Proceedings of the 8th International Congress on Environmental Geotechnics Volume 1

Waste mechanics focuses on the degradation characteristics and mechanical behaviors of municipal solid waste (MSW). Knowledge of waste mechanics helps solve the severe geoenvironmental challenges for MSW landfills. This paper first summarized and compared the physical components and chemical composition of MSWs from 20 countries, including developed and developing countries, and proposed a MSW classification system based on the food waste content and the ratio of cellulose to lignin. Secondly, the degradation characteristics between high food waste content (HFWC) and low food waste content (LFWC) MSWs, originated from their differences in chemical composition due to the distinctions in physical components of MSWs, were compared quantitatively by mass loss, leachate generation, landfill gas (LFG) generation, and contaminants in leachate. Thirdly, mechanical behaviors closely related to the degradation characteristics of both HFWC and LFWC MSWs, including permeability, compressibility, shear strength, and lateral pressure, were elaborated on. Fourthly, degrees of hydrolysis, methane generation, and consolidation, calculated by the stabilization-consolidation model, were introduced to characterize the stabilization process of HFWC MSW landfills, which provided a basis for sustainable landfilling for HFWC MSW landfills. The obtained features of HFWC MSW landfills, including the distributions of leachate mounds and LFG, settlement, and slope stability, showed the causes of main geo-challenges at HFWC MSW landfills, including high risks of leachate leakage and slope instability, and low LFG collection efficiency, were consistent with the monitoring results of several cases. Finally, technologies, practices, and designs towards sustainable landfilling for HFWC MSW landfills in China were presented, which could also serve as useful references and guidelines for other countries in similar situations.

Deep coal reserves represent a valuable resource, both in terms of their potential for the sequestration of anthropogenic carbon dioxide and for energy extraction through underground coal gasification (UCG). This paper looks at the current field and research status of these technologies and, in line with on-going work at Cardiff University’s Geoenvironmental Research Centre (GRC), focuses special attention on the role of numerical modelling in advancing the research agenda. In response to poor carbon dioxide injectivity experienced in carbon sequestration trials and order-of-magnitude permeability losses caused by sorption induced coal swelling, the direction of work at the GRC is to improve the current understanding of the mechanical response of coal using a coupled thermal, hydraulic, chemical, mechanical modelling framework. Hence, the current focus of theoretical developments in this area are summarized. In relation to UCG, on-going developments to a comprehensive numerical model are discussed. The ultimate aim is to identify and quantify coupled mechanisms controlling syngas composition and production rate, heat and mass transport, geochemical reactions, geomechanical responses, and cavity growth to subsequently improve the state-of-the-art towards minimizing geoenvironmental risks.

This paper summarizes the findings of various investigations carried out for some time in the research group on unsaturated soils at Ecole des Ponts ParisTech. It focusses in more details on the links that can be made between nano, micro, and meso scale phenomena, and the macroscopic response of various Engineered Barrier Systems made up of bentonite, used in various concepts of radioactive waste disposal at great depth. Meso-scale observations using X-Ray microtomography usefully complete some findings established by using more standard techniques of microstructure investigation, like scanning electron microscopy and mercury intrusion porosimetry. The morphology of sand-bentonite and pellet-bentonite powder mixtures can be better understood, together with their changes during hydration. Also, nano-scale mechanisms that govern the hydration of smectites through the consecutive and ordered placement of layers of water molecules along the faces of the smectite minerals are useful for a better understanding of the macroscopic response of Engineered Barrier Systems submitted to hydration under constrained volume conditions.

The objective of the paper is to give an update in key topics related to performance issues of barrier systems for landfills. The objective of using barrier systems is to minimize the impact of contaminants on the surrounding environment. To achieve this goal puncture protection of the geomembrane must be ensured. An update is first given is this matter. The question of the stability on slope of geosynthetic barrier systems is then discussed and an insight is given in modeling and laboratory measurement of parameters required to perform reliable modeling, especially as regards the case of piggy-back landfills. Finally, the question of transfers though bottom barrier systems is addressed, giving an update especially in the analytical solutions developed in the past 10 years in China in this matter.

Status of regulations, practices, and challenges on the reuse of excavated soils with natural contaminations in Japan are presented. Geotechnical and geoenvironmental efforts have been conducted in recent years to contribute to the cost-effective measures to reuse such excavated soils under proper contaminant control. Evaluations of leaching behavior from the soils of concern as well as attenuation capacity of the surrounding ground are both essential to design the cost-effective measures. Since methods and/or protocols which consider the nature of natural contamination are required, several different leaching tests were performed on different types of soils and rocks with natural contaminations by the authors. A series of these experimental works revealed that the testing conditions of column leaching tests, such as column length and flow rate, should carefully be decided to simulate the situations where the soils are reused in embankments or other geotechnical applications. Either original grounds or soil layers installed beneath the naturally contaminated soils are expected to function as attenuation layer. Therefore, attenuation capacities of several different types of soils are discussed. Effects of mineral agents enhancing the sorption performance are also presented in this paper.

Environmental systems are complex. For unravelling this complexity both observation and modelling concepts are being developed and applied - still and mostly in independent ways. Developing and establishing continuous workflows in environmental systems analysis integrating observation as well as modelling aspects shall help overcoming this disparity. In this paper we present basic concepts of technical workflow development in geosciences and show examples from different applications in geotechnics. Technical workflows combine data integration, numerical simulation and data analysis and therefore support the modelling process. Benchmarking is an essential tool for proving complex workflows, e.g., the consistency between experimental work and process modelling.

A mature transport infrastructure such as that in the UK is often intensively used, but has key elements that were built without the benefit of a modern understanding of soil mechanics and geotechnical design. Operation of any transport infrastructure network is critically dependent on the performance of such elements, in particular cutting and embankment slopes. In a temperate European climate, seasonal winter wetting and summer drying impose potentially onerous cycles of loading that can precipitate both ultimate and serviceability failures, especially in vegetated slopes. Seasonal shrinkage and swelling of clay fill railway embankments can directly disturb railway track geometry, resulting in train speed restrictions that disrupt normal operations. Very wet winter periods can cause result in slope failures requiring closure of the line for repair and in some cases potentially serious train derailments. As part of an ongoing long-term research programme, observations from field instrumentation are being used to understand how weather and vegetation drive changes in water content and pore water pressure in the earthworks, in turn leading to ground movements. The field observations have also been used to develop and calibrate numerical models able to replicate weather-driven pore water pressure changes and slope failure. The lecture will summarise recent progress, and show how historical and current weather event sequences have been applied using the models developed to understand and assess slope deterioration processes under future climate scenarios up to and including the 2080s.

Environmental pollution including the soil and groundwater contamination has been a major problem faced by the U.S., and many other countries across the world. Realizing the impact contaminated sites had on human health and environment, some of the major environmental regulatory agencies were formed that imposed strict regulations to condemn improper waste disposal practices and to clean up the contaminated sites. Over the years, the environmental regulations and policies have evolved from being ambitious and impractical to a more rational risk-based remediation approach. Several remediation technologies have been developed based on their suitability to different site characteristics. However, the choice of the final remedial technology has always been dictated by its ability to reduce the contaminant concentrations to remedial goals, the cost, and speed of implementation of the technology at the contaminated site. The enormous use of energy and resources by the remediation activities and consequently, the broader environmental impacts that follow from various remediation activities goes unaccounted. In recent years, a more holistic approach, the green and sustainable remediation, involving the quantification of net environmental, economic, and social impacts/benefits (the triple bottom line) of site remediation activities is given great importance to achieve sustainable development. Moreover, with the global climate change and regularly occurring extreme events, it is essential that the remediation plan and design is resilient/adaptable to the extreme events. This study presents an overview of risk-based site remediation approach, and green and sustainable remediation and the tools that aid in quantifying the sustainability of remediation alternatives. In addition, the importance of considering resilient design in remediation projects is discussed. Finally, the challenges and opportunities that needs to be addressed to realize sustainable and resilient remediation are highlighted.

Population explosion and rapid industrialization have led to generation of large amount of solid and liquid wastes, which require safe disposal and containment. Currently, land disposal or shallow disposal of these wastes is being practiced by industries and the municipal authorities. However, subsequent interaction of the disposed of waste with rain or ground water generates leachates, which in due course of time contaminate the geoenvironment viz., soil, rock and the ground water (Shu et al. 2018). In addition, high-level radioactive waste generated by nuclear industry comprising of radionuclides of transuranics (viz., Pu, Np and Am) and fission products (viz., I, Cs and Sr), require safe handling and disposal in the geological formations. The efficacy of these formations must be established based on detailed investigations related to their geological, hydrological, geochemical, geophysical and geotechnical characteristics and their impact on integrity of the waste form (IAEA 1993; Gurumoorthy and Singh 2004a, b). It must be noticed that the migration of radionuclides from these waste forms depends on the type and condition of the rock mass (intact or fractured) and the soil mass (saturated on unsaturated). The fractured rock mass creates a pathway for the ground water movement and thereby enhances the probability of dissolution and migration of radionuclides from the radioactive waste matrix and resulting in contamination of the geosphere (Hakanen 1993; Jedinakova 1998).

Landfilling often is not regarded as a technically and operationally highly demanding waste management option as e.g. incineration. In many cases landfills are seen as a cheap way to get rid of the waste. Mistakes in the design and operation often may become relevant after many years or decades and remediation will be in general become very costly.Siting, lining and drainage are key factors for the long-term functionality of a landfill. It always has to be kept in mind that these systems have to be operational “for ever”.Landfills have to be operated in a way that the biologically degradable waste is degraded in a relatively short time (few decades after landfill closure); by these means the emission potential will be significantly reduced. Measures to reduce the aftercare phase are mechanical-biological pre-treatment and in-situ aeration.Important part of landfill operation is aftercare and release of a landfill from aftercare. Under which conditions can a landfill be released and does that mean that then no more care will be necessary?Open questions are also how to deal with high water levels and temperatures in landfills. Another important issue is the question how the bottom drainage system can be kept functional over long periods of time (avoid clogging and collapsing of drain pipes) and in case of damage how they can be repaired or substituted.

There are millions of contaminated areas in the world that need to be remediated so that they can be reused without risk to health. This article presents the main remediation techniques applied to soils, sediments, and groundwater. These technologies can be classified as five processes, i.e. physical, chemical, biological, thermal, and combined. This article also offers a method for choosing the best technique to remediate a place, called sustainable remediation. An evaluation of the toxicity of remediation techniques is presented. Finally, a summary of remediation practice in China is discussed, and the main challenges of future remediation research are presented. The following concluding observations can be reached: the development of a software for the selection of soil remediation technologies can be very helpful to professionals in the field. However, it is important to note that each remediation technology has its own characteristics, limitations, advantages and disadvantages, and no universal method can satisfy all needs.

Advances over the past 35 years in terms of minimizing impact to the environment by containment, collection, and treatment of contaminants as well as by minimizing the generation of contaminants are highlighted in this keynote lecture. The lecture examines past advances in understanding hydraulic conductivity of soils (both clayey and granular soils) permeated by contaminated fluids. And the lecture considering the present, the substantial use of geo-membranes in fluid containment and the advances in construction quality assurance to minimize holes are examined, as well as Looking to the future, the lecture highlights the need for taking a systems approach to environmental geotechnical design.

The osmotic, hydraulic and self-healing efficiency of bentonite-based barriers for the containment of subsoil pollutants is governed not only by the intrinsic chemico-physical parameters of the bentonite, but also by the chemico-mechanical state parameters. A theoretical framework has been set up that is able to describe the chemical, hydraulic and mechanical behavior of bentonites in the case of one-dimensional strain and flow fields. The proposed theoretical hydro-chemico-mechanical framework has been validated through a comparison with both the direct measurements of the arrangement of bentonite fabric.

Contaminated landfill sites have been selected for brownfield redevelopment due to their locations and property sizes. To facilitate the redevelopment, the remediation of those contaminated landfill sites has to be designed and integrated with the site redevelopment to avoid conflict between the remedial system and the redevelopment site features. A proactive approach to have both development and remediation teams to understand how redevelopment design and construction can accommodate the remediation system is critical in order to maintain protectiveness for future use of the site.

Carbon Capture and Storage, or CCS, is a technology that involves capture of CO2 from large point sources and subsequent injection of the captured CO2 into deep geological formations. This technology has the potential to contribute substantially to carbon mitigation efforts. CCS is the only existing technology that allows continued use of fossil fuels while simultaneously addressing the carbon problem.

This paper will provide a 50-year perspective on vertical barriers formed from cement-bentonite; soil-bentonite, soil-attapulgite, sand-cement bentonite and plastic concrete. These barriers are commonly referred to as cutoff walls and are regularly used for the control of groundwater and/or the management of contamination. Applications include the water-tight element in dams and levees and the control of groundwater migration at contaminated sites.

Soil and groundwater remediation is the most common and most mature application of biogeotechnical engineering in engineering practice. However, new and enhanced biogeotechnical techniques to mitigate soil and groundwater contamination are still being developed. Furthermore, biogeotechnical techniques can contribute to environmental protection and restoration in a variety of other ways. New and enhanced biogeotechnical techniques for soil and groundwater remediation under development include sequestration of groundwater contaminants via co-precipitation of carbonates, precipitation and phosphorous from ground and surface water, and microbial chain elongation. Other biogeotechnical applications in environmental protection and remediation include fugitive dust control, mitigation of soil erosion due to surface water runoff, precipitation of phosphorus and reduction of nitrates in surface water runoff, mitigation of internal erosion of soil, and creation of low permeability subsurface barriers. Replacement of Portland cement as a binder for aggregates also contributes to environmental protection.

Currently, in Japan, recycling of various industrial waste is proceeding to create a recycling-oriented society. Waste gypsum boards generated at the time of constructing and dismantling buildings are industrial waste requiring recycling. Waste gypsum boards are separated into board paper and recycled gypsum in the intermediate processing facilities. The recycled gypsum powder is effectively used as a raw material for cement, raw material for neutral ground improvement materials, and ground improvement materials for agriculture. However, when used as a ground improvement material, it is pointed out that the fluorine contained in recycled gypsum powder may dissolve into the improved ground. Therefore, to use recycled gypsum powder effectively on the ground, it is important to ensure that the fluorine is insolubilized for the environmental safety. In this research, applicability of ground improvement solidification material using regenerated hemihydrate gypsum powder was investigated. Especially on improvement of soft ground, the results of investigation is reported focusing on the improved properties of regenerated hemihydrate gypsum improved soil, long term durability, and re-sludge characteristics.

The note presents the results of an experimental research study on the hydraulic behavior of Finnish soft clays treated by quicklime. The effect of a wide range of water contents and of curing time on hydraulic characteristics of the treated soil was studied. 7% of quicklime was identified as the optimum lime amount by means of initial consumption of lime tests and by evaluating the drying capability of different lime amounts. Soil-lime samples were prepared by wet mixing and Standard Proctor compaction. Hydraulic conductivity tests are carried out in flexible wall permeameters both on treated and untreated soil. A general increase in hydraulic conductivity due to the addition of lime is observed (2 order of magnitude at optimum conditions). For the treated specimens, a decrease of two orders of magnitude in permeability values was observed, increasing the water content of the soil. Reduction of permeability due to curing time is within 1 order of magnitude. Lime addition reduced water sensitivity and improves the draining capability of the soil.

Addition of Water Treatment Sludge (WTS) to soils in earthworks may reduce land disposal of WTS and exploitation of natural soils. In this perspective, geotechnical properties of mixtures of a Brazilian tropical soil with WTS in the proportions 5:1, 4:1 and 3:1 (by wet weight) were evaluated. Grading curve and Atterberg limits were obtained for the WTS, soil and mixtures. One-dimensional consolidation, triaxial compression and permeability tests were carried out on compacted specimens of the soil and the soil-WTS mixtures. Geotechnical characteristics of the mixtures resulted slightly different from those of the soil, and previous air-drying affected the compaction parameters of the mixtures. The mixtures presented higher compression indexes than the soil, however swelling indexes were similar for all materials. Hydraulic conductivity decreased with WTS addition, whereas internal friction angles of the mixtures increased and effective cohesion decreased with increase of WTS content. The geotechnical parameters of the mixtures are acceptable for earthworks and indicate possibility of WTS reuse, to be further analyzed relative to environmental feasibility.

Application of chemically solidified dredged marine clay as land reclamation fill can not only mitigate the issue of local scarcity of ideal filling material, but also allow significant volumes of unwanted marine clay arising from dredging to be disposed economically and ecologically. Nevertheless, treatment efficiency of pure chemical solidification at extra-high water content is very low or even marginal. This study aims to develop a new physicochemical method (PCM) for efficient treatment of dredged clay slurry waste at extra-high water content. It is essentially to reduce the equivalent water content by the flocculation component in the initial curing stage and solidify the dewatered clay slurry by the chemical solidification component in the later curing stage. A number of laboratory experiments are performed on clay samples treated by both the pure chemical method (CM) and PCM. Comparison results show that, when the initial water content of the dredged clay slurry is higher than 300%, the undrained shear strength of PCM treated marine clay slurry is 8 times larger than that of CM mix with the same content of chemical solidification component. This demonstrates well the feasibility and efficiency of PCM for land reclamation purpose.

This paper examines the effect of temperature, with the range of 20 to 70 °C, on the hydraulic conductivities of remolded sewage sludge from different regions compared with the kaolin and clay. And the hydraulic conductivities of the heated sludge were measured with the confining stress of 60,100 and 200 kPa. The measured values of hydraulic conductivities for all the sludge increase with increasing temperature, and the hydraulic conductivities at 70 °C increase up to about 25–60 times those at 20 °C, while kaolin and clay are 2–4 times. When cooling from 70 °C to 20 °C, the hydraulic conductivities of sludge were about 7 times the initial values at 20 °C, revealing a hysteresis phenomenon. The changes in viscosity of water, the amount of bound water and organic matter contents with increasing temperature contribute greatly to the significant increase of hydraulic conductivity of sludge. The study also showed the hydraulic conductivities of sludge did not decrease with increasing confining stress.

The macroscopic mechanical properties of solidified sludge are determined by its microstructure. However, microorganisms can biodegrade organics, which influences the microstructure of solidified sludge. The SEM image of solidified sludge was analyzed to study its three-dimensional (3D) qualitative and quantitative microstructure using ArcGIS technology. The results show that 3D micro-porosity can be extracted by ArcGIS technology, where it is not affected by the threshold selection and produces more reasonable results. 3D micro-porosity increases gradually with the biodegradation time, and a relationship between them can be expressed by a modified hyperbolic model. The change of 3D micro-porosity is determined by the internal organics biodegradation of solidified sludge.

Demand on freshwater tends to increase in the next years; consequently, the production of water treatment sludge (WTS) shall increase as well. Beneficial reuse of WTS as a geotechnical material may be an important strategy to reduce the environmental impacts due to improper WTS disposal. However, even after dewatering WTS consistency is closer to fluids rather than soils. Aiming to the reuse of WTS at considerable amounts, the incorporation of additives to stabilize WTS may be an interesting alternative in the future. For this purpose, the knowledge of rheological characteristics of WTS in fresh state is mandatory. This paper presents a brief about viscoelasticity and rheology concepts, preliminary results of WTS rheological behavior, and two different methods, rotational rheometry and laboratorial miniature Vane test, to evaluate WTS behavior. Rheological tests indicated that Cubatão WTS presents shear thinning behavior at low shear rate, shear thickening at high shear rate, and suggested thixotropic behaviour at low shear rates. Rotational rheometry may be a powerful tool to characterize rheological behavior of WTS, since is very fast method, adapted to pastes and fluids, and can be applied to different conditions of solicitation. Vane test is limited to high water content materials, and higher quantities of sample is needed, but is standardized, and a minimum disturbance of sample occurs. Both methods may be appropriated to characterize WTS and the choosing of the best method depends on the research purpose.

This paper described the adsorption characteristics of heavy metal-cadmium from aqueous solution onto activated carbon and recycle materials. The adsorbent materials selected in our study were activated carbon, sawdust, and peanut shell. The effects of adsorption time, particle size of adsorbent, adsorbent mass and initial adsorbate concentration were investigated using batch adsorption experiments. The adsorption isotherms were obtained using concentrations of the cadmium ion ranging from 5 to 40 mg/L. Our results demonstrate that the removal rate of cadmium for each material initially increased rapidly with the increase of adsorption time and the optimal removal efficiencies were reached within 3 h; with the increase of the adsorbent particle size, the removal rate of cadmium for both sawdust and peanut shell decreased whereas for activated carbon almost all cadmium were removed; The removal rate increased when the amount of sawdust and peanut shell increased from 0.2 g to 1 g, the amount of activated carbon increased from 0.05 g to 0.4 g; the removal rate decreased with the increase of initial cadmium concentration.

This paper presented a new type of ecological riverbank protection, which was constructed by a combined use of the porous ecological concrete and geocell. The mechanism and construction technology of the ecological riverbank protection were detailed described. Considering the water level, the riverbank protection was divided into three portions: the presented ecological riverbank protection was mainly adopted above the normal water level; the precast concrete block, sand and stone cushion were combined used below the water level; and the jointly used of the dry block stone and water plants was applied in the areas where the water level changes. Since the inclusion of the solid waste and organic matter in the substratum of the ecological cement, this technology is much more suitable for the growth of the plants, and featured the cost-effective and environment-friendly. As a result, the technology can provide maximum resistance to the erode of the water flow on the basis of the high structural stability and ecosystem stability, and has significant potential in the application of riverbank protection.

When large strains are expected, such as for dredged sediments in confined disposal facilities, models that take into account constitutive relations for compressibility and hydraulic conductivity are required to study consolidation processes. A study has been carried out to design the filling and consolidation phases of a confined disposal facility for dredged marine sediments. The possibility to determine consolidation constitutive laws has been investigated using common incremental loading oedometer tests instead of more suitable but timeconsuming tests. The void ratio-hydraulic conductivity domain determined by oedometer test results has been compared with direct measurements at different void ratios. The results show a low trustworthy of this approach.

Due to the increase of construction wastes and end-of-life tyres, recycling of the waste concrete and scrape tyre have become an important issue around the world. Therefore, the aim of this research is to study the effect of crumb rubber on strength properties of recycled concrete aggregate (RCA) as base/subbase pavement layers. In this study, crumb rubber with particle size of 10–15 mm was added to 20 mm RCA at 0.5, 1 and 2% by weight percentages of the RCA, and the strength properties of the samples were examined by unconfined compression strength as well as resilient modulus tests. It was concluded that addition of crumb rubber resulted in decreasing the UCS and resilient modulus, and increasing the toughness in terms of failure strain and deformability index.

Steel slag, a kind of by-products of steel industry, is enormously produced, however, its re-usage was still limited for the mutative chemical compositions and the low cementation. In this investigation, the composition adjustment and activation of the steel slag were first carried out to improve the cementation and to form the optimal slag-based composite, where the controlling indexes of cement clinker were introduced. Hereafter, the composite was used to modify Hefei expansive soils for the application of embankment construction. The basic physical properties including free swelling rate (FSR), Compaction test and California bearing ratio (CBR) were conducted to understand the engineering performance and to clarify the mechanism of expansive soils modified by the slag-based composite. The results show that when the soil was modified by the composite, the expansion potential was obviously suppressed, and then the treated soil can satisfy the requirement when the composite incorporation ratio was more than 5%. Thereafter, the compaction and CBR of the modified expansive soils suggests the excellent performance when the composite incorporation ratio is more than 7%. The above findings improve the reuse efficiency of the steel slag, and propose a material for the modification of expansive soils.

The granulated blast furnace slag is classifies as a high permeable stiff material with sand size particles that when it interacts with water it shows a time dependent self-hardening behavior. The previously mentioned properties indicates that the slag is a promising material that can be effectively utilized in various geotechnical aspects where it was reported that it has been used as earth reinforcement technique in harbor construction projects. However, onshore utilization of slag material is limited. It was reported that utilizing sand compaction pile (SCP) method imposes crushing the slag particle resulting in significant education of the hydraulic permeability. This study aims at evaluating the strength development of slag material under various curing times. In order to prevent the significant drop of the hydraulic permeability as a result of early hardening of the crushed particles, the slag particles were mixed with sandy soil sand and subjected to various curing durations then were examined by evaluating the strength development of the adopted mixtures.

Since Japan does not have enough space for landfilling, the use of incineration bottom ash (IBA) from municipal solid waste (MSW) as a construction material is being explored. However IBA contains significant toxic materials, and it has to be immobilized before it can be used as a ground geo-material. This study examines aging methods to immobilize IBA by natural rain and carbon dioxide in the air at landfill sites. This paper reports the leaching properties of IBA from MSW in order to evaluate the environmental safety by means of Japanese leaching test No. 46 (Notifications No. 46 by Japanese Ministry of the Environment (JLT 46)), up-flow percolation column test, and pH-dependent test. The leaching concentrations of heavy metals from IBA were found to be influenced by the aging process. It was revealed that the concentration of lead (Pb), hexavalent chromium (Cr (VI)), cadmium (Cd) and boron (B) meet the environmental quality standard values for ground material. Also it was revealed that the possibility of leaching in the long term is low.

This paper presents an experimental study on the physical and mechanical properties of porous ecological concrete by performing ten groups of tests. It shows that the coarse aggregate size, porosity, water-cement ratio, and admixture have significant effect on the strength of the porous ecological concrete. The pH value of the porous ecological concrete is effectively reduced to a certain range that is suitable for the growth of the vegetation. An optimized aggregate size from 15 mm to 25 mm, a water-cement ratio of 0.35–0.40 and the inclusion of the special admixture is introduced, so that the porous ecological concrete can have enough space for the vegetation growth and eligible strength for the structural application. The porous ecological concrete is also proved to be suitable for the growth of the vegetation.

Based on the basic principle of geopolymer technology, the geopolymer cementitious materials were prepared by waste concrete powder and fly ash. Geopolymer recycled concrete is the preparation of geopolymer cementitious material and the waste concrete recycled aggregate. The optimum mix ratio of the geopolymer cementitious material, physical and mechanical properties of recycled aggregates, and mechanical properties of recycled concrete is determined by experiment. The results show that the optimum ratio of geopolymer cementitious material is 30:70 for the ratio of waste concrete powder to fly ash (CP: FA), NaOH solution concentration is 18 mol/L and water glass modulus is 1.5. When content of geopolymer cementitious material is 5% to 7%, the unconfined compressive strength of recycled concrete is greater than 3.0 MPa, splitting strength is greater than 0.4 MPa, and the uniaxial compression resilient modulus is between 2750 MPa and 4000 MPa. Geopolymer recycled concrete can not only solve the treatment of waste concrete, but also reduce the exploitation of natural stone, the use of cement and the emission of air pollutants, which has obvious environmental, economic benefits.

Incineration of municipal solid waste (MSW) is relatively new in India. The process results in generation of residues, bottom ash (BA) and fly ash which are presently dumped back in landfills. The study investigated the properties of MSW incineration (MSWI) BA from two MSW waste-to-energy (WtE) plants in Delhi and the results have been compared with coal bottom ash (CBA) from a local thermal power plant and two local soils, namely: Delhi silt and Yamuna sand. MSWI BA with particle size predominantly in the sand size range was found to be coarser to CBA and local soils making it suitable for earthworks. The chemical composition revealed that SiO2 in the form of quartz is the major constituent of MSWI BA. The organic content was more than regulatory levels for earthworks. Dissolved solids, chlorides and sulfates were very high in comparison to CBA and local soils. The above findings indicate that MSWI BA can possibly be reused in embankments or filling of low-lying areas, provided some environmental control measures are adopted at site or pre-treatment is undertaken to attenuate the leaching of salts and reduce organic content.

Amendment of biochar (BC) in soil is an efficient and popular way to enhance agricultural productivity. In recent times, BC obtained from the by-products or wastes is gaining recognition in various engineering applications. Water hyacinth (WH), which is a highly invasive weed, can be turned into biochar for its productive usage. Recent studies investigated WH BC composite’s cracking potential, water retention capacity and agricultural productivity but did not focus much on its infiltration characteristics. The objective of this study is to investigate dependence of infiltration rate on crack intensity factor (CIF), suction and volumetric water content (VWC). The experiments were performed on the samples of bare soil, 5% and 10% BC (by weight) composites for 63 days (9 drying-wetting cycles) in natural conditions. The experimental data was used to train artificial neural networks (ANN). An ANN model was developed to predict the infiltration rate for each soil composition. Infiltration rate was relatively lower in case of 10% WH BC soil composite. CIF played a major role in governing the infiltration rate for bare soil but its significance relatively reduced as the BC content increased. BC content increases the relative importance of VWC in prediction of infiltration rate. Suction’s role in predicting infiltration rate, for both bare soil and BC composites was more or less the same. For applications (such as slopes or landfill cover) desiring less infiltration rate with a constraint of practically non-varying moisture content, 10% WH BC composite was found to be an ideal choice.

In this research experiments were undertaken with the goal of evaluating the optimum dosage of Tire Derived Aggregates. The effects on compressive strength, stress-strain, and thermal conductivity were evaluated. The test results showed that the specimen with optimum tire shred content had property of low thermal conductivity without reducing compressive strength extremely. The conclusions of this research support the use of Tire Derived Aggregates as alternative fine aggregates in low strength concrete to be a new type wall insulation materials applications if properly confined.

Adsorption is an extensively-studied, cost-effective method of removing heavy metal ions from wastewater, such as lead, which is known to be toxic. Removal of metals with adsorbents that beneficially use waste materials are particularly advantageous to study due to their low cost. This research determined the adsorption capacity of three fly ashes (two biomass and one weathered coal ash) for Pb(II) from aqueous solutions. The adsorptive capacity of the alternative ashes were compared to one sample of activated carbon. The biomass fly ashes demonstrated good removal capacity for Pb(II) through a combination of adsorption and precipitation mechanisms. The weathered coal fly ash had low adsorption capacity (less than 3 mg/g). Biomass fly ashes have potential as low-cost alternatives for heavy metal removal.

This paper presents a case history where about 950,000 m3 of the excavated soils (or construction sludge) generated from Hanshin Expressway shield tunnel construction site was properly managed and reused as reclamation material. Three challenges existed to proceed this entire project. First, separated tunnel and reclamation projects were firmly connected. Reclamation was planned and conducted to fill an area of 8.3 ha which was previously used as an old lumber yard and expected to be an industrial space. The entire project connected a series of highway construction generating the excavated soils and land reclamation project. This type of project was the first attempt in Japan. Second, ICT (information and communication technology) based on the electronic toll collection (ETC) system was applied to manage the soils. In this project, the ETC manifest system was developed and operated to secure traceability concerning the transportation of a large amount of excavated soils. This system improves the efficiency of issuing manifests, minimizes traffic congestion, and avoids overloaded vehicles. Third, to avoid adverse subsidence of land and facilities adjacent to the reclamation, several countermeasures were conducted, such as improvements of reclaimed and original grounds as well as consideration of reclamation procedure. Excavated soils were subjected to soil improvement to obtain sufficient mechanical properties as reclamation material at a soil improvement plant installed at the site next to the reclamation site. Gypsum-based stabilizing agent was applied to secure the neutral condition in pH. A ground improvement method which is able to improve the ground under ripraps was applied to the original ground beneath the revetments, based on the numerical analysis of ground deformation.

The increased crushed rock aggregate consumption resulting from road construction has greatly contributed to the depletion of national rocks in Uganda, hence environmental degradation. The purpose of this study was therefore to investigate the use of carbon black in reduction on the amount of crushed rock aggregates used in mechanical stabilization of unsuitable lateritic soils for road base construction. Preliminary tests on the lateritic soil were carried out to determine if the soil required stabilization. The test results classified the soil as Clayey Gravel with Sand of high plasticity based on the Unified Soil Classification System (USCS) and it required stabilization for use on road base. The combined effect of carbon black and crushed rock aggregates was investigated based on the compaction characteristics, Atterberg Limits, Particle size distribution and California Bearing Ratio tests. Results obtained were analyzed graphically and a blend of 50% lateritic soil, 40% aggregates and 10% carbon black was found to be the most effective in producing a suitable base material. It gave a CBR of 69.4 at 95% relative compaction and a plasticity index of 7 which meet the requirements of CBR above 60% as per the General Specifications for Road and Bridges (2004) of the Ministry of Works, Housing and Communication in Uganda. In relation to previous research, by Jjuuko et al. (2014) which recommended 50% aggregates and 50% lateritic soil, there is a 10% reduction in crushed rock aggregate consumption.

The hydraulic conductivity of solidified sewage sludge is low because of its high organic matter content, which in turn limits the application of solidified sludge to areas where high hydraulic conductivity is needed. In this study, permeability tests and centrifuge tests were conducted investigate the hydraulic conductivity characteristics of solidified sludge in intact and remolded situations and their relationship to variations in pore size distribution. The results show that solidification changed the sludge morphology from loose flocks to small particles with a diameter of around 50 μm. In addition, the hydraulic conductivity of intact solidified sludge ranged from 10−7 to 10−6cm/s. After remolding, sludge cured with 40% SAC (sulfoaluminate cement) showed an increase in hydraulic conductivity of two orders of magnitude. The fundamental process governing increases in hydraulic conductivity is the formation of a dual-porosity structure in the remolding process.

With the urbanization process, enormous construction wastes (CW) are produced, which were usually disposed in landfill in the past, resulting in waste of resources and appropriation of land. To recycle CW, this investigation aims to treat CW as the subbase materials instead of traditional backfill in embankment engineering. To achieve this objective, CW was first crushed into appropriate size, then mixed with silt and cement referring the field procedure to prepare the samples with various CW proportions (CWP). Hereafter, basic performances including compactability, unconfined compression shearing strength, California Bearing Ratio were conducted. Results show that the engineering behaviour of silt soils is significantly improved by the CW incorporation. The maximum dry density of the mixture increases with of the CWP, and the largest maximum dry density is obtained when CWP is 50%. UCS and CBR at the maximum dry density with 50% CWP and after 7-day’s curing is about 6.6 and 10.0 times of compacted silt just treated by cement, suggesting that this mixture can satisfy the requirement of subbase materials.

Ladle furnace basic slag (ladle slag) is a by-product generated from the secondary steelmaking industry. The subsequent disposal of this slag in Singapore is problematic due to its quantity and impact on the environment. A possible solution is to incorporate the ladle slag with deep cement mixing for soft ground improvement. Hence, this study investigates the stabilization/solidification of the ladle slag in the cement-stabilized clay, focusing on the influence of ladle slag on mechanical properties of cement-stabilized soft clay and the leaching of heavy metals. A range of laboratory tests were conducted, including unconfined compressive strength (UCS), X-ray diffraction (XRD), scanning electron microscopy (SEM), and leaching tests. The results showed the addition of ladle slag slightly reduced the UCS of cement-stabilized clays at 14 days, but did not affect or even slightly increased the UCS at and after 28 days if the ladle slag/cement ratio was within 0.15. The leaching of heavy metal elements all meet the requirement of the non-hazardous waste standard. This implies the potential incorporation of ladle slag into soft clay stabilization as a sustainable waste management strategy.

A great amount of red mud waste in the world urgently need to be solved. In order to explore the effect of red mud modified over-wet loess, the cyclic loading test was carried out by the GDS dynamic three axis system. The dynamic stress-strain relations, accumulated plastic strain, dynamic modulus and damping ratio of the modified soil are analyzed, which also are compared with unmodified loess. The results show that the addition of red mud can effectively ameliorate over-wet loess, improving the bearing capacity and the ability to resist deformation. The cumulative plastic strain increases with the increase of the dynamic stress, yet decreases with the increase of confining pressure. It shows different development trends with the increase of dynamic strain: stable type and failure type, and the critical dynamic stress of the modified soil is higher than the measured maximum dynamic stress of subgrade. With the dynamic strain increases, the dynamic elastic modulus increases first and then decreases, but damping ratio slightly decreases first and then increases. The dynamic modulus of modified soil is modified about 4 times than that of loess but damping ratio is lower. The modified soil has no leaching toxicity and good environmental effect. The research results provide a theoretical basis for red mud used in the improvement of over-wet soil or soft foundation.

Geopolymers are inorganic aluminosilicate polymers which have been synthesized from pure sources and more recently, from industrial byproducts. In this study, the industrial by-products, coal gangue, fly ash and red mud were used to synthesize geopolymers at low and elevated temperatures. NaOH, which is often used to raise the pH of the mixture, has been partly replaced using red mud. The strength characteristics of geopolymers synthesized using binary mixtures of coal gangue and red mud as well as ternary mixtures of coal gangue, fly ash and red mud were examined. The compressive strength of the end products was determined using unconfined compression tests. The textural and morphological properties of the end products were also studied. The results reveal the influences of temperature and Si/Al and Na/Al ratios of the raw materials in the geopolymerization reactions and the subsequent development of strength, textural and morphological characteristics. The binary mixtures of coal gangue and red mud showed an increase in strength with curing temperature while the ternary mixtures of coal gangue, fly ash and red mud developed higher strength at lower curing temperatures.

For the adsorption between the solid and liquid phases, the solid liquid ratio s/l and initial adsorbate concentration $$ C_{0} $$ are usually considered as the significant influence factors. The solid solute ratio s/a, i.e., the adsorbent dosage to adsorbate concentration ratio or the ratio of s/l to $$ C_{0} $$ , has been proposed to be a new influence factor, and an empirical equation between the adsorption capacity and s/a has been developed to describe the adsorption characteristics of heavy metals on soil in previous studies. In the present study, the effect of s/a on the adsorption amount at equilibrium of coal gangue has examined by conducting a series of batch tests. For comparison, the influence of s/l and $$ C_{0} $$ were also investigated by the model fitting. The results indicate s/a could illustrate the effects of s/l and $$ C_{0} $$ , and make it more succinctly to describe adsorption. Furthermore, the empirical equation was further verified by literature analysis, and it turned out to be generally applicable for various kinds of adsorbent and adsorbate not only heavy metal ions, but also organic matters. It’s possible to predict adsorption directly by using the empirical equation of s/a.

The recovery of materials from municipal solid waste (MSW) reduces burden on natural resources, facilitates reduction of environmental risks by reducing the amount of waste to be disposed off at landfill site and also saves operation costs for final disposal. This paper aims to quantify the current status of reusable and recyclable fractions and presents the trend of material recovery from MSW in Kathmandu Valley of Nepal.300 scrap shops were surveyed randomly to estimate the amount of reusable and recyclable materials recovered from MSW. The MSW composition of municipalities in Kathmandu Valley provides a great potential for material recovery. In an average, 44% of MSW is comprised of major reusable and recyclable materials (i.e., plastic, papers, metal, glass, rubber and leather, and textiles), among which more than 250 metric tons day−1 (MTD) is being currently recovered. The study shows the increasing trend of recovery of materials from MSW in Kathmandu Valley over the years, from 100 MTD in 2005 to 140 MTD in 2013, and 250 MTD in 2017. The current economic value of these recovered materials at source of generation is estimated to be yearly US$ 18 million (US$1.00 = NRs. 100.00).

Utilization of recycled and reusable materials in construction industry has become an alternative way to substitute natural resources. However, national regulations might discourage to use them in construction works. With this understanding of the complexity, an alternative approach for utilization of naturally contaminated soils is proposed and numerically evaluated. The natural contaminated soil is deposited as a core material in the embankment with an earthen cover constructed from in-situ available soil. This research consists of two parts. At first, a water balance analysis was conducted using conventional equations for the cover layer. After that, a two-dimensional finite element contaminant transport analysis was performed with the advective-dispersive solute transport approach. Kyoto City, Japan, was selected as the investigation site, and its average monthly precipitation and mean temperature over the past thirty years were used as input data. Results reveal that annually approximately 28% of precipitation gets into cover from surface layer and the maximum percolation occurs on March. Moreover, it is concluded that the initial pressure head which is related to the initial saturation degree dramatically affects the contamination transport. Although the capillary barrier effects do not last for a long time, the contamination values will not be equal to source contamination within one-year period at the bottom of models. This is a promising finding for utilization of naturally contaminated soil in the embankments with a suitable design concept.

In the remediation design of organic contaminated sites with soil vapor extraction method or thermal desorption method, one of the key problems is the volatilization of organic compounds from soil. In this research, the heptane was selected as the organic contaminants. Through a series of laboratory experiments, the volatilization process of heptane from unsaturated sands were studied under controlled conditions. The heptane-contaminated sand samples with different water content and organic content were prepared, and the kinetic process of volatilization was simulated in the laboratory. A thermostatic water bath was adopted to control the temperature of sand samples in the experiments. The results indicate that the removal process of heptane from soil by volatilization can be divided into two stages. It evaporates quickly in the first stage and then the removal rate becomes slower and slower. The volatilization rate of heptane is higher under high concentration than that under low concentration in the same period of time. In addition, the temperature has a great impact on heptane removal efficiency. Increasing temperature can improve the volatilization rate of heptane from soil samples.

The trend of using GCL for liners from MSW landfill in developing countries is growing. Leachate in general presents high ammonium and chlorides concentrations and there are noticeable with high migration possibility. Recent studies indicate a presence of several emerging organic compounds, among them bisphenol A (BPA) which is considered an endocrine disrupting chemical (EDCs). This article presents batch tests for bentonite and geotextile, carried out separately using ammonium and BPA mono solutions with maximum concentrations in the range of 1600–1800 mg.L−1 and 1000 pg.L−1, respectively. The maximum value of ammonium adsorbed by bentonite was 10,61 mg.L−1, and no sorption for geotextile. The BPA sorption tended to 3,72 mg.L−1 for bentonite whereas for the geotextile BPA adsorbed was in order of 6,52 pg.L−1.

Soils excavated in construction works often contain non-anthropogenic heavy metals and metalloids due to their geologic histories. When leaching concentrations of these substances are high, they are reused after containment, such as core materials of embankment structures. Evaluation of the leaching behaviors of non-anthropogenic heavy metals and metalloids is essential to predict the environmental impact and achieve an optimum containment design. However, applicability of the conventional leaching tests to soils containing non-anthropogenic substances is uncertain, mainly because their chemical forms and leaching processes are different from those in contaminated soils. This paper addresses the leaching behavior of arsenic (As) and other inorganic constituents by performing column percolation tests for a marine sediment sample by employing two different-size columns ( $$ \phi $$ 50 mm × h 300 mm and $$ \phi $$ 150 mm × h 700 mm) with saturated/unsaturated flow conditions. Long term leaching profiles were analyzed to assess the effects of specimen size and flow conditions. At the middle of the unsaturated larger column, higher As leaching concentrations were observed under neutral condition. However, due to precipitation of As with co-precipitation of iron and aluminum compounds, As leaching was limited at the bottom. As a result, there was no significant difference in As leaching amount obtained in two column percolation tests.

Compacted clay liners have been widely used as bottom liners in municipal solid waste landfills around the world. However, landfill leachate contains a large variety of pollutants with widely different migration characteristics, and the interaction between multiple pollutants have an effect on migration of pollutants. In this study, a numerical parametric study is conducted to investigate the transport behaviors of commonly found leachate pollutants through compacted clay liner. Prior to the numerical parametric study, the numerical model was verified by centrifuge test results. Parameters considered include dispersivity of compacted clay liner, diffusion coefficients and retardation factors of typical pollutants. The simulation results showed that the pollutant transported through compacted clay liner faster when multiple pollutants were simultaneously present in the leachate. Under a high leachate water head, the effect of diffusion coefficient was not obvious on the pollutants transport through compacted clay liner, moreover, the influence of dispersivity and retardation factor was more significant.

Semi-analytical model for methane transport and oxidation through CCL cover was developed. Influence of gas diffusion coefficient and methane oxidation rate on the transport of methane and oxygen through CCL cover was investigated. Methane diffusion coefficient has great influence on methane transport through CCL cover but has no obvious influence on oxygen concentration profile. When t = 0.1 day, methane concentration for the case with Dm = 3.81 × 10−6 m2/s is 8 times greater than the case with Dm = 3.81 × 10−7 m2/s at depth z = 0.1 m. Oxygen concentration at the same depth increases with the increase of oxygen diffusion coefficient. Methane oxidation rate has great influence on methane transport through CCL cover but has on effect on oxygen transport through CCL cover. When t = 1 day, concentration of methane at z = 0.1 m for the case with k = 9.12 × 10−5 s−1 is approximately 40 times greater than the case with k = 9.12 × 10−4 s−1. It is also indicated that time needed to reach steady-state increases with the decrease of methane oxidation rate.

Leachate recirculation has the better effect to the biogas production in landfill. A pilot scale test of leachate recirculation considered the gas and liquid well was conducted in a landfill. The long term record of the leachate recirculation volume and gas production was preserved. The variation of the methane production was addressed under different recirculation schemes. The recirculation loading was the key parameter in recirculation scheme, especially considering the special condition in landfill. The recycling program and collection method implemented in the sites have an important effect on the evaluation of leachate recirculation for methane generation enhancement. It will be provided useful evidence for assessing the gas production by Leachate recirculation and collection well design in landfill.

In this study, we compared the bulk concentrations and the water soluble fractions extracted by the simple batch leaching test of toxic elements (B, Cr, Pb, As, Cd and Se) of the alluvial marine clays taken from Osaka Plain, Japan, to assess the risk of naturally-derived toxic elements are required to promote the utilizations of excavation surplus soils. The results showed that (1) the concentrations of B, Cr and Pb of bulk sediments and the water soluble fraction leached by simple batch test were higher at the middle of marine clay layer where clay fraction is dominant, (2) the accumulation of As into the sediments and its release would be related to the change of redox condition in the sandy layers deposited in tidal zone, (3) 0.45-pm MF was not enough to remove colloidal particles, which would affect to the reproducibility of batch leaching test, especially Pb concentration, and (4) The contents of water soluble phase were small compared to the bulk concentrations, while the change of redox condition, in which the excavation surplus soils would be exposed, must be considered to evaluate the risk of toxic element dissolution.

Nanoscale zero valent iron (nZVI) has shown great potential in the remediation of contaminated groundwater. For many different types of contaminant, adsorption was the main remediation mechanism, so it is necessary to figure out the adsorption models of remediation by nZVI. In this study, copper ion, phosphate anion and methyl orange were used respectively as simulative pollutants to investigate the remediation capacity of nZVI. Langmuir model and Freudlich model were used to describe the adsorption isotherm. Furthermore, kinetic model was established to describe the remediation process. It was found that nZVI exhibited high efficiency in the remediation of various types of contaminants. This study promoted further understanding of the remediation mechanism and kinetic process of groundwater remediation by nZVI.

A non-equilibrium model for adsorption process of single ionic species onto solid adsorbent has been proposed within the framework of irreversible thermodynamics. Based on Ziegler’s principle of maximal rate of dissipation and combining mass balance equation of ionic species, a theoretical formulation of general description for non-equilibrium adsorption was obtained. Fatherly, the dispersion-type energy functions included two Helmholtz free energy and one dissipation rate density were constructed by complementary error function, which introduced into the general form of non-equilibrium model to achieve the specific form. The predicted results of the presented model were compared with the tested kinetics of adsorption processes of Pb2+ and Cd2+ onto Beidellite, which provided a better agreement with the experimental data.

Numerical modeling of groundwater and geothermal problems has expanded in the past few years due to the increase in computational power and software. The size and complexity of solutions attempted has grown in step with computational abilities. Problems with larger numbers of total nodes, with complex geology involving faulting, as well as coupling of multiple physical processes (geothermal, CO2 sequestration) are now being attempted. Los Alamos National Laboratory (LANL) has invested over 50 man-years of effort into the FEHM control volume finite element solver over the past number of decades. The code has been used on US EPA Superfund sites, low and high level nuclear waste sites, and a variety of fundamental hydrogeological applications. The code allows for complex coupling of processes including non-isothermal models and can solve more complex problems than existing commercial codes. LANL and SoilVision Systems Ltd., have combined efforts to offer groundwater and geothermal numerical modeling solutions of larger and more complex systems. In order to gain confidence in the combined front end, solver, and back end visualization system, a number of benchmarks have been created in order to document performance. This paper presents the results of benchmarks created to test the performance of the new groundwater and geothermal modeling system. Performance of the system is discussed as well as challenges and hurdles encountered in the collaboration. The ability of the system to scale up to model field-scale systems will be discussed.

Electrical Resistivity Tomography (ERT) method has been recognised as a robust technique with unique features for achieving three-dimensional noninvasive measurements and enabling multi-scale characterisation of a range of soil or fluid properties linked to electrical resistivity. This paper introduces a research programme established to develop a versatile high-density ERT (HERT) system for studying model-scale flow and solute transport phenomena under normal and accelerated gravity (in a geotechnical centrifuge) conditions. The programme consisted of element-scale calibration tests and a suite of 1D and 3D infiltration model tests using fine glass ballotini and composite soils as model soils. Illustrative results from a centrifuge soil column test indicated that the moisture migration and redistribution process at different accelerated gravity levels can be reasonably well represented by the time lapse resistivity profiles obtained from the HERT system. Further research is underway to explore the method’s full potential in other studies related to subsurface seepage and solute transport with varied boundary conditions.

Although important for many geotechnical issues, hydraulic conductivity heterogeneity is rarely considered in geotechnical practice for two main issues. First, it is almost impossible to sample the entire area of interest. Second, it is very difficult to account for scale effects in our numerical models. In this paper, we divulgated an important result obtained in a previous work [1], where those two problems were faced. An innovative approach in geotechnics based on simple averaging process is showed. That approach incorporates spatial variability, multiscale data, and uncertainty treatment into a workflow that could be implemented in the daily practice of geotechnical engineers in order to perform hydraulic conductivity upscaling. The approach described allows a practical and reliable hydraulic conductivity upscaling for the studied soil, proving itself as a good solution for the daily practice of the geotechnical modeler.

This study was performed to determine parameters of contaminant migration in the soil-water environment. The flow tests were conducted in Trautwein apparatus in conditions of constant head and full saturation. Based on the results of the dynamic studies, the parameters of the advective-dispersion equation of pollutant transport were determined. Results of presented study revealed that the advection dominates during the chloride transport through sandy soil. Ammonium and nitrate ions transport in loam is mainly influenced by diffusion. Obtained values of retardation factors indicate that sorption of ammonium and nitrate ions onto sand can be classified as small. Nitrate ions are adsorbed onto loam with average intensity. For identification of sorption parameters, the “batch” experiment was performed. The interpretation of the sorption phenomena was carried out using Henry, Langmuir, and Freundlich isotherms.

Recent studies reveal that ice formation via vapour-ice desublimation in unsaturated freezing soils can lead to damage to infrastructures. Actually, the role of vapor flow in a freezing soils is unclear, and it is usually ignored when analyzing water migration process. In this study, a theoretical framework is established to formulate the coupled thermal and hydrological process, where the vapour diffusion governs the mass transfer process. The new model is designed to avoid using the local equilibrium assumption and the hydraulic relations that accounts for liquid water flow. This model contains 6 undetermined variables that are interacted in the 6 governing equations. In order to validate the numerical formulations/codes, a series of laboratory experiments are performed on a coarse sand which is not considered as frost susceptibility soil. The computed results show that the proposed model can indeed reproduce the unusual moisture accumulation observed in relatively dry soils, while the result agree well with the experimental date. This model provides an explanation for coupled movement of heat and moisture in cold and arid regions.

Sodium bentonite (NaB) commonly is used in engineered barriers due to the advantageous properties of the bentonite for waste containment, such as high swell, low hydraulic conductivity, and low diffusion coefficients. However, the sensitivity of NaB to chemical incompatibility has motivated development of enhanced bentonites, such as bentonite polymer composites (BPC), for improved chemical resistance and superior barrier performance. Although recent studies have indicated that BPC may maintain lower values of hydraulic conductivity (k) than NaB when exposed to solutions with high ionic strength and/or concentrations of multivalent species, data to compare diffusion performance remains limited, even though diffusion is a significant contaminant transport mechanism in clays for the reported values of $$ k( < 10^{ - 9} {\text{m}}/{\text{s}}) $$ . Therefore, the goal of this study was to measure diffusion through BPC and NaB specimens using a series of dialysis-leaching tests and potassium chloride (KCl) solutions ranging in concentration from 0 to 200 mM. Apparent diffusion coefficients, Da, for chloride (Cl−) for the BPC increased from 1.1 × 10−12 m2/s to 1.1 × 10−9 m2/s as the average concentration of Cl− in the specimen (Cave) increased from 25 to 211 mM, These results were consistent with trends reported in a previous study based on the through-diffusion test method. The Da values for NaB increased from 3.3 × 10−12 m2/s to 1.4 × 10−9 m2/s as the Cave for Cl− increased from 5.6 to 177 mM, which was consistent with expectations based on diffuse double-layer theory. Similar values of Da were measured for chloride for both NaB and BPC, indicating equivalent diffusive performance of the two materials for strong monovalent solutions.

Biochar studies for environmental applications becoming more and more widespread. Biochar of banana peel (BPB) and orange bagasse (OBB) produced at 400 and 600 °C were characterized and studied the sorption of the ammonium from a landfill leachate and monosolution. The characterization show a alkaline pH for all biochars produced. The BPB shows high concentration of mineral elements, indicated by a high electrical conductivity and special the K. The total Carbon show values around 50% for BPB and 70% for OBB. For the monosolution, the BPB showed slightly higher sorption capacity than the OBB, with 1000 mg/L, about 12 mg/g, and the OBB about 6 mg/g. The same trend was observed for those produced at 600 °C, used in the leaching tests, with BPB 600 °C showing better sorption capacity. The isotherms were better adjusted by Freundlich for all samples. The sorption results shows the influence of feedstock and that the pyrolysis temperature with BPB carbonized at 600 °C showing the greatest sorption capacity. The research showed promising results for the use of these biochar as leaching treatment.

Light non-aqueous phase liquid (LNAPL) has high toxicity and exists in a large number of petroleum-contaminated sites, while the heterogeneity of natural media and changes in hydrodynamic conditions make the migration of LNAPL more complex in the subsurface. Especially during the implementation of groundwater pumping, treatment and recharging remediation project, due to the heterogeneity of aquifer media, it may cause pollutants in groundwater to accumulate in porous media due to changes in groundwater flow, velocity, groundwater level, etc. The place with a large amount of aggregates can form a free phase LNAPL; After the “pumping, treatment and recharging” of groundwater is stopped, pollutants in the porous media are released into the groundwater, and when the free phase LNAPL disappears, the concentration of pollutants in the groundwater “rebounds”. Understanding the seepage, retention and distribution of LNAPL in heterogeneous porous media is the precondition for effective removal of LNAPL pollution in underground water - containing media. This paper analyzes the characteristics of precipitation, migration and occurrence of free phase LNAPL in groundwater are analyzed by pumping test, recharge test and pull-recharge test. Finally, it determines the formation mechanism of free phase LNAPLs and the mechanism of migration and transformation from the distribution rule of pollutants, roof elevation change of saturated layer, the difference of adsorption ability of different lithology to pollutants, the variation of groundwater flow field under the condition of hydraulic disturbance and hydraulic disturbance, etc., which is of great practical significance to study the risk control and restoration of petroleum contaminated sites, especially the contaminated aquifers.

In order to investigate the influencing flow factors in the process of soluble contaminant transport and analyze the seepage velocity regularity of sand with different particle size distribution. This article made a series of indoor tests, in which single hole tracing method based on the dilution method was used to measure the seepage velocity of sand. Six kinds of different particle size distribution of sand were used as research objects. The tracer was placed in the observation hole in the sand to mark the water and simulate the migration of soluble pollutants. Divided into different particle size distribution of sand is primarily performed by coefficient of uniformity and coefficient of curvature. The results show that the logarithmically measured test data in the observation hole is linearly and negatively correlated with the time, and the percolation velocity increases linearly with the increase of the head. There are obvious and definite differences between the calculated seepage velocity and the measured seepage velocity of each sand sample. Considering that the difference is related to the basic properties of the sample, a correction coefficient γ is introduced to correct the formula for calculating the seepage velocity in the single-hole tracing method.

Cesium-137 is a radioactive element that could be released within the byproducts of a nuclear power plant. Breakthrough curves obtained from a column test are commonly used to simulate the in situ transport process in case of a leakage, and to obtain key parameters such as coefficient of distribution (Kd) and retardation factor (Rd). Four existing methods, which vary by complexity, theoretical soundness and easiness to implement, were used to extract Kd and Rd values. Breakthrough curves of cesium cation migrating through saturated and unsaturated soil column from previous literature were analyzed and compared. Preliminary results suggest that in fully saturated condition, the closeness of Rd values derived by above-mentioned methods decrease as the Peclect number decreases. In unsaturated condition, however, immobile water around the dead end pores could induce different results of one-region model and two-region model.

The reformative EDI (electrodeionization) technology was shown to be a useful tool as a newly designed permeable reactive barrier (PRB) system in this study. In the PRB, ion exchange resins was employed as adsorption and biological denitrification media under the action of electric field, which can break water forming dissolved oxygen and H+ and OH− ions simultaneously. Ions like $$ {\text{NH}}_{4}^{ + } $$ can be accumulated and then oxidized to $$ {\text{NO}}_{3}^{ - } $$ in the concentrated compartment, and the $$ {\text{NO}}_{3}^{ - } $$ produced together with $$ {\text{NH}}_{4}^{ + } $$ could be biologically de-nitrificated. For obtaining a high standard effluent, the multistage operation of the PRB device was adopted, satisfactory accumulation and denirification performance were presented. The results show a promising application prospect of the system in treating groundwater pollution.

This study describes pot experiments conducted to investigate the effect of enhanced phytoremediation on a mixed contaminated soil extracted from a historically polluted site. The site soil was contaminated with a mixture of Pb, Cr and PAHs. A part of the soil was amended with yard waste compost. Pots were filled with the soil and phytoremediation experiments were conducted using oat plant (Avena sativa) and sunflower (Helianthus annuus) over two months. Plants grown in unamended pots were used as controls. The germination, survival and biomass of the plants were better when planted in the compost amended soil compared to the control soil. Soil Pb content was not affected by the presence of plants or by soil amendment. Cr removal was achieved by both plant species in amended and unamended soil. Soil PAH degradation did not show any noticeable trend in the presence of plants or compost amendment. The results suggest that phytoremediation of soil in combination with compost amendment is a promising remediation technology for mixed contaminated sites with aged contamination. Comparison of the present results with the results of previous experiments on spiked soil showed that the behavior of contaminants varies for historically contaminated soil and laboratory spiked soils.

The use of agro-based waste materials in treatment zones for removal of heavy metals from the aqueous phase by adsorption represents a low-cost and possibly effective remediation alternative. In this study, the adsorption of lead (Pb2+) on a rice-husk residue was tested in different experiments with initial 100 mg Pb2+/L, initial pH values of 3, 5, or 7, and solid:liquid ratio (mass basis) of 1:20. In some experiments pH was allowed to vary, whereas in other experiments pH was kept approximately fixed. For the experiments with variable pH, Pb2+ was most adsorbed (93%) in the test where pH increased from 3 to 5.1, and least adsorbed in the test where pH decreased from 7 to 6.4. The point of zero charge of the rice husk was determined to be pH 4.5. For the experiments with fixed pH, the optimum pH for Pb2+ adsorption (95%) was found to be pH 5, and the test at pH 3 removed 67% of the initial Pb2+. The results allowed to grasp the significant effect pH control plays on Pb2+ adsorption, and the relevance of studying the factors that control pH during Pb2+ adsorption in a field application (in-situ treatment zone).

A series of Pb and Cu contaminated silty soil columns were made to simulate contaminated site, and ethylenediaminetetraacetic acid disodium saltdihydrate (EDTA) was used to flush contaminated soils. The concentration of Na+ and heavy metal concentrations were considered to study the removal behaviors of heavy metals. Studies show that the existence of Na+ inhibits the removal efficiency of both Cu and Pb from contaminated silty soils. The inhibitory effect of Na+ on Cu removal efficiency becomes smaller when increasing the concentration of Cu, and removal ratio of Cu is decreased by 25.8–39.0% when the concentration of Na+ is 100 mg/kg. The inhibitory effect of Na+ on Pb removal efficiency becomes stronger when increasing the concentration of Pb, and removal ratio of Pb is decreased by 10.1–29.4% when the concentration of Na+ is 200 mg/kg. The removal difference caused by different concentration of Na+ is not that obvious as increasing the concentration of heavy metals in contaminated soils. The results can provide some theoretical basis for in situ soil flushing to remediate heavy metal contaminated soil.

The shear characteristics of typical petroleum hydrocarbon contaminated soils are investigated by electrical detection in this paper. Kerosene was used and the concentrations are at selected level of 0, 2%, 4%, 6%, 8%, 10% (weight ratio) respectively. Direct shear tests were used to investigate the influence of kerosene on shear characters of soil samples. It is found that with the addition of kerosene, shear strength, cohesion, and friction angle of contaminated soils are smaller than uncontaminated samples. The higher concentration of kerosene penetrated in soils, the smaller of these characteristics of contaminated soils were observed. In addition, electrical resistivity with the same status of strength tests were measured. Results show that there is an increasing tendency of resistivity with the increase of kerosene concentrations in soils. It is found that, under fixed compactness and saturation, shear strength of oil-contaminated soils decreased with the increase of resistivity, indicating that the resistivity can be used to evaluate the shear characteristics of petroleum hydrocarbon contaminated soils.

This paper presents a comprehensive investigation of chemical properties, including soil pH, acid neutralizing capacity, metal leachability and chemical speciation, of a Zn, Pb and Cd contaminated site soil stabilized by KMP. The results show that the KMP stabilized soils have lower pH and higher resistance to acid attack than the untreated soil; the KMP is effective in reducing the metal leachability and changing the metal speciation, and the corresponding leached concentrations significantly below their regulatory limits; furthermore, lower acid soluble fraction contents contributes to the lower metal leachability in contaminated soils.

The physical and chemical performances of stabilised/solidified contaminated model soil were investigated to reveal the benefit of stabilisation/solidification treatment using novel binders over conventional binders. Different combinations of binders selected from materials including Portland cement (PC), ground granulated blastfurnace slag (GGBS), pulverised fly ash (PFA) and magnesia (MgO) were mixed with contaminated soil, the water/cement (w/c) ratio at 0.5:1 was used in this study. The strength and the leaching properties of these mixes via the unconfined compressive strength (UCS) test and the batch leaching test are presented. The immobilisation degree under different mixes and strength difference under two w/c ratios are discussed. The results show that although less binder dosage was applied in mixes with a w/c ratio at 0.5:1, all these mixes produced higher UCS values than mixes with a w/c ratio at 1:1 (the ratio used in the field taken from previous studies). Moreover, the leachate concentrations of Ni, Cu and Zn in all mixes were far below their drinking water standards at 0.02 mg/l, 2 mg/l and 3 mg/l, respectively. Although most mixes cannot meet the regulative requirement of immobilising Pb, the Pb immobilisation degrees of MgO-based mixes (>99.95%) were found higher than PC-based mixes (98.8%).

Effective diffusion coefficient and partition coefficient are essential parameters to quantitatively assess the adverse impact of contaminated or stabilized soil on surrounding environment. In this study, a new method is developed to back-calculate the effective diffusion coefficient and partition coefficient of contaminants in the stabilized soil. Furthermore, the migration characteristics of Pb, Zn and Cd in a novel phosphate-based binder stabilized soil are investigated. The test results show that the effective diffusion coefficients of Pb and Zn (8.5 × 10−13 m2/s and 7 × 10−13 m2/s) in the stabilized soil are significantly lower than that of Cd (1.5 × 10−12 m2/s). While the partition coefficients of Pb and Zn (8200 mg/L, 4500 mg/L) are significantly higher than that of Cd (2100 mg/L).

Huge amount of excavated rock is generated in tunnel construction for roads and railways. The excavated rock contains toxic trace metals and/or metalloids at the same level or slightly higher than background level. Our previous studies showed that in the column leaching test, the amount of arsenic leached from the excavated rock till the arsenic concentration was steadily below 0.01 mg/L was comparable with the amount of the first two arsenic fractions in the sequential extraction. In this study, the leachable arsenic fraction was removed from the excavated rock (mudstone) sample in order to obtain the excavated rock sample which artificially undergoes the leaching process. The column leaching test using the leachable-arsenic-arsenic-fraction-removed sample shows the behavior of arsenic leaching was different depending on the samples. They decreased from 66% to 31% of summed amounts of F1 and F2 arsenic fraction in the sequential extraction, respectively.

Solidification/stabilization (S/S) has been considered as one of the most effective techniques for remediation of the heavy metal-contaminated sites. Among various binders adopted in S/S, soda residue is extensively accepted and investigated due to its strong adsorptive capacity for heavy metal ions. In this paper, the engineering properties of the high concentration zinc-contaminated soil solidified/stabilized by soda residue blended with cement have been investigated. Test results showed that the unconfined compressive strength (UCS) of the treated specimen increased with the increase of the soda residue content and the curing time. A higher UCS can be obtained for specimens with lower zinc concentration. In toxicity characteristic leaching procedure (TCLP) test, the concentration of the leached heavy metal ions decreased with the increase of the curing time. Results of UCS and TCLP illustrated that cement-soda residue stabilized zinc-contaminated soil satisfied the standard of strength and leachability when the mass ratio of cement to soda residue was 2 to 8. X-ray diffraction (XRD) analysis obviously showed the formation of the hydrated products such as CSH, CAH and Aft. Zinc ions can be immobilized by precipitating as Zn(OH)2 or incorporating with hydrates to form CaZn2(OH)6H2O.

Solidification/Stabilization (S/S) with binders is an established remedial approach to reduce the mobility of organic and inorganic contaminants and simultaneously improve the geotechnical properties of soils, sediments and a variety of waste materials.This paper presents the results of a design treatability testing program for the S/S treatment of acid organic waste associated with the remediation and closure of four waste impoundment units at a former chemical manufacturing facility. S/S was selected as the most appropriate technique to improve the compressive strength and reduce the permeability of the waste and reduce the leachability of a complex suite of organic constituents of concern. A variety of mix design formulations were evaluated to implement a two-step treatment process consisting of a neutralization treatment of the acidic waste, followed by S/S treatment.

Resistivity CPTU, as the development of standard CPTU, has the advantages of being able to obtain in-situ continuous data and has a good practical application prospect. This paper takes a contaminated site of Shanghai Dye Chemical eight plants as the research background and indicates the accuracy of RCPTU test results according to RCPTU experimental data and the traditional laboratory test data analysis.

The present research is concerned with the abatement of dye contamination in groundwater due to certain dye molecules such as Eriochrome black – T (C20H12N3O7SNa, EBT), Calcon carboxylic acid (C21H14N2O7S, CCD) and Calcon (C20H13N2NaO5S, CD) using Titanium encapsulated aluminosilicate microspheres (TiAS300 and TiAS500). Removal efficiency of dye as a function of synthetic dye solutions (EBT, CCD and CD) at various concentrations separately and in the form of 1:1, 2:3 and 3:2 mixtures was investigated at an optimized pH 3 for an equilibrium time of just 20 min. The dye uptake of Ti encapsulated aluminosilicate (AS) microspheres was more efficient than that of virgin AS microspheres by 18 times. The performance of TiAS300 and TiAS500 in the presence of other interfering anions such as nitrate, fluoride and sulfate was quite promising. It was apparent that the use of thermally regenerated adsorbent had to be more in quantity depending upon the cycle number for the complete removal of EBTD as compared with the freshly used TiAS quantities. The characterization studies such as SEM and XRD for the virgin, EBTD loaded and thermally regenerated adsorbents were done. The various stretching frequencies of groups present in the adsorbent materials were confirmed by FTIR. The morphological change from mullite to sillimanite during the loading process and distortion of spherical morphology in Titanium encapsulated ASMS due to hydrothermal process at 300 °C and 500 °C were well ascertained by XRD and SEM studies.

In this study, the equations for electrochemical impedance characteristics, including Nyquist diagrams and Bode chart, of contaminated soils was obtained by using soil mechanics, chemical, electrochemical and microscopic analysis. The analysis is implemented in light of the relationship between mineral composition, microstructure, macro-performance and electrochemical characteristics of contaminated soil. The parameters for physical, mechanical and electrochemical properties were then obtained based on the EIS characteristic. By theoretical EIS analysis, the relationship between electrochemical properties (electrolyte resistance, charge transfer resistance, electric double layer capacitor and diffusion resistance coefficient) and soil properties (the mineral compositions, moisture, soil microstructure, pore distribution and soil strength) was determined. As a result, the equivalent circuit model and corrosion evaluation system for the contaminated soil were established, which can evaluate the soil contaminations and provide advices on electric double layer, electrode material, solid electrolyte and corrosion protections of metallic materials embedded in the soils. It also provides important engineering data and scientific basis for evaluation of ecological suitability, which has significant economic and social benefits.

ZSM-5, as a hydrophobic zeolite, has a good adsorption capacity for MTBE in batch adsorption studies. This study explores the potential of ZSM-5 as an adsorbent for MTBE in a laboratory scale fixed-bed column study. A series of column tests were carried out to determine the breakthrough curves and evaluate the adsorption performance at different bed lengths. Logit method, Adams-Bohart model, Yoon and Nelson model and Dose-Response model were applied to fit the experimental data in order to predict the breakthrough curves and determine the adsorption kinetics of MTBE onto ZSM-5 in the fixed-bed columns. Dose-Response model was found to best describe the breakthrough curves and the maximum adsorption capacity increased with the increase of bed length. In addition, ZSM-5 can be thermally regenerated at 80 °C and the MTBE removal percentage still remained at >85% after 4 regeneration cycles.

Recent implementation of environmental geophysical exploration technique in rapid detection and evaluation of soil contamination is widely involved. Typical soil contaminants tend to alter the pore fluid and hence the variation of soil electrical properties, the transmission path of electrical currents or electromagnetic waves may be affected within the contaminated region. This in turn provided the detection basis of the electrical and electromagnetism geophysical methods. As contaminated soils consisted of composite materials of three or four phases, the relationship between their electrical properties and water content, porosity, contaminant concentration are relatively complex. The demand for a wide electrical spectral range has hence arisen for contaminated soil characterization. This study proposed an innovative time domain reflectometry (TDR) approach, in order to measure a broadband complex dielectric spectrum (including both real and imaginary parts of complex dielectric permittivity, CDP) within MHz–GHz frequency range and to perform a more complete electrical characterization of contaminated soil. The robustness, in-situ applicability, and performance of the proposed method is verified using series of laboratorial and in-situ experiments, involving various contaminants. The measurement system can be setup, calibrated, and operated easily, holding great potential for better hydrophysical and environmental characterization of soils.

This paper introduces the Malaysian Contaminated Land Management and Control Guidelines and one case study on Environmental Site Assessment (ESA) conducted at one contaminated site in Malaysia. The site was contaminated with spent transformer oil, i.e. Total Petroleum Hydrocarbons (TPH). Five types of environmental samples were collected, i.e. surface soil, surface water, subsurface soil, groundwater and air. Samples were analysed for Total Petroleum Hydrocarbons (TPH) and fractioned into different carbon fractions namely C6-C9, C10-C14, C15-C28 and C29-C36. Risk Assessment was also performed utilising Risk Based Corrective Action (RBCA) method. The drilling bore-log showed that the site is located on residual weathered meta-sediment rock with thick clayey silt. The study discovered the spent oil was trapped inside the made layer gravel within ~22 to 60 cm on top of the residual clayey silt. Chemical results showed TPH in surface soils ranged from 1310 to 26747 mg/kg with the average value of 17200 mg/kg. In surface water (inside the contaminated area), the concentration of TPH was measured in between of 1 to 2646 mg/L (averaging 454 mg/L). RBCA analysis showed that indoor and outdoor air were the pathways with lower risk level with all risk values (Hazard Quotient, HQ) below the upper limit of 1.0. Baseline risk level for soil is slightly higher than the upper limit level with a risk of 1.5. Critical pathway is through groundwater with baseline risk level significantly higher than the upper risk level with a value of 5.4E+6.

This paper focuses on the issue of two-dimensional hydrodynamic dispersion of soluble pollutants in soils and by doing indoor tests, some meaningful results are obtained: (1) When the void ratio is the same and the hydraulic gradient is similar, the dispersion rate of pollutants in the heterogeneous soil is much faster than that in the homogeneous soil; (2) In both homogeneous and heterogeneous soils, the longitudinal dispersion coefficient and the transverse dispersion coefficient are both linearly related to the flow velocity; (3) The heterogeneity of material can amplify the scale effect of dispersivity.

The present note discusses some laboratory complexities linked to the geotechnical characterization of the soft polluted sediments sampled down from the Mar Piccolo, i.e. a marine basin located within the urban area of Taranto (south of Italy), for which the environmental remediation has been identified as a national priority. The long-lasting industrial activities, together with the waste collection from the densely populated urban center of Taranto, have been responsible for the severe environmental contamination of the Mar Piccolo. In the field of the remediation and management strategies promoted by the Italian Government, a multidisciplinary investigation has been carried out to achieve the chemical, geological and geotechnical characterization of the sediment in the basin. With this purpose, the standard procedures and equipment for geotechnical testing were properly modified to both minimize the soil disturbance and to take account of the influence of both the pore fluid salinity and the presence of organic compounds, shells, mussels and lapideous elements or industrial waste in the soil.

Between July 2001 and February 2002, a waste, classified as inert, was transported from the Portuguese Iron and Steel Company facilities located in Maia, where it had been stored from 1976 to 2001, and dumped on the spoils of an old coal mine in Sao Pedro da Cova, close to Oporto. In 2010, LNEC- Laboratorio Nacional de Engenharia Civil (National Laboratory for Civil Engineering) studied the waste disposal to reassess its hazardousness. The results obtained showed that the waste was hazardous and, therefore, its removal to a hazardous waste landfill was necessary given the risk to the public health and the environment. In this paper the actions developed during the phases of site investigation of the waste disposal and environmental rehabilitation are presented. These actions include boreholes, waste and subsoil sampling, laboratory tests (physical, chemical and environmental), waste removal, and evaluation of the contamination of the subsoil underlying waste disposal. This characterization showed that the migration of the pollutants from waste to subsoil was not very significant after being in contact for about twelve years.

The objective of this study was to investigate methods of identification and quantification of potentially contaminated sites and the definition of one them for its application in the city of Erechim, State of Rio Grande do Sul, Brazil. For this research, national and international identification methods were consulted through a systematic bibliographic review. The compilation of data allowed the selection of the method developed by Company of Environmental Sanitation Technology of the State of São Paulo (CETESB), as it presented the largest number of steps for the identification process. The city of Erechim was selected because it presented industrial activity as the fastest growing sector. The application of the method allowed identification of 366 potentially contaminated sites, as well as the elaboration of a map with the location of areas. Finally, it was also noticed the need for greater public attention on the management of potentially contaminated sites, since there is still no consolidated structure responsible for the subject.

Nutrients enter into lakes through point and non-point sources are finally settled in bottom sediments where they accumulate and eventually release back into the overlaying water. Sediment phosphorus release is one of the main reasons for eutrophication in many shallow lakes around the world. This present study examines sediment samples collected from Lake Johanne, a shallow, meso-eutrophic lake, and its neighboring wetland, to which the lake inlet is opened, for sediment phosphorus concentration and its speciation to understand the potential of sediment phosphorus to release into the lake water. Speciation of the sediment phosphorus was performed according to the SMT sequential extraction technique. The sequential extraction technique allowed extraction and quantification of different forms of phosphorus in the sediment as follows: (i) non apatite inorganic phosphorus (ii) apatite inorganic phosphorus, (iii) organic phosphorus and total phosphorus. The lake sediment and water quality were also monitored in terms of heavy metal concentrations.

Non-aqueous phase liquids (NAPLs) are persistent sources of contamination in the ground, providing a long-term supply of dissolved phase contamination and taking significant periods to dissipate naturally. Light NAPLs (LNAPLs) take the form of a separate phase within the ground, often as individual ganglia in pore spaces within the capillary zone such that the contaminated region is diffuse and comprised of many unconnected small contaminant sources. Consequently, remedial action is challenging and success may be limited to ex-situ remediation techniques. The ability of plants to phytoremediate dissolved-phase contamination is well known, but the impact of LNAPLs on plant growth and subsequent contaminant behaviour is largely unknown. Experimental work with ryegrass (Lolium perenne) is presented, exploring the impact of the physical presence of an LNAPL (mineral oil) on plant growth, root distribution and oil removal. The presence of the oil was found to significantly impact root biomass and distribution, leading to zones of increased root growth alongside decreased shoot growth. Significant removal of the LNAPL was noted in both hydroponic conditions and planted soil.

Micro-nano-bubbles (MNBs) technique is a novel technology for remediation of organics-contaminated groundwater. MNBs are tiny bubbles with diameter less than 100 µm, and able to stay stable in water for extended periods of time. Ozone is a strong oxidant which is widely used in wastewater treatment, and ozone MNBs presented high mass transfer efficiency. They can migrate with groundwater flow to reach large affecting area, and efficiently provide dissolved ozone to oxidize organic contaminants in groundwater. In this study, the ozone MNBs were used for groundwater remediation at a trichloroethylene (TCE) contaminated site in Japan. Groundwater was extracted by the extraction well, and pre-treated to remove soil particles and TCE. Ozone MNBs were generated inside the water. H2O2, which can significantly accelerate the oxidation of TCE by ozone, was also added with a mass ratio of ozone: H2O2 of 1:1. Water containing oxidants was injected back into the site through an injection well. The treatment was conducted from 9 am to 6 pm for six days, and groundwater was sampled from monitoring wells to monitor distribution of TCE concentration. The concentration of TCE in groundwater showed significant reduction during the treatment, and an overall removal of 99% was reached after six days. The final TCE concentration in the treated area decreased to below the local permissible limit, and this field application of ozone MNBs presented an efficient new technology for organics-contaminated site remediation.

Environmental conservation and post-closure land use are important considerations in seashore MSW landfills. A system consisting of a drainage layer and thick soil cover installed over a waste layer is considered an effective measure for the containment of waste leachate and post-closure land use. In this study, the effectiveness of such a system of drainage layer and thick soil cover was evaluated via laboratory experiments and numeral analysis. Laboratory experimental results indicated that water discharged through the drainage layer achieves satisfactory quality, as waste leachate can be properly contained in the waste layer owing to the function of the drainage layer. Numerical analysis also revealed the effectiveness of the drainage layer in containing waste leachate. The proposed system is expected to perform satisfactorily in terms of leachate containment and post-closure land use.

The development of convenient and effective permeable reactive barriers (PRBs) for groundwater remediation is of highly interest. Self-powered removal of phenol using a redox fuel cell as a feasible PRB reactor system was presented in this work. This system can employ Fe species in water with a high oxidation state Fe(III) acting as an oxidant in the cell, and Fe(III) can be easily regenerated by the oxidation of Fe(II) by oxygen. The results showed that the open circuit potential (OCP) was 0.39 V, and the maximum power density of the cell is 312 mW m−2 with the current density of 1669 mA m−2 in phenol-Fe(III) cell. Meanwhile, the degradation of phenol was observed. Furthermore, in order to test cell’s performance conveniently, phenol-Cr(VI) cell was assembled due to much toxic and highly oxidizing Cr(VI). The absolute removal amounts of Cr(VI) and phenol were 298 mg L−1 and 528 mg L−1, after ca. 60 h running, respectively. It is expected that the self-powered pollutants removal system could be a promising candidate for the application of PRBs in groundwater remediation.

In this study, a series of tests are conducted to investigate the performance of monopotassium phosphate (MKP) activated basic oxygen furnace slag (BOFS) to stabilize a lead, zinc and cadmium-contaminated smelter industrial soil. Various mass ratios of MKP to BOFS are used to activate BOFS slag in order to explore the optimum MKP/BOFS ratio. Meanwhile, the influences of preparation and activation conditions of the BOFS slag are also investigated. The soil pH and leachability properties of the stabilized soil are used to evaluate the activation effectiveness of BOFS slag. The test results show that the leachate concentrations of Pb, Zn and Cd are significantly reduced with the addition of MKP activated BOFS and the optimum MKP/BOFS ratio is 2–4%. The mixing method has a remarkable influence on the immobilization effectiveness of heavy metals, and the activated BOFS obtained from wet mixing is found to possess superior performance. It is also found that the drying temperature has little influence on the immobilization effectiveness of heavy metals.

The technology of chemically improvement of soil properties is a widely accepted approach. It is also economically viable to increase the strength of soil as well as to limit water absorption, control soil erosion and soil settlement. Encountered extensively in wetlands, fibrous peat is considered as problematic organic soil because it exhibits low compressive strength. It is generally estimated that there are around 30 million hectares of tropical land covered with highly organic soil throughout the world, out of which about 3 million hectares lie in Malaysia. The present study aimed to investigate the effect of liquid polymer as a non-traditional soil additive which namely as SS299 in peat improvement. The influence of different concentration of selected additive (1%, 2%, 3%, 4% and 5%) were investigated on compressive strength improvement of unsoaked and soaked tropical peat samples by using unconfined compressive strength (UCS) tests. In addition, the morphology changes of treated samples were assess using field emission scanning electron microscopic (FESEM) tests. The results indicated that the SS299 soil additive is able to significantly increase the unconfined compression strength of selected peat.

The migration behaviour and long-term distribution of Light Nonaqueous Phase Liquids (LNAPLs) are greatly influenced by the geological conditions of the sites. In order to investigate the influence of geological heterogeneity on it, the migration process of LNAPLs in a two-dimensional site was numerically studied in this research. Typical conditions including one homogeneous soil layer, multi-layered strata and lens of clayey soil were specially considered. Calculation results indicate that the contour map of the mass ratio of LNAPLs gradually develops from a circular area into an umbrella area if it is leaked from a point source such as underground storage tank. Once the contaminant front of the LNAPLs arrives at the margin of the capillary saturated zone, their horizontal migration distance reaches the maximum value. When lens of low permeability soil area exists, it can effectively prevent the downward migration and promote the horizontal migration of LNAPLs. In the case of multiple sand layers, the migration behaviour of LNAPLs is mainly affected by the permeability of each layer of sand. Lower permeability soil layer will not only slow down the vertical movement of LNPLs, but also promotes their horizontal migration. Such results may help to scientifically design the vertical barriers and determine the optimum soil vapour extraction systems according to the geological heterogeneity of the real sites.

To understand the enrichment ability of plants to heavy metals in Jinchuan mining area, the contents of heavy metals (Cu, Pb, Zn and Ni) in soil and native plants were analyzed, respectively. The results showed that the soil heavy metal pollution near the tailings dam and waste slag pile was serious. The content of Pb and Zn in most plants in the study area was higher than that of Cu and Ni. The highest concentrations of Pb and Zn were in plants of Salsola passerina Bunge (SPB) and Halogeton glomeratus (HG). Through cluster analysis and correlation analysis, and combining ability of absorption, enrichment of heavy metals by plants, plant biomass, such as the overall situation, HG, Arnebia guttata Bunge (AGB) and Peganum harmala Linn. (PHL) were relatively appropriate for the local heavy metal pollution treatment.

We present a feasible method to evaluate the ability of ground penetrating radar (GPR) to detect underground oil contaminated areas. An in-situ simulation of the process of underground oil pollution was conducted and GPR was used for 180 consecutive days. Based on detection results, deductions were made regarding the abnormal GPR characteristics collected during the degradation process and the factors influencing these anomalous GPR results. A contaminated area determination method and an oil content analysis method were also developed using GPR results. Results indicated that the oil contaminated area was abnormally characterized by a high-amplitude wave during the initial stage of degradation. In the first 20 days, the ratio of the maximum amplitude and the initial amplitude remained between 0.7 and 0.8. After the 20th day, the ratio reduced, and it reduced to 0.1 after 120 days, which was below a detection level. In addition, the water content in the soil had a large effect on the anomaly; the higher the soil water content, the clear the abnormal characteristics of oil pollution. The area of the abnormal zone was well described using the time-slice method, which is indicated by the amplitude ratio and GPR energy at different positions at the same time. Finally, there was a positive correlation between soil oil content and GPR amplitude, but no quantitative relation was constructed between the two.

The problem of organic pollution of soil and groundwater is becoming more and more serious. In this paper, methyl orange was selected as the representative to carry out the test of removing organic pollutants from sandy soil foundation with ozone micro-nano bubbles. The test results show that the removal rate can reach more than 99%, and the ozone micro-nano bubbles have strong oxidation capacity. Micro-nano-bubble technology can achieve a good repair effect. In the field of environmental pollution control, technology for in-situ repair of micro-nano bubbles has obvious advantages, which is expected to make the in-situ restoration of organic pollution of soil and groundwater more direct, efficient and thoroughly.

The in-situ chemical oxidation (ISCO) is an effective technology for the remediation of organic contaminated groundwater. However, the requirement of adding oxidants, e.g. persulfate or H2O2, externally obviously reduces the economical efficiency of the overall treatment process. The method of in-situ generation of oxidants can avoid the disadvantage of conventional ISCO. Herein, our study indicates that the active chlorine can be effectively produced in a permeable reactive barrier (PRB) reactor, i.e. PRB-type two-compartment electrochemical device under the electric field. COD, i.e. chemical oxygen demand, as an indicator of organic pollutants in water was degraded by the in-situ electrogenerated active chlorine through the electrolysis of NaCl solution. The amount of COD removed in the anode chamber was 104 mg/L after operating the two-compartment device at 7.0 V for 12 h under the given working conditions, and COD detected in the cathode chamber was near zero, meaning all COD is removable in effluent. The results show that the in-situ electrogeneration of oxidants technology can provide a promising option for the treatment of groundwater organic pollutants.

Soil vapor extraction (SVE) has been one of the most widely used technologies for remediation of volatile organic compound contaminated sites. However, it is found that various environment factors may have quite different influence on the final remediation effect. In order to learn the influencing factors which affect the removal efficiency of toluene-contaminated sandy soils by SVE method, a series of one-dimensional SVE column tests were conducted. The factors such as grain size, air flow rate and water content were investigated separately. The results indicate that: (1) grain size has a great influence on toluene removal efficiency. The finer the sand is, the lower the removal rate will be; (2) increasing the vapor flow rate will lead to higher contaminant removal efficiency, but the increment of remediation efficiency was not significant at higher flow rate levels; (3) At low water content level, the increase of water content will lead to the decrease of contaminant removal efficiency.

The objective of this study was to evaluate the toxicity of nZVI to the indigenous microorganisms of the soil. The toxicity of nZVI was assessed by the CO2 production for the soil native microorganisms. Different concentrations of nZVI were added to the soil (0, 4, 15 and 50 g/kg) for further analysis of the microbiological activity. For a better interpretation of toxicity effects, was used glucose (g/kg) as a carbon source. As soil mixtures, nZVI and glucose were inserted into sealed vials for an evaluation of the microbiological activity. The quantification of CO2 produced by the indigenous microbes respiration was performed by stoichiometry, using NaOH to absorb the gas and using HCl to determine the concentration. The analyzes were performed every 02 days, until a total monitoring time of 40 days. It was observed that at a concentration of 50 g/kg it has not released any carbon dioxide, demonstrating a maladaptation of the microorganisms under these conditions. The nZVI concentrations of 4 and 15 g/kg showed an increase of CO2 production, indicating an adaptation of the microorganisms as available conditions. Thus, the application of nZVI as remediation technology can be performed up to concentrations of 15 g/kg without causing damage to native soil microorganisms. However, applications above these may cause toxic and/or inhibitory effects to the microbes, restricting a possible combination of nano and bioremediation.