Developing a fuzzy bi-objective programming and MCDM model for bridge maintenance strategy optimization.

Bridges serve as critical links in road networks, requiring continuous maintenance to ensure proper functionality throughout their lifespan. Given their pivotal role in the urban landscape, connecting various parts of a city, this research presents a multi-objective optimization model for the maintenance and repair of bridges in Babolsar, Iran. The model takes into account budget constraints and aims to minimize the total life cycle and user costs, encompassing traffic delays and vehicle expenses, while maximizing the reliability of the bridge network. Recognizing the inherent complexity of this problem, a multi-objective particle swarm optimization algorithm has been developed for an accurate solution. The study further conducts sensitivity analysis on the objective function concerning the available budget, evaluating key parameters such as hourly costs and the time value of vehicles. The results show that with an increase in the budget level, the number of repairs related to the most costly maintenance has significantly risen. In other words, as the budget expands, the model tends to favor repairs with higher costs because their impact on the bridge's performance is more substantial.

Developing a composite index for urban ecosystem services (Hyrcanian forests-Gorgan).

The current era has been termed the "Anthropocene," because of the irreversible impact of human activities. Land use change and urban growth are examples of these disturbances leading to the reduction in many ecosystem services (ESs). The subject of this study, Gorgan, has undergone significant changes that significantly affected the area. Studying these changes and understanding their effects on the ecosystem is essential. An integrated method was used to investigate the process of changing the urban ESs over 35 years, considering the physical and ecological characteristics of the area. This marks the first time such a study has been conducted using the hexagonal unit. Then, the composite total ecosystem services (TESs) index was calculated from the modeled and quantified combination of six ESs, including water yield, flood volume, net primary production, soil retention, carbon sequestration, and air pollution removal. Thereafter, the ESs were mapped and evaluated across time and space. The TES is proposed as an appropriate measure for quantifying ES supply and can indicate the overall function of ESs. According to the findings, the TES value declined from 0.427 in 1985 to 0.247 in 2005 and declined to 0.192 in 2020. Moreover, the Hyrcanian forests were the main source of the highest TES in Gorgan city, whereas urban areas had the lowest levels. The shortage of ESs in the study area has resulted in various crises. These include reduced air quality, heightened flood risk, soil erosion, and ecological imbalances in urban regions. Integr Environ Assess Manag 2024;20:465-480. © 2023 Society of Environmental Toxicology & Chemistry (SETAC).

Preparation and characterization of biopolymer-based adsorbents and their application for methylene blue removal from wastewater.

In the present study, four biopolymer-based materials consisting of native corn starch (CS), phosphate corn starch (PS), starch nanocrystals (SNCs), and phosphate corn starch nanocrystals (PSNCs) were synthesized and used for methylene blue (MB) removal as a function of various parameters, including initial MB concentration (C0, 10-500 mg L-1), adsorbent dosage (Cs, 0.02-0.15 g), contact time (t, 5-15 min), solution pH (2-11), and temperature (25-45 °C). The removal percentage of MB increased dramatically upon increasing the biopolymer dosage, temperature, and pH; while it decreased upon increasing the initial MB concentration. The adsorption behavior of biopolymer-based materials towards MB was found to be accurately described by the pseudo-second-order kinetic and Langmuir isotherm models. According to the Langmuir model, the maximum adsorption capacities of the adsorbents were ordered as follows: PSNCs (88.53 mg g-1) > SNCs (79.55 mg g-1) > PS (73.17 mg g-1) > CS (63.02 mg g-1). PSNCs was able to remove 96.8% and 76.5% of 20 mg L-1 MB in greywater and petrochemical wastewater, respectively, at an optimum pH of 9 and retained 86.42% of its usability even after five adsorption-desorption cycles. The analysis of the surface charge of the adsorbents before and after MB adsorption, combined with the FTIR spectrum of MB-saturated biopolymer-based materials, provided evidence that electrostatic interactions was the primary mechanism involved in the adsorption of MB. Meanwhile, hydrogen bonding and π-π interactions were found to have a minor contribution to the adsorption process. Based on the results, it can be inferred that PSNCs has promising potential as an adsorbent for the treatment of MB-containing wastewater, owing to its exceptional properties, which include high adsorption capacity, low cost, and applicability for multiple reuses.

Spatiotemporal ecosystem services: Response to structural changes (A case study in Lahijan, Iran).

Structure and function are the inherent characteristics of each ecosystem providing various services such as clean air, extreme weather mitigation, and mental and physical well-being. The objective of this study is to develop a unified model combining Integrated Valuation of Ecosystem Services, ecological network (EN), and correlation analysis to investigate changes in ecosystem structure, function, and process. In this context, carbon sequestration, soil reduction, and flood risk mitigation were quantified from 2000 to 2020 and predicted for 2040 using the cellular automata and Markov chain (CA-Markov) model. Finally, correlation analysis was used to analyze the relationship over time between the land use (LU) classes and the components of the forest EN that provide and exchange desired ecosystem services (ESs). Thus, the changes in LU in the region in recent years led to significant reduction of ESs in the region as well as changes in the interaction between services. These changes, on the one hand, reduced the area of cores and increased isolated forest patches and, on the other hand, led to the horizontal expansion of cities and agricultural lands. If this trend continues, the decline in services provided by the ecosystem will persist into the future. Consequently, it can be said that structural changes in the ecosystem can lead to changes in the ESs. Integr Environ Assess Manag 2023;00:1-13. © 2023 SETAC.

Synthesis and optimization of spherical nZVI (20-60 nm) immobilized in bio-apatite-based material for efficient removal of phosphate: Box-Behnken design in a fixed-bed column.

In the present study, bio-apatite/nZVI composite was synthesized through Fe(III) reduction with sodium borohydride and was fully characterized by FTIR, XRD, SEM-EDX, TEM, BET, BJH, and pHPZC. Column experiments were carried out for the removal of phosphate as a function of four operational parameters including initial phosphate concentration (100-200 mg L-1), initial solution pH (2-9), bed height (2-6 cm), and influent flow rate (2.5-7.5 mL min-1) using a response surface methodology (RSM) coupled with Box-Behnken design (BBD). 2D contour and 3D surface plots were employed to analyze the interactive effects of the four operating parameters on the column performance (e.g., uptake capacity and saturation time). According to ANOVA analysis, the influent flow rate and bed height are the most important factor on phosphate uptake capacity and saturation time, respectively. A quadratic polynomial model was excellently fitted to experimental data with a high coefficient of determination (> 0.96). The RSM-BBD model predicted maximum phosphate adsorption capacity of 85.71 mg g-1 with the desirability of 0.995 under the optimal conditions of 135.35 mg L-1, 2, 2 cm, and 7.5 mL min-1 for initial phosphate concentration, initial solution pH, bed height, and influent flow rate, respectively. The XRD analysis demonstrated that the reaction product between bio-apatite/nZVI composite and phosphate anions was Fe3 (PO4)2. 8H2O (vivianite). The suggested adsorbent can be effectively employed up to five fixed-bed adsorption-desorption cycles and was also implemented to adsorb phosphate from real samples.

Landscape conservation and protected areas (case of Dena, Iran).

Inefficient management of protected areas (PAs) is often due to ignoring their surrounding matrix in the baseline studies, especially in wooded landscapes. In Iran, the application of landscape structure studies in protection policies and PA management is not prevalent. In this study, land cover changes in Dena Rural District (including parts of inside and outside Dena PA) have analyzed using the process of the Landsat images along with field survey two times (1989 and 2018). The landscape structural integrity was quantified based on the situation of oak forest land and its alteration. The composition and the configuration of oak forest land were assessed by metrics based on the moving extent of the Persian squirrel, Sciurus anomalus (which is an endangered focal endemic species completely dependent on the oak forest). Alterations of landscape structural integrity were compared for inside and outside Dena PA and at different altitudes. The results show connectivity loss and increased fragmentation of oak remnant patches, but this deforestation is more severe near areas facing direct human impacts and interventions. These are among attributes that are to be considered for zoning PA (such as controlling zone and training/participation zone). At higher altitudes, physical protection and strict control are more effective, while training local communities for stewardship is more essential at lower altitudes for conserving woodland integrity.

A kinetic analysis of the aflatoxin detoxification potential of lactic acid bacteria in Terxine (a cereal-based food).

Aflatoxin B1 (AFB1) is a hazardous component that can seriously threaten the public health. Terxine is a component used in traditional soup and found in the western mountainous regions of Iran. Several microorganisms have been reported to bind or degrade aflatoxins (AFs) in foods and feeds. This research aimed to investigate the effect of Terxine fermentation by Lactobacillus plantarum strains AF1 and LU5 on AFB1. Fermentation was carried out, and pH, lactic acid and AFB1 amount and microbial count were further determined. In addition, the kinetic experimental data of AFB1 by L. plantarum AF1 and LU5 (obtained at 37°C) were fitted to the zero-order, first-order and parabolic diffusion models. According to the coefficient of determination (R2) and root mean square of errors (RMSE), the zero-order model best described AF degradation. The growth of Lactobacillus strains was increased by the rise in the fermentation time; in this regard, the number of L. plantarum AF1 increased from 4.2 to 5.1 log cfu/g and that of L. plantarum LU5 increased from 4.1 to 5.2 log cfu/g in the first 8 h, reaching 7.2 and 7.4 log cfu/g in the next 8 h, respectively. The results also showed that the amount of lactic acid increased whereas the pH value decreased during the 24 h fermentation. Both microorganisms reduced the amount of AFB1 while L. plantarum AF1 was more effective. Therefore, L. plantarum strains AF1 and LU5 can be effectively used to reduce AFB1 in fermented foods.

The potential use of ultrasound-assisted bleaching in removing heavy metals and pigments from soybean oil using kinetic, thermodynamic and equilibrium modeling.

In this research, the sorption behavior (kinetic, isotherm, and thermodynamic modeling) of heavy metals (Cu (II) and Fe (II)) and pigments (carotenoid and chlorophyll) onto activated bentonite clay was investigated for soybean oil under industrial (IBM) and ultrasonic bleaching method (UBM). A nonlinear fitting approach was used to determine the best-fit isotherm and kinetic models by two statistical criteria including the coefficient of determination (R2) and chi-square (χ2). The adsorption of metal ions and pigments onto activated bentonite clay under UBM was quite well by the pseudo-first-order model. In both bleaching methods, the equilibrium adsorption data follows the Toth isotherm model, presenting the sorption occurrence tends to be on a heterogeneous surface. The results indicated that the adsorption thermodynamics was endothermic in nature and the process was spontaneous between 35 and 65 °C.

A new approach in adsorption modeling using random forest regression, Bayesian multiple linear regression, and multiple linear regression: 2,4-D adsorption by a green adsorbent.

The mathematical model's usage in water quality prediction has received more interest recently. In this research, the potential of random forest regression (RFR), Bayesian multiple linear regression (BMLR), and multiple linear regression (MLR) were examined to predict the amount of 2,4-dichlorophenoxy acetic acid (2,4-D) elimination by rice husk biochar from synthetic wastewater, using five input operating parameters including initial 2,4-D concentration, adsorbent dosage, pH, reaction time, and temperature. The equilibrium and kinetic adsorption data were fitted best to the Freundlich and pseudo-first-order models. The thermodynamic parameters also indicated the exothermic and spontaneous nature of adsorption. The modeling results indicated an R2 of 0.994, 0.992, and 0.945 and RMSE of 1.92, 6.17, and 2.10 for the relationship between the model-estimated and measured values of 2,4-D removal for RFR, BMLR, and MLR, respectively. Overall performances indicated more proficiency of RFR than the BMLR and MLR models due to its capability in capturing the non-linear relationships between input data and their associated removal capacities. The sensitivity analysis demonstrated that the 2,4-D adsorption process is more sensitive to initial 2,4-D concentration and adsorbent dosage. Thus, it is possible to permanently monitor waters more cost-effectively with the suggested model application.

Evaluation of analytical and numerical solutions of mass transfer model for breakthrough curves simulation: Co2+ adsorption by hydrogen peroxide-bio-originated composite.

Accurate estimation of breakthrough curve (BTC) is required to scale -up the column adsorption process. A mathematical model (unsteady advection-dispersion-diffusion-adsorption equation) was solved analytically and numerically to simulate the dynamic adsorption of Co(II) ions on hydrogen peroxide-modified bone waste. The performance of both analytical and numerical approaches was evaluated under varying initial Co(II) concentrations (25, 50 and 75 mg L-1), bed heights (3, 6 and 9 cm), flow rates (0.6, 1.2 and 1.8 mL min-1), and pH (2, 4, 6, 8). Both analytical (R2 = 0.990) and numerical (R2 = 0.993) approaches described the experimental data well. The comparison results indicate that in spite of the capability of the analytical modeling for predicting the BTC (NRMSE = 9.32%), numerical modeling is more efficient in the simulation of Co(II) adsorption by adsorbent (NRMSE = 7.56%). So, it can be concluded that analytical modeling can be an easy and quick alternative to numerical modeling for predicting BTC with acceptable accuracy.

2,4-D adsorption from agricultural subsurface drainage by canola stalk-derived activated carbon: insight into the adsorption kinetics models under batch and column conditions.

In this study, the experimental and kinetic modeling investigations were performed to evaluate the ability of mesoporous and microporous canola stalk-derived activated carbon (CSAC) on 2,4-dichlorophenoxyacetic acid (2,4-D) removal from synthetic and natural water in both batch and continuous systems. Three empirical models (pseudo-first-order equation (PFOE), pseudo-second-order equation (PSOE), and the Elovich equation (EE)) and three theoretical models (film diffusion model (FDM), particle diffusion model (PDM), and second-order chemical reaction rate model (SOCRRM)) were compared in terms of diffusion coefficients, maximum 2,4-D adsorption, and rate constants at various operating conditions. CSAC was prepared at 600 °C and activated with water steam under a controlled flow and subsequently characterized by various analytical methods. The results showed that the maximum 2,4-D uptake by CSAC was achieved as 135.8 mg g-1 under a pH of 2 and an initial 2,4-D concentration of 150 mg L-1. The CSAC removed 38.3% of Na+, 43.49% of K+, 8.96% of Mg2+, 45.14% of Ca2+, 17.2% of Cl-1, 39.48% of HCO3-, 63.74% of SO42-, and 100% of the herbicide from agricultural subsurface drainage water and also retained its usability after regenerated by acetone for five cycles. It was concluded that the 2,4-D was adsorbed on the surface of the CSAC through its aromatic ring interaction with the reactive functional groups of the adsorbent. The model result indicated that the PDM is the best-fitting kinetic model for the adsorption of 2,4-D by CSAC, followed by FDM, SOCRRM, PSOE, PFOE, and EE. The mass balance equation based on PDM describes the dynamic behavior of the column satisfactorily. Graphical abstract.

Optimization of Hg(II) adsorption on bio-apatite based materials using CCD-RSM design: characterization and mechanism studies.

Bio-apatite based materials were prepared from bovine bone wastes (BBW) by thermal treatments using a direct flame (BBS) and annealing at 500-1,100 °C (BB500-BB1100). These low-crystalline materials were characterized by means of SEM, XRD, FTIR, TG, and pHPZC and were used for the adsorption of Hg(II) ions. A CCD-RSM design was used to optimize and analyze independent variables consisting of initial mercury concentration (10-100 mg L-1), pH (2-9), adsorbent mass (0.1-0.5 g), temperature (20-60 °C), and contact time (15-120 min). The results indicated that the order of the mercury uptakes for bio-apatite based adsorbents was BB500 > BB600 > BB800 > BB1100 > BBS > BBW. The dissolution-precipitation and ion-exchange reaction are the two dominant mechanisms for the removal of Hg(II) ions at low and high pH values, respectively. The CCD-RSM predicted maximum mercury adsorption of 99.99% under the optimal conditions of 51.31 mg L-1, 0.44 g, 6.5, 67.5 min, and 50 °C for initial mercury concentration, adsorbent mass, pH, contact time, and temperature, respectively. The findings of the present study revealed that the bio-apatite based materials, particularly BB500, are suitable and versatile adsorbents for the treatment of mercury-containing wastewater.

Modification of the Thomas model for predicting unsymmetrical breakthrough curves using an adaptive neural-based fuzzy inference system.

The Thomas equation is a popular model that has been widely used to predict breakthrough curves (BTCs) when describing the dynamic adsorption of different pollutants in a fixed-bed column system. However, BTCs commonly exhibit unsymmetrical patterns that cannot be predicted using empirical equations such as the Thomas model. Fortunately, adaptive neural-based fuzzy inference systems (ANFISs) can be used to model complex patterns found in adsorption processes in a fixed-bed column system. Consequently, a new hybrid model merging Thomas and an ANFIS was introduced to estimate the performance of BTCs, which were obtained for Cd(II) ion adsorption on ostrich bone ash-supported nanoscale zero-valent iron (nZVI). The results obtained showed that the fair performance of the Thomas model (NRMSE = 27.6% and Ef = 64.6%) improved to excellent (NRMSE = 3.8% and Ef = 93.8%) due to the unique strength of ANFISs in nonlinear modeling. The sensitivity analysis indicated that the initial solution pH was a more significant input variable influencing the hybrid model than the other operational factors. This approach proves the potential of this hybrid method to predict BTCs for the dynamic adsorption of Cd(II) ions by ostrich bone ash-supported nZVI particles.

Adsorption of 2,4-dichlorophenoxyacetic acid using rice husk biochar, granular activated carbon, and multi-walled carbon nanotubes in a fixed bed column system.

The 2,4-dichlorophenoxyacetic acid (2,4-D) herbicide, as an aromatic hydrocarbon, is a dangerous and toxic organic pollutant among the agricultural pesticides. In this research, the performance of the biochar made from rice husk (BRH), granular activated carbon (GAC), and multi-walled carbon nanotubes (MWCNTs) was investigated for adsorption of 2,4-D in a fixed-bed column system. The influence of pH (2, 5, 7, 9), flow rate (0.5, 1, 1.5 mL min-1), bed depth (3, 6, 9 cm), and influent 2,4-D concentration (50, 100, 150, 300 mg L-1) on the adsorption process was evaluated. The resulting breakthrough curves indicated that the higher removal efficiency of 2,4-D took place at the lower flow rate, lower influent 2,4-D concentration, higher bed depth, and lower pH. While in most cases the removal ability of GAC was better than other adsorbents, generally, this study confirmed that the BRH, as a cheap and sustainable material, can be a viable alternative to GAC and MWCNTs for remediation and treatment scenarios, particularly in developing countries.

A response surface methodology for optimization of 2,4-dichlorophenoxyacetic acid removal from synthetic and drainage water: a comparative study.

The potential of a granular activated carbon (GAC), a rice husk biochar (BRH), and multi-walled carbon nanotubes (MWCNTs) for removing 2,4-dichlorophenoxyacetic acid (2,4-D) from simulated wastewater and drainage water has been evaluated. In this regard, a response surface methodology (RSM) with a central composite design (CCD) (CCD-RSM design) was used to optimize the removal of 2,4-D from simulated wastewater under different operational parameters. The maximum adsorption capacities followed the order GAC > BRH > MWCNTs, whereas the equilibrium time increased in the order MWCNTs < GAC < BRH. In the case of GAC and BRH, the 2,4-D removal percentage increased significantly upon increasing the adsorbent dosage and temperature and decreased upon increasing the initial 2,4-D concentration and pH. The results showed that the contact time and temperature were not important as regards the adsorption efficiency of 2,4-D by MWCNTs, whereas rapid removal of 2,4-D from simulated wastewater was achieved within the first 5 min of contact with the MWCNTs. The results confirmed that the Freundlich isotherm model with the highest coefficient of determination (R2) and the lowest standard error of the estimate (SEE) satisfactorily fitted the 2,4-D experimental data. In addition, successful usage of the three adsorbents investigated was observed for removal of 2,4-D from drainage water from an agricultural drainage system. An economic analysis with a rate of return (ROR) method indicated that BRH could be used as an eco-friendly, low-cost, versatile, and high adsorption capacity alternative to GAC and MWCNTs for the removal of 2,4-D.

Adsorption/reduction of Hg(II) and Pb(II) from aqueous solutions by using bone ash/nZVI composite: effects of aging time, Fe loading quantity and co-existing ions.

In this research, a versatile and highly efficient method for the stabilization of nanoscale zerovalent iron particles (nZVI) on the surface of ostrich bone ash (OBA) was presented as a novel inorganic adsorbent (OBA/nZVI) for the removal of Hg(II) and Pb(II) ions from aqueous solutions, even after 1 year of storage under room conditions. The removal behavior of the OBA/nZVI was assessed as a function of the initial pH, contact time, initial pollutants concentration, temperature, amount of adsorbent, effect of competitive metal ions, and ionic strength. The synthesized adsorbent was characterized by several techniques including N2 adsorption at - 196 °C, FT-IR spectroscopy, scanning electron microscopy, X-ray diffraction, and zeta potential. The results confirmed that the OBA is a good candidate as support of nZVI. The maxima adsorption capacity for Hg(II) and Pb(II) ions found from experimental results were 170 and 160 mg g-1, when the loading quantities of Fe were 20%. The equilibrium sorption data obeyed a Langmuir-Freundlich isotherm type model. The kinetic data of the adsorption followed the mechanism of the pseudo-second-order model. The thermodynamic experiments indicated that the removal of metal ions were feasible, endothermic, and spontaneous. It can be found that fresh and aged OBA/nZVI maintained its usability even after five cycles in the order: fresh (OBA/nZVI)-Hg(II) > fresh (OBA/nZVI)-Pb(II) > aged (OBA/nZVI)-Hg(II) > aged (OBA/nZVI)-Pb(II), which indicate that OBA/nZVI can be regenerated as adsorbent. The existence of Fe in the OBA/nZVI was proved by SEM-EDX results and X-ray diffraction analysis also confirmed adsorption/reduction of some of the Hg(II) to Hg0 and Pb(II) to Pb0.

The effect of natural sounds on the anxiety of patients undergoing coronary artery bypass graft surgery.

BACKGROUND: This study aims to investigate the effect of natural sounds on the anxiety of patients undergoing coronary artery bypass graft surgery (CABG). METHODS: In this clinical trial, 90 patients, who were candidates for CABG in an urban area of Iran, were selected and randomly assigned to intervention and control groups by the minimization method. In the intervention group, natural sounds were broadcast through headphones for 30 min. In the control group, headphones connected to a silent device were used. The research instruments were a demographic questionnaire and the Spielberger State-Trait Anxiety Inventory (STAI). These were used before the intervention, 30 min after the music, and before the surgery in the waiting room for both groups. Data was analyzed using SPSS software. RESULTS: The mean anxiety level of the intervention group has been found to be significantly lower than that of the control group half an hour after the intervention as well as in the waiting room in the preoperative period (p = 0.001). Moreover, the mean anxiety of the intervention group decreases, while it increases for the control group over time (p < 0.001). CONCLUSION: Natural sounds can be used as a non-pharmacological way to reduce the anxiety of patients undergoing CABG. TRIAL REGISTRATION: IRCT2017011723190N3, Registered 1 March 2017.

Modeling caffeine adsorption by multi-walled carbon nanotubes using multiple polynomial regression with interaction effects.

Permanent monitoring of environmental issues demands efficient, accurate, and user-friendly pollutant prediction methods, particularly from operating variables. In this research, the efficiency of multiple polynomial regression in predicting the adsorption capacity of caffeine (q) from an experimental batch mode by multi-walled carbon nanotubes (MWCNTs) was investigated. The MWCNTs were specified by scanning electron microscope, Fourier transform infrared spectroscopy and point of zero charge. The results confirmed that the MWCNTs have a high capacity to uptake caffeine from the wastewater. Five parameters including pH, reaction time (t), adsorbent mass (M), temperature (T) and initial pollutant concentration (C) were selected as input model data and q as the output. The results indicated that multiple polynomial regression which employed C, M and t was the best model (normalized root mean square error = 0.0916 and R2 = 0.996). The sensitivity analysis indicated that the predicted q is more sensitive to the C, followed by M, and t. The results indicated that the pH and temperature have no significant effect on the adsorption capacity of caffeine in batch mode experiments. The results displayed that estimations are slightly overestimated. This study demonstrated that the multiple polynomial regression could be an accurate and faster alternative to available difficult and time-consuming models for q prediction.

Adsorption of Hg(II) and Pb(II) ions by nanoscale zero valent iron supported on ostrich bone ash in a fixed-bed column system.

In this research, ostrich bone ash (OBA) was modified with nanoscale zerovalent iron (nZVI) particles and applied as a novel composite adsorbent (OBA/nZVI) for dynamic adsorption/reduction of Hg(II) and Pb(II) ions in a fixed-bed column system. Entrapment of nZVI in OBA beads barricades the particles from oxidation and aggregation. The dynamic behavior of metal ions removal by OBA/nZVI was assessed as a function of inlet flow rates, bed height, initial pollutants concentration and pH. The synthesized OBA/nZVI composite was characterized by several physicochemical techniques. Increase in pH and bed height and decrease in flow rates and initial metal concentration resulted in delay of breakthrough time. OBA breakthrough profile is sharper than the OBA/nZVI breakthrough curve for both metal ions and the breakthrough times increase in the order OBA/nZVI-Hg(II) > OBA/nZVI-Pb(II) > OBA-Pb(II) > OBA-Hg(II). Based on the experiment results, redox reaction is expected to occur to a certain extent, as the standard reduction potentials of Hg(II) and Pb(II) are more than that of Fe(II). From a practical point of view, the OBA/nZVI could be applied as a material to remove Hg(II) and Pb(II) ions from natural surface and ground water with a pH value of 5-9.