Soil Remediation Technologies Research Articles

Effects of flue gas recirculation on the thermal performance of the gas remediation well

Gas thermal remediation (GTR) is a promising novel soil remediation technology. Many problems such as high energy consumption and unreasonable temperature distribution are still commonly found in the application of the gas remediation well. External flue gas recirculation (e-FGR) was applied to improve the thermal performance of the well. A 3D CFD model of the gas remediation well coupled with e-FGR was developed to analyze the heat transmission and combustion process. Four representative e-FGR ratios, 15 %, 30 %, 45 %, and 60 %, were selected to analyze the relationship between the e-FGR ratio and the well thermal performance. The results show that limited impact is obtained at a low e-FGR ratio and excellent results can only be achieved when the e-FGR ratio reaches 60 %. The maximum flame temperature was reduced by about 28 % at an e-FGR ratio of 60 % when compared with conventional combustion conditions. Localized high-temperature areas on the well surface are eliminated. The total heat transfer of the well increased from 4.69 kW to 6.16 kW when the e-FGR ratio increased from 0 to 60 %, which means a 23.9 % reduction in the remediation cycle and fuel consumption can be achieved at an e-FGR ratio of 60 %.

Basic Study on Electrochemical Remediation of Heavy Metal Contaminated Water and Soil

Heavy metal pollution of soil is one of the major environmental problems at this stage, and soil pollution itself has the characteristics of accumulation and irreversibility, which is difficult to completely recover from the root. Therefore, the research work on soil remediation technology and practice has become the main work content. The research progress in recent years includes physical remediation, chemical remediation, bioremediation, agricultural remediation and other models. It is also imperative to study its technical characteristics and application scope.

Research progress of bio-slurry remediation technology for organic contaminated soil.

Bio-slurry remediation technology, as a controllable bioremediation method, has the significant advantage of high remediation efficiency and can effectively solve the problems of high energy consumption and secondary pollution of traditional organic pollution site remediation technology. To further promote the application of this technology in the remediation of organically polluted soil, this paper summarizes the importance and advantages of bio-slurry remediation technology compared with traditional soil remediation technologies (physical, chemical, and biological). It introduces the technical infrastructure and its technological processes. Then, various factors that may affect its remediation performance are discussed. By analyzing the applications of this technology to the remediation of typical organic pollutant-(polycyclic aromatic hydrocarbons(PAHs), polychlorinated biphenyls(PCBs), total petroleum hydrocarbons(TPH), and pesticide) contaminated sites, the following key features of this remediation technology are summarised: (1) the technology has a wide range of applications and can be used in a versatile way in the remediation projects of various types of organic-contaminated soil sites such as in clay, sand, and high organic matter content soil; (2) the technology is highly controllable. Adjusting environmental parameters and operational conditions, such as nutrients, organic carbon sources (bio-stimulation), inoculants (bio-augmentation), water-to-soil ratio, etc., can control the remediation process, thus improving the restoration performance. To sum up, this bio-slurry remediation technology is an efficient, controllable and green soil remediation technology that has broad application prospects.

Modeling and Analysis of the Soil Vapor Extraction Equipment for Soil Remediation

Soil vapor extraction (SVE) is one of the most commonly used technologies for soil remediation of contaminated sites, and the use of models to accurately predict and evaluate the operational effectiveness of SVE is a necessary part of site contamination treatment projects. A pneumatic model-based equipment model is proposed to comprehensively describe the SVE operation process. Though the numerical simulation, the influence of fan frequency, air valve opening, pressure, and total flow was analyzed, and an optimal extraction strategy was validated. Then, field experiments were carried out to verify the validity of the model. The proposed model and experimental results can provide a theoretical basis for the design and duration evaluation of SVE.

Degradation of 1,2,3-trichloropropane by unactivated persulfate and the implications for groundwater remediation

Persulfate (PS) is widely used as an in situ chemical oxidation (ISCO) technology for groundwater and soil remediation. While conventional theory generally assumes that PS needs to be “activated” to produce reactive radicals for pollutant degradation, herein, PS without explicit activation system was discovered for the degradation of 1,2,3-TCP with the generation of reactive oxidation species (ROS). Comparison of five common ISCO oxidants (PS, peroxymonosulfate, hydrogen peroxide, potassium permanganate, and sodium percarbonate) indicated that only unactivated PS was able to degrade 1,2,3-TCP in both pure water and 12 natural water samples. 50 μM 1,2,3-TCP degradation can be continued as long as there is enough PS (50 mM). The degradation rate of 1,2,3-TCP increased 450 % when the PS concentration increased from 10 mM to 50 mM and 500 % when the temperature increased from 25 °C to 45 °C. Electron paramagnetic resonance (EPR) analyzes, hydroxyl radicals (·OH) probe reaction and radical quenching experiments confirmed the involvement of both sulfate radicals (SO4·-) and ·OH that were responsible for 1,2,3-TCP degradation and ·OH played a more important role. HCO3−, Cl− and NOM are three groundwater matrix species that are most likely to inhibit PS oxidation of 1,2,3-TCP. Compared to activated PS, unactivated PS is more promising and more practical for groundwater remediation, since it has several advantages: (1) longer lifetime and better long-term availability; (2) ability of enduring contaminant degradation; (3) applicable for low-permeability zones remediation and potential to alleviate contaminant rebound or tailing problems; (4) environmental friendly; and (5) lower cost. Overall, results of this study show that unactivated PS is a promising in situ remediation technology that may be a good candidate for the most challenging low permeable zone remediation.

Remediation of pesticides in commercial farm soils by solarization and ozonation techniques

Soil contamination by pesticides is a growing environmental problem. Even though nowadays numerous soil remediation technologies are available, most of them have not been tested at field scale. This study attempts to demonstrate the efficiency of solarization-ozonation techniques for the removal of twelve pesticides at full scale. Initial solarization and ozonation trials were conducted in plots located in a greenhouse using freshly and aged contaminated soils under controlled pilot conditions. The combination of solarization and ozonation treatment was efficient for all the studied pesticides both in freshly and in aged contaminated soils, being the lower degradation values found for the second type. This low removal suggests that the increase of pesticides' adsorption on soil resulting from ageing decreases their availability. Once the essays were carried out at pilot scale, the solarization-ozonation applicability was evaluated in a commercial farm soil. This trial was carried out in a greenhouse whose soil had previously been contaminated with some of the pesticides studied. A significant degradation (53.8%) was observed after 40 days of treatment. Pesticides’ main metabolites were identified during the different remediation experiments. In addition, the cost of the combined solarization and ozonation technology was evaluated. Finally, our results suggest that this combination of techniques could be considered a promising technology to degrade pesticides in soil.

Diffusion of Cement Kiln Co-Processing of Contaminated Soil in Selected Provinces of China: Engineering Practices, Modeling, and Driving Factors

Promoting the diffusion of remediation technologies is an attractive solution to environmental protection and urban sustainability challenges. To better understand technology diffusion, we reviewed the engineering practices of cement kiln co-processing (CKC) of contaminated soil and obtained diffusion parameters using the Bass model in three provinces of China. Our results show that CKC has been adopted for the disposal of multiple contaminants and that the optimal feed rate of contaminated soil is 4–5%. The obtained diffusion parameters can be used to analyze and predict CKC diffusion. Driving factors analysis suggest that CKC diffusion is regulation-driven and obeys the S-curve pattern. Policies at the national level shape the basic pattern of the diffusion curve, while local policies, market scales, and contaminant types produce variations in diffusion rates across provinces. Results also reveal that the co-processing quota management on contaminated soil has little impact on CKC adoption. This study provides insights into contaminated soil remediation technology diffusion and the effectiveness of environmental policy implementation at home and abroad.

Green Remediation Technology for Total Petroleum Hydrocarbon-Contaminated Soil

In order to improve the bioremediation efficiency of petroleum-contaminated soil, five test groups were selected in this study, including native bacteria, Acinetobacter venetianus, Vetiveria zizanioides L., and Vetiveria zizanioides L. combined with Acinetobacter venetianus and biochar to compare the degradation efficiency of petroleum-contaminated soil. The results of the study showed that after a six-month bioremediation, there was no significant difference between the native bacteria and the A.V. bacteria group in the removal efficiency of TPH, and the proportion of degradable TPH accounts for about 50~70%. The removal efficiency of TPH could be increased by 18.1–29% by increasing the phytoremediation of Vetiveria zizanioides L. The cultivation of Vetiveria zizanioides L. could not only stabilize the soil’s pH and conductivity but could also increase the soil’s bacterial abundance. It was suggested that bioremediation could be carried out through the combination of native bacteria and the planting of Vetiveria zizanioides L. Although the addition of biochar to the soil was able to improve the remediation effect of Vetiveria zizanioides L., it would increase the soil conductivity and reduce the abundance of soil bacteria. Therefore, it was recommended to reduce the conductivity of biochar before adding it, which may improve processing efficiency.

Self-regulated immobilization behavior of multiple heavy metals via zeolitization towards a novel hydrothermal technology for soil remediation

More efficient soil remediation technologies are highly anticipated to treat large quantities of heavy metal-polluted urban sites nowadays. Herein, a novel hydrothermal technology of converting heavy metal-polluted soils into zeolites for in-situ immobilizing heavy metals was proposed. The zeolites (analcime and cancrinite) could be synthesized hydrothermally with certain Na/Si and Al/Si ratios. The formed zeolites could manage to change their species and structure during zeolitization to accommodate different heavy metals in soil according to their size and charge. Since smaller-size Cu2+ was introduced, analcime and some cancrinite possessing small cages could be formed adaptively to immobilize the Cu2+ by replacing Na+ and forming Cu2+-OH and Cu2+-O. Whereas, cancrinite with large channels managed to form to immobilize the larger-size Cd2+ by forming Cd2+-O. Interplanar spacing variation of zeolites also corresponded to their structural change for accommodating different heavy metals. Leaching results showed the amounts of Cu and Cd leached from the synthesized zeolites were reduced to 0.005% and 0.05% respectively, reflecting a more stable immobilization of smaller heavy metals by small cages, in agreement with the results of distribution coefficient (Kd). Negligible effect of pH environment on the leaching rates further confirmed the stable structural immobilization of heavy metals by zeolites.

Technological Developments and Remediation Mechanisms for Phytoremediation of PCB-Contaminated Soils

Polychlorinated biphenyls (PCBs) have been detected in a variety of environmental media, and they have been continuously introduced into the environment for industrial reasons, despite their harmful impact upon ecological health. Considering the adverse effects of PCBs, many researchers have begun to analyze remediation technologies for PCB-contaminated soil. In this study, the rise and fall of PCBs, as well as their physical and chemical properties and environmental impact, were reviewed. The pollution status of PCBs in soil was summarized. Based on the analysis and comparison of various remediation technologies, the limitations of several phytoremediation technologies in PCB-contaminated soils were analyzed. The influencing factors and transformation mechanisms of the phytoremediation of PCB-contaminated soil were investigated, and the research direction of enhancing the degradation of PCBs through the use of plants was also discussed.

Tandem Electrokinetic/Electrocatalytic Remediation of Pfas in Soils

Per-/polyfluorinated species (PFAS) are a class of widely used, highly stable chemicals that do not readily break down in the environment or human body. As a result of their widespread use and persistence in the environment, PFAS can be found in soil, air, and water at numerous sites across the United States. Recent work has linked exposure to some types of PFAS found in the environment to adverse health effects in humans. The bio-accumulative nature of PFAS along with the potential adverse health effects has provided strong motivation for active remediation of these emerging contaminants at environmental sites. Development of energy- and cost-efficient technologies for the in-situ treatment of PFAS-contaminated soils would greatly facilitate efforts to remediate these contaminated sites and alleviate the public health threat they represent.This talk will discuss recent efforts to develop a tandem electrokinetic/electrocatalytic technology for energy-efficient concentration and destruction of PFAS in contaminated soils. In this approach (Figure A), electrokinetic soil remediation technology is used to drive the PFAS contaminants to a localized area around the electrokinetic anode and electrocatalysis reactors situated near this electrokinetic anode degrade and destroy the concentrated PFAS species. Data will be presented describing the electrokinetic transport observed for various C4-C12 linear-chain PFAS in a Dayton, OH till soil on the bench scale (see Figure B). Experimental results to date suggest that larger PFAS species (above ~C6) experience sufficiently strong physicochemical attraction to the soil particles that electrokinetic transport is mostly or completely suppressed. Based on these results, current work is identifying ways to improve electrokinetic PFAS remediation by disrupting these PFAS-soil interactions in a fashion that is economically and environmentally favorable. Results demonstrating the ability to enhance electrocatalytic PFAS destruction through the use of pulsed-waveforms (relative to traditional direct current methods) will also be presented.Figure Caption. (A) Mechanism of tandem electrokinetic/electrocatalytic PFAS destruction. (B) Bench-scale apparatus for soil electrokinetics tests. Figure 1

Study on Remediation Technology of PAH-contaminated Soil

Study on Remediation Technology of PAH-contaminated Soil

Consumers' Willingness to Pay for Rice from Remediated Soil: Potential from the Public in Sustainable Soil Pollution Treatment.

Remediation of polluted soil on arable land is mostly funded by governments, with the understanding that the public’s willingness to pay for food produced on remediated soil can help establish a soil remediation model with more stakeholders. In contrast to previous studies that have focused on soil-remediation technologies’ diffusion, this study employs choice experiments to evaluate market preferences for crops grown from lands of varying quality that are reflected in consumers’ willingness to pay (WTP). The results show that consumers are willing to pay a small premium for rice labeled with remediated-soil claims, but the WTP for remediated-soil claim is less than that of an uncontaminated-soil claim. Consumers’ WTP for remediated-soil claim increases by 29.03% when combining with a well-known brand, and it increases by 71.17% when information is provided about the efficacy of cadmium and heavy-metal-pollution remediation; however, combining with the region-of-origin label does not increase WTP. We also find that, in early stages of promotion, online stores may reach target consumers more easily. Based on these results, we propose four implications for policymakers.

Beneficial utilization of derivatives from petroleum-contaminated soil by ferrate-assisted pyrolytic remediation to adsorb heavy metal in wastewater

Conventional remediation technologies for petroleum-contaminated soil (PCS) usually consider harmless treatment as the primary goal, ignoring the reutilization value of PCS derivatives; they generally face the dilemma of high cost or low efficiency. In this study, PCS was treated by ferrate-assisted pyrolysis for highly efficient remediation and transformation to Fe-loaded carbonized soil (Fe-CS) as a heavy metal adsorbent. The total petroleum hydrocarbons and dissolved organic matter in the obtained Fe-CS were almost completely removed. When the pyrolysis temperature was 500 °C, retention time was 30 min, and 10 % K2FeO4 was added, The Langmuir model showed that the maximum adsorption capacities of Pb2+ and Cu2+ of Fe-CS were 347.9 and 106.3 mg/g, respectively. The adsorption processes of Pb2+ and Cu2+ onto Fe-CS fit the pseudo-second and pseudo-first kinetic models, respectively. X-ray diffractometer (XRD), Raman spectroscopy, Fourier transform infrared (FTIR), Brunauer–Emmett–Teller (BET), and X-ray photoelectron spectroscopy (XPS) were used to characterize the adsorbent. XPS analysis showed that iron oxide, metal carbonate, and CO on the Fe-CS surface were significantly increased compared with the carbonized soil (CS) obtained by pyrolysis alone. In addition, the BET specific surface area and micropore volume of Fe-CS are higher than those of CS. The chemical specifications of the heavy metals in Fe-CS showed that they are mainly bound to carbonates and iron oxides. This study provides an innovative method for the simultaneous realization of the efficient remediation and high-value reuse of PCS.

Fe-C-based materials: synthesis modulation for the remediation of environmental pollutants-a review.

Presently, the rapid pace in the discovery of emerging aquatic pollutants is increasing the demand for the remediation and treatment of our natural resources. Regarding this, nanotechnology is being considered the potential solution for contaminated water remediation with techniques such as filtration, adsorption, catalysis, and desalination. For this purpose, zerovalent iron (ZVI) is being widely used in the remediation of environmental pollutants due to its large specific surface area and high reactivity. However, ZVI is easy to agglomerate and oxidize, limiting its application in the real environment. Therefore, the present study was designed to discuss the preparation and characterization methods of ZVI composite materials, factors affecting adsorption, the removal effect, and adsorption mechanism of different pollutants by Fe-C materials because the optimization and modification of nano-zero-valent iron is a hot research topic nowadays in this field. Moreover, this paper does also analyze the possibility of the practical application prospects of the team's technology for preparing iron-carbon materials. Thus, this information will be helpful for the development and application of Fe-C-based technologies for water and soil remediation and the prediction of the future research direction of Fe-C composite materials.

Evaluation of the lipase from castor bean (Ricinus Communis L.) as a potential agent for the remediation of used lubricating oil contaminated soils.

Bioremediation of hydrocarbons-contaminated soils, using enzymes, is considered an alternative technology for soil remediation, obtaining shorter remediation times, greater removal efficiencies, and less waste generation. The lipases from invasive plants such as castor bean (Ricinus Communis L.) could represent an opportunity for its application in this purpose. This paper reports the results of evaluating enzymatic treatment at different conditions for the remediation of used lubricating oil-contaminated soils. Four assays were performed for the removal of the contaminant in a soil sample: (1) natural attenuation and (2) biostimulation with urea (10% w/v), both used as blanks, (3) enzymatic treatment with lipases at ambient conditions (room temperature, soil pH) and (4) enzymatic treatment with lipases at ideal conditions (temperature 37°C, pH 4.5). After seven weeks of treatment, removal percentages of 14.23 ± 1.92%, 35.71 ± 5.17%, 14.11 ± 6.71%, and 94.26 ± 1.91%, respectively, were obtained. The degradation of the contaminant was analyzed by Fourier-transform Infrared spectroscopy (FTIR) for each assay. Results show the potential of the lipases for catalyzing the degradation of this contaminant in the soil at ideal conditions, representing an alternative technology to be applied as treatment ex-situ. This paper is the first study known to show the utilization of castor bean lipase for the remediation of hydrocarbons-contaminated soils.

Remediation Technology Inventions for Soil and Groundwater Contamination

The reducing quality of groundwater resulted from accidental wastes compounded with soil leaching has become the topmost health concerns. Groundwater plays an important role in provisioning central source of drinking water to human population. The extensive contamination of ground water urges for remedial actions by many to control the damage. This narrative review will attempt to present the current state of remediation technologies for soil and groundwater contamination implemented to prevent further damage to the biodiversity of surrounding ecosystem. Components of each in-situ and ex-situ technologies were examined in detail to suit the characteristics of contamination site. The discoveries of reliable in-situ remediation technology of removing contaminants are another milestone for green environment sustainability. Therefore, adequate knowledge on characteristics of contamination site, understanding of groundwater flow conditions, site assessments and contaminant transport activities are crucial for future planning remediation technologies.

Research Progress of Heavy Metal Contaminated Soil Remediation Methods in China

In order to effectively remediate heavy metal pollution in soil, a variety of physical, chemical and biological remediation method of materials have been proposed in the past decades. In practical application, these restoration methods have their own advantages and disadvantages in terms of scope of application, efficiency and cost. Therefore, this newspaper summarizes several common soil remediation technologies in combination with the relevant literatures in the field of heavy metal contaminated soil collected by CNKI. It is found that most physical remediation technologies have the advantages of simple equipment, easy popularization and sustainability, but they are limited to small areas and highly polluted soils; Compared with logistics repair technology, chemical repair technology with low cost, high efficiency and wide application range is used by more people; In recent years, bioremediation technology, which has the advantages of small environmental disturbance, no secondary pollution, stable and harmless products, has solved the ecological damage caused by physical and chemical remediation. The research on the remediation of heavy metal contaminated soil will help to have a comprehensive understanding of this field, which is of great significance to attract more scholars to participate in it, and provide solutions for the current ecological civilization construction of the government and other departments from the aspect of remediation of heavy metal contaminated soil ecological environment.

Vital evidence for arbuscular mycorrhizal fungi, bacteria and cattail plant to remove Pb-Cd heavy metals from contaminated soils

Phytoremediation is a low-cost but highly efficient and environmentally friendly technology for heavy metal soil remediation. However, its success in soils is dependent on the chosen plant and microbes. Moreover, the effect of mycorrhizal fungi and bacteria on CO2 release, mineralization rate, and metal translocation in cadmium and lead-contaminated cattails plant is unknown. The goal of the research was to look into the effects of bacteria, mycorrhiza, and cattails on CO2 release, mineralization rate, lead (Pb), and cadmium (Cd) removal from soil. The experiment used six different combinations (mycorrhiza, bacillus 10 mL, bacillus 100 mL, mycorrhiza + bacillus 10 mL, mycorrhiza + bacillus 100 mL, and control). The results showed that combining mycorrhiza with bacillus 100 mL resulted in greater increases in CO2 release, polysaccharides content and mineralization rate (2.84 mg CO2 g−1 in dry soil, 0.90 mg, 0.021 mg C g−1 dry soil day−1). More crucially, mycorrhiza + bacillus 100 mL roots had the greatest quantities of Cd and Pb (18.26 mg kg−1 and 155.22 mg kg−1), showing that bacteria had a prominent part in the phytoextraction process. Regarding Cd, the bacillus 100 mL had the highest translocation factor (TF) (3.99) and biological accumulation factor (BAF) (75.54), indicating effective translocation and excessive Cd accumulation in the plant. Bacillus 100 and mycorrhiza + bacillus 100 had the highest Pb TF (0.49) and BAF (6.08). Ultimately, the elimination of Cd and Pb was linked to the maximum bacterial cell density, mycorrhizal activity, and CO2 emission, resulting in a unique phytoremediation in Pb-Cd contaminated cattails rhizosphere soils.

Ozonation for remediation of pesticide-contaminated soils at field scale

This work is the first ever study under field conditions for the removal of different classes of pesticides from soil using ozonation as a remediation technique. Initial assays were conducted with three different soil matrices to assess the effectiveness of the methodology under lab conditions. Field scale experiments were carried out on plots located in a greenhouse during the winter of 2020. The polluted soil was exposed to different treatments to test the effect of the mode of ozone application on pesticide degradation (S: polyethylene film covering, SOS: polyethylene film + surface ozone application, SOD: polyethylene film + deep application, SODS: polyethylene film + dual application, and C: no treatment). Ozonation impact was also assessed by variations on physical–chemical characteristics of the soil. Higher degradation was detected in ozonized soils, particularly in the SODS treatment, where ozone was dually applied on the surface and deep. During monitoring of remediation experiments, 15 of the main transformation products (TPs) were found. The results suggest that ozonation has favourable prospects to be considered a credible alternative technology for remediation of pesticide polluted soils.