Removals of Chlorinated Aliphatic Hydrocarbons by Fe <sup>0</sup> : Full-scale PRB vs Column Study
American Society of Civil Engineers eBooks, Oct 27, 2006
Evaluation of the hydraulic performance of a full scale permeable reactive barrier by a tracer study
Investigation of the hydraulic performance of a funnel-and-gate permeable reactive barrier (PRB),... more Investigation of the hydraulic performance of a funnel-and-gate permeable reactive barrier (PRB), packed with zero-valent iron (Fe°) and installed at the Vapokon site, Denmark, has been conducted with a natural gradient tracer study. The purposes of this study were to evaluate the flow pattern and determine the seepage velocity (ν x ) of groundwater through the PRB. After collecting and analysing about 13 000 groundwater samples over a period of 10 months, the moving path of the tracer (i.e. lithium, Li + ) was identified in which the Li + plume was observed passing through the reactive barrier. However, probably owing to clogging caused by mineral precipitates, there was a preferential path inside the Fe 0 PRB. Comparison of the water table contour in the Vapokon site obtained in March 2000 and January 2003 showed formation of a low permeability zone within the reactive barrier, thereby further verifying clogging caused by mineral precipitates. Spatial moments analysis of the Li distribution illustrates the similarity of the maximum Li + mass passing through the upgradient and downgradient locations of the Fe 0 PRB and thereby indicated the conservative of the Li - across the reactive barrier as well as the absence of bypassing flow. Based upon the results of first moment analysis, a ν x of 99.5 m year -1 within the PRB was calculated. The ν x just upgradient of the reactive barrier, however, was only about 6.86 m year -1 , most likely owing to the effect of disturbance exerted by the clogged upgradient interface of the upper part of the Fe 0 PRB.
Special Issue with Awarded and Shortlisted Papers from the HKIE Outstanding Paper Award for Young Engineers/Researchers 2021, 2021
A new measurement system called Crosshole Sonic Logging Tomography (CSLT) provides information on... more A new measurement system called Crosshole Sonic Logging Tomography (CSLT) provides information on the size, shape, and orientation of defects in a bored pile. The CSLT measurement system has not (yet) been accredited in Hong Kong for foundation testing. Bored piles in Hong Kong are generally wide and deep. Existing measurement accuracy studies do not consider this large type of bored piles. The objective of this research is to quantify the measurement accuracy and precision of the CSLT method for large diameter bored piles (the most common pile type for public housing projects in Hong Kong). A test pile was constructed with known defects and perform experiments with a CSLT measurement system to quantify its accuracy and precision. CSLT is found to be accurate in detecting shape, size, and location of large defects but small defects close to the tube are difficult to detect. Generally speaking, CSLT has satisfactory accuracy and precision for practical use. The use of CSLT can be con...
Nanotechnologies for Water Environment Applications
This book is useful to undergraduate and graduate students in engineering and practicing engineer... more This book is useful to undergraduate and graduate students in engineering and practicing engineers, as well as educators, scientists, government officials, policymakers, and industrial process managers.
Z-scheme photocatalyst BiVO4/Ag/g-C3N4 was constructed and applied for rapid disinfection of E. c... more Z-scheme photocatalyst BiVO4/Ag/g-C3N4 was constructed and applied for rapid disinfection of E. coli cells in water and wastewater.
Oxidation of Sb(III)-tartrate and Sb(III) in the Fe 0-H2O-O2 system was studied. WMF greatly enha... more Oxidation of Sb(III)-tartrate and Sb(III) in the Fe 0-H2O-O2 system was studied. WMF greatly enhanced Sb(III)-tartrate and Sb(III) removal by ZVI. WMF also increased the removal capacity of Sb(III)-tartrate and Sb(III) by ZVI. Tartrate significantly retarded Sb(III) removal by ZVI. The mechanisms of the inhibiting effect of tartrate were clarified.
JOURNAL OF ENVIRONMENTAL ENGINEERING AND LANDSCAPE MANAGEMENT, 2015
This study aimed to maximize the utilization of contaminated marine mud and sediment for benefici... more This study aimed to maximize the utilization of contaminated marine mud and sediment for beneficial reuse by solidification/stabilization (S/S) treatment with cement and pulverized fuel ash (PFA). For the purposes of waste maximization and enhancing the mechanical property of the S/S mixtures, mixing 75% by mass of either contaminated marine mud or sediment with 20% and 5% of cement and PFA, respectively, was found to be the optimal mix design. Their unconfined compressive strengths reached up to 8.32 MPa and 4.47 MPa, respectively. Apart from the mechanical property, according to the U.S.EPA, the TCLP results show that all regulated heavy metals were immobilized to a safe level and are available for engineering application such as fill material. The results of XRD reveal that the formation of CSH gel in the S/S treated mud and sediment is responsible for the strength development and heavy metal immobilization.
Industrial & Engineering Chemistry Research, 2014
A novel magnetic polymeric adsorbent, namely magnetic hydrogel, was used to investigate its reusa... more A novel magnetic polymeric adsorbent, namely magnetic hydrogel, was used to investigate its reusability and applicability in Cr(VI)-bearing wastewater treatment using magnetic separation. Different concentrations and amounts of NaCl solution, and a step-wise approach were used for the regeneration experiment. A step-wise adsorption process followed by step-wise 3.0 M NaCl regeneration with 40:1 wastewater-to-recovery volume ratio was found to be the most applicable working condition. The Cr concentration in the recovery solution was increased 25-30 times to 500-600 mg/L. The Cr(VI) removal and recovery performance of magnetic hydrogel was maintained for 20 cycles. An industrial wastewater treatment prototype, including a magnetic separation unit, was developed. The magnetic separation unit was designed to provide a magnetic field at the bottom with a zigzag pathway feature for maximizing the chance of capturing magnetic hydrogel. The separation efficiency for the magnetic hydrogel was above 97% throughout the 20 cycles of treatment. The results of the prototype experiment also indicated that magnetic hydrogel can *Manuscript Click here to view linked References effectively remove Cr(VI) and can also be separated and recovered by the magnetic separation unit in 20 cycles.
Couples of Precipitation-Dissolution and Reduction-Oxidation Reactions
Natural Processes and Systems for Hazardous Waste Treatment, 2007
Redox and Precipitation
Remediation Technologies for Soils and Groundwater, 2007
Chemical Reactive Barriers
Remediation Technologies for Soils and Groundwater, 2007
Competitive Effects on the Dechlorination of Chlorinated Aliphatic Hydrocarbons by Zero-valent Iron
Zero-Valent Iron Reactive Materials for Hazardous Waste and Inorganics Removal, 2006
Dechlorination of chlorinated aliphatic hydrocarbons (CAHs) by zero-valent iron (Fe 0 ) was found... more Dechlorination of chlorinated aliphatic hydrocarbons (CAHs) by zero-valent iron (Fe 0 ) was found to be influenced by the competitive effects exerted by other groundwater contaminants. Laboratory column study of the competitive effects on CAH dechlorination by Fe 0 indicated that the presence of 1,1,1-trichloroethane (1,1,1-TCA) in the trichloroethylene (TCE)-contaminated groundwater could decrease the normalized dechlorination rate constant (k SA ) of TCE from 3.04 x 10 -2 to 2.74 x 10 -2 mL m -2 hr -1 . In a similar fashion, introduction of chloroform (TCM) into the synthetic groundwater containing TCE and 1,1,1-TCA led to a 40 to 54% drop in TCE and 1,1,1-TCA k SA , thus indicating competition among TCE, 1,1,1-TCA and TCM during dechlorination reactions induced by Fe 0 . Activation energy ranging from 34.3 to 53.7 kJ/mol for the simultaneous dechlorination of TCE, 1,1,1-TCA and TCM by Fe 0 showed that the process of the electron transfer from Fe 0 to the CAHs is the dominant step limiting the rate of the dechlorination reactions so that the electron released from Fe 0 is most likely in competition with TCE, 1,1,1-TCA and TCM during the dechlorination reactions. In addition to CAHs, abiotic reduction of hexavalent chromium [Cr(VI)] by Fe 0 also exerted effects on TCE dechlorination leading to a 31% drop in TCE k SA after the addition of Cr(VI) into the TCE-contaminated groundwater. Groundwater geochemical factors such as alkalinity and contaminant concentration could potentially influence competition among TCE, 1,1,1-TCA, TCM and Cr(VI) during the abiotic reduction of chemical substances by Fe 0 .
Hydraulic Studies of Zero-Valent Iron in Permeable Reactive Barriers Using Tracer Experiment
Zero-Valent Iron Reactive Materials for Hazardous Waste and Inorganics Removal, 2006
Configuration and Construction of Zero-valent Iron Reactive Barriers
Zero-Valent Iron Reactive Materials for Hazardous Waste and Inorganics Removal, 2006
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