Groundwater Remediation Techniques Research Articles

Groundwater remediation techniques around Kodungaiyur dump yard

Abstract The groundwater around the Kodungaiyur dump yard, in Tamil Nadu, India, is polluted due to the percolation of leachate from the dumpsite. This paper proposes three remedial techniques to make the groundwater drinkable for the people living near the Kodungaiyur trash yard. Twelve bore wells around the Kodungaiyur dumpsite provided water samples for which the physicochemical parameters were measured. Moderately high concentrations of Total Hardness (TH), Total Alkalinity (TA), Chloride, Sulphate, Nitrate, Sodium, and Total Dissolved Solids (TDS) are present in the groundwater around the dump yard. The Physicochemical parameters of the samples tend to deviate from the standards prescribed by WHO and BIS. Therefore, remedial measures such as solar distillation, Activated Charcoal, and the Phytoremediation process are suggested to reduce the contaminants in the groundwater. The activated charcoal removes the unpleasant color of the water completely and makes the water clear and transparent through filtration. The solar distillation process does not affect the pH value and is reduced by 4.5% in the phytoremediation technique. Similarly, the level of chlorides is reduced by 99% in solar distillation and by 56% in the phytoremediation technique. Total hardness is reduced by 89.88% in the solar still process and 56.65% in the phytoremediation technique. Sodium is reduced by 99.88% in solar still and 57.03% in the phytoremediation technique. The economical and eco-friendly nature of the suggested techniques makes it sustainable for future generations.

Investigating reactive transport and precipitation patterns of calcium carbonate in fractured porous media

HypothesisUnderstanding calcium carbonate (CaCO3) precipitation in various polymorphs from nanoparticle size (amorphous calcium carbonate) to microparticle size (vaterite, aragonite, dendrite, calcite) is important for practical applications, including carbon geo-storage (e.g., basalt formations), hydrogen storage, groundwater management, and soil stabilization. Our hypothesis suggests that the interplay of Péclet numbers (Pe), Damköhler numbers (Da), and Supersaturation Index (SI) significantly impacts the evolution of CaCO3 precipitation in fractured porous media in terms of mixing patterns, spatiotemporal evolution, crystal morphology, crystal size, and clogging behavior. ExperimentsThis study takes a novel approach to explore the colloidal formation and precipitation dynamics of CaCO3 within a fractured microfluidic system. Here, calcium chloride (CaCl2) and sodium bicarbonate (NaHCO3) solutions were injected and reacted under varied Pe (0–11), Da (0–1), and SI (2–5). FindingsOur analysis revealed distinct precipitation patterns and mixing types, such as transverse, longitudinal, and incomplete mixing, providing insights into the behavior in fractured porous media. We systematically analyzed the temporal and spatial evolution of precipitation, demonstrating how Pe, Da, and SI dictate precipitation rates and spatial distribution. Additionally, the study uncovered a range of CaCO3 polymorphic forms, illustrating their evolution and coexistence. Morphological changes and crystal sizes were examined to decode nucleation and growth processes. Significantly, our findings highlight the relationship between precipitation and clogging in the fractured medium, offering a deeper understanding of reactive transport in complex porous environments. These insights are crucial for enhancing carbon containment security and storage efficiency in underground formations, improving groundwater remediation techniques, and developing novel construction materials through controlled precipitation processes.

Influence of Arrangement and Configuration of Extraction Wells to the Capture Zone in Pump and Treat System

Urbanization, industrial wastes, non-point sources from agricultural activities, and various types of wastes within a landfill system have posed major threats to groundwater quality in Malaysia. One of the common contaminated groundwater remediation techniques is pump and treat system. This work was conducted to investigate the influence of extraction wells in pump and treat system to remove the contaminant by evaluating the capture zone under different arrangements and configurations of well in an unconfined aquifer system. A conceptual model was developed using PMWIN software at pre-determined soil characteristics and boundary conditions. In the numerical simulation, 17 models were simulated to examine the influence of pumping rate of wells, distance between two wells, wells orientation and the number of wells to the width of capture zone under four study cases. The results show that the width of the capture zone corresponded linearly to the increment of pumping rate. In the two and four wells system, the width of the capture zone was reduced when the extraction wells were aligned parallelly to the flow direction and the distance between wells were increased. However, the capture zone was extended when the well orientation was aligned perpendicular to the flow direction. The simulation results show that the drawdown in the wells was reduced when the number of wells has increased due to the distribution of total pumping rate into two or four wells system. The finding indicated that the arrangement of extraction wells in pump and treat system has a major impact on the capture zone induced by the wells. The simulation results can help to improve the effectiveness of extraction well in pump and treat system by optimizing the extraction process and thus minimize the cost of groundwater remediation.

Experimental and numerical investigation of Engineered Injection and Extraction (EIE) induced with three-dimensional flow field

Abstract In situ groundwater remediation technique is a commonly adopted method for the treatment of contaminated groundwater and the porous media associated with it. Engineered Injection and Extraction (EIE) has evolved as an improved methodology for in situ remediation, where sequential injection and extraction of clean water around the treatment area enhances the spreading of treatment reagents by inducing additional flow fields. Conventional EIE studies were based on flow fields in two dimensions. There are only limited experimental and theoretical studies exploring the potential of inducing a three-dimensional flow field using EIE. The present study experimentally and numerically evaluates the effect of a three-dimensional flow field induced by partially screened wells. EIE experiments were conducted on a laboratory-scale aquifer model with laterite soil as the porous medium. Tracer transport in porous medium was studied by measuring the concentration at various observation points and enhanced dilution was observed when EIE was employed with partially screened wells. Experimental observations were also used to calibrate and validate the numerical model developed using Visual MODFLOW Flex. Enhancement in spreading was quantified in terms of concentration mass attenuation and maximum mass attenuation was observed when EIE was employed with partially screened wells.

Permeable Reactive Barriers as an In Situ Groundwater Remediation Technique for Open Solid Waste Dumpsites: a Review and Prospect

Permeable Reactive Barriers as an In Situ Groundwater Remediation Technique for Open Solid Waste Dumpsites: a Review and Prospect

Novel green technology for wastewater treatment: Geo-material/geopolymer applications for heavy metal removal from aquatic media

The aim of this paper is to show the concise chemico-physical adsorbent performance of water purification systems utilizing geo- (e.g., allophane, clinoptilolite, and smectite) and bio-polymer materials (e.g., chitosan or cellulose nanocomposite materials) and to propose an optimal ground-water remediation technique. The performance of geo-materials is evaluated based on the individual sorption and immobilization capacities for various priority substances and pollutants (e.g., lead, zinc, cadmium, copper, arsenic, and others), their availability, and cost-efficient use. A systematic assessment of the sorption potential of geo-materials in comparison to other available sorbents used for the removal of harmful aqueous metal ions is made through a literature review. This paper introduces novel sustainable technologies based on natural and tailored silicate-polymerized substances (geo-materials and geopolymers), and highlights their applicability in the treatment of water and solid matter contaminated by heavy metal ions. The advantages of geo-materials and geopolymers over other commercially available sorbents used for heavy metal ion removal from solution are presented through a literature review. Benefits and current challenges of geo-materials and geopolymers applications in water processing technologies and in environmental remediation are discussed, with recognition of their performance, individual sorption and immobilization capacities, availability, and cost-efficient use. The applications described here comprise: (i) the removal of heavy metal ions from contaminated water using in-situ remediation strategies; (ii) heavy metal ion immobilization through co-precipitation with silicate binders in underground stabilization and waste solidification scenarios; and (iii) a proposal for a new geo-material/geopolymer-based solidification and stabilization technology for efficient, sustainable, and simultaneous treatment of soil/sediment and groundwater at environmental hotspots. Clay-substituted geopolymers, smectite, and zeolites are distinguished by their superb sorption and immobilization capacities for heavy metal ions, while biosorbents can play an important role in the removal of metals, metalloids (e.g., arsenic), and other contaminants. More research on individual removal mechanisms of heavy metals will provide new clues on the development of remediation strategies in advanced scientific and field applications, and on atomic-to-micron scale processes occurring at the solid–liquid interface.

Feasibility Assessment of the Application of Groundwater Remediation Techniques in Rural Areas: A Case Study of Rural Areas in the Soutpansberg Region, Limpopo Province, South Africa

Groundwater contribution towards human health and livelihood depends on the contaminants level in groundwater. Many people in rural communities are being exposed to waterborne diseases resulting from drinking untreated contaminated groundwater. This study argues that the lack of implementation of available groundwater remediation methods and associated high costs are exposing rural communities to health risks. This study assessed 22 years of groundwater quality data from 12 boreholes and 2 springs to understand the contaminants level in the Soutpansberg region. A feasibility assessment of the application and design of a sustainable groundwater remediation technique was carried out based on individual- and community-based groundwater remediation types. The assessment considered groundwater management, cost and risk of theft and damage to infrastructure model for rural settings. This study determined that groundwater was not suitable for drinking purposes in some parts due to high concentration levels of NO3− and F−. The feasibility assessment indicated that community-based groundwater remediation schemes are more sustainable in rural areas when compared to individual household remediation. In this study, it is recommended that groundwater remediation plans must be included in any proposed water supply or drought intervention project in rural communities.

Temperature influence on the NAPL-water interfacial area between 10 °C and 60 °C for trichloroethylene

Underground thermal energy storage (UTES) can contribute to renewable energy usability, especially in urban areas with the most demand and available infrastructure. But UTES may interact in those areas with non-aqueous phase liquids (NAPL) by increasing the temperature in storage formations. To determine temperature effects on NAPL dissolution rates into groundwater, the effective specific interfacial area (anw) between trichloroethylene (TCE) and water, as a function of temperature and TCE pore saturations, was calculated. The interfacial tension between the flushing solution and the NAPL, the adsorption coefficient and the retardation of a reactive tracer were determined by the drop weight method and interfacial tracer tests at 10 °C, 30 °C and 60 °C. From 10 to 60 °C anw increased by a factor of six to eight. Based on the results, a function to describe the anw between TCE and water was developed, which could improve numerical models on NAPL dissolution rates. The main mechanisms for the increase in anw are suggested to be NAPL blob migration on pore scale, and thermal-induced changes in wettability and in blob shape correlating with a temperature-induced decline in effective porosity of up to 32%. These results contribute to the understanding and predictability of UTES in contaminated aquifers, the general response of NAPL behavior on artificial increasing aquifer temperatures and the improvement of thermal and other groundwater remediation techniques.

Anaerobic Corrosion of Zero-Valent Iron at Elevated Temperatures.

Increasing groundwater temperatures caused by global warming, subsurface infrastructure, or heat storage projects may interfere with groundwater remediation techniques using zero-valent iron (ZVI) technology by accelerating anaerobic corrosion. The corrosion behavior of three ZVIs widely used in permeable reactive barriers (PRBs), Peerless cast iron (PL), Gotthart-Maier cast iron (GM), and an ISPAT iron sponge (IS), was investigated at temperatures between 25 and 70 °C in half-open batch reactors by measuring the volume of hydrogen gas generated. Initially, the corrosion rates of all tested ZVIs increased with temperature; at temperatures ≤40 °C, a material-specific steady state is reached, and at temperatures >40 °C, passivation causes a decrease in long-term corrosion rates. The observed corrosion behavior was therefore assumed to be superimposed by accelerating and inhibiting effects, caused by surface precipitates where the fitting of measured corrosion rates by a modeling approach, using the corroded amount of Fe0 to account for passivating minerals, yields intrinsic activation energies (Ea, ZVI) of 81, 90, and 107 kJ mol-1 for IS, GM, and PL, respectively. An increase in H2 production might not be directly transferable to an increase in general ZVI reactivity; however, the results suggest that an increase in chlorinated hydrocarbon degradation rates can be expected for ZVI-PRBs in the immediate vicinity of low-temperature underground thermal energy storages (UTESs) or in the impact areas of high-temperature UTES with temperatures of ≤40 °C.

Influence of the carbon source concentration on the nitrate removal rate in groundwater

ABSTRACT At present, groundwater nitrate pollution in China is serious. The use of microorganisms for biological denitrification has been widely applied, and it is a universal and efficient in situ groundwater remediation technique, but this approach is influenced by many factors. In this study, glucose was adopted as the carbon source, four different concentrations of 0, 2, 5 and 10 g/L were considered, and natural groundwater with a nitrate concentration of 300.8 mg/L was employed as the experimental solution. The effect of the carbon source concentration on the nitrate removal rate in groundwater was examined through heterotrophic anaerobic denitrification experiments. The results showed that the nitrate removal rate could be improved by the addition of an external carbon source in the process of biological denitrification, and an optimal concentration was observed. At a glucose concentration of 2 g/L, the denitrification effect was the best.

Denitrification using permeable reactive barriers with organic substrate or zero-valent iron fillers: controlling mechanisms, challenges, and future perspectives.

Nitrate as a diffusive agricultural contaminant has been causing substantial groundwater quality deterioration worldwide. In situ groundwater remediation techniques using permeable reactive barriers (PRBs) have attracted increasing interest. Particularly, PRBs based on biological denitrification, using the organic substrate as a biostimulator, and chemical nitrate reduction, using zero-valent iron (ZVI) as a reductant, are two major PRB approaches for groundwater denitrification. This review paper analyzed the published studies over the past 10 years (2010-2020) using laboratory, modeling, and field-scale approaches to explore the performance and mechanisms of these two types of PRBs. Important factors affecting the denitrification efficiencies as well as the influential mechanisms were discussed. Several research gaps have been identified and further research needs are discussed in the end.

Nanoscopic Zero-Valent Iron Supported on MgO for Lead Removal from Waters

Lead is one of the most toxic heavy metals that can create a severe risk to water ecosystem health. Zero-valent iron is an effective material for Pb2+ removal treatments. In particular, nanoscopic zero-valent iron (nZVI) particles are characterized by high reaction rates; nevertheless, their utilization in water and groundwater remediation techniques requires further investigations. Indeed, it is necessary to define effective methods able to avoid the drawbacks due to the aggregation tendency of nanoparticles and their potential uncontrolled transport in groundwater. In this work, nZVI was supported on magnesium oxide grains (MgO_nZVI) to synthesize an alternative material for lead removal from aqueous solutions. Many experiments were conducted under several operating conditions in order to analyze the effectiveness of the produced material in Pb2+ abatement. The performance of MgO_nZVI was also compared with those detected using commercial microscopic Fe0 (mZVI) as a reactive material. The experimental findings showed a much greater reactivity of the supported nanoscopic iron particles. By means of a kinetic analysis of batch tests results, it was verified that, both for MgO_nZVI and mZVI, the lead abatement follows a pseudo-second-order kinetic law. The reaction rates were affected by the initial pH of the treatment solution and by the ratio between the Fe0 amount and initial lead concentration. The efficiency of MgO_nZVI in a continuous test was steadily around 97.5% for about 1000 exchanged pore volumes (PV) of reactive material, while by using mZVI, the lead removal was approximately 88% for about 600 PV. X-ray diffraction (XRD) and energy-dispersive spectroscopy EDS analyses suggested the formation of typical iron corrosion products and the presence of metallic lead Pb0 and Pb2+ compounds on exhausted materials.

Heavy metal removal capacity of individual components of permeable reactive concrete

Permeable reactive barriers (PRBs) are a well-known technique for groundwater remediation using industrialized reactive media such as zero-valent iron and activated carbon. Permeable reactive concrete (PRC) is an alternative reactive medium composed of relatively inexpensive materials such as cement and aggregate. A variety of multimodal, simultaneous processes drive remediation of metals from contaminated groundwater within PRC systems due to the complex heterogeneous matrix formed during cement hydration. This research investigated the influence coarse aggregate, portland cement, fly ash, and various combinations had on the removal of lead, cadmium, and zinc in solution. Absorption, adsorption, precipitation, co-precipitation, and internal diffusion of the metals are common mechanisms of removal in the hydrated cement matrix and independent of the aggregate. Local aggregates can be used as the permeable structure also possessing high metal removal capabilities, however calcareous sources of aggregate are preferred due to improved removal with low leachability. Individual adsorption isotherms were linear or curvilinear up, indicating a preferred removal process. For PRC samples, metal saturation was not reached over the range of concentrations tested. Results were then used to compare removal against activated carbon and aggregate-based PRBs by estimating material costs for the remediation of an example heavy metal contaminated Superfund site located in the Midwestern United States, Joplin, Missouri.

New insights into atrazine degradation by cobalt catalyzed peroxymonosulfate oxidation: Kinetics, reaction products and transformation mechanisms

The widespread occurrence of atrazine in waters poses potential risk to ecosystem and human health. In this study, we investigated the underlying mechanisms and transformation pathways of atrazine degradation by cobalt catalyzed peroxymonosulfate (Co(II)/PMS). Co(II)/PMS was found to be more efficient for ATZ elimination in aqueous solution than Fe(II)/PMS process. ATZ oxidation by Co(II)/PMS followed pseudo-first-order kinetics, and the reaction rate constant (kobs) increased appreciably with increasing Co(II) concentration. Increasing initial PMS concentration favored the decomposition of ATZ, however, no linear relationship between kobs and PMS concentration was observed. Higher efficiency of ATZ oxidation was observed around neutral pH, implying the possibility of applying Co(II)/PMS process under environmental realistic conditions. Natural organic matter (NOM), chloride (Cl−) and bicarbonate (HCO3−) showed detrimental effects on ATZ degradation, particularly at higher concentrations. Eleven products were identified by applying solid phase extraction-liquid chromatography–mass spectrometry (SPE-LC/MS) techniques. Major transformation pathways of ATZ included dealkylation, dechlorination-hydroxylation, and alkyl chain oxidation. Detailed mechanisms responsible for these transformation pathways were discussed. Our results reveal that Co(II)/PMS process might be an efficient technique for remediation of groundwater contaminated by ATZ and structurally related s-triazine herbicides.

An iterative approach to multi-objective engineering design: Optimization of engineered injection and extraction for enhanced groundwater remediation

This study contributes an iterative problem reformulation technique for multi-objective evolutionary algorithm (MOEA) decision support. Problem formulations consist of objectives, decision variables, and constraints, and directly influence the results generated by the MOEA. Typically, design problems are optimized based on a single problem formulation established a priori. In this paper, we demonstrate an approach to perform iterative optimization using problem formulations updated from analyses of results from prior rounds of optimization, which often reveal design components not initially considered. To demonstrate the approach, we consider a novel groundwater remediation technique, Engineered Injection and Extraction (EIE), which has never been optimized in the literature. Iterative problem reformulation enabled the MOEA to generate EIE solutions with better performance than the heuristically-developed solution used in prior work.

Multiobjective Groundwater Remediation Design Using a Coupled MFree Point Collocation Method and Particle Swarm Optimization

Pump and treat (PAT) is one of the commonly used techniques for groundwater remediation in which the contaminated groundwater is pumped, treated, and put back to the aquifer system or other sources. For an effective PAT system design, simulation-optimization (S/O) models are very useful; the simulation model helps in predicting the spatial and temporal variation of the contamination plume, and optimization models are used to minimize the cost of pumping. For large-scale groundwater flow and transport simulation, grid-based or mesh-based models such as the finite difference method (FDM) and the FEM have been found to be cumbersome and time consuming. Meshfree (MFree)-based numerical models that use a set of nodes scattered within the problem domain and on the boundaries of the domain regardless of the connectivity information between them are found to be very effective for large-scale field problems. In this study, the MFree point collocation method (PCM) is used for the groundwater flow and transport simulation, and an evolutionary algorithm based on particle swarm optimization (PSO) is proposed for optimization. The S/O model based on PCM and PSO with multiobjective (PCM-PSO-PAT-MO) strategies are developed and applied for remediation of an unconfined aquifer polluted by total dissolved solids (TDS) using PAT. The PCM-PSO–based models are found to be simple and effective in groundwater remediation design using PAT.

Geochemical investigation of groundwater contamination in Perungudi dumpsite, South India

Unscientific disposal of municipal solid waste causes groundwater contamination. The migration of leachate from the solid waste dumpsite to the aquifer varies according to the geohydrological profile of the dumpsite. A detailed study of the mechanism of leachate percolation to the groundwater helps to design a proper groundwater remediation technique. Multilevel boreholes were drilled in the periphery of the Perungudi dumpsite, Chennai, India. The major lithological layers and the geochemical analysis of the contaminant migrated from the dumpsite to the underlying aquifer has been studied. The distribution of heavy metals such as Pb, Fe, Zn, Cr, and Cd follows a similar trend in the pollutant source, groundwater samples around the dumpsite, and at various litho units beneath the dumpsite. The analysis thus helps to find an appropriate groundwater remediation technique to remove the specific contaminant and thereby provide a safe drinking water for the surrounding community.

Simulation–optimization model for groundwater contamination remediation using meshfree point collocation method and particle swarm optimization

Remediation of the groundwater contamination problem is a tedious, time consuming and expensive process. Pump and treat (PAT) is one of the commonly used techniques for groundwater remediation in which the contaminated groundwater is pumped, treated and put back to the aquifer system or other sources. Developing simulation-optimization (S/O) model proved to be very useful in the design process of an effective PAT system. Simulation models help in predicting the spatial and temporal variation of the contamination plume while optimization models help in minimizing the cost of pumping. Generally, grid or mesh based models such as Finite Difference Method (FDM) or Finite Element Methods (FEM) is used for the groundwater flow and transport simulation. But it is found that grid/mesh generation is a time consuming process. Therefore, recently Meshfree (MFree) based numerical models are developed to avoid this difficulty of meshing and remeshing. MFree Point Collocation Method (PCM) is a simple meshfree method used for the simulation of coupled groundwater flow and contaminant transport. For groundwater optimization problems, even though number of methods such as linear programming, nonlinear programming, etc. are available, evolutionary algorithm based techniques such as genetic algorithm (GA) and particle swarm optimization (PSO) are found to be very effective.In this paper, a simulation model using MFree PCM for confined groundwater flow and transport and a PSO based single objective optimization model are developed and coupled to get an effective S/O model for groundwater remediation using PAT. The S/O model based on PCM and PSO is applied for a polluted hypothetical confined aquifer and its performance is compared with Finite Element Method–Binary Coded Genetic Algorithm (FEM–GA) model. It is found that both the models are in good agreement with each other showing the applicability of the present approach. The PCM–PSO based S/O model is simple and more effective in groundwater contamination remediation design using PAT.

Evaluation of groundwater contamination and its impact: an interdisciplinary approach

The study aimed at determining the socio-economic issues due to municipal solid waste dumping, the extent of groundwater contamination and the groundwater dependency around Perungudi dumpsite in Tamil Nadu, India. Sampling and analysis of groundwater and leachate show the contamination migration is due to dumpsite leachate. The concentrations of contaminants were more severe within 1.5 km along groundwater flow direction mainly due to the geological profile. The Piper diagram also shows that the groundwater sampled within 3 km in the flow direction was classified as Na–Cl type. Studies conducted within contaminated areas to determine the groundwater usage showed that higher percentage of lower and middle socio-economic status categories was using the groundwater for domestic purposes, which may lead to health issues. The present study suggests that proper solid waste management and groundwater remediation techniques along with the people’s involvement are necessary to reduce the consequences of groundwater contamination on the people residing around the dumpsite.

Groundwater remediation optimization using a point collocation method and particle swarm optimization

Groundwater contamination is a major problem in many parts of the world. Remediation of contaminated groundwater is a tedious, time consuming and expensive process. Pump and treat (PAT) is one of the commonly used techniques for groundwater remediation. Simulation-optimization (S/O) models are very useful in appropriate design of an effective PAT remediation system. Simulation models can be employed to predict the spatial and temporal variation of contaminant plumes. Optimization models, on the other hand, can be used to minimize the cost of pumping or recharge. Generally, grid or mesh based models using Finite Difference Methods (FDM) or Finite Element Methods (FEM) are used for groundwater flow and transport simulation. Recently, Meshfree (MFree) based numerical models have been developed due to the difficulty of meshing and remeshing in these methods. The MFree Point Collocation Method (PCM) is a simple MFree method to simulate coupled groundwater flow and contaminant transport. It saves time for pre-processing such as meshing or remeshing. Evolutionary algorithm based techniques such as for particle swarm optimization (PSO) and genetic algorithms (GA) have been found to be very effective for groundwater optimization problems. In this paper, a simulation model using MFree PCM for unconfined groundwater flow and transport and a PSO based optimization model are developed. These models are coupled to get an effective S/O model for the groundwater remediation design using PAT. The S/O model is applied to the remediation design of an unconfined field aquifer polluted by Total Dissolved Solids (TDS) by using pump and treat and flushing. The model provides an effective remediation design of pumping rate for the selected wells and costs of remediation.