn oxides, organic matter and clay mineral, according to the form in which the heavy metal bound with soil constituents. Individual contaminated soil fractions and synthetic soils were prepared for the study of soil extraction using ethylenediaminetetraacetic acid (EDTA). The effect of contact time and EDTA concentration were evaluated for both individual soil fractions and synthetic soils. The extraction reached equilibrium rapidly, after about 30 min. A 0.01 M EDTA solution was less effective than a 0.05 M or a 0.10 M EDTA. EDTA was proved to be effective for metal removal from the four individual soil fractions and synthetic soils. In general, approximately 90% of metals were removed from synthetic soils by 0.10 M EDTA. EDTA extraction of Pb from a contaminated carbonate fraction was thought to be affected by the formation of lead carbonates. A simple equation based on the sum of the released heavy metal from the individual components is used to check if there are interactions among the different soil components when mixed. The estimated values agreed well with the experimentally measured results only for the 0.10 M EDTA system.

EDTA Extraction of Heavy Metals from Different Soil Fractions and Synthetic Soils

The Superfund Amendments and Reauthorization Act requires the use of remedial technologies that permanently and significantly reduce the volume, toxicity, or mobility of contaminated materials at affected sites. Extractive processes can accomplish the requirements of the Superfund Amendments and Reauthorization Act. Ethylenediaminetetraacetic acid (EDTA), N-2(acetamido)iminodiacetic acid (ADA), pyridine-2,6-dicarboxylic acid (PDA), and hydrochloric acid (HCl) were evaluated over a range of concentrations and reaction times in batch studies for their ability to remove lead (Pb) and cadmium (Cd) from a Superfund soil (Pbtotal= 65,200 mg/kg, Cdtotal= 52 mg/kg). Lead extraction was limited by a slow overall reaction. The order of Pb removal by extractant was EDTA > ADA > PDA > HCL. The soil was subjected to three repeated 1 h extractions in which a maximum of 86, 84, 70, and 54% of the total soil Pb was removed with EDTA, ADA, PDA, and HCl, respectively. The soil was not treated to below the Pb regulatory lim...

Ex-situ remediation of a metal-contaminated Superfund soil using selective extractants

Influence of solution acidity and CaCl2 concentration on the removal of heavy metals from metal-contaminated rice soils.

A bench-scale study of seven Pb-contaminated soils from actual sites was undertaken to determine the feasibility of soil washing to meet cleanup goals. In addition, soil characteristics and operational factors affecting washing performance were identified. Soils were characterized by a sequential extraction method and scanning electron microscopy (SEM). Following a treatment process that consisted of particle size and density separation, and batch soil washing, soil Pb treatment goals were met for five of the seven sandy soils. Toxicity characteristic leaching procedure (TCLP) limits were met for all soils. In soil washing, the most important factor affecting removal of Pb was pH, with greater removals observed at a lower pH. Ethylenediaminetetraacetic acid (EDTA) addition significantly improved soil-washing performance at pH 3, and the temperature and liquid-to-solid (L/S) ratio had a minimal effect for the range of conditions studied. Washing results were in qualitative agreement with expectations extrapolated from the soil-characterization data. However, definitive identification and distribution of the Pb-binding mechanisms in these real waste-site soils could not be ascertained from the sequential extraction or SEM data.

Evaluation and Analysis of Soil Washing for Seven Lead-Contaminated Soils

Cleaning excavated soil using extraction agents: A state-of-the-art review

Abstract In this paper, an online monitoring method of insulation faults based on the stator magnetic field for insulation life tests is developed. In recent years, a trend towards higher operating voltages, higher switching frequencies, and shorter voltage rise times has been observed for low-voltage motors, mainly driven by increasing electromobility. An insulation system must withstand these requirements over the entire operating range and the required service life. Significant over-dimensioning of the insulation is not justifiable, since this has a negative impact on the utilization or the efficiency of the machine. Lifetime tests are therefore required for dimensioning the insulation. For this purpose, end-of-life (EOL) tests are usually carried out. Here, different damage patterns occur, which are distinguished during the analysis. In addition to the EOL test, insulation faults can be detected by monitoring the magnetic field of a stator during the operating time (“online”). An early shutdown often prevents the drive from further damage. In this paper, five methods to evaluate the magnetic field are presented. The operation is investigated using a 2D FEM simulation (sinus excitation) and a network simulation (PWM excitation) and evaluated through measurements on a 4 kW PM external rotor stator. Subsequently, an application of the method on a test rig setup with continuous monitoring of the insulation system is presented. The test setup serves as a basis for future investigations on the influence of voltage rise time, switching frequency, and DC link voltage on insulation faults to estimate the lifetime of insulation systems of electrical machines. 

https://link.springer.com/content/pdf/10.1007/s00502-023-01130-8.pdf

D. Dietz

Papers

Cleaning excavated soil using extraction agents: A state-of-the-art review

Online monitoring method based on magnetic field for stator insulation lifetime tests