Application In Soil Remediation Research Articles

Modeling and monitoring of foam propagation in highly permeable porous media under lateral water flow

Foam injection is a promising option for soil remediation applications. However, predicting how it will propagate in highly permeable aquifers under groundwater flow is challenging. Here, we have studied pressure and saturation variations during foam propagation. A 2D tank packed with 1 mm glass beads was used to study foam injection in highly permeable porous media under lateral flow. Specifically, we evaluated the efficiency of pressure and time-domain reflectometer (TDR) sensors to predict foam propagation using an imaging technique. A numerical model coupling two-phase flow and surfactant transport was developed to simulate the experimental results. This model takes into account the effect of non-Newtonian behavior of foam, surfactant concentration, and critical capillary pressure through the definition of the mobility reduction factor (MRF). The experimental results show that the foam injection pressure first increases with a logarithmic law and then stabilizes. This pressure stabilization can be related to the state of pseudo-equilibrium between foam generation and destruction. We observed an asymmetrical foam propagation due to water lateral flow. Comparisons of the liquid saturation fields calculated by analysis of TDR probes and estimated by imaging show that the TDR sensors monitor foam propagation well in saturated porous media. They can predict the shape of the injected foam. Contrary to pressure sensors, it is possible to capture weak foam behavior using TDR sensors. Finally, the numerical model we have developed correctly captures the shape of foam propagation and its ability to divert water flows. This model produces the propagation of the strong foam well and predicts the saturation and pressure fields with good precision.

Transformation of sulfidized nanoscale zero-valent iron particles and its effects on microbial communities in soil ecosystems

Sulfidized nanoscale zero-valent iron (S-nZVI) is a promising material for in situ soil remediation. However, its transformation (i.e., aging) and effects on the microbial community in soil ecosystems are largely unknown. In this study, S-nZVI having low (S-nZVI (L)) and high sulfur-doping (S-nZVI (H)) were incubated in soil microcosms and bare nZVI was used as a control. Their aged products were characterized using microspectroscopic analyses and the changes in the corresponding soil microbial community were determined using high-throughput sequencing analyses. The results indicate that severe corrosion of both bare and S-nZVI occurred over 56 days of aging with significant morphological and mineral changes. Magnetite, lepidocrocite, and goethite were detected as the main aged products. In addition, sulfate ions, pyrite, and iron polysulfide were formed in the aged products of S-nZVI. Cr(VI) removal test results indicated that S-nZVI(L) achieved the best results after aging, likely because of the optimal FeS arrangement on its nanoparticle surfaces. The presence of nZVI and S-nZVI increased the abundance of some magnetotactic microorganisms and altered bacterial and fungal community structures and compositions. Moreover, the addition of S-nZVI enriched some bacterial and fungal genera related to sulfur cycling because of the presence of sulfide-bearing material. The findings reveal the transformation of S-nZVI during aging and its effects on microbial communities in soil ecosystems, thereby helping to the evaluation of S-nZVI application in soil remediation.

BIOSURFACTANT PRODUCTION BY ENDOPHYTIC ISOLATES FROM RHIZOMES OF ZINGIBER ZERUMBET

Biosurfactants (BS) or green surfactants are amphiphilic compounds that enhance the bioavailability of hydrophobic organic compounds and also exhibit anti-phytopathogenic properties. BSproducing isolates thus find applications in soil remediation and development of biocontrol agents. Endophytes that confer several benefits to host plant constitute a good resource for prospecting BSproducing isolates. The present study screened the Z. zerumbet endophytes identified in earlier studies for BS production by hydrocarbon overlay agar method, CTAB- Methylene blue agar assay and determining Emulsification Index (EI24). EI24 was observed as the most desirable parameter to determine BS production compared to hydrocarbon overlay agar and CTAB- methylene blue agar plate assay. Isolate ZzADK4 (Bacillus spp) showed highest emulsification activity (58%) determined as EI% with kerosene. UV-vis spectral scans identified the endophytes as producing LP class of BS with absorbance maxima spanning 207- 216 nm. LP class of BS producing endophytic isolates identified in the present study constitute potential solutions with applications in soil remediation and the development of biocontrol agents (BCAs).

Layered double hydroxides: Scale production and application in soil remediation as super-stable mineralizer

Soil contamination by heavy metals has presented severe risks to human health through food chain. As one of the most promising remediation technologies, in-situ immobilization strategy has been widely adopted in practice. However, considering the large quantities of contaminated soil, it is still a huge challenge to design low-cost amendments with strong and long-term immobilization ability. Layered double hydroxides (LDHs) have drawn tremendous attention in fundamental research and practical application because of their unique properties. Moreover, owing to its super-stable mineralization effect to heavy metal ions, LDHs have exhibited great potential in the field of soil remediation. In this work, we mainly focused on the scale production strategy of LDHs with low-cost, and its application in soil remediation. Besides, several key challenges in using LDHs as amendments for immobilization of heavy metal ions are presented. We hope that this mini-review could shed light on the sustainable development of LDHs as amendment for heavy metals in future research directions.

Recent Advances in the Reutilization of Granite Waste in Various Fields

Quarrying and processing of granite produce large amounts of waste residues. Besides being a loss of resources, improper disposal of these wastes results in pollution of the soil, water and air around the dumpsites. The main components of granite waste are quartz, feldspars and a small amount of biotite. Due to its hard and dense texture, high strength, corrosion resistance and wear resistance, granite waste may be recycled into building materials, composite materials and fine ceramics, effectively improving their mechanical properties and durability. By using the flotation process, high value-added products such as potash feldspar and albite may be retrieved from granite waste. Also, granite waste has the potential for application in soil remediation and sewage treatment. This review presents recent advances in granite waste reutilization, and points out the problems associated with its use, and the related countermeasures, indicating the scale of high value-added reutilization of granite waste.

Experimental study of foam propagation and stability in highly permeable porous media under lateral water flow: Diverting groundwater for application to soil remediation

Foam propagation and stability in highly permeable porous media, encountered in soil pollution applications, are still challenging. Here, we investigated the application of foam for blocking the aquifer to divert the flow from a contaminated zone and, therefore, ease the remediation treatments. The main aim was to better understand the critical parameters when the foam is injected into a highly permeable aquifer with high groundwater flow velocity (up to 10 m/day). A decimetric-scale 2D tank experimental setup filled with 1 mm glass beads was used. The front part of the 2D tank was made of transparent glass to photograph the foam flow using the light-reflected method. The water flow was generated horizontally through injection and pumping points on the sides of the tank. The pre-generated foam was injected at the bottom center of the tank. Water streamlines (using dye tracing) and water saturation were investigated using image interpretation. Results show that 100% of the water flow was diverted during the injection of the foam. Foam stability in porous media depends significantly on the horizontal water flow rate. Recirculating water containing the surfactant increases foam stability. The main mechanism of destruction was identified as the dilution of the surfactant in water. However, the head-loss measurements showed that despite foam destruction, the relative permeability of the water phase in the media remained quite low. Injection of foam increases the radius of gas propagation, thanks to foam's high viscosity, compared to a pure gas injection case. These results are new highlights on the efficiency of foam as a blocking agent, showing that it can also serve as a means for gas transport more efficiently in porous media, especially for soil remediation applications.

Super-stable mineralization effect of layered double hydroxides for heavy metals: Application in soil remediation and perspective.

Agriculture soil plays a crucial role in sustainable development of human society. Unfortunately, soil quality is continuing degradation due to industrial and agricultural activities. Among them, agriculture soil contamination by heavy metals has become a serious threat to global food safety and human health. Because of low-cost, easy to implement, and fast effects, in situ chemical stabilization strategy has drawn great attention in soil remediation fields. However, since heavy metals are not removed from soil, it is still a great challenge to develop the cost-effective stabilizers with strong and long-term immobilization ability. Layered double hydroxides (LDHs) have been extensively applied in environmental fields owing to their unique structure. Very recently, LDHs have been used as amendment in in situ soil remediation for immobilization of heavy metals, exhibiting excellent long-term stability in practice application through trapping heavy metal ions into the lattice of LDHs layer. Given that the super-stable mineralization effect of LDHs for heavy metals, we summarize the structure of LDHs, key points of super-stable mineralization, practical challenges, and potential applications in other heavy metals pollution scenarios in this article, wishing that could provide new strategies and insights into rational designing of amendments for soil remediation.

Insights into effects of ageing processes on Cd-adsorbed biochar stability and subsequent sorption performance

The conversion of agricultural biomass wastes into biochar has enormous potential to improve soil quality. Particularly, biochar particles introduced into the natural environment readily bind environmental pollutants. The interaction of biochar and adsorbed pollutants will, however, be impacted by long term ageing. The mechanism of biochar adsorption performance that could be affected by such early-adsorbed pollutant is not understood. Herein, we study the effects of different ageing processes on Cd-adsorbed biochar stability by K2CrO7–H2SO4 oxidation method for carbon loss evaluation, and sorption capacity towards diethyl phthalate (DEP). We adopted artificially accelerated ageing methods to simulate various processes: HNO3/H2SO4, H2O2 oxidative, leaching, high temperature, freeze-thaw cycles, and dry-wet cycles. The results showed that all the Cd-adsorbed aged biochars had more C–C/C–H functional groups and exhibited higher carbon stability than pristine aged biochars. Specially, the carbon loss (20.2–25.2%) of Cd-adsorbed biochar showed almost two times lower than pristine biochar (34.5–35.4%) after high temperature and leaching ageing due to enhancing Cd-π bonding, which could resist strong K2Cr2O7/H2SO4 oxidation. Such interaction synergistically promoted the sequestration of adsorbed Cd on biochars. The subsequent sorption performance for DEP on Cd-adsorbed biochars was slightly higher than pristine biochar after H2O2 oxidative and leaching ageing. Whereas, the dominate mechanism of DEP removal on Cd-adsorbed biochars changed to hydrophobic partitioning after high temperature, freeze-thaw cycles and dry-wet cycles ageing, leading to a decreased DEP sorption capacity. Hence, the biochar application must be comprehensively considered the susceptibilities due to reciprocal effects of early adsorbed pollutant and natural ageing environment, which helps us both assess and take measures to minimize potential risks in the environment. The present study suggests the continuous irrigation and tropical or temperature climate regions would be suitable for long-term biochar application in soil remediation and carbon sequestration.

Recent Advances of Nanoremediation Technologies for Soil and Groundwater Remediation: A Review

Nanotechnology has been widely used in many fields including in soil and groundwater remediation. Nanoremediation has emerged as an effective, rapid, and efficient technology for soil and groundwater contaminated with petroleum pollutants and heavy metals. This review provides an overview of the application of nanomaterials for environmental cleanup, such as soil and groundwater remediation. Four types of nanomaterials, namely nanoscale zero-valent iron (nZVI), carbon nanotubes (CNTs), and metallic and magnetic nanoparticles (MNPs), are presented and discussed. In addition, the potential environmental risks of the nanomaterial application in soil remediation are highlighted. Moreover, this review provides insight into the combination of nanoremediation with other remediation technologies. The study demonstrates that nZVI had been widely studied for high-efficiency environmental remediation due to its high reactivity and excellent contaminant immobilization capability. CNTs have received more attention for remediation of organic and inorganic contaminants because of their unique adsorption characteristics. Environmental remediations using metal and MNPs are also favorable due to their facile magnetic separation and unique metal-ion adsorption. The modified nZVI showed less toxicity towards soil bacteria than bare nZVI; thus, modifying or coating nZVI could reduce its ecotoxicity. The combination of nanoremediation with other remediation technology is shown to be a valuable soil remediation technique as the synergetic effects may increase the sustainability of the applied process towards green technology for soil remediation.

Soil Remediation Applications of Nanotechnology

With the growth of urbanization, the anthropogenic activities have increased and thus increase occurrence of soil contaminants. In order to eliminate the contaminants in soil environment, the application of nanotechnology for soil remediation has become a great concern in the world. This review will discuss about the fate of contaminants in soil environment; the mechanisms of nanotechnology with various types of nanomaterials for the soil remediation; the advantages and disadvantage of nanomaterials towards the terrestrial organisms, human health as well as the soil environment; and the challenges of using nanotechnology for soil remediation.

Metal(loid) nanosorbents in restoration of polluted soils: geochemical, ecotoxicological, and remediation perspectives

Nowadays, the applications of nanomaterials (NMs) are becoming the edge over others and referred as one of the pillars of emerging science and technology. Thereby, a wide array of NMs have been developed along with the products that can be used for the reclamation of contaminated terrestrial ecosystems. The NMs got a great consideration due to their peculiar characteristics and high efficacy. Therefore, this review addresses in depth the ability of metal(loid) NMs as nanosorbents along with their applications in soil remediation. Adsorption is commonly employed for the elimination of innumerable contaminants because of low expenses, reliability, and convenience. The first emphasis of this work will be the use of nanoscale meta(loid) adsorbents for contaminated soil remediation along with their geochemistry. Because NMs mediated soil remediation promises more efficient and cost-effective than conventional methods and can enhance the probability of in situ contaminants remediation. However, the extensive usage of NMs is enhancing their concentrations in the environment and get a route to enter the surrounding flora and fauna that can induce serious concerns due to the lack of absolute understanding regarding NMs interactions with living organisms. Therefore, the second focus of this work will be on the ecotoxicological impacts with special attentions on morpho-physiological alterations in edible plants.

Mechanistic foam flow model with variable flowing foam fraction and its implementation using automatic differentiation

Foam injection is an effective method for modifying gas mobility in subsurface flow applications making it ideal for environmental remediation applications. Remediation of contaminated soils/aquifers of nonaqueous phase liquids using foamed surfactant solutions is a viable option but a predictive foam model is needed that is flexible to the addition of more accurate physical descriptions. Such a model is essential to ensure successful operations in soil remediation applications. The objective of this paper is to develop a full-physics, mechanistic transient foam flow model and integrate it into the multiphysics, modular AD-GPRS framework (Automatic Differentiation–General Purpose Research Simulator). We chose AD-GPRS because it allows rapid prototyping and addition of complex physics and modeling strategies. We develop the model ground-up from pore-scale observations and implement a new flowing foam fraction constitutive relation that depends on the local pressure gradient, local permeability, and flowing bubble density. Our model predicts the two flow regimes commonly observed in steady-state pressure gradient measurements: the low-quality regime and the high-quality regime. Additionally, the model is used to match transient experimental results of homogeneous and slightly heterogeneous cores with a wide range of permeability values. The implementation of this model within AD-GPRS allows testing of ideas and modeling strategies as well as inclusion of more complex physics or foam generation kinetics.

Degradation of pyrene in contaminated water and soil by Fe2+-activated persulfate oxidation: Performance, kinetics, and background electrolytes (Cl-, HCO3- and humic acid) effects

SO4−-based oxidation technologies have been considered as key solution in polycyclic aromatic hydrocarbons (PAHs) degradation. This study constructed Fe2+-activated persulfate oxidation to degrade pyrene in water and soil by using batch and column experiments. Pyrene degradation kinetic in polluted water and effects of soil background electrolytes (Cl−, HCO3− and humic acid) on pyrene degradation were both investigated. The variation of soil properties during pyrene degradation in soil was evaluated. Polluted water remediation results showed that approximately 93.2 % of pyrene was degraded by 65 mM of persulfate with Fe2+/persulfate molar ratio of 0.25. In soil, 88.5 % of pyrene was degraded under the same persulfate concentration and Fe2+/persulfate molar ratio, and there was a slight decrease of soil pH (from 6.7 to 5.4). Cl−, HCO3− and humic acid in soil brought an adverse effect to pyrene degradation through scavenging SO4−. Column study of soil remediation proved the superiority of Fe2+ in activating persulfate, whose application in soil remediation can finally reduce soil pollution and simultaneously avoid the excessive soil acidification in in-situ remediation. In addition, by evaluating the soil organic matter and total organic carbon during the remediation process, it was found that the soil properties have been improved. Therefore, Fe2+-activated persulfate oxidation would be a feasible way to remediate pyrene polluted water/soil.

Preparation and Characterization of Biochar from Rice Straw and Its Application in Soil Remediation

Preparation and Characterization of Biochar from Rice Straw and Its Application in Soil Remediation

Carbon mineralization, biological indicators, and phytotoxicity to assess the impact of urban sewage sludge on two light-textured soils in a microcosm.

The agricultural reuse of urban sewage sludge (USS) modifies soil properties depending on sludge quality, management, and pedo-environmental conditions. The aim of this microcosm study was to assess C mineralization and subsequent changes in soil properties after USS addition to two typical Mediterranean soils: sandy (Soil S) and sandy loam (Soil A) at equivalent field rates of 40 t ha-1 (USS-40) and 120 t ha-1 (USS-120). Outcomes proved the biodegradability of USS through immediate CO2 release inside incubation bottles in a dose-dependent manner. Accordingly, the highest rates of daily C emission were recorded with USS-120 (3.7 and 3.9mg kg-1 d-1 for Soils S and A, respectively) after 84 d of incubation at 25 °C. The addition of USS also improved soil fertility by enhancing soil macronutrients, microbial proliferation, and protease activity. Protease showed significant correlation with N, total organic C, and heterotrophic bacteria, reflecting the biostimulation and bioaugmentation effects of sludge. Soil indices like C/N/P stoichiometry and metabolic quotient (qCO2 ) varied mostly with mineralization rates of C and P in both soils. Despite a significant increase of soil salinity and total heavy metal content (lead, nickel, zinc, and copper) with USS dose, wheat germination was not affected by these changes. Both experimental soils showed intrinsic (Soil A) and incubation-induced (Soil S) phytotoxicities that were alleviated by USS addition. This was likely due to the enhancement of biodegradation and/or retention of phytotoxicants originating from previous land uses. Urban sewage sludge amendments could have applications in soil remediation by reducing the negative effects of allelopathic and/or anthropogenic phytoinhibitors.

Biochar application to detoxification of the heavy metal-contaminated fluvisols

Sorption of heavy metals on solid matrices such as soils is one of the key processes which determine the fate of contaminants in the environment. Knowledge of adsorption behavior of heavy metals using biochar is essential for their application in soil remediation. Using the adsorption method, the possibility of using a wood biochar to detoxify Fluvisols contaminated with heavy metals (for example, copper) was studied. It is shown that the addition of biochar increases the metal adsorption capacity of soil. The results were analysed using the Langmuir and Freindlich isotherm equations. It was concluded that biocar can be applied to immobilize heavy metals in contaminated soils.

Evaluation of biochemical and physiological responses of salsola spp at their natural habitats

Halophytes are naturally salt-tolerant plants that are useful for soil remediation applications. Biochemical and physiological responses of Salsola species, namely; S. ruthenica, S. dendroides and S. crassa were evaluated at their natural habitats for their salt tolerance in which the biochemical responses such as peroxidase (POX, EC.1.11.1.7) and catalase (CAT, EC.1.11.1.6) enzymes, inorganic ion accumulation, proline (Pro), malondialdehyde (MDA), chlorophyll contents (Chl-a, Chl-b) were measured. The results showed that variation existed in Salsola spp. in their response to salinity. Although all Salsola spp. showed similar trends, S. ruthenica expressed higher activities of antioxidant enzymes along with the higher accumulation of proline, MDA contents than those of S. dendroides and S. crassa spp. Leaves of all three species exhibited high Na+ content while K+, Ca++ and Mg++ contents are low. S. ruthenica accumulated 94.5 g kg-1 DW of Na+ ions while S. dendroides and S. crassa accumulated 82.1 g kg-1 DW and 71.4 g kg-1 DW Na+ ions, respectively. The increase in enzymatic activities and higher metabolic contents and lower MDA levels in Salsola spp., especially in S. ruthenica, suggested that these species could well be used for phytoremediation purposes. With moderate height and root-length, these plants have high potentials to be used as companion plants with glycophytes to reduce salt stress in moderately saline conditions.

Transport potential of super-hydrophobic organic contaminants in anionic-nonionic surfactant mixture micelles

Surfactant mixtures are commonly used in agricultural and soil remediation applications, necessitating an understanding of their micellization behavior and associated impact on the fate of co-existing chemicals in the subsurface. A polymer-water sorption isotherm approach was shown to present an alternative to traditional methods for quantifying, understanding and predicting surfactant mixture properties. Micelle compositions were measured for anionic-nonionic surfactant mixtures. This is important since micelle composition can alter the apparent aqueous solubility of super-hydrophobic organic contaminants (SHOCs) resulting in surfactant facilitated transport (SFT). A key parameter in predicting SFT for SHOCs is their micelle-water partition constant (KMI). These were determined for polychlorinated dibenzo-p-dioxins (PCDDs) and polychlorinated biphenyls (PCBs) with representative anionic-nonionic surfactant mixtures using a polymer depletion method. These previously unreported constants were intermediate between those for pure anionic and nonionic surfactant solutions, with magnitude depending on micelle composition. Separate linear relationships were found between log KMI and log KOW for PCDDs and PCBs. This work provides new methods and preliminary results relating to binary surfactant mixtures (e.g. critical micelle concentration and micelle composition) and SHOCs (KMI) that are important in the evaluation of the fate and transport of SHOCs in the subsurface environment and provide insight into the environmental mobility of these important contaminants.

Preparation and Modification of Biochar Materials and their Application in Soil Remediation

As a new functional material, biochar was usually prepared from biomass and solid wastes such as agricultural and forestry waste, sludge, livestock, and poultry manure. The wide application of biochar is due to its abilities to remove pollutants, remediate contaminated soil, and reduce greenhouse gas emissions. In this paper, the influence of preparation methods, process parameters, and modification methods on the physicochemical properties of biochar were discussed, as well as the mechanisms of biochar in the remediation of soil pollution. The biochar applications in soil remediation in the past years were summarized, such as the removal of heavy metals and persistent organic pollutants (POPs), and the improvement of soil quality. Finally, the potential risks of biochar application and the future research directions were analyzed.

Biomineralization based remediation of cadmium and nickel contaminated wastewater by ureolytic bacteria isolated from barn horses soil

Abstract Environmental contamination by toxic heavy metals such as cadmium and nickel is a serious problem. Metal carbonate precipitation has been suggested based on urea decomposition for use in wastewater and soil remediation applications. Therefore, Cd(II) and Ni(II) removal was examined from an environmental viewpoint. In this work, biomineralization of cadmium and nickel in aqueous solutions by six urease-producing bacterial strains isolated from barn horse’s soil samples has been investigated based on microbially induced precipitation (MIP). The enzyme urease produced by these bacteria can hydrolyze urea to carbonate ions leads to increase pH of the wastewater which results in mineralization of the heavy metal ions and their final conversion to metal carbonates precipitates. Only two bacterial strains have been adopted depending on their ability to tolerate high concentrations of toxic metal ions. Bioprecipitation of Cd(II) and Ni(II) was assessed by consideration some factors that affecting on metal bioprecipitation process. These factors include metal toxicity to the bacteria (in term of initial metal concentration) and treatment time. The bioprecipitates were characterized using scanning electron microscopy (SEM) and X-ray diffraction (XRD). The selected bacterial isolates demonstrated high endurance with toxic heavy metals and therefore, high Cd(II) and Ni(II) removal rates, ranging from 96% for cadmium to 89% for nickel following incubation for 48 h and at 500 mg/L initial concentration of each Cd(II) and Ni(II). Furthermore, coprecipitation of Cd(II) and Ni(II) with calcite precipitation has been also performed and the results demonstrated that this technique can be beneficial for Cd(II) and Ni(II) biosequestration.