Transport of phenolic compounds through a compacted organoclay liner

1998 ◽  
Vol 38 (2) ◽  
pp. 143-150 ◽  
Author(s):  
Irene M. C. Lo ◽  
Raymond K. M. Mak
Keyword(s):  
Phenolic Compounds ◽  
Hydraulic Conductivity ◽  
Computer Program ◽  
Silty Sand ◽  
Natural Clay ◽  
Liner Material ◽  
Manufactured Products ◽  
Organically Modified ◽  
Soil Liner ◽  
Hydrophobic Bonding

The transport of phenolic compounds through a compacted liner improved with organically modified bentonite (organoclay BB-40) was studied. Organoclay BB-40 is one of the manufactured products of Biomin International, Inc. and is modified with 40 lb of dicetyldimethylammonium per 100 lb of clay. The adsorption of phenolic compounds onto organoclay BB-40 is found to be significant, which could be attributed to the formation of hydrophobic bonding. The hydraulic conductivities of organoclay BB-40 are 1.98 × 10−7, 2.28 × 10−7 and 5.49 × 10−7 cm/sec for the phenol cell, 2-chlorophenol cell and 2,4,6-trichlorophenol cell, respectively. The experimental results of adsorption tests and hydraulic conductivity tests were input into the computer program “Pollute v9” to simulate the transport of phenolic compounds through a compacted organoclay liner material. The simulation result was then compared with phenol transport through the conventional soil liner (90% silty sand and 10% natural clay mineral). It indicates that the retardation of the transport of phenolic compounds using organoclay as a liner material is more significant than using the conventional soil liner, particularly for higher hydrophobic organics.

Study on the Hydraulic Conductivity of Sand-Bentonite mixtures used as Liner System of Waste Landfill

2011 ◽  
Vol 194-196 ◽  
pp. 909-912 ◽  
Author(s):  
Si Fa Xu ◽  
Zhe Wang ◽  
Yong Zhang
Keyword(s):  
Hydraulic Conductivity ◽  
Soil Layer ◽  
Low Permeability ◽  
Test Results ◽  
Natural Clay ◽  
Compacted Soil ◽  
Waste Landfill ◽  
Liner System ◽  
Flexible Wall ◽  
Soil Liner

A liner system such as liner sheet underlying impermeable soil layer having hydraulic conductivity less than 1*10-7 cm/s and a thickness larger than 100 cm is often used in china. As there is very little natural clay having such low permeability, bentonite is usually mixed into sand to decrease the permeability. In this paper, the compaction tests and permeability testing using flexible-wall permeameter are conducted. The test results show that the value of critical benonite ratio depends on bentonite ratio, and the hydraulic conductivity of the sand mixed with critical bentonite ratio for distilled water shows of the order of 1*10-8 cm/s that satisfies the china standard requested as compacted soil liner of waste landfill. Finally, the permeability testing used leachate including calcium component was conducted.

Insight into hydraulic conductivity testing of geosynthetic clay liners (GCLs) exhumed after 5 and 7 years in a cover

2017 ◽  
Vol 54 (8) ◽  
pp. 1118-1138 ◽  
Author(s):  
R.K. Rowe ◽  
R.W.I. Brachman ◽  
M.S. Hosney ◽  
W.A. Take ◽  
D.N. Arnepalli
Keyword(s):  
Hydraulic Conductivity ◽  
Unit Area ◽  
Divalent Cations ◽  
Hydraulic Gradient ◽  
Silty Sand ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Percentage Area ◽  
Bundle Size ◽  
Insight Into

Four geosynthetic clay liners (GCLs) serving as single liners were exhumed from below 0.7 m of silty sand on a 3:1 (horizontal:vertical) north-facing slope at the QUELTS site in Godfrey, Ontario, after 5 and 7 years. The 300 mm GCL overlaps with 0.4 kg/m supplemental bentonite were all physically intact. The exchangeable bound sodium was completely replaced with divalent cations. The GCL with the smallest needle-punched bundle size (average of 0.7 mm) and percentage area covered by bundles (4%) maintained low hydraulic conductivity (k) when tested under 0.07–1.2 m head with 10 mmol/L CaCl2 solution as the permeant. For GCLs with larger bundles (1.1–1.6 mm) and higher percentage area covered by bundles (9%–14%), k was low when the head was low (0.07 m). Once the applied head increased, k increased by 1–4 orders of magnitude depending on the (i) hydraulic gradient, (ii) size and number of the needle-punched bundles, and (iii) structure and mass of the bentonite per unit area. The results suggest that the GCLs can perform effectively as a single hydraulic barrier in covers providing that the head above the GCL is kept low (e.g., by a suitable drainage layer above the GCL).

A Computer Program to Facilitate Performance Assessment of Underground Low-Level Waste Concrete Vaults

1995 ◽  
Vol 412 ◽  
Author(s):  
K. A. Snyder ◽  
J. R. Clifton ◽  
J. Pommersheim
Keyword(s):  
Hydraulic Conductivity ◽  
Service Life ◽  
Computer Program ◽  
Performance Assessment ◽  
Performance Prediction ◽  
Transport Coefficients ◽  
Reinforcement Corrosion ◽  
Low Level ◽  
Empirical Relations ◽  
Synergistic Degradation

AbstractA computer program (4SIGHT) to facilitate performance assessment of underground concrete vaults for low level waste (LLW) disposal facilities is being developed at the National Institute of Standards and Technology (NIST). Specifically, the program predicts the hydraulic conductivity and the service life of an underground concrete vault. The hydraulic conductivity estimate is based upon empirical relations. The service life is estimated from consideration of three major degradation processes: steel reinforcement corrosion, sulfate attack, and leaching. The performance prediction is based upon ion transport equations for both diffusion and advection. Most importantly, the computer program incorporates the synergistic degradation effects of all three processes, and their effect upon the transport coefficients.

Preparation of Organovermiculite for Adsorption of Organic Compounds

2012 ◽  
Vol 727-728 ◽  
pp. 1451-1456
Author(s):  
Andréa Lopes Silva ◽  
Francisco Kegenaldo Alves de Souza ◽  
Gelmires Araújo Neves ◽  
Romualdo Rodrigues Menezes ◽  
Hélio Lucena Lira ◽  
...  
Keyword(s):  
Organic Compounds ◽  
Organic Pollutants ◽  
Organic Contaminants ◽  
Exchange Capacity ◽  
Natural Clay ◽  
Modified Clay ◽  
Organically Modified ◽  
Dimethyl Ammonium ◽  
Cationic Exchange ◽  
Clay Materials

Organically modified clay minerals are widely used as sorbents for hydrophobic organic compounds e.g., organic pollutants treatment from water solutions. Natural clay materials are hydrophilic and therefore they are not efficient sorbents for organic compounds. Intercalations of natural clay materials, with organic cations, with quaternary ammonium groups may become these clays hydrophobic. Vermiculite is the mineralogical name given to hydrated laminar magnesium-aluminum-iron silicate; this natural clay was modified and used for the production of organically modified clay (organovermiculite), with the purpose of its use in removing organic contaminants. The organovermiculite was prepared using different concentrations of distearyl dimethyl ammonium chloride (praepagen) based on cationic exchange capacity of the clay. It was evident from the X-ray diffraction that the salt was incorporated to the clay structure confirming its organophilization and through the Foster swelling test it was observed the affinity between the organic pollutants and the organovermiculite.

Evaluation of Lime Treated Oil Contaminated Soils for Use in Waste Containment Applications

2013 ◽  
Vol 824 ◽  
pp. 66-72
Author(s):  
Thomas Stephen Ijimdiya
Keyword(s):  
Hydraulic Conductivity ◽  
Moisture Content ◽  
Contaminated Soils ◽  
Optimum Moisture Content ◽  
Soil Samples ◽  
Liner Material ◽  
British Standard ◽  
Waste Containment ◽  
Relative Compaction ◽  
Waste Containment Systems

This paper presents the results of an evaluation of lime treated oil contaminated soil for use in waste containment systems. Soil samples were treated with up 6 % lime contents. Specimens were prepared at optimum moisture content and compacted using British Standard Light (BSL) or Standard Proctor (relative compaction = 100%) to evaluate its effectiveness when used in waste containment applications. The hydraulic conductivity values increased with higher lime contents but were less than 1 x 10-9 m/s required for a liner material.

scholarly journals Impact of In Situ Soil in Soil-Bentonite Cutoff Wall Backfill on Compressibility and Hydraulic Conductivity

2021 ◽  
Vol 2021 ◽  
pp. 1-12
Author(s):  
Ridong Fan ◽  
Yuling Yang ◽  
Songyu Liu
Keyword(s):  
Hydraulic Conductivity ◽  
Void Ratio ◽  
Size Fraction ◽  
Characteristic Parameter ◽  
Compression Index ◽  
Natural Clay ◽  
Cutoff Wall ◽  
Clay Size Fraction ◽  
The Impact

Soil-bentonite cutoff walls, consisting of excavated in situ soil and bentonite as backfills, are used extensively as vertical barriers for groundwater pollution control. Sand mixed with high-quality natural sodium bentonite (NaB) is commonly used as a research object to investigate the hydraulic and compression properties of soil-bentonite backfills. However, pure sand could rarely be found in real conditions, and natural NaB may not be available readily in some countries such as China, India, and Turkey. This paper presents a comprehensive laboratory investigation on the compressibility and hydraulic conductivity (k) of soil-bentonite backfills created by simulated in situ soil and low-quality sodium activated calcium bentonite (SACaB). The simulated in situ soils are prepared using sand-natural clay mixtures with sand to natural clay mass ratios ranging from 0.5 to 6.0, and the bentonite content (BC) in the base mixture ranges from 0 to 15%. The result indicates that BC dominates the compression index (Cc) of the backfill, and a unique relationship between void ratio at effective vertical compression stress of 1 kPa and compression index is proposed for various types of soil-bentonite backfills. An increase in either BC or clay size fraction (CF) in simulated in situ contributes to reducing k, but the impact of CF in simulated in situ soil on k tends to be insignificant for backfill with BC higher than 6%. A new characteristic parameter based on the concept of void ratio of bentonite (eb), named apparent void ratio of clay size fraction (eC), is developed for predicting soil-bentonite backfills created by in situ soils and bentonites with various contents.

scholarly journals The Effect of Heterogeneity on the Distribution and Treatment of PFAS in a Complex Geologic Environment

2021 ◽  
Vol 2 ◽  
Author(s):  
Rick McGregor ◽  
Leticia Benevenuto
Keyword(s):  
Activated Carbon ◽  
Hydraulic Conductivity ◽  
Emerging Contaminants ◽  
Fractured Rock ◽  
Ion Exchange Resin ◽  
Subsequent Treatment ◽  
Silty Sand ◽  
Aquifer System ◽  
Pump And Treat

Per-and polyfluoroalkyl substances (PFAS) have been identified as emerging contaminants of concern in the environment in a wide variety of media including groundwater. Typically, PFAS-impacted groundwater is extracted by pump and treat systems and treated using sorptive media such as activated carbon and ion exchange resin. Pump and treat systems are generally considered ineffective for the remediation of dissolved phase contaminants including PFAS but instead are considered applicable for plume containment. An alternative to pump and treat is in-situ treatment. The demonstrated use of in-situ treatment for PFAS-impacted groundwater is limited with only colloidal activated carbon (CAC) being shown to effectively attenuate PFAS over short and moderate time periods. Active research topics for the in-situ treatment of PFAS include the effect of heterogeneity on the distribution of the CAC, the lifespan of the CAC itself, the effect of competitive adsorption/absorption, and the effect of other geochemical conditions on the removal process. This study looked at the effect of heterogeneity on the distribution of CAC and subsequent treatment of PFAS at a site with a multiple aquifer system. The site’s geology varied from a silty sand to sand to fractured bedrock with all three units being impacted by PFAS and benzene (B), toluene (T), ethylbenzene (E), and xylene (X). Parameters evaluated included the distribution of the CAC as well as the subsequent treatment of the PFAS and BTEX. Results of groundwater sampling indicated that the PFAS detected within the groundwater were treated effectively to below their respective reporting limits for the duration of the 1-year test in both the silty sand and sand aquifers. The PFAS in the fractured rock aquifer showed a different treatment profile with longer carbon chained PFAS being attenuated preferentially compared to the shorter carbon chained PFAS. These results suggest that competitive sorptive reactions were occurring on the CAC within the fractured rock. Analysis of the unconsolidated aquifer materials determined that direct push injection of the CAC was effective at delivering the CAC to the target injection zones with post-injection total organic carbon (TOC) concentrations increasing by up to three orders of magnitude compared to pre-injection TOC concentrations. Heterogeneity did have an impact on the CAC distribution with higher hydraulic conductivity zones receiving more CAC mass than lower hydraulic conductivity zones.

The Influence of Compaction Effort in Laterite Soil with the Appearance of Sodium Bentonite as a Soil Liner

2017 ◽  
Vol 873 ◽  
pp. 198-202
Author(s):  
Nor Azizah Che Azmi ◽  
Mazidah Mukri ◽  
Nur Aisyah Kasim ◽  
Asmawati Che Hasan ◽  
Nazri Nasir
Keyword(s):  
Hydraulic Conductivity ◽  
High Strength ◽  
Environment And Public Health ◽  
Health Issues ◽  
Laterite Soil ◽  
Sodium Bentonite ◽  
Liner System ◽  
Soil Liners ◽  
Soil Liner ◽  
Positive Results

Soil liner which is placed at the foundation of a landfill is very important in order to isolate waste materials and leachate from the environment. However, if not properly managed, the leachate can beriskytothe safety and serviceability of which are directly related to the environment and public health issues. Soil liners were proposed to minimize leachate egress and prevent ground pollution. In soil liner design, it is important to compact the layer properly in order to achieve low hydraulic conductivity and high strength of soil. In this study, different percentages of sodium bentonite were added to laterite soil to act as soil liner to stabilize the liner system. Sodium bentonite can easily absorb water more than a hundred percent of its weight. Thus, the sodium bentonites were chosen to be mixed with laterite soil. The differentpercentagesof sodium bentonite used are 5%, 10%, 15% and 20%. This research was carried out asan attempt to see the compaction effort for laterite soil mixedwith sodium bentonite. The outcomesof this study give positive results due to the potential of sodium bentonite to fulfill spaces in between soil particles. It is also found that sodium bentonite influences the resistance properties, hydraulic conductivity and the strength of soil.

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