Temperature-dependent microbial reactions by indigenous microbes in bentonite under Fe(III)- and sulfate-reducing conditions.

Bentonite is a promising buffer material for constructing spent nuclear fuel (SNF) repositories. However, indigenous microbes in bentonite can be introduced to the repository and subsequent sealing of the repository develops anoxic conditions over time which may stimulate fermentation and anaerobic respiration, possibly affecting bentonite structure and SNF repository stability. Moreover, the microbial activity in the bentonite can be impacted by the heat generated from radionuclides decay. Therefore, to investigate the temperature effect on microbial activities in bentonite, we created microcosms with WRK bentonil (a commercial bentonite) using lactate as the electron donor, and sulfate and/or ferrihydrite (Fe(III)) as electron acceptors with incubation at 18 â„ƒ and 50 â„ƒ. Indigenous WRK microbes reduced sulfate and Fe(III) at both temperatures but with different rates and extents. Lactate was metabolized to acetate at both temperatures, but only to propionate at 18 â„ƒ during early-stage microbial fermentation. More Fe(III)-reduction at 18 â„ƒ but more sulfate-reduction at 50 â„ƒ was observed. Thermophilic and/or metabolically flexible microbes were involved in both fermentation and Fe(III)/sulfate reduction. Our findings illustrate the necessity of considering the influence of temperature on microbial activities when employing bentonite as an engineered buffer material in construction of SNF repository barriers.

Delineation of LNAPL plumes in a clay-rich site in Gyeongsangnam-do Province, South Korea: integration of geophysical survey data with borehole data and soil sampling information.

To effectively delineate the spatial distribution of oil contaminant plumes, geophysical methods indirectly measure the physical properties of the subsurface and can provide spatial information and images on a large scale, as opposed to traditional direct methods such as borehole drilling, sampling, and chemical analysis, which are time-consuming and costly. However, interpreting geophysical responses over non-aqueous phase liquid (NAPL)-contaminated sites is not straightforward due to inconsistent responses from biodegraded oil contaminants. In this study, we performed multi-geophysical surveys including seismic refraction, ground-penetrating radar, electrical resistivity tomography (ERT), and induced polarization (IP) surveys, to locate NAPL-contaminated zones in a clay-rich site. To reduce ambiguity in discriminating between oil contaminants and clay layers, we first figure out the geological structure of the site by interpreting geophysical data incorporating with borehole data. The ERT data highlighted the heavily contaminated regions in the unsaturated zone but were less distinctive below groundwater levels. Conversely, IP responses revealed potential hotspots within the clay layers, extending beneath the groundwater. Considering the 3D geological model, NAPL-contaminated zones are properly delineated through interpretation of ERT and IP data together with borehole data, and the contaminant source zone was properly estimated within the site.

Potential natural attenuation of petroleum hydrocarbons in fuel contaminated soils: Focusing on anaerobic fuel biodegradation involving microbial Fe(III) reduction.

Liquid fossil fuels, collectively known as total petroleum hydrocarbons (TPHs), are highly toxic and frequently leak into subsurface environments due to anthropogenic activities. As an in-situ biological remedial option for TPH contamination, aerobic TPH biodegradation is limited due to oxygen's low solubility in water, and because it is consumed quickly by aerobic bacteria. Thus, we investigated the potential of anaerobic TPH degradation by indigenous fermenting bacteria and Fe(III)-reducing bacteria. Twenty 6-10 m soil cores were collected from a closed military base subject to ongoing TPH contamination since the 1980s. Physicochemical and microbial properties were determined at 0.5-m intervals in each core. To assess the relationship between TPH degradation and microbial Fe(III) reduction, soil samples were grouped into high-TPH (>500 mg kg-1) and high-Fe(II) (>450 mg kg-1), high-TPH and low-Fe(II), low-TPH and high-Fe(II), and low-TPH and low-Fe(II) groups. Alpha diversity was significantly lower in high-TPH groups than in low-TPH groups, suggesting that high TPH concentrations exerted a strong selective pressure on bacterial communities. In the high-TPH and low-Fe(II) group, fermenting bacteria, including Microgenomatia and Chlamydiae, were more abundant, suggesting that TPH biodegradation occurred via fermentation. In the high-TPH and high-Fe(II) group, Fe(III)-reducing bacteria, including Geobacter and Zoogloea, were more abundant, suggesting that microbial Fe(III) reduction enhances TPH biodegradation. In contrast, the fermenting and/or Fe(III)-reducing bacteria were not statistically abundant in the low-TPH groups.

Weathering extents and anthropogenic influences shape the soil bacterial community along a subsurface zonation.

Subsurface environments are composed of various active soil layers with dynamic biogeochemical interactions. We investigated soil bacterial community composition and geochemical properties along a vertical soil profile, which was categorized into surface, unsaturated, groundwater fluctuated, and saturated zones, in a testbed site formerly used as farmland for several decades. We hypothesized that weathering extent and anthropogenic inputs influence changes in the community structure and assembly processes and have distinct contributions along the subsurface zonation. Elemental distribution in each zone was strongly affected by the extent of chemical weathering. A 16S rRNA gene analysis indicated that bacterial richness (alpha diversity) was highest in the surface zone, and also higher in the fluctuated zone, than in unsaturated and saturated zones due to the effects of high organic matter, high nutrient levels, and/or aerobic conditions. Redundancy analysis showed that major elements (P, Na), a trace element (Pb), NO3, and the weathering extent were key driving forces shaping bacterial community composition along the subsurface zonation. Assembly processes were governed by specific ecological niches, such as homogeneous selection, in the unsaturated, fluctuated, and saturated zones, while in the surface zone, they were dominated by dispersal limitation. These findings together suggest that the vertical variation in soil bacterial community assembly is zone-specific and shaped by the relative influences of deterministic vs. stochastic processes. Our results provide novel insights into the relationships between bacterial communities, environmental factors, and anthropogenic influences (e.g., fertilization, groundwater, soil contamination), and into the roles of specific ecological niches and subsurface biogeochemical processes in these relationships.

Variable effects of soil organic matter on arsenic behavior in the vadose zone under different bulk densities.

The nonstationary nature of water and oxygen content in the vadose zone determines various biogeochemical reactions regarding arsenic (As) therein, which affects the groundwater vulnerability to As contamination at a site. In the present study, we evaluated the effect of soil organic matter (OM) on the behavior of As using specifically designed soil columns that simulated the vadose zone. Three wet-dry cycles were applied to each of the four columns with different OM contents and bulk densities. OM was found to exhibit variable effects, either inhibiting or accelerating the mobilization of As, depending on bulk density. At a moderate bulk density (< 1.27 g/cm3), OM slightly lowered the pH of pore water, which enhanced the sorption of As onto the iron (Fe) oxides, promoting the retention of As in soil. In the soil column with a relatively higher bulk density (1.36 g/cm3), however, the dissimilatory reduction of iron oxides was triggered by rich OM under oxygen-limited conditions. X-ray absorption spectroscopy analysis revealed that alternate wetting and drying transformed the Fe oxides in the soil by reductive dissolution and subsequent re-precipitation. Consequently, As was not stably retained in the soil, and its mobilization downwards was further accelerated.

A synthetic microplastic fiber-manufacturing method and analysis of airborne microplastic fiber transport behavior in porous media.

Long-term environmental contamination through microplastic (MP) exposure remains poorly understood and may pose economic and geochemical threats. Notably, only a few studies have been conducted on MP contamination of soils. This study investigated the migration of AMP fibers and their influence on water flow rates through porous media. Multiple columns with diameters of 5 cm and water flow rates of 3 ml/min were filled with glass beads or sand. The particle sizes varied between 3 mm for glass beads and 1-2 or 2-4 mm for sand. A method on how to artificially manufacture MP fibers with sizes ranging from 500 to 1000 µm representing AMP fibers occurring in the environment is introduced. The MP fibers were then introduced into water at varying concentrations that were reported in previous studies. The results revealed that regardless of their concentration, the MP fibers suspended in the water did not clog the porous media. In fact, although the fibers penetrated and accumulated in the soil, they did not disrupt the water flow. We recommend that future research focuses on using MP particles with varying densities and at lower concentrations, to prevent flocculation and increase the experiment run time.

Transient behavior of arsenic in vadose zone under alternating wet and dry conditions: A comparative soil column study.

The water and oxygen contents of the vadose zone change cyclically depending upon the meteorological condition (e.g., intermittent rainfall), which can affect the biogeochemical reactions that govern the fate of arsenic (As). To simulate and evaluate the transient behavior of As in this zone when subjected to repeated wet and dry conditions, soil column experiments with different soil properties were conducted. Three wetting-drying cycles resulted in the fluctuation of water and dissolved oxygen contents, and consequently, the reduction-oxidation potential in the soil columns. Under these circumstances, the biotic reduction of As(V) to As(III) was observed, especially in the column filled with soils enriched in organic matter. Most of the As was found to be associated with soil particles rather than to be dissolved in the pore water in all of the columns tested. Retention of As was more preferable in the soil column with a higher Fe content and bulk density, which provided more sorption sites and reaction time, respectively. However, a considerable amount of soil-bound As could be remobilized and released back to the pore water with the repetition of wetting and drying due to the transformation of As(V) to As(III).

Diversity and composition of soil Acidobacteria and Proteobacteria communities as a bacterial indicator of past land-use change from forest to farmland.

The land-use change from natural to managed farmland ecosystems can undergo perturbations and significantly impact soil environment and communities. To understand how anthropogenic land-use alteration determines in-depth relationships among soil environmental factors and soil bacterial communities, high-resolution characterization was performed using soil samples (27 spots × 3 depths; top 10-20 cm, middle 90-100 cm, bottom 180-190 cm) from a natural forest and a 50 year-old farmland. The soil bacterial community abundance (number of OTU's per sample) and diversity (Faith's phylogenetic diversity) was significantly higher in the top layer of farmland soil than in forest soil. However, the differences in bacterial community abundance between farmland and forest decreased with depth, suggesting that the effect of fertilization was limited to top and middle layers. The phyla Acidobacteria and Proteobacteria were distributed distinctively during the land-use change. The subgroups Gp1-3 of Acidobacteria were more abundant in the forest samples (pH 3.5-5), while Gp4-7 and Gp10 were predominant in the farmland (pH 4.5-9.5). Members belonging to α-Proteobacteria and Xanthomonadales in γ-Proteobacteria were dominant in the forest, whereas ß-, δ-, and γ-Proteobacteria were relatively abundant in the farmland. Both multivariate and correlation network analyses revealed that Acidobacteria and Proteobacteria communities were significantly affected by soil pH, as well as toxic metals from pesticides (Zn, Cr, Ni, Cu, Cd, As) and terminal electron acceptors (NO3, bioavailable Fe(III), SO4). In line with the long history of anthropogenic fertilization, the farmland site showed high abundance of membrane and ATP-binding cassette transporter genes, suggesting the key for uptake of nutrients and for protection against toxic metals and environmental stresses. This study provides new insights into the use of both Acidobacteria and Proteobacteria community structures as a bacterial indicator for land-use change.

Waste foundry dust (WFD) as a reactive material for removing As(III) and Cr(VI) from aqueous solutions.

This study evaluates the use of waste foundry dust (WFD) as a reactive material for mitigating water pollution using As(III) and Cr(VI) as model contaminants. A detailed structural characterization of WFD was performed using X-ray diffraction (XRD), X-ray fluorescence (XRF), scanning electron microscopy-energy dispersive X-ray spectroscopy (SEM-EDX), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS). Batch removal experiments and kinetic studies for removal of both As(III) and Cr(VI) were conducted at various initial pH values (2-10), concentrations (1-100 mg/L), and solid-to-liquid ratios (2.5-125 g/L). The results show that WFD consisted of small particles (< 30 µm) with magnetic properties, mainly composed of quartz (SiO2) and magnetite (Fe3O4). The maximum removal capacity of WFD was 12.6 mg/g for As(III) at pH 3.0 and 6.1 mg/g for Cr(VI) at pH 5.0. WFD was effective in a wide pH range, from 3.0 to 8.0, and in high concentrations, up to 100 mg/L. WFD removed As(III) and Cr(VI) from aqueous solutions through complex processes including adsorption, precipitation, and redox reactions by oxidation of Fe(II). The results of this study suggest that WFD can be used as a reactive material for removal of As(III) and Cr(VI) from aqueous solutions.

Data describing characteristics of waste foundry dust (WFD), sorbent obtained before and after batch sorption tests using As(III) and Cr(VI) aqueous solutions.

This article presents data on characteristics of waste foundry dust (WFD), sorbent obtained before and after batch sorption tests using As(III) and Cr(VI) aqueous solutions, by performing X-ray Diffraction (XRD), field-emission scanning electron microscopy (FE-SEM) coupled with energy dispersive X-ray spectroscopy (EDX), Fourier-transform infrared spectroscopy (FT-IR), and X-ray photoelectron spectroscopy (XPS) analyses. Data are related to a research article "Waste foundry dust (WFD) as a reactive material for removing As(III) and Cr(VI) from aqueous solutions" [1]. The data provide information obtained from various analytical methods to investigate mechanisms of As(III) and Cr(VI) removal from aqueous solutions by WFD, an industrial by-product. These data can be of interest to researchers studying contaminant removal mechanisms by reactive materials, in particular industrial by-products.

Revisiting soil bacterial counting methods: Optimal soil storage and pretreatment methods and comparison of culture-dependent and -independent methods.

Although a number of different methods have been used to quantify soil bacteria, identifying the optimal method(s) for soil bacterial abundance is still in question. No single method exists for undertaking an absolute microbial count using culture-dependent methods (CDMs) or even culture-independent methods (CIMs). This study investigated soil storage and pretreatment methods for optimal bacterial counts. Appropriate storage temperature (4°C) and optimal pretreatment methods (sonication time for 3 min and centrifugation at 1400 g) were necessary to preserve bacterial cell viability and eliminate interference from soil particles. To better estimate soil bacterial numbers under various cellular state and respiration, this study also evaluated three CDMs (i.e., colony forming unit, spotting, and most probable number (MPN) and three CIMs (i.e., flow cytometry (FCM), epifluorescence microscopy (EM) count, and DNA quantitation). Each counting method was tested using 72 soil samples collected from a local arable farm site at three different depths (i.e., 10-20, 90-100, and 180-190 cm). Among all CDMs, MPN was found to be rapid, simple, and reliable. However, the number of bacteria quantified by MPN was 1-2 orders lower than that quantified by CIMs, likely due to the inability of MPN to count anaerobic bacteria. The DNA quantitation method appeared to overestimate soil bacterial numbers, which may be attributed to DNA from dead bacteria and free DNA in the soil matrix. FCM was found to be ineffective in counting soil bacteria as it was difficult to separate the bacterial cells from the soil particles. Dyes used in FCM stained the bacterial DNA and clay particles. The EM count was deemed a highly effective method as it provided information on soil mineral particles, live bacteria, and dead bacteria; however, it was a time-consuming and labor-intensive process. Combining both types of methods was considered the best approach to acquire better information on the characteristics of indigenous soil microorganisms (aerobic versus anaerobic, live versus dead).

Uranium sequestration in fracture filling materials from fractured granite aquifers.

The migration of the uranium (U) in high-level radioactive waste that is held in deep geological repositories via fractures in deep granite aquifers is a serious safety concern, thus, this study investigates the effect of fracture filling materials designed to mitigate these concerns. Geochemical analysis was conducted on granite rock core and groundwater samples collected from boreholes located in granite areas. Sequential extraction tests on fracture filling material (FFM) samples were also conducted. The rock core samples were classified as two-mica granite that had uranium (U) content ranging from 1900 to 22,100 µg/kg with an arithmetic mean of 8500 µg/kg. The total U concentration in the FFM samples was found to range from 790 to 80,781 µg/kg. The U in the FFM samples was mainly associated with a carbonate phase that made up from 29.9 to 100% of the total U in the FFM. The U fraction of carbonate phase was closely correlated with the Ca fraction. U associated with crystalline inorganic FFM constituents (e.g, clay minerals and metal oxyhydroxides) was also found in FFM samples in fractions ranging from 21.1 to 70.1%. U in FFM is mainly incorporated via Ca-carbonate, which might have not been formed in modern groundwater, but the time and temperature during formation are unknown. In addition, the Fe, Si, Al, Ca, K, and U levels were found to be well correlated with each other, suggesting that U can also become geochemically associated with crystalline clay minerals or Fe-oxyhydroxides.

Chlorite alteration in aqueous solutions and uranium removal by altered chlorite.

Chlorite alteration and the U removal capacity of altered chlorite were investigated. Batch kinetic dissolution tests using clinochlore CCa-2 were conducted for 60days in aqueous solutions of various pHs and ionic strengths. Batch sorption tests using these altered chlorite samples were conducted for 48h with natural groundwater containing 3.06×10-6M U. Chlorite dissolution was influenced more by pHo than by the ionic strength of the solution. TEM analysis revealed Fe(oxy)hydroxide aggregates in the solid residue from the batch dissolution test with 0.1M NaClO4 solution at pHo=10. The U removal capacity of the reacted chlorite samples at pHo=6-10 was higher than that of the reacted chlorite samples at pHo=3. The degree of dissolution of chlorite samples reacted at pHo=3-8 was inversely proportional to the U removal capacity, but that of chlorite samples reacted at pHo=10 was proportional to the U removal capacity. The positive correlation between the U removal capacity and degree of chlorite dissolution at pHo=10 might be due to the formation of Fe-containing secondary minerals and changes in the reactive sites.

A microfluidic approach to water-rock interactions using thin rock sections: Pb and U sorption onto thin shale and granite sections.

The feasibility of using microfluidic tests to investigate water-rock (mineral) interactions in fractures regarding sorption onto thin rock sections (i.e., shale and granite) of lead (Pb) and uranium (U) was evaluated using a synthetic PbCl2 solution and uranium-containing natural groundwater as fluids. Effluent composition and element distribution on the thin rock sections before and after microfluidic testing were analyzed. Most Pb removal (9.8mg/cm2) occurred within 3.5h (140 PVF), which was 74% of the total Pb removal (13.2mg/cm2) at the end of testing (14.5h, 560 PVF). Element composition on the thin shale sections determined by µ-XRF analysis indicated that Pb removal was related primarily to Fe-containing minerals (e.g., pyrite). Two thin granite sections (biotite rich, Bt-R and biotite poor, Bt-P) exhibited no marked difference in uranium removal capacity, but a slightly higher amount of uranium was removed onto the thin Bt-R section (266µg/cm2) than the thin Bt-P section (240µg/cm2) within 120h (4800 PVF). However, uranium could not be detected by micro X-ray fluorescence (µ-XRF) analysis, likely due to the detection limit. These results suggest that microfluidic testing on thin rock sections enables quantitative evaluation of rock (mineral)-water interactions at the micro-fracture or pore scale.

Effect of Cr(VI) concentration on gas and particle production during iron oxidation in aqueous solutions containing Cl- ions.

Zero-valent iron (ZVI) is commonly used as a medium in permeable reactive barriers (PRBs) because of its high reducing ability. The generation of H2 gas in PRBs, however, can decrease the permeability of PRBs and reduce the contact area between the PRB and contaminated groundwater. This study investigated the effect of the initial Cr(VI) concentration ([Cr(VI)init]) in aqueous solutions containing Cl- ions on the generation of H2 gas. ZVI chips were reacted in reactors with 0.5-M NaCl solutions with [Cr(VI)init] ranging between 51 and 303 mg/L. The initial pH was set at 3. The oxidation of ZVI chips by Cr(VI) in aqueous solutions containing Cl- ions produced H2 gas and particles (Fe(III)-Cr(III)(oxy)hydroxides). The Cr(VI) removal from aqueous solutions increased as the [Cr(VI)init] increased, as did H2 gas generation. The positive effect of [Cr(VI)init] on H2 gas generation might be due to an increase in the redox potential gradient as [Cr(VI)init] increases. This increased gradient would enhance H+ ion penetration through the passive film (Fe(III)-Cr(III)(oxy)hydroxides), which formed on the ZVI surface, by diffusion from the solution to pits beneath the passive film.

Adsorption characteristics of U(VI) on Fe(III)Cr(III) (oxy)hydroxides synthesized at different temperatures.

In this study, the adsorption behavior of U(VI) on (oxy)hydroxides synthesized at different temperatures (25 and 75 °C) was investigated. Four (oxy)hydroxides were synthesized by drying slurries of Fe(III) and Fe(III)Cr(III) (oxy)hydroxide in a vacuum desiccator (25 °C) or in an oven (75 °C). Batch adsorption tests were conducted using the (oxy)hydroxides thus synthesized and groundwater containing uranium ions. In general, the U(VI) removal fraction significantly increased with increasing pH from 3 to 5, remained constant with increasing pH from 5 to 9, and decreased at pH greater than 9, regardless of the type of (oxy)hydroxides and solid-to-liquid ratio. The effect of pH on the U(VI) removal fraction was more significant at a low solid-to-liquid ratio. The oven-dried Fe(III) (oxy)hydroxide exhibited a U(VI) removal fraction lower than that of the vacuum-dried one, whereas the oven-dried Fe(III)Cr(III) (oxy)hydroxide exhibited a U(VI) removal fraction higher than that exhibited by the vacuum-dried one. X-ray photoelectron spectroscopy (XPS) analysis results indicated that the difference in the U(VI) removal fraction is attributed to the dissolution and precipitation of the Fe(III) (oxy)hydroxide during oven drying and dehydration of the Fe(III)Cr(III) (oxy)hydroxide during oven drying.

Heavy metal concentrations and contamination levels from Asian dust and identification of sources: a case-study.

The aims of this study were to determine concentrations of selected metals (As, Cd, Cr, Co, Cu, Ni, Sb, Pb and Zn) in Asian and non-Asian dust collected in Daejeon, Korea between February 2007 and December 2007 and to estimate the pollution sources. The geoaccumulation index (Igeo) and the enrichment factor (EF) show that the pollution levels of Cd, Pb, Zn, Sb, Cu, and As are much higher than those of Cr, Co and Ni. As, Cd, Cu, Sb, Pb, and Zn are the ones most strongly affected by anthropogenic inputs such as airborne pollutants. The (206)Pb/(207)Pb ratios of Asian and non-Asian dust are similar to those of the airborne particles in some heavily industrialized Chinese cities and the soils of the Alashan desert. To address the highly elevated levels of heavy metals found in Asian and non-Asian dust, studies should be performed to assess the potential impacts of settled particles on surface ecosystems, water resources, and human health in Korea.

Evaluation of the CO2 sequestration capacity for coal fly ash using a flow-through column reactor under ambient conditions.

An in-situ CO(2) sequestration method using coal ash ponds located in coastal regions is proposed. The CO(2) sequestration capacity of coal fly ash (CFA) by mineral carbonation was evaluated in a flow-through column reactor under various conditions (solid dosage: 100-330 g/L, CO(2) flow rate: 20-80 mL/min, solvent type: deionized (DI) water, 1 M NH(4)Cl solution, and seawater). The CO(2) sequestration tests were conducted on CFA slurries using flow-through column reactors to simulate more realistic flow-through conditions. The CO(2) sequestration capacity increased when the solid dosage was increased, whereas it was affected insignificantly by the CO(2) flow rate. A 1 M NH(4)Cl solution was the most effective solvent, but it was not significantly different from DI water or seawater. The CO(2) sequestration capacity of CFA under the flow-through conditions was approximately 0.019 g CO(2)/g CFA under the test conditions (solid dosage: 333 g/L, CO(2) flow rate: 40 mL/min, and solvent: seawater).

Effect of extraction solutions on carbonation of cementitious materials in aqueous solutions.

Carbonation efficiency was evaluated for three cementitious materials having different CaO-bearing minerals (lime, Portland cement and waste concrete) using various extraction reagents (HCl, CH3COOH, NH4Cl and deionized water). The cementitious materials were subjected to Ca extraction and carbonation tests under ambient pressure and temperature conditions. The Ca extraction efficiency generally decreased in the order lime, Portland cement and waste concrete, regardless of the extraction solution. Among the extraction solutions, NH4Cl was the most effective for Ca extraction and carbonation. The results of this study suggest that the types of extraction solution and CaO-bearing mineral of the materials are primary factors affecting carbonation efficiency.

Evaluation of factors affecting performance of a zeolitic rock barrier to remove zinc from water.

This study examined the factors affecting the performance of zeolitic rocks as reactive media in a permeable reactive barrier (PRB) used to remediate groundwater contaminated with Zn. Serial batch kinetic and sorption tests were conducted on zeolitic rock samples under a variety of conditions (i.e., reaction time, pH, initial Zn concentration, and particle size) using Zn(NO(3))(2).6H(2)O solutions. Serial column tests were also conducted on zeolitic rock samples at various flow rates. The removal of Zn increased approximately from 20-60 to 70-100% with increasing pH from 2 to 4 and decreasing initial Zn concentration from 434 to 5mg/L. Zn removal was not affected by the particle size, regardless of the zeolitic rock samples used in this study. The Zn removal increased approximately from 20-70 to 60-100% with increasing the cation exchange capacity (CEC) from 124.9 to 178.5meq/100g and increasing zeolite (i.e., clinoptilonite and mordenite) and montmorillonite contents from 53.7 to 73.2%. The results from the column and batch tests were comparable. Increasing the flow rate caused the earlier breakthrough of Zn (sorbing cation) and a rapid decrease in the concentration of Na, Ca, and Mg (desorbing cations). The hydraulic conductivities of the samples were unaffected by the particle size and mineral components.