Remediation Time Research Articles

FITOAKUMULASI MERKURI OLEH AKAR TANAMAN BAYAM DURI (AMARANTUS SPINOSUS LINN) PADA TANAH TERCEMAR

The studies entitled Fitoakumulasi Mercury By Root Crops Spinach Thorns ( Amarantus spinosus Linn ) In Contaminated Soil has been done with the purpose of remediation time know effect on the ability of plant roots to absorb mercury thorn spinach and determine the maximum concentration of mercury that accumulates in the roots of spinach plants thorns in the remediation time . The method used in this study is defined as phytoremediation technology recovery , cleanup , removal or reduction of contaminants in soil or water by using the help of plants . Time remediation consists of 4 stages 7 , 14 , 21 and 42 days . While planting media concentration is 25 ppm , 50 ppm , 75 ppm and 100 ppm . The maximum concentration of adsorbed on the roots of spinach plants thorns is 0 , the dry weight of roots harvested at a institusen empire with a concentration of 100 ppm , the remediation time is day 14 ( P2 ) . And the ability of the roots to absorb mercury remediation significantly different with respect to time .

Cell cycle characteristics of the pancreas in an animal model of isolated pancreatic trauma

In our previous study, we established a small animal model that mimicked the pathophysiology of isolated pancreatic trauma. To gain further insights into the relationships between tissue damage and the ability of the pancreatic cells to regenerate, we induced pancreatic trauma in rats maintained over 7 days and analyzed both the alteration of the cell death and the cell cycle distribution of the pancreatic cells in this study. The rats were divided into two groups as follows: impact and control. The pancreas in the impact group was injured by a BIM-III biotical impact machine. Pancreatic enzyme activity, the level of Ca in the serum, pancreatic cell death, and cell cycle characteristics were examined after the trauma. In the impact groups, lipase was activated later than amylase and lasted persistently. The levels of serum Ca decreased at 6 hours after injury, sharply declined at 24 hours and 72 hours compared with the control groups, and returned to normal levels at 7 days. The pancreatic trauma also induced the compensatory proliferation of pancreatic cells. The results from a TUNEL stain, flow cytometry, Western blot, and immunohistochemistry indicated that pancreatic trauma induces cell death and the compensatory proliferation of pancreatic cells. Detecting amylase and lipase at the same time can help us determine the exocrine function of pancreas. Serum Ca can be used as an indicator for estimating the severity of pancreatic trauma. The cell cycle characteristics of the pancreas in the animal model of isolated pancreatic trauma indicate that the proper remedial time is in the first 24 hours after the pancreatic trauma.

Soil remediation via bioventing, vapor extraction and transition regime between vapor extraction and bioventing

Aims: The main objectives of this study were evaluation of the efficiencies of bioventing (BV), soil vapor extraction (SVE) and transition regime between BV and SVE (air injection bioventing [AIBV]) for benzene and toluene removal from polluted sandy soils. Materials and Methods: Laboratory-scale set-up consisted of three cylindrical units (with 29 cm in length with a 7.29 cm i.d.) was conducted to study the removal efficiency of three in-situ remediation technologies. Results: The results showed that, after 48-h air injection with constant air flow rate of 250 mL/min, benzene (initial concentration of 1 mg/g of soil) removal efficiency in BV, SVE and AIBV reactors were almost 84, 98 and >99.5%, respectively. Also results indicated that, toluene with a similar concentration was successfully (>99.5%) reduced via AIBV technology, after 72-h continuous air injection.Conclusion: Comparison of the BV, SVE and AIBV technologies indicated that all of those technologies are efficient for remediation of unsaturated zone, but after specific remediation time frames, only AIBV able to support guide line values and protect ground waters.

Biodegradation of Petroleum Hydrocarbons in a Soil Polluted Sample by Oil-Based Drilling Cuttings

Microbial degradation of hydrocarbons in soils polluted by oil-based drilling mud and cuttings has been investigated by static methods such as composting or biopiling. Bioremediation of polluted soils by oil-based drilling cuttings through a slurry bioreactor has not previously been reported. The main aim of this work is to monitor hydrocarbon biodegradation in slurry of drilling cuttings and unpolluted soils and the effects of nutrients on it. Indigenous, bacterial-mixed culture isolated from a polluted soil by drilling cuttings adapted to drilling mud concentrations up to 15% (v/v) was done during a 15-month program. The total petroleum hydrocarbons’ (TPHs) removal efficiency in C/N/P 100/5/1 ratio was 90.5 and 79.85% under experimental and control conditions, respectively. The microbial count on the first day, 15 × 107 CFUg−1, reached 20 × 109 CFUg−1on the twenty-first day at experimental conditions. The TPH removal efficiency in C/N/P 100/10/2 was 92.5 and 82.25% at experiment and control, respectively. Increasing nitrogen and phosphorous amount couldn't increase microbial count in comparison with C/N/P ratio 100/5/1. The measured biomass contents and microbial counts in experiments were significantly higher than the control and confirmed hydrocarbons’ biodegradation during the time. Results showed that slurry bioreactors could accelerate the biodegradation of TPHs and reduce remediation time in soil polluted by oil-based drilling cuttings.

Enhanced electrokinetic remediation of lead-contaminated soil by complexing agents and approaching anodes

Optimizing process parameters that affect the remediation time and power consumption can improve the treatment efficiency of the electrokinetic remediation as well as determine the cost of a remediation action. Lab-scale electrokinetic remediation of Pb-contaminated soils was investigated for the effect of complexant ethylenediaminetetraacetic acid (EDTA) and acetic acid and approaching anode on the removal efficiency of Pb. When EDTA was added to the catholyte, EDTA dissolved insoluble Pb in soils to form soluble Pb-EDTA complexes, increasing Pb mobility and accordingly removal efficiency. The removal efficiency was enhanced from 47.8 to 61.5 % when the EDTA concentration was increased from 0.1 to 0.2 M, showing that EDTA played an important role in remediation. And the migration rate of Pb was increased to 72.3 % when both EDTA and acetic acid were used in the catholyte. The "approaching anode electrokinetic remediation" process in the presence of both EDTA and acetic acid had a higher Pb-removal efficiency with an average efficiency of 83.8 %. The efficiency of electrokinetic remediation was closely related to Pb speciation. Exchangeable and carbonate-bounded Pb were likely the forms which could be removed. All results indicate that the approaching anode method in the presence of EDTA and acetic acid is an advisable choice for electrokinetic remediation of Pb-contaminated soil.

Dynamics of plant metal uptake and metal changes in whole soil and soil particle fractions during repeated phytoextraction

Phytoextration of metal polluted soils using hyperaccumulators is a promising technology but requires long term successive cropping. This study investigated the dynamics of plant metal uptake and changes in soil metals over a long remediation time. A soil slightly polluted with metals (S1) was mixed with highly polluted soil (S4) to give two intermediate pollution levels (S2, S3). The four resulting soils were repeatedly phyto-extracted using nine successive crops of Cd/Zn-hyperaccumulator Sedum plumbizincicola over a period of 4 years. Shoot Cd concentration decreased with harvest time in all soils but shoot Zn declined in S1 only. Similar shoot Zn concentrations were found in S2, S3 and S4 although these soils differed markedly in metal availability, and their available metals decreased during phytoextraction. A possible explanation is that plant active acquisition ability served to maintain plant metal uptake. Plant uptake resulted in the largest decrease in the acid-soluble metal fraction followed by reducible metals. Oxidisable and residual fractions were less available to plants. The coarse soil particle fractions made the major contribution to metal decline overall than the fine fractions. Sedum plumbizincicola maintained long term metal uptake and the coarse soil particles played the most important role in phytoextraction.

A Design of Continuous and Universal <i>In Situ</i> Remediation Appliance of Soil Combines

Continuous and universal in-situ remediation appliance of soil combines taking soil, transmission and restoration of soil, which can achieve the in-situ remediation continuously and avoid the drawback of massive labor power and material resources using domestic soil ex-situ remediation device. The appliance supports many kinds of soil remediation technology, realizing the function of universal technology. And as for the area with serious pollution, various technology combinations can be selected to extend its function. The motion of specific remediation device in the appliance utilizes the single-chip controlling technology, controlling the remediation time interval of different technology. The program selection with various remediation technologies can be finished with buttons. Single-chip controlling system responds quickly, runs stably and precisely controls the remediation device.

Impact of DNAPL contact on the structure of smectitic clay materials

Smectitic clays have a flexible structure that may be impacted by contact with dense nonaqueous phase liquids (DNAPLs) present at hazardous waste sites. Measurements of the basal spacing of air-dry clays contacted with pure chlorinated solvents and chlorinated DNAPL wastes showed that the intraparticle spacing is similar to that in air. Basal spacings of water-saturated clays contacted with pure chlorinated solvents are similar to those in contact with water, even after extended equilibration times (300d). In contrast, contact with chlorinated DNAPL wastes reduced the basal spacing of water-saturated sodium smectites in a relatively short time frame, resulting in cracks that were as large as 1mm in aperture. The penetration of these wastes into the intraparticle spacing of clay and the resultant cracking may contribute to the accumulation of chlorinated compounds in clay layers observed in the field and the extended remediation times associated with this mass storage.

우라늄 제거를 위한 실험실 규모 동전기 장치의 개선 방안

The original pilot-scale electrokinetic equipment suitable to soil contamination characteristics of Korean nuclear facility sites was manufactured for the remediation of soil contaminated with uranium. During the experiment with the original electrokinetic equipment, many metal oxides were generated and were stuck on the cathode plate. The uranium removal capability of the original electrokinrtic equipment was almost exhausted because the cathode plate covered with metal oxides did not conduct electricity in the original electrokinetic equipment. Therefore, the original electrokinetic equipment was improved. After the remediation experience for 25 days using the improved electrokinetic remediation equipment, the removal efficiency of uranium from the soil was 96.8% and its residual uranium concentration was 0.81 Bq/g. When the initial uranium concentration of soil was about 50 Bq/g, the electrokinetic remediation time required to remediate the uranium concentration below clearance concentration of 1.0 Bq/g was about 34 days. When the initial uranium concentration of soil was about 75 Bq/g, the electrokinetic remediation time required to remediate below 1.0 Bq/g was about 42 days. When the initial uranium concentration of soil was about 100 Bq/g, the electrokinetic remediation time required to remediate below 1.0 Bq/g was about 49 days.

Microwave heating remediation of soils contaminated with diesel fuel

Diesel fuel represents a permanent source of soil pollution, and its removal is a key factor for human health. To address the limitations of conventional remediation techniques, microwave (MW) heating could be employed due to its great potentiality. This work presents the lab-scale experiments performed to study the potential of MW processing for diesel-polluted soils treatment and related modeling for the optimization of MW systems operating conditions. A sandy soil was artificially contaminated with diesel fuel, moisturized with different amounts of water content, and thermally treated by MW radiation using a lab-scale apparatus to investigate the effect of soil moisture on soil temperature profiles and contaminant removal kinetics. An operating power, ranging from 100 to 1,000 W, and treatment times of 5, 10, 18, 30, and 60 min were investigated. Contaminant residual concentration values were fitted using the first order kinetic model, and desorption parameters were calculated for each soil at different operating powers. Main results show that the operating power applied significantly influences the contaminant removal kinetics, and the moisture content in soil has a major effect on the final temperature reachable during MW heating. Minimal contaminant concentrations were achievable by applying powers higher than 600 W for a treatment time longer than 60 min. For remediation times shorter than 10 min, which result in a soil temperature of about 100 °C, the effect of the distillation process increases the contaminant removal, whereas for longer times, soil temperature is the main key factor in the remedial treatment. MW thermal desorption of diesel-polluted soil was shown to be governed by pseudo-first-order kinetics, and it could be a better choice for remediation of diesel-polluted soils, compared to several biological, chemical–physical, or conventional thermal treatments, due to its excellent removal efficiency. The results obtained are of scientific and practical interest and represent a suitable tool to optimize the treatment operating conditions and to guide the design and the scale-up of MW treatments for full-scale remediation activities of diesel-polluted soils.

The Value of Groundwater Modeling to Support a Pump and Treat Design

AbstractA wide range of rules, algorithms, and models are available to design an effective pump and treat remediation system. Often, one refers to the effectiveness of the developed pump and treat system to demonstrate how valuable the use of a groundwater model can be. An economic valuation of the groundwater model is usually missing. This study provides a framework that puts the discussion concerning the use of groundwater models in an economic perspective. It is not only demonstrated that a more effective pump and treat system can be designed using a groundwater model, but also the economic implications of using a groundwater model are calculated. A set of economic decision rules is applied to determine the economic value of a groundwater model. It is shown that investing in a groundwater model can be economically worthwhile. The remediation time is reduced, remediation costs are saved and the property can be sold more early. These benefits outweigh the costs of developing a groundwater model, and hence a positive net benefit (NB) is determined.

A mechanistic study of arsenate removal from artificially contaminated clay soils by electrokinetic remediation

Batch desorption experiments and bench-scale electrokinetic experiments were performed to elucidate the electrokinetic remediation mechanisms of arsenate from artificially contaminated kaolinite. The electrokinetic experiments in which a constant voltage was applied demonstrated that high soil pH favored arsenate remediation with respect to both the remediation time and electricity consumption. It was also demonstrated that applying a pulse voltage (1h ON, 1h OFF) significantly improved the electricity consumption efficiency when the soil pH was maintained at the initial value during the experiments; this trend was not observed when the soil pH was gradually increased from the cathode side. These electrokinetic experimental results, with the support of arsenate desorption data obtained from batch experiments, indicate that the remediation rate-limiting step varied with soil pH. When the soil pH was maintained at the initial value of 7.2 during the experiments, arsenate desorption was the remediation rate-limiting step rather than the migration of dissolved arsenate toward the anode. Conversely, when the cathode pH was not controlled and the soil pH was correspondingly increased gradually from the cathode side, the migration of hydroxyl and desorbed arsenate ions toward the anode played a more important role in the control of the overall remediation efficiency.

Biocomplementation of SVE to achieve clean-up goals in soils contaminated with toluene and xylene

Soil vapor extraction (SVE) and bioremediation (BR) are two of the most common soil remediation technologies. Their application is widespread; however, both present limitations, namely related to the efficiencies of SVE on organic soils and to the remediation times of some BR processes. This work aimed to study the combination of these two technologies in order to verify the achievement of the legal clean-up goals in soil remediation projects involving seven different simulated soils separately contaminated with toluene and xylene. The remediations consisted of the application of SVE followed by biostimulation. The results show that the combination of these two technologies is effective and manages to achieve the clean-up goals imposed by the Spanish Legislation. Under the experimental conditions used in this work, SVE is sufficient for the remediation of soils, contaminated separately with toluene and xylene, with organic matter contents (OMC) below 4%. In soils with higher OMC, the use of BR, as a complementary technology, and when the concentration of contaminant in the gas phase of the soil reaches values near 1mg/L, allows the achievement of the clean-up goals. The OMC was a key parameter because it hindered SVE due to adsorption phenomena but enhanced the BR process because it acted as a microorganism and nutrient source.

Remediation of Heavy Metal (Cd, Cr, Cu, Co, and Ni) Ions from Kaolinite Clay Using Molecular Micelles Chelators and D-Optimum Experimental Design

This study investigated the potential utility of poly (sodium N-undecanoyl-L-leucyl-valinate) (poly-L-SULV), poly (sodium N-undecanoyl-L-leucyl-alanate) (poly-L-SULA), and poly (sodium N-undecanoyl-glycinate) (poly-SUG) molecular micelles (MMs) as chelators for heavy metal (Cd, Cr, Cu, Co, and Ni) ion remediation of kaolinite clay using D-optimum experimental design. D-optimum experimental design was employed to simultaneously investigate the influence of design variables such as the buffer pH, chelator concentration, and centrifuge speed to evaluate the optimum conditions and to reduce the time and cost of metal ion remediation. The partition coefficients of the metal ion concentrations between the kaolinite clay and chelator equilibrium were also evaluated. In addition, the influence of metal ion concentrations on the remediation capability of the chelators was evaluated by conducting remediation studies at four different (10 ppm, 40 ppm, 60 ppm, and 80 ppm) metal ion concentrations. In general, the results of the remediation efficiency and partition coefficients obtained in this study are highly metal ion dependent and also dependent upon the chelator used for the remediation. Specifically, the remediation efficiency of the molecular micelles was found to be comparable to or better than the corresponding remediation efficiency obtained when SDS or EDTA was used for the remediation. However, at optimum conditions, poly-SULV and poly-L-SULA molecular micelle chelators demonstrated superior remediation efficiencies for Cr, with remediation efficiency of 99.9 ± 8.7% and 99.1 ± 0.7%, respectively.

GROUNDWATER REMEDIATION AND THE COST EFFECTIVENESS OF PHYTOREMEDIATION

In 1999, phytoremediation was applied at the site of a Belgian car factory to contain two BTEX plumes. This case study evaluates the cost effectiveness of phytoremediation compared to other remediation options, applying a tailored approach for economic evaluation. Generally, when phytoremediation is addressed as being cost effective, the cost effectiveness is only determined on an average basis. This study however, demonstrates that an incremental analysis may provide a more nuanced conclusion. When the cost effectiveness is calculated on an average basis, in this particular case, the no containment strategy (natural attenuation) has the lowest cost per unit mass removed and hence, should be preferred. However, when the cost effectiveness is determined incrementally, no containment should only be preferred if the value of removing an extra gram of contaminant mass is lower than €320. Otherwise, a permeable reactive barrier should be adopted. A similar analysis is provided for the effect determined on the basis of remediation time. Phytoremediation is preferred compared to ‘no containment’ if reaching the objective one year earlier is worth €7 000.

마이크로버블 오존 산화제와 공압파쇄 장치를 연계 적용한 지중 화학적 산화법의 정화효율 평가

ABSTRACT A new type of chemical oxidation technology utilizing micro bubble ozone oxidizer and a pneumatic fracturing equipmentwas developed to enhance field applicability of a traditional chemical oxidation technology using hydrogen peroxide as anoxidizer for in-situ soil remediation. To find an efficient way to dissolve gaseous ozone into hydrogen peroxide, ozone wasinjected into water as micro bubble form then dissolved ozone concentration and its duration time were measured comparedto those of simple aeration of gaseous ozone. As a result, dissolved ozone concentration in water increased by 31%(1.6 ppm → 2.1 ppm) and elapsed time for which maximum ozone concentration decreased by half lengthened from 9 min to33 min. When the developed pneumatic fracturing technology was applied in sandy loam, cracks were developed and grownin soil for 5~30 seconds so that the radius of influence got longer by 71% from 392 cm to 671 cm. The remediation systemusing the micro bubble ozone oxidizer and the pneumatic fracturing equipment for field application was made anddemonstrated its remediation efficiency at petroleum contaminated site. The system showed enhanced remediation capacitythan the traditional chemical oxidation technology using hydrogen peroxide with reduced remediation time by about 33%.Key words :Micro bubble ozone oxidizer, Pneumatic fracturing, In-situ chemical oxidation, Field demonstration,Radius of influence

In Situ Radio‐Frequency Heating for Soil Remediation at a Former Service Station: Case Study and General Aspects

AbstractIn situ radio‐frequency heating (ISRFH) was successfully applied during remediation of a former petrol station. Using a three‐electrode array in combination with extraction wells for soil vapor extraction (SVE), pollution consisting mainly of benzene, toluene, ethylbenzene, xylenes, and mineral oil hydrocarbons (in total about 1100 kg) was eliminated from a chalk soil in the unsaturated zone. Specially designed rod electrodes allowed selective heating of a volume of approximately 480 m3, at a defined depth, to a mean temperature of about 50 °C. The heating drastically increased the extraction rates. After switching off ISRFH, SVE remained highly efficient for some weeks due to the heat‐retaining properties of the soil. Comparison of an optimized regime of ISRFH/SVE with conventional “cold” SVE showed a reduction of remediation time by about 80 % while keeping the total energy consumption almost constant.

Field-Scale Modeling of Benzene, Toluene, Ethylbenzene, and Xylenes (BTEX) Released from Multiple Source Zones

ABSTRACT A field-scale three-dimensional numerical flow and transport model was applied to simulate the fate and transport of benzene, toluene, ethylbenzene, and xylenes (BTEX) from six source zones of light non-aqueous-phase liquids (LNAPLs). A number of scenarios were defined to evaluate the effect of natural attenuation and enhanced remediation methods on the fate of BTEX. Two strategies were defined for cleaning up the site: (1) reduction of BTEX over the entire site down to the maximum concentration limit (MCL), and (2) remediation of the site to a level that reduces BTEX below MCLs only at the nearest discharge wells. The results show that under natural attenuation alone, the remediation time for benzene (time needed to decrease concentrations to a specified level) is more than 60 years, whereas that of TEX is longer, but only benzene will reach the receptors. LNAPL removal and enhanced bioremediation techniques could decrease this time to about 30 years for benzene. A cost-effective two-stage enhanced remediation operation should be applied. In the first stage, the entire dissolved BTEX plume should be treated, whereas in the second stage, after the remediation of benzene, the operation area should be limited to the remaining TEX plume areas. In the second strategy, air injection will be sufficient to prevent the BTEX plume from reaching the receptors. Addition of oxygen and hydrogen peroxide is likely too expensive.

In situ source zone sediment mixing coupled to groundwater biostimulation to enhance phenol natural attenuation

Phenol is an industrially key compound that has a wide range of applications and also one of the most commonly found toxic pollutants in wastewaters and groundwater. This paper demonstrates the applicability of in situ remediation at a deactivated industrial site using source zone excavation and sediment mixing associated with nutrients delivery into groundwater. Sediment excavation and mixing displaced the entrapped source zone enhancing mass transfer into groundwater and contaminant bioavailability. A nutrient solution prepared with nitrate, phosphate, sodium hydroxide and hydrogen peroxide was continuously delivered into groundwater to stimulate biodegradation and restrict plume migration. The observed correlation between phenol-dependent Enterobacteriaceae concentrations throughout the remediation time frame supported circumstantial evidence of biodegradation. Phenol concentration in groundwater (up to 1,300 mg/L) was reduced >99% after 5 months following remediation and remained under the established site specific target level (4 mg/L). Nitrate and phosphate concentrations returned to background concentrations levels at the end of the remediation. Overall, the proposed in situ remediation scheme was effective to remediate this particular aquifer contaminated with phenol for over 20 years.

Simulation-Optimization Model for In Situ Bioremediation of Groundwater Contamination Using Mesh-Free PCM and PSO

Groundwater pollution is a major problem in many parts of the world. Many of the contaminated sites, especially in industrial areas, are affected by organic biodegradable contaminants such as trichloro-ethylene (TCE), tetrachloroethylene, or other organic contaminants. In situ bioremediation is especially suitable for such organic contaminants. In situ bioremediation of groundwater involves the injection of oxygen to enhance the biodegradation and accelerate the remediation of contaminated sites using microorganisms (yeast, fungi, or bacteria) to break down or degrade hazardous substances into less toxic or nontoxic substances. For the optimal design of an in situ bioremediation system, one should know the optimal injection rate and other physical processes taking place. Because of the nonlinear, nonanalytical nature of the groundwater pollution transport and remediation process, numerical methods are a must to solve the problem. Modeling bioremediation involves solving biodegradation equations, locating the oxygen injection wells, and fixing up the time of remediation The mesh-free (MFree) method is a numerical approach to solve these partial differential equations (PDE) in a simple manner. The method uses the number of scattered nodes in the domain and on the boundary. In this paper, for simulation of bioremediation, an MFree point collocation method (PCM)–based simulation model, PCM-BIO, is proposed. To determine the optimal injection rate, use of an optimization model along with a simulation model ensures that designs are optimal for the specified site conditions. To solve complex optimization problems, particle swarm optimization (PSO) is found to be very effective and simple. In the present study, a PSO-based model is proposed for optimization of in situ bioremediation. Furthermore, combining the PCM simulation model and PSO optimization model, a PCM-BIO-PSO model is developed to study the complex bioremediation process of groundwater contamination. The developed PCM-transport model is initially verified with the available analytical solution, and PCM-BIO is verified with the BIOPLUME II model. Moreover the PCM-BIO-PSO model results are compared with the results of a model based on the FEM–successive approximation linear quadratic regulator (FEM-SALQR) results. Both of the model comparisons showed good agreement with each other, proving the applicability of the present approach.