Leachability and Microstructural Analysis of Clay and Lime Stabilized/Solidified Polluted Sediment – Long-Term Performance (original) (raw)
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Zastita materijala
Sustainable and economically feasible polluted sediment treatment is gaining more and more importance. Stabilization/solidification (S/S) technologies are widely used for treatment of sediment and possibilities of using low-cost and readily available materials and binders are increasingly being examined. This work is concerned with aquairing more data about long-term performance of this kind of treatment in therms of metal leaching and microstructural cnaracterization when treating sediment with fly ash and lime. Extraction potential of metals and the effectiveness of the S/S treatment applied, together with compliance with national legislative, were performed by using Toxicity Characteristic Leaching Procedure-TCLP and The German standard leaching test-DIN 3841-4 S4. Leaching test results showed that the applied S/S treatment was effective in immobilizing metals even after seven years of aging. Scanning electron microscope (SEM) and X-ray diffraction analysis confirmed that pozzolanic reactions took place during 28 days and continued along S/S mixture maturation. Compressive strength measurement further proved the treatment efficacy in terms of obtained matrix stability, which enables their subsequent use. It can be concluded that the S/S technique, with the usage abundant materials has a significant potential for treatment of metal polluted sediment.
Leaching evaluation of cement stabilisation/solidification treated kaolin clay
Sustainable land management often requires redevelopment of existing and often contaminated Brownfield sites over use of Greenfield or agricultural land. Stabilisation / solidification (S/S) offer a viable remediation option with particular suitability in treating heavy metal contaminants. However, uncertainties over longterm durability and previously cheap landfill disposal costs resulted in limited use in many countries. There is a need to characterise treated material and assess components containment and release, to improve S/S confidence and inform remedial design, using the evaluation of the leaching controlling mechanisms. To improve understanding of key features that will enable improvements to such designs, this paper presents an evaluation of leaching for CEM II stabilised kaolin, using the leaching behaviour of 4 main components-aluminium, silicon, calcium and sulphur. Results show no detrimental implications on chemical durability due to kaolin degradation with hydration under induced alkalinity, with increased formation of stable cementitious minerals. Availabilities for components show that aluminium and silicon had minimal leachability compared to total content, whilst calcium and sulphur show almost total leaching availability. Decreasing calcium and silicon leachability under natural chemical conditions with increased hydration duration supports the increased formation of stable cementitious products with time, using the products of kaolin dissociation.
2011
The aim of this study was to investigate the effect of cement on the geotechnical properties of contaminated harbor sediments with the use of S/S technology Treatment techniques such as Solidification and Stabilization are becoming increasingly important in the contaminated land sector while they increase awareness of the environmental impact arising from its activities and resulting materials. This study was conducted on harbour sediments derived from Le Havre Harbour (France). The main objectives of this study were to determine the basic geotechnical and chemical characteristics of the harbour sediments, to mix harbour sediments with alcalosynthetic zeolites and ordinary Portland cement (OPC) at 5, 7.5 and 10 percent, by dry weight of the sediments, to determine the compressive strength of the stabilized sediments after curing for 7, 14 and 28 days and 90 days and to examine the leaching characteristics (in accordance with the norm EA NEN 7375:2004 protocol) of the stabilized material with emphasis to alcalosynthetic zeolites Heavy metal concentrations.
Land Contamination & Reclamation, 2005
Many chemical compounds and mixtures of compounds, because of their widespread use, and in some instances, persistent nature, have continued to accumulate in soils and sediments. Toxic contaminants in bottom sediments of lakes create the potential for continued environmental degradation. The process and techniques of stabilisation/ solidification (s/s) of polluted soils and sediments have matured into an accepted and important part of remediation technology. This paper gives an overview of s/s technologies and their mechanisms. The application of each of these methodologies to sustainable waste management is summarised.
Mineralogical study and leaching behavior of a stabilized harbor sediment with hydraulic binder
Environmental Science and Pollution Research, 2013
The environmental assessment of potential effects of contaminated harbor sediments stabilized with hydraulic binders and the determination of remediation endpoints require the determination of pollutants leaching potentials. Moreover, little information about the speciation and mobility of inorganic contaminants in these specific solid matrices is available in the literature. The objective of this paper is to investigate the relationship between mineralogy and leachability of contaminants (copper, lead, and zinc) present in a French harbor sediment stabilized with quicklime and Portland cement. Batch equilibrium leaching tests at various pH, chemical analysis of leachates, and mineralogical studies (X-ray diffraction, scanning electron microscopy-energy dispersive spectroscopy, and diffuse reflectance infrared Fourier transform) have been combined in the present investigation. The acid neutralization capacity of the stabilized matrix studied is first controlled by the dissolution of portlandite (pH~12), followed by the dissolution of C-S-H (pH~11) and the dissolution of ettringite (pH 10). Finally, a very high buffering capacity of this stabilized sediment is observed for pH values around 6. This equilibrium is mainly controlled by the dissolution of iron sulfides and carbonate minerals. Consequently, the mobilization of inorganic contaminants as a function of pH remains very low (<0.1 wt%) for pH values above 6 and significantly increases for pH below these values. This research confirms the importance of a combined methodology for the intrinsic characterization of potential mobilization of contaminants in a stabilized sediment and for a better understanding of geochemical processes that affect contaminant fate, transformation, and transport in the subsurface environment.
International Journal of Environmental Science and Natural Resources , 2021
Increased remediation of heavy metal contaminated soil is becoming attractive due to unprecedented degradation of soil systems. Therefore, sustainable remedial approach and the study of contaminant geochemistry are topical areas of intense research. In this study, clay minerals, a constituent part of the soil system has been evaluated as an underlying influence to soil cleaning. Two contaminated soils namely, Copsa mica (S CM) and Campina (S CP) sourced from Romania were subjected to leaching behaviour using two different chelating agents; ethylene diamine tetraacetic acid, (EDTA) and citric acid (CA) on a dynamic system configuration for the purpose of soil cleaning. Geochemical characteristics and metal quantification were conducted on the samples using x-Ray powder diffraction (XRD) and inductive coupled plasma-optical emission spectroscopy (ICP-OES) respectively. Results showed dissimilarity in metal leaching behaviour with higher percentage (four-fold) recovery observed for S CM more than S CP, regardless of extractants used. The presence of montmorillonite clay and other observed mineral oxides influenced the extraction of the targeted metals in S CP other than S CM-induced kaolinite clay.
Stabilization and recycling of contaminated marine sediments
E3S Web of Conferences
The paper deals with the treatment and reuse of submarine sediments, i.e. a relevant environmental issue due to the annual huge quantities of dredged sediments (over half contaminated) in Europe. In a vision of sustainability and circular economy, stabilization and solidification (S/S) treatments represent an interesting solution for both environmental protection and reuse of sediments in engineering works. The investigation involved polluted clayey sediments taken up to depths of about 1.5m from the seafloor of the Gulf of Taranto (South of Italy). The research investigates the effects of a treatment with cement and lime enhanced by the addition of green additives, such as active carbon and biochar, for chemical remediation. The last one is a promising and cheap adsorbent material, that is the by-product of - mainly - agricultural waste pyrolysis. The first results suggest that appropriate mix designs and curing times could allow the reuse of sediments by both improving their geote...
Solidification / Stabilisation of Pond Sediments of Union Carbide India Limited, Bhopal
2016
During the manufacture of carbamate type of pesticides at the Union Carbide India Limited, Bhopal, acidic waste water was generated. This was neutralised and disposed in solar evaporation pond. After evaporation, ponds were left with sediments containing mainly inorganic salts. Due to practical conditions and cost factors, various different treatment alternatives were not considered. Studies were attempted to adopt solidification / stabilisation technique to make blocks with the objective of reuse of blocks and to minimize leaching. Studies were carried out by mixing the sediment with various admixtures namely cement, lime and fly ash. Solidified blocks were subjected to aqueous leaching and compressive strength tests before and after leaching to assess the leaching potential and mechanical strength of the blocks respectively. The studies revealed that solidification / stabilisation technique with commonly available admixtures was not suitable to arrest the leaching and the mechanic...
Leaching of Heavy Metals from Contaminated Soil Stabilised by Portland Cement and Slag Bremen
Ecological Chemistry and Engineering S, 2022
Leaching behaviour is an important evidence of soil quality. The assessment of leaching of heavy metals from the contaminated soil is vital for environmental applications. However, leaching may differ in soil stabilised by various ratios of binders. In this study we measured leaching behaviour of soil contaminated by As, Cd, Co, Cr, Cu, Hg, Ni, Pb, V, Zn, methyl Hg, aliphatic compounds of hydrocarbons, polycyclic aromatic hydrocarbons (PAHs), polychlorinated biphenyls (PCBs) and dissolved organic carbon (DOC). To evaluate leaching of these substances we tested the effects of changed amount of binder (120 kg and 150 kg) and binder ratios (70/30 %, 50/50 % and 30/70 %) added to soil samples. Soil was dredged from several stations in Ostrand area, SCA Sundsvall Ortvikens Pappersbruk. The results demonstrated a systematically decreasing leaching with the increased slag. The contribution of this research include: (i) devising systematic approach to extract information on leaching from stabilised soil collected from the coastal area of Bothnian Bay, (ii) developing a workflow for stabilising soils by various combination of Portland cement Basement CEM II/A-V (SS EN 197-1) and ground granulated blast furnace slag (GGBFS), Bremen type (SS EN 15167-1), (iii) determining water ratio and density for the untreated and stabilised soil and performing comparative analysis, (iv) evaluating chemical content of pollutants and toxic elements in the aggregated soil samples. Treatment of the contaminated soil by binders improved its parameters by the increased strength and decreased leaching of heavy metals and toxic elements.
Leaching behaviour of sintered contaminated marine sediments
Fresenius Environmental Bulletin
Contaminated marine sediments from Cantabrian estuaries have been compacted and fired to produce sintered ceramic materials. The effect of sintering on the leaching behaviour has been investigated by means of the comparison of concentrations of species proposed by the European Waste Landfill Directive present in leachates and regulatory limits for them. The impact of the specimens on the environment is assessed.