Ayad A. H. Faisal

Cement kiln dust (CKD)-filter sand permeable reactive barrier for the removal of Cu(II) and Zn(II) from simulated acidic groundwater

The hydraulic conductivity and breakthrough curves of copper and zinc contaminants were measured in a set of continuous column experiments for 99 days using cement kiln dust (CKD)-filter sand as the permeable reactive barrier. The results of these experiments proved that the weight ratios of the cement kiln dust-filter sand (10:90 and 20:80) are adequate in preventing the loss of reactivity and hydraulic conductivity and, in turn, avoiding reduction in the groundwater flow. These results reveal a decrease in the hydraulic conductivity, which can be attributed to an accumulation of most of the quantity of the contaminant masses in the first sections of the column bed. Breakthrough curves for the description of the temporal contaminant transport within the barrier were found to be more representative by the Belter-Cussler-Hu and Yan models based on the coefficient of determination and Nash-Sutcliffe efficiency. The longevity of the barrier was simulated for the field scale, based on the laboratory column tests and the values verified that cement kiln dust can be effectively used in the future, as the reactive material in permeable reactive barrier technology. These results signify that the longevity of the barrier is directly proportional to its thickness and inversely to the percentage of the CKD used.

Removal of zinc from contaminated groundwater by zero-valent iron permeable reactive barrier

AbstractThe possibility of using zero-valent iron (ZVI) as permeable reactive barrier (PRB) to remove zinc from a contaminated groundwater was investigated. Batch equilibrium tests were carried out. The effects of many parameters such as contact time between adsorbate and adsorbent (0–240 min), initial pH of the solution (4–8), sorbent dosage (1–12 g/100 ml), initial metal concentration (50–250 mg/l), and agitation speed (0–250 rpm) were studied. The best values of these parameters that achieve the maximum removal efficiency of Zn+2 (=91%) were 3 h, 5, 10 g/100 ml, 50 mg/l, and 200 rpm, respectively. Langmuir isotherm model gives better fit for the sorption data of Zn+2 ion by ZVI than Freundlich model under the studied conditions. Finite difference method and COMSOL Multiphysics 3.5a software, which is based on finite element method, were used to simulate the one-dimensional equilibrium transport of zinc through sandy aquifer with and without presence of PRB. The predicted and experimental results proved...

Simultaneous adsorption–precipitation characterization as mechanisms for metals removal from aqueous solutions by cement kiln dust (CKD)

AbstractIsotherm equations are useful for simulating adsorption data, but they cannot be easily adapted to simulate the precipitation phase. This work presents a new analytical isotherm model, based on the mass conservation principle, which can distinguish between the adsorption and precipitation mechanisms when both these processes occur simultaneously. This model was validated with the results of batch experiments conducted at the appropriate conditions using cement kiln dust as a reactive adsorbent on two metal species: copper and zinc. Thus, a new experimental procedure was established for description of the precipitation process. The developed model was found to be more representative than the conventional models in characterization of the relationship between the total sorption (adsorption–precipitation) and residual concentration of the contaminant. This model can be potentially integrated with several contaminant transport codes such as COMSOL Multiphysics 3.5a (2008), which only considers the ads...

A review of permeable reactive barrier as passive sustainable technology for groundwater remediation

The pollution of groundwater by organic or inorganic pollutants, originating from either soil leaching or anthropogenic activities, is one of the major environmental issues. Remediation of this water source is of highest priority because many countries use it for drinking purpose. Pump-and-treat method is represented for many decades the major technique to treat groundwater infected with organic/inorganic pollutants. In last two decades, this technique becomes to be in lack with the sense of modern concepts of sustainability and renewable energy. Permeable reactive barriers (PRBs) technology was introduced as an alternative method for traditional pump-and-treat systems to remediate contaminated groundwater that was achieving these concepts. Within this issue, this technology has been proven to be a successful and most efficient promising method used by many researchers and in several projects due to its direct and simple techniques to remediate groundwater. A rapid progress from bench scale to field scale implementation in the PRB technique is recognized through the last few years. In addition, this technique was modeled theoretically for characterizing the migration of contaminants spatially and temporally through the barrier and, consequently, these models can be used for estimating the longevity of this barrier. An overview of this technique and the promising horizons for scientific research that integrates this method with sustainability and green technology practices are presented in the present study.

Using Granular Dead Anaerobic Sludge as Permeable Reactive Barrier for Remediation of Groundwater Contaminated with Phenol

AbstractThe possibility of using granular dead anaerobic sludge (GDAS) biosorbent as a permeable reactive barrier (PRB) to remove phenol from contaminated shallow groundwater was investigated. Batch tests were performed to characterize the equilibrium sorption properties of GDAS and sandy soil in phenol-containing aqueous solutions. The Langmuir isotherm model gives a better fit for the sorption data of phenol by GDAS and soil than other models under the studied conditions. One-dimensional column experiments were performed at a pilot scale, and an integrated model based on the solution of an advection-reaction-dispersion mass balance equation, using the finite-element method, was developed to study the space and time normalized concentration of phenol within groundwater. Numerical and experimental results proved that the PRB plays a potential role in the restriction of the contaminant plume migration. Also, these results showed that the removal of phenol by PRB was increased as function of its thickness a...

Dominant Mechanisms for Metal Removal from Acidic Aqueous Solutions by Cement Kiln Dust

Copper and zinc ions were removed from synthetic acidic aqueous solutions onto cement kiln dust (CKD) particles in a single component system. The objectives of this study were to: distinguish between adsorption and precipitation when both mechanisms are occurring simultaneously; define their individual contributions; and consequently, specify the dominant mechanism. This was achieved by conducting a new experimental procedure for the precipitation phase that depended on CKD leachate in combination with a derivation of a simultaneous adsorption-precipitation equation. High removal efficiencies, approaching 100 %, of the Cu and Zn ions, were attained. Precipitation was the dominant mechanism for removing low concentrations of these metals, while adsorption appears to be more significant in removal of high metal concentrations.ZusammenfassungAus synthetischen sauren wässrigen Lösungen wurden Kupfer- und Zinkionen an Zementstaubpartikeln (CKD)in einem Einkomponentensystem entfernt. Die Ziele der Studie waren, zwischen der Adsorption und der Ausfällung bei einem gleichzeitigem Auftreten beider Mechanismen zu unterscheiden, deren individuelle Wirkung zu bestimmen und somit den dominierenden Mechanismus abzugrenzen. Dazu wurde ein neues experimentelles Verfahren für die Ausfällungsphase durchgeführt. Die Auswertung der Versuche stützt sich auf die Herleitung einer simultanen Adsorptions-Fällungs-Gleichung. Für Cu- und Zn-Ionen wurden hohe Ausscheidungsgrade von nahe 100 % erreicht. Bei niedrigen Konzentrationen war die Ausfällung der dominierende Mechanismus für die Entfernung dieser Metalle. Die Adsorption erscheint bei hohen Metallkonzentrationen signifikanter.ResumenSe removieron cobre y cinc desde soluciones acuosas ácidas sobre partículas de polvo de horno de cemento (CKD) en un sistema de un único componente. Los objetivos de este estudio fueron: distinguir entre adsorción y precipitación cuando ambos mecanismos están ocurriendo simultáneamente; definir sus contribuciones individuales y, consecuentemente, especificar el mecanismo dominante. Esto se logró mediante un nuevo procedimiento experimental para la fase de precipitación que dependió del lixiviado CKD en combinación con una derivación de una ecuación de adsorción-precipitación simultánea. Se obtuvieron altas eficiencias de remoción de Cu y Zn, aproximadamente de 100 %. La precipitación fue el mecanismo dominante para la remoción de bajas concentraciones de estos metales mientras que la adsorción aparece como más significativa en la remoción de altas concentraciones de metales.水泥窑粉尘去除酸性废水金属离子机理

Effect of pH on the performance of olive pips reactive barrier through the migration of copper-contaminated groundwater

Adsorption data are modeled using the popular Langmuir and Freundlich isotherm models. These isotherms are primarily useful for simulating data collected at a fixed pH value. This study attempted to develop an adsorption isotherm based on the Langmuir model, to simulate pH-dependent adsorption effects. It is derived based on the results of a batch of experiments conducted under appropriate conditions using olive pips as the reactive bio-sorbent on a copper-contaminated solution. This isotherm is used as a linear correlation between the maximum adsorption capacity and the initial pH values of the feed solution, while a nonlinear power correlation is used to represent the affinity coefficient–initial pH relationship. This isotherm is integrated with the advection–dispersion equation for simulating the effect of the initial pH on the contaminant transport scenarios. The integrated model, solved numerically by the implicit finite difference method, is proven, in which the initial pH has a potential effect on ...

Groundwater protection from lead contamination using granular dead anaerobic sludge biosorbent as permeable reactive barrier

AbstractThis study investigated the performance of granular dead anaerobic sludge (GDAS) biosorbent as permeable reactive barrier (PRB) in removing lead from contaminated shallow groundwater. Batch tests were performed to characterize the equilibrium sorption properties of the GDAS and sandy soil in lead-containing aqueous solutions. Fourier transform infrared analysis proved that the carboxylic, alcohol, and alkyl halides groups were responsible for the biosorption of lead onto GDAS. A two-dimensional numerical model, solved by COMSOL Multiphysics 3.5a software, which is based on finite element method, was developed to simulate the equilibrium transport of lead within groundwater. This model considered the pollutant sorption onto the GDAS and sandy soil using Langmuir equation. Numerical and experimental results proved that the PRB plays a potential role in the restriction of the contaminant plume migration. Furthermore, the barrier started to saturate with contaminant as a function of the travel time, a...

Performance of granular dead anaerobic sludge as permeable reactive barrier for containment of lead from contaminated groundwater

AbstractThis study investigates the performance of granular dead anaerobic sludge (GDAS) bio-sorbent as permeable reactive barrier (PRB) in removing lead from a contaminated shallow groundwater. Batch tests have been performed to characterize the equilibrium sorption properties of the GDAS and sandy soil in lead-containing aqueous solutions. A 1D advection–dispersion equation, solved by computer solutions Multiphysics 3.5a software which is based on finite element method, has been used to simulate the equilibrium transport of Pb+2 ions within groundwater. This equation has taken into account the pollutant sorption onto the GDAS and sandy soil which is performed by Langmuir equation. Numerical results proved that the PRB plays a potential role in the restriction of the contaminant plume migration. These results also show that the thicker PRB is better than the thinner ones in lead treatment and the barrier starts to saturate with contaminant as a function of the travel time. A good agreement between the pr...

Using sewage sludge as a permeable reactive barrier for remediation of groundwater contaminated with lead and phenol

ABSTRACT We investigated the efficiency of granular dead anaerobic sludge (GDAS) biosorbent as a permeable reactive barrier for remediation of groundwater contaminated with lead–phenol (Pb-Ph) present simultaneously. Batch tests were performed to characterize the equilibrium sorption properties of the GDAS and sandy soil in the Pb-Ph containing aqueous solutions. Computer solutions (COMSOL) Multiphysics 3.5a software was used for simulating the two-dimensional equilibrium transport of lead–phenol including the sorption process through the saturated sandy soil in the presence of GDAS. A good agreement between the predicted and experimental results was recognized with the root-mean-squared error not exceeding 0.049.