Evaluation of an HDPE geomembrane after 14 years as a leachate lagoon liner

2003 ◽  
Vol 40 (3) ◽  
pp. 536-550 ◽  
Author(s):  
R Kerry Rowe ◽  
Henri P Sangam ◽  
Craig B Lake
Keyword(s):  
Ionic Species ◽  
Mechanical Tests ◽  
Compacted Clay ◽  
Composite Liner ◽  
Physical Chemical ◽  
Significant Difference ◽  
Volatile Organic ◽  
Liner System ◽  
Exposure Levels ◽  
And Diffusion

A geomembrane – compacted clay composite liner system used to contain municipal solid waste (MSW) landfill leachate for 14 years is evaluated. Field observations of the geomembrane revealed many defects, including holes, patches, and cracks. Physical, chemical, and mechanical tests conducted on samples collected from five different locations of the liner suggest that samples continuously exposed to sunlight and high temperatures experienced more degradation compared to samples that were covered by leachate or soil. Sorption and diffusion tests revealed that the permeation coefficients of volatile organic compounds were in the range of 4 × 10–12 to 6 × 10–11 m2/s and that, with respect to these parameters, there was no significant difference between samples with different exposure levels. However, the permeation coefficients were between four and five times lower than values obtained for unaged HDPE geomembranes typical of present day production. Contaminant modelling of the entire lagoon liner suggests that the geomembrane liner most likely stopped being effective as a contaminant barrier to ionic species sometime between 0 and 4 years after the installation.Key words: liquid containment, composite liner, diffusion, HDPE geomembrane, performance.

Investigation of a decommissioned landfill barrier system containing polychlorinated biphenyl (PCB) waste after 25 years in service

2020 ◽  
Vol 57 (6) ◽  
pp. 882-902 ◽  
Author(s):  
R.S. McWatters ◽  
D.D. Jones ◽  
R.K. Rowe ◽  
J.M. Markle
Keyword(s):  
Diffusion Coefficient ◽  
Volatile Organic Compounds ◽  
Organic Compounds ◽  
Polychlorinated Biphenyl ◽  
Compacted Clay ◽  
Partitioning Coefficient ◽  
Compacted Clay Liner ◽  
Volatile Organic ◽  
Primary Base ◽  
And Diffusion

The excavation and analysis of the barrier systems for four engineered containment cells, constructed from 1984 to 1987, is described. Very limited polychlorinated biphenyl (PCB) migration was observed over the 22–25 year period prior to decommissioning. PCBs were predominantly, and preferentially, retarded by the geotextiles (GTXs) and, where present, geomembranes (GMBs). The migration of PCBs in the primary compacted clay liner (CCL) during this period was limited both when used alone and with a GMB. The exhumed GMBs, from both cover and base barriers, had diffusive properties (with respect to volatile organic compounds) comparable to unaged GMBs. For cells with a CCL as the primary base barrier, the inferred PCB diffusion coefficient, De, was 1–2 × 10−10 m2/s and distribution coefficient, Kd, was 10–15 mL/g. For cells where a GMB was the primary base barrier, the inferred PCB partitioning coefficient, Sgf, was 150 000 and diffusion coefficient, Dg, was 1 × 10−14 m2/s. Modelling beyond the 25 years in service predicts no unacceptable PCB impact of the landfill on groundwater and indicates that the design of the barrier system was adequate for an indefinite period given the low service temperatures to which it was subjected. In this diffusion-governed system, small changes to the diffusive properties were found to have a large impact on migration.

Behavior of Geosynthetic Clay Liners due to the Migration of Heavy Metal

2014 ◽  
Vol 989-994 ◽  
pp. 433-436 ◽  
Author(s):  
Jing Jing Fan
Keyword(s):  
Heavy Metal ◽  
Low Cost ◽  
Compacted Clay ◽  
Geosynthetic Clay Liners ◽  
Clay Liners ◽  
Composite Liner ◽  
Landfill Liner ◽  
Low Leakage ◽  
Liner System ◽  
Underlying Soil

To protect the underlying soil and groundwater from landfills, the landfills are commonly lined with layered liner systems. Geosynthetic clay liners (GCL) have been increasingly used in the landfill liner systems to substitude the traditional compacted clay liners (CCL) because of their low cost, easily construction behavior and low leakage rate. To study the behavior of the GM+GCL liner system used in China due to the migration of Pb2+, we introduce in detail GM+GCL liner systems proposed by the Chinese specification. Then one dimensional finite layer model is used to investigate the anti-pollution behavior of the CM+GCL composite liner systems, with the focuses on the heavy metal Pb2+. It could be concluded that the main migration way through the GM+GCL composite liner system is that the transport of Pb2+through a GM+GCL composite liner system of a landfill cover takes place primarily through the holes in the GM. The findings provide useful reference for preventing, controlling and treating groundwater pollution in the GM+GCL liner system technically and scientifically.

Effect of Superplasticizer Additives for Class Type Cpii E32 Cements

2015 ◽  
Vol 820 ◽  
pp. 483-487
Author(s):  
H.F. Grillo ◽  
Neide Aparecida Mariano ◽  
Alfeu Saraiva Ramos ◽  
Fabio Ferraço ◽  
K.V.F. Grillo ◽  
...  
Keyword(s):  
Mechanical Properties ◽  
Mechanical Tests ◽  
Hydration Process ◽  
High Quality ◽  
Setting Times ◽  
Physical Chemical ◽  
Technological Advances ◽  
Significant Difference ◽  
E 32

Concrete mixing technology has spread with the development of water-reducing additives, enabling production of high quality products. Despite the discoveries and important technological advances, occurrences concerning the incompatibility between sealers and additives have been reported. The main incompatibilities occur between additive and cement of different brands, or different batches. This study investigated the influence of a superplasticizer on the properties of two cements of the same class (type CP II E 32), but different manufacturers. Two cements (without the presence of the additive) were characterized by physical, chemical and mechanical tests. The setting times for pastes made ​​from cement, water and superplasticizer mixtures were determined. The results showed a significant difference in physical, chemical and mechanical properties of cements, as well as those related to the hydration process thereof.

scholarly journals Shellfish Chitosan Potential in Wine Clarification

2021 ◽  
Vol 11 (10) ◽  
pp. 4417
Author(s):  
Veronica Vendramin ◽  
Gaia Spinato ◽  
Simone Vincenzi
Keyword(s):  
Molecular Structure ◽  
Chemical Properties ◽  
Allergic Reactions ◽  
Chitin Content ◽  
Deacetylation Degree ◽  
Physical Chemical ◽  
Similar Chemical ◽  
Fungal Chitosan ◽  
Significant Difference ◽  
Fish Industry

Chitosan is a chitin-derived fiber, extracted from the shellfish shells, a by-product of the fish industry, or from fungi grown in bioreactors. In oenology, it is used for the control of Brettanomyces spp., for the prevention of ferric, copper, and protein casse and for clarification. The International Organisation of Vine and Wine established the exclusive utilization of fungal chitosan to avoid the eventuality of allergic reactions. This work focuses on the differences between two chitosan categories, fungal and animal chitosan, characterizing several samples in terms of chitin content and degree of deacetylation. In addition, different acids were used to dissolve chitosans, and their effect on viscosity and on the efficacy in wine clarification were observed. The results demonstrated that even if fungal and animal chitosans shared similar chemical properties (deacetylation degree and chitin content), they showed different viscosity depending on their molecular weight but also on the acid used to dissolve them. A significant difference was discovered on their fining properties, as animal chitosans showed a faster and greater sedimentation compared to the fungal ones, independently from the acid used for their dissolution. This suggests that physical–chemical differences in the molecular structure occur between the two chitosan categories and that this significantly affects their technologic (oenological) properties.

scholarly journals Optimal Design and Testing of a Thermoplastic Pressurized Passenger Door Manufactured Using Thermoforming

Polymers ◽  
2021 ◽  
Vol 13 (19) ◽  
pp. 3394
Author(s):  
Roman Růžek ◽  
Josef Křena ◽  
Radek Doubrava ◽  
Josef Tkadlec ◽  
Martin Kadlec ◽  
...  
Keyword(s):  
Numerical Simulations ◽  
Impact Damage ◽  
Research Work ◽  
Variable Cross Section ◽  
Mechanical Tests ◽  
Point Of View ◽  
Topological Optimization ◽  
Variable Cross ◽  
Thermoplastic Resin ◽  
Significant Difference

The present paper documents and discusses research work associated with a newly designed passenger door structure demonstrator. The composite structure was manufactured from carbon-fiber-reinforced thermoplastic resin. A composite frame with a variable cross-section was designed, optimized, and fabricated using thermoforming technology. Both numerical simulations and experiments supported structural verification according to the damage tolerance philosophy; i.e., impact damage is presented. The Tsai-Wu and maximal stress criteria were used for damage analysis of the composite parts. Topological optimization of the metal hinges from the point of view of weight reduction was used. All expected parameters and proposed requirements of the mechanical properties were proved and completed. The door panel showed an expected numerically evaluated residual strength (ultimate structure load) as well as meeting airworthiness requirements. No impact damage propagation in the composite parts was observed during mechanical tests, even though visible impact damage was introduced into the structure. No significant difference between the numerical simulations and the experimentally measured total deformation was observed. Repeated deformation measurements during fatigue showed a nonlinear structure behavior. This can be attributed to the relaxation of thermoplastics.

Absence of Association Between Abatacept Exposure and Initial Infection in Patients With Juvenile Idiopathic Arthritis

2021 ◽  
pp. jrheum.200154
Author(s):  
Nicolino Ruperto ◽  
Hermine I. Brunner ◽  
Nikolay Tzaribachev ◽  
Gabriel Vega-Cornejo ◽  
Ingrid Louw ◽  
...  
Keyword(s):  
Juvenile Idiopathic Arthritis ◽  
Pediatric Patients ◽  
Opportunistic Infections ◽  
Infection Risk ◽  
Rank Tests ◽  
Link Type ◽  
Kaplan Meier ◽  
Significant Difference ◽  
Exposure Levels ◽  
The Relationship

Objective To assess the relationship between infection risk and abatacept exposure levels in patients with polyarticular-course juvenile idiopathic arthritis (pJIA) following treatment with subcutaneous and intravenous abatacept. Methods Data from two published studies (NCT01844518, NCT00095173) of abatacept treatment in pediatric patients were analyzed. One study treated patients aged 2–17 years with subcutaneous abatacept and the other treated patients aged 6–17 years with intravenous abatacept. Association between serum abatacept exposure measures and infection was evaluated using Kaplan–Meier plots of probability of first infection versus time on treatment by abatacept exposure quartiles and log-rank tests. Number of infections by abatacept exposure quartiles was investigated. Results Overall, 343 patients were included in this analysis: 219 patients received subcutaneous abatacept and 124 patients received intravenous abatacept. Overall, 237/343 (69.1%) patients had ≥1 infection over 24 months. No significant difference in time to first infection across four quartiles of abatacept exposure levels was observed in the pooled (p = 0.4458), subcutaneous (2–5 years p = 0.9305; 6–17 years p = 0.4787), or intravenous (p = 0.4999) analyses. Concomitant use of methotrexate and glucocorticoids (at baseline and throughout) with abatacept did not increase infection risk across the abatacept exposure quartiles. There was no evidence of association between number of infections and abatacept exposure quartiles. No opportunistic infections related to abatacept were reported. Conclusion In patients aged 2–17 years with pJIA, no evidence of association between higher levels of exposure to intravenous or subcutaneous abatacept and incidence of infection was observed.

scholarly journals Faecal Scent as a Novel Non-Invasive Biomarker to Discriminate between Coeliac Disease and Refractory Coeliac Disease: A Proof of Principle Study

Biosensors ◽  
2019 ◽  
Vol 9 (2) ◽  
pp. 69 ◽  
Author(s):  
Maxine D. Rouvroye ◽  
Alfian Wicaksono ◽  
Sofie Bosch ◽  
Edo Savelkoul ◽  
James A. Covington ◽  
...  
Keyword(s):  
Coeliac Disease ◽  
Ion Mobility ◽  
Clinical Symptoms ◽  
Area Under The Curve ◽  
Gluten Free ◽  
Future Studies ◽  
Non Invasive ◽  
Significant Difference ◽  
Volatile Organic ◽  
Refractory Coeliac Disease

Currently, the gold standard for diagnosis of coeliac disease (CD) is based on serology and gastroduodenoscopy with histology of duodenal mucosal biopsies. The aim of this study was to evaluate the potential of faecal volatile organic compounds (VOCs) analysis as a novel, non-invasive tool to discriminate between CD in remission in patients on a gluten-free diet (GFD), refractory coeliac disease (RCD) and controls without CD. Patients with an established diagnosis of CD on a GFD, RCD and healthy controls (HC) were instructed to collect a faecal sample. All subjects completed questionnaires on clinical symptoms, lifestyle and dietary information. Faecal VOCs were measured using gas chromatography-ion mobility spectrometry. A total of 13 CD, 7 RCD and 10 HC were included. A significant difference in VOC profiles between CD and RCD patients (area under the curve (AUC) ± 95% CI: 0.91 (0.79–1) p = 0.000) and between CD and HC (AUC ± 95% CI: 0.71 (0.51–0.91) p = 0.0254) was observed. We found no significant differences between faecal VOC patterns of HC and RCD. Based on faecal VOCs, CD could be discriminated from RCD and HC. This implies that faecal VOC analysis may hold potential as a novel non-invasive biomarker for RCD. Future studies should encompass a larger cohort to further investigate and validate this prior to application in clinical practice.

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