Utilization of wollastonite, jarosite, and their blends for the sustainable development of concrete paver block mixes containing reclaimed asphalt pavement aggregates.

While several research studies considered the utilization of reclaimed asphalt pavement (RAP) aggregates for asphalt and concrete pavements, very few attempted its possible utilization for precast concrete applications like concrete paver blocks (CPBs). Moreover, few attempts made in the recent past to improve the strength properties of RAP inclusive concrete mixes by incorporating certain supplementary cementitious materials (SCMs) have reported an insignificant or marginal effect. The present study attempts to comprehensively investigate the utilization potential of some locally and abundantly available materials having suitable physicochemical properties to improve the performance of a zero-slump CPB mix containing 50% RAP aggregates. The studied filler materials, namely, wollastonite (naturally occurring calcium metasilicate mineral) and jarosite (hazardous zinc industry waste), were used to replace 5-15% and 10-20% by volume of Portland cement in the 50% RAP CPB mix. Apart from their individual effects, the efficacy of wollastonite-jarosite blends was also investigated. Considering the lack of indoor storage facilities and economic aspects of CPBs, the influence of water spray curing regime on the performance of the RAP CPB mixes was studied and compared to that of continuous water curing regime. Inclusion of the considered fillers was found to statistically and significantly enhance the flexural strength, tensile splitting strength, and abrasion resistance of the 50% RAP CPB mix; however, the compressive strength (in most cases), permeable voids, water absorption, and water permeability properties showed an insignificant improvement. Results of thermogravimetric analysis confirmed the occurrence of pozzolanic reactivity, and microstructure analysis revealed improvements in packing of concrete matrix and ITZ with filler inclusion qualitatively substantiating the improvements in strength and durability characteristics. The toxicity characteristics of heavy metals that may leach from the hazardous jarosite-based RAP CPB mixes were found to be within permissible limits. Based on the performance requirements specified by IS, IRC, and ASTM standards, all the RAP CPB mixes with filler inclusions fulfilled the acceptance criteria for heavy traffic applications, and water spray curing can enact as an alternate method for curing these mixes. However, to avail maximum performance benefits, it is recommended to use 5% wollastonite, 15% jarosite, and a combination of 10% wollastonite and 10% jarosite as a Portland cement substitute to produce sustainable eco-friendly RAP CPB mixes.

Biomedical waste generation at Ayurveda hospitals in South Asia: A mini review of the composition, quantities and characteristics.

Ayurveda hospitals generate biomedical wastes (BMW). However, details on composition, quantities and characteristics are very scarce, details which are important to formulate a proper waste management plan for subsequent implementation and continual improvement. Therefore, this article presents a mini review of the composition, quantities and characteristics of BMW generated from Ayurveda hospitals. Additionally, this article presents some best possible treatment and disposal procedures. Most of the information was gleaned from peer-reviewed journals, although some information was collected by the author and from grey literature available to the author; 70-99% (by wet weight) of the solid waste is non-hazardous; biodegradables contributing to 44-60% by wet weight due to more used Kizhi (medicinal bags for fomentation) and other medicinal/pharmaceutical wastes (excluding waste medicated oils, which is 12-15% of the liquid medicinal waste stream and are not readily biodegradable) largely derived from plants. The hazardous waste component includes infectious wastes, sharps, blood as pathological wastes (from Raktamoksha - bloodletting), heavy metal containing pharmaceutical wastes, chemical wastes and heavy metal rich wastes. Quantities of infectious wastes followed by sharps and blood form a major portion of hazardous wastes. Most of the infectious waste material contaminated with blood or other body fluids and sharps from Raktamoksha are very similar (appearance, moisture content and bulk density) to what is generated from hospitals practicing Western medicine. However, hospital-specific waste studies are required in future to better understand the sources, areas of generation, types, quantities and characteristics of BMW, and hence to formulate more accurate waste management plans.

Hazardous waste management (Buxus papillosa) investment for the prosperity of environment and circular economy: Response surface methodology-based simulation.

Dealing with the current defaults of environmental toxicity, heating, waste management, and economic crises, exploration of novel non-edible, toxic, and waste feedstock for renewable biodiesel synthesis is the need of the hour. The present study is concerned with Buxus papillosa with seeds oil concentration (45% w/w), a promising biodiesel feedstock encountering environmental defaults and waste management; in addition, this research performed simulation based-response surface methodology (RSM) for Buxus papillosa bio-diesel. Synthesis and application of novel Phyto-nanocatalyst bimetallic oxide with Buxus papillosa fruit capsule aqueous extract was advantageous during transesterification. Characterization of sodium/potassium oxide Phyto-nanocatalyst confirmed 23.5 nm nano-size and enhanced catalytic activity. Other characterizing tools are FTIR, DRS, XRD, Zeta potential, SEM, and EDX. Methyl ester formation was authenticated by FTIR, GC-MS, and NMR. A maximum 97% yield was obtained at optimized conditions i.e., methanol ratio to oil (8:1), catalyst amount (0.37 wt%), reaction duration (180 min), and temperature of 80 °C. The reusability of novel sodium/potassium oxide was checked for six reactions. Buxus papillosa fuel properties were within the international restrictions of fuel. The sulphur content of 0.00090% signified the environmental remedial nature of Buxus papillosa methyl esters and it is a highly recommendable species for biodiesel production at large scale due to a t huge number of seeds production and vast distribution.

A critical review on sustainable hazardous waste management strategies: a step towards a circular economy.

Globally, industrialisation and urbanisation have led to the generation of hazardous waste (HW). Sustainable hazardous waste management (HWM) is the need of the hour for a safe, clean, and eco-friendly environment and public health. The prominent waste management strategies should be aligned with circular economic models considering the economy, environment, and efficiency. This review critically discusses HW generation and sustainable management with the strategies of prevention, reduction, recycling, waste-to-energy, advanced treatment technology, and proper disposal. In this regard, the major HW policies, legislations, and international conventions related to HWM are summarised. The global generation and composition of hazardous industrial, household, and e-waste are analysed, along with their environmental and health impacts. The paper critically discusses recently adapted management strategies, waste-to-energy conversion techniques, treatment technologies, and their suitability, advantages, and limitations. A roadmap for future research focused on the components of the circular economy model is proposed, and the waste management challenges are discussed. This review stems to give a holistic and broader picture of global waste generation (from many sources), its effects on public health and the environment, and the need for a sustainable HWM approach towards the circular economy. The in-depth analysis presented in this work will help build cost-effective and eco-sustainable HWM projects.

Facility Recommendations for Medical Aesthetic Procedures in Canada.

This article articulates core facility recommendations for regulated health care providers and professionals performing medical aesthetic procedures involving the use of topical and local anesthesia in a private clinic setting in Canada. The recommendations help ensure patient safety, confidentiality, and ethics. Information is provided about the setting/environment where medical aesthetic procedures are performed, safety equipment and emergency medications that should be on-site for medical aesthetic procedures, infection prevention and control measures, the way that medications and medical supplies should be stored, how to handle biomedical hazardous waste, and how to protect patient information.

Valorization of hazardous waste cooking oil for the production of eco-friendly biodiesel using a low-cost bifunctional catalyst.

Biodiesel is considered the prospective substitute for non-renewable fossil fuel-derived sources of energy. However, the high costs of feedstocks and catalysts inhibit its large-scale industrial implementation. From this perspective, the utilization of waste as the source for both catalyst synthesis and feedstock for biodiesel is a rare attempt. Waste rice husk was explored as a precursor to prepare rice husk char (RHC). Sulfonated RHC was employed as a bifunctional catalyst for the simultaneous esterification and transesterification of highly acidic waste cooking oil (WCO) to produce biodiesel. The sulfonation process coupled with ultrasonic irradiation proved to be an efficient technique to induce high acid density in the sulfonated catalyst. The prepared catalyst possessed a sulfonic density and total acid density of 4.18 and 7.58 mmol/g, respectively, and a surface area of 144 m2/g. A parametric optimization was conducted for the conversion of WCO into biodiesel using the response surface methodology. An optimal biodiesel yield of 96% was obtained under the conditions of methanol to oil ratio (13:1), reaction time (50 min), catalyst loading (3.5 wt%), and ultrasonic amplitude (56%). The prepared catalyst showed higher stability up to five cycles with biodiesel yield greater than 80%.

Pyrolysis of Ca/Fe-rich antibiotic fermentation residues into biochars for efficient phosphate removal/recovery from wastewater: Turning hazardous waste to phosphorous fertilizer.

Ca/Fe-rich antibiotic fermentation residues (AFRs), a type of hazardous waste, can be regarded as recyclable biomass and metal resources. However, concurrent detoxification and reutilization of biomass and metals resources from AFRs have never been reported before. In this study, Ca/Fe-rich vancomycin fermentation residues were pyrolyzed into biochar to adsorb phosphate for the first time. The residual vancomycin and antibiotic resistance genes were completely decomposed during pyrolysis. The resultant Ca/Fe-rich biochar exhibited excellent performance at adsorbing phosphate without further modifications. The process had rapid kinetics and a maximum adsorption capacity of 102 mg P/g. Ca and Fe were the active sites, whereas different mechanisms were observed under acidic and alkaline conditions. Surprisingly, HCO3- enhanced phosphate adsorption with an increase of adsorption capacity from 43.9 to 71.0 mg/g when HCO3- concentration increased from 1 to 10 mM. Furthermore, actual wastewater could be effectively treated by the biochar. The phosphate-rich spent biochar significantly promoted seed germination (germination rate: 96.7 % vs. 80.0 % in control group, p < 0.01) and seedling growth (shoot length was increased by 57.9 %, p < 0.01) due to the slow release of bioavailable phosphate, and thus could be potentially used as a phosphorous fertilizer. Consequently, the hazardous waste was turned into phosphorous fertilizer, with the additional benefits of detoxifying AFRs, reutilizing biomass and metal resources from AFRs, controlling phosphate pollution, and recovering phosphate from wastewater.

Transformation of hazardous sacred incense sticks ash waste into less toxic product by sequential approach prior to their disposal into the water bodies.

Incense sticks ash is one of the most unexplored by-products generated at religious places and houses obtained after the combustion of incense sticks. Every year, tonnes of incense sticks ash is produced at religious places in India which are disposed of into the rivers and water bodies. The presence of heavy metals and high content of alkali metals challenges a potential threat to the living organism after the disposal in the river. The leaching of heavy metals and alkali metals may lead to water pollution. Besides this, incense sticks also have a high amount of calcium, silica, alumina, and ferrous along with traces of rutile and other oxides either in crystalline or amorphous phases. The incense sticks ash, heavy metals, and alkali metals can be extracted by water, mineral acids, and alkali. Ferrous can be extracted by magnetic separation, while calcium by HCl, alumina by sulfuric acid treatment, and silica by strong hydroxides like NaOH. The recovery of such elements by using acids and bases will eliminate their toxic heavy metals at the same time recovering major value-added minerals from it. Here, in the present research work, the effect on the elemental composition, morphology, crystallinity, and size of incense sticks ash particles was observed by extracting ferrous, followed by extraction of calcium by HCl and alumina by H2SO4 at 90-95 °C for 90 min. The final residue was treated with 4 M NaOH, in order to extract leachable silica at 90 °C for 90 min along with continuous stirring. The transformation of various minerals phases and microstructures of incense sticks ash (ISA) and other residues during ferrous, extraction, calcium, and alumina and silica extraction was studied using Fourier transform infrared (FTIR), dynamic light scattering (DLS), X-ray fluorescence (XRF), X-ray diffraction (XRD), field emission scanning electron microscopy (FESEM), and inductively coupled plasma-optical emission spectroscopy (ICP-OES). DLS was used for analyzing the size during the experiments while FTIR helped in the confirmation of the formation of new products during the treatments. From the various instrumental analyses, it was found that the toxic metals present in the initial incense sticks ash got eliminated. Besides this, the major alkali metals, i.e., Ca and Mg, got reduced during these successive treatments. Initially, there were mainly irregular shaped, micron-sized particles that were dominant in the incense sticks ash particles. Besides this, there were plenty of carbon particles left unburned during combustion. In the final residue, nanosized flowers shaped along with cuboidal micron-sized particles were dominant. present in If, such sequential techniques will be applied by the industries based on recycling of incense sticks ash, then not only the solid waste pollution will be reduced but also numerous value-added minerals like ferrous, silica, alumina calcium oxides and carbonates can be recovered from such waste. The value-added minerals could act as an economical and sustainable source of adsorbent for wastewater treatment in future.

Review on treatment and utilization of barium slag in China.

Barium slag (BS) is generated as a by-product waste during the production of barium salts from barite. A large amount of BS is discharged annually threating the ecological environment and restricting the development of the barium salts industry. In China, BS is classified as hazardous waste due to its corrosivity, and more importantly because of its extraction toxicity of barium. Soluble barium is toxic and can result in barium poisoning for environment and human beings. The current review presents a detailed summary on general characteristics, discharge and disposal status, harmless treatment pathways and comprehensive utilization of BS in China. BaO, SiO2, CaO, and SO3 occur as main chemical compositions in BS, especially BaO accounting approximately for 35-40%. The mineral compositions include unreacted barite, quartz, clay minerals, newly-formed phases from the side reactions such as BaCO3, BaSiO3 and BaSO3, and residual carbon. A special attention is given to the assessment of the harmless treatment methods for BS from hazardous waste to general waste, which will decrease its management costs. Precipitation and solidification of soluble barium is the common pathway for harmless treatment of BS, and the using of other industrial waste can realize cost-saving. Methods for comprehensive utilization of BS include recovery of barium and carbon, application in building materials, and using as adsorbents for wastewater treatment. In particular, we analyzed and discussed the advantages and disadvantages of these existing process routes, intending to promote potentials for comprehensive utilization of BS in the future.

Complementary advantages of spent pot lining and coal gangue in the detoxification and valuable components recovery process.

As a hazardous solid waste rich in carbon and fluorine, spent pot lining (SPL) is a huge threat to sustainable production and environmental security. As abundant carbon and fluorine resources, the use of such valuable components has great practical and economic significance. Based on the environmental concerns and the component characteristics of SPL, coal gangue (CG), the largest output of solid wastes in the coal-producing industry and rich in aluminum and silicon, was introduced in the utilization and detoxification process of SPL in this work. The substance flow of the co-utilization process presents a circular economy and complementary advantages of SPL and CG. Pure regular fibrous silicon carbides were obtained owing to the synergy effect of SPL and CG. Aluminum from CG and SPL was utilized to prepare dawsonite combined with the sodium from the impurities removal process. Pure cryolite was obtained via mixing wastewater from the silicon carbide purification process and the dawsonite extraction process. Almost all components in SPL and CG were converted into valuable products, and no wastewater and residue was discharged. Thus, a sustainable process of trash to treasure and circular economy for treating CG and SPL was established here with environmental and economically friendly characteristics, which gave a new insight into utilizing wastes with complementary advantages.

Regional distribution, properties, treatment technologies, and resource utilization of oil-based drilling cuttings: A review.

Oil-based drilling cuttings (OBDC) are hazardous wastes produced during the extensive use of oil-based drilling mud in oil and gas exploration and development. They have strong mutagenic, carcinogenic, and teratogenic effects and need to be properly disposed of to avoid damaging the natural environment. This paper reviews the recent research progress on the regional distribution, properties, treatment technologies, and resource utilization of OBDC. The advantages and disadvantages of different technologies for removing petroleum pollutants from OBDC were comprehensively analyzed, and required future developments in treatment technologies were proposed.

Using molybdenum carbiding to induce digestion of carbon in H2O2: A sustainable approach to eliminate radioactivity for hazardous graphite waste inherited from nuclear enterprise.

To properly manage nuclear wastes is critical to sustainable utilization of nuclear power and environment health. Here, we show an innovative carbiding strategy for sustainable management of radioactive graphite through digestion of carbon in H2O2. The combined action of intermolecular oxidation of graphite by MoO3 and molybdenum carbiding demonstrates success in gasifying graphite and sequestrating uranium for a simulated uranium-contaminated graphite waste. The carbiding process plays a triple role: (1) converting graphite into atomic carbon digestible in H2O2, (2) generating oxalic ligands in the presence of H2O2 to favor U-precipitation, and (3) delivering oxalic ligands to coordinate to MoVI-oxo anionic species to improve sample batching capacity. We demonstrate > 99% of uranium to be sequestrated for the simulated waste with graphite matrix completely gasifying while no detectable U-migration occurred during operation. This method has further been extended to removal of surface carbon layers for graphite monolith and thus can be used to decontaminate monolithic graphite waste with emission of a minimal amount of secondary waste. We believe this work not only provides a sustainable approach to tackle the managing issue of heavily metal contaminated graphite waste, but also indicates a promising methodology toward surface decontamination for irradiated graphite in general.

Bacterial diversity and competitors for degradation of hazardous oil refining waste under selective pressures of temperature and oxygen.

Oil refining waste (ORW) contains complex, hazardous, and refractory components, causing more severe long-term environmental pollution than petroleum. Here, ORW was used to simulate the accelerated domestication of bacteria from oily sludges and polymer-flooding wastewater, and the effects of key factors, oxygen and temperature, on the ORW degradation were evaluated. Bacterial communities acclimated respectively in 30/60 °C, aerobic/anaerobic conditions showed differentiated degradation rates of ORW, ranging from 5% to 34%. High-throughput amplicon sequencing and ORW component analysis revealed significant correlation between bacterial diversity/biomass and degradation efficiency/substrate preference. Under mesophilic and oxygen-rich condition, the high biomass and abundant biodiversity with diverse genes and pathways for petroleum hydrocarbons degradation, effectively promoted the rapid and multi-component degradation of ORW. While under harsh conditions, a few dominant genera still contributed to ORW degradation, although the biodiversity was severely restricted. The typical dominant facultative anaerobes Bacillus (up to 99.8% abundance anaerobically) and Geobacillus (up to 99.9% abundance aerobically and anaerobically) showed oxygen-independent sustainable degradation ability and broad-spectrum of temperature adaptability, making them promising and competitive bioremediation candidates for future application. Our findings provide important strategies for practical bioremediation of varied environments polluted by hazardous ORW.

Managing the hazardous waste cooking oil by conversion into bioenergy through the application of waste-derived green catalysts: A review.

Waste cooking oil (WCO) is a hazardous waste generated at staggering values globally. WCO disposal into various ecosystems, including soil and water, could result in severe environmental consequences. On the other hand, mismanagement of this hazardous waste could also be translated into the loss of resources given its energy content. Hence, finding cost-effective and eco-friendly alternative pathways for simultaneous management and valorization of WCO, such as conversion into biodiesel, has been widely sought. Due to its low toxicity, high biodegradability, renewability, and the possibility of direct use in diesel engines, biodiesel is a promising alternative to mineral diesel. However, the conventional homogeneous or heterogeneous catalysts used in the biodiesel production process, i.e., transesterification, are generally toxic and derived from non-renewable resources. Therefore, to boost the sustainability features of the process, the development of catalysts derived from renewable waste-oriented resources is of significant importance. In light of the above, the present work aims to review and critically discuss the hazardous WCO application for bioenergy production. Moreover, various waste-oriented catalysts used to valorize this waste are presented and discussed.

Green conversion of hazardous red mud into diagnostic X-ray shielding tiles.

Red mud is a solid hazardous alumina industrial waste, which is rich in iron, titanium, aluminum, silicon, calcium, etc. The red mud contains 30-60% of hematite, which is suitable for shielding high energy X- and gamma rays. So, the iron rich red mud was converted into diagnostic X-ray shielding tiles through ceramic route by adding a certain weight percentage of BaSO4 and binders (kaolin clay or sodium hexametaphosphate) with it. The kaolin clay tile possess sufficient impact strength (failure point is 852 mm for 19 mm steel ball) and flexural strength of ~25 N/mm2, which is suitable for wall applications. The 10.3 mm and 14.7 mm thick red mud:BaSO4:kaolin clay tile possess the attenuation equivalent to 2 mm and 2.3 mm lead at 125 kVp and 140 kVp, respectively. No heavy elements were found to leach out except chromium and arsenic from the sintered tiles. However, the leaching of Cr (0.6 ppm) and As (0.015 ppm) was found to be well below the permissible limit. These tiles can be used in the X-ray diagnosis, CT scanner, bone densitometry, and cath labs instead of toxic lead sheet and thereby to protect the operating personnel, public, and environment from radiation hazards.

High-value utilization of mask and heavy fraction of bio-oil: From hazardous waste to biochar, bio-oil, and graphene films.

At present, it is very common to wear mask outdoors in order to avoid coronavirus disease 19 (COVID-19) infection. However, this leads to the formation of numerous plastic wastes that threaten humans and ecosystem. Against this major background, a novel co-pyrolysis coupled chemical vapor deposition (CVD) strategy is proposed to systematically convert mask and heavy fraction of bio-oil (HB) into biochar, bio-oil, and three-dimensional graphene films (3DGFs) is proposed. The biochar exhibits high higher heating value (HHV) (33.22-33.75 MJ/kg) and low ash content (2.34%), which is obviously superior to that of the walnut shell and anthracite coal. The bio-oil contains rich aromatic components, such as 1,2-dimethylbenzene and 2-methylnaphthalene, which can be used as chemical feedstock for insecticides. Furthermore, the 3DGF800 has a wide range of applications in the fields of oil spill cleanup and oil/water separation according to its fire resistance, high absorbability (40-89 g g-1) and long-term cycling stability. This research sheds new light on converting plastic wastes and industrial by-products into high added-value chemicals.

The use of dental amalgam and amalgam waste management in Kosova: An environmental policy approach.

Dental amalgam from dental clinics in Kosova is an uncontrolled source of mercury. The environmental legislative framework related to its use does not fully provide measures that reduce amalgam use and the release of its waste into the environment. This paper highlights issues related to environmental policy covering mercury amalgam waste management. Existing national regulations on hazardous waste management in Kosova consider the waste from dental health care as hazardous. Currently, however, no regulations restrict the use of dental amalgam or specifically oblige the generators of amalgam to treat or dispose of waste properly, thus leading to inconsistent legislation. New regulations, revised hazardous waste management standards, and new infrastructure for waste treatment and disposal, in compliance with EU regulations, should be developed to create a holistic approach that prevents the adverse effects of amalgam waste. Integr Environ Assess Manag 2021;17:1037-1044. © 2021 SETAC.

Effect of Si/Al molar ratio on the immobilization of selenium and arsenic oxyanions in geopolymer.

The effect of Si/Al molar ratio of geopolymer on the immobilization of Se and As oxyanions was studied through leaching test and solid characterizations including XRD, FTIR, TG, NMR, XAFS, and N2 adsorption-desorption isotherm. As a whole, the leaching percentages of Se and As oxyanions increased with the increase of the Si/Al molar ratio of geopolymer. Linear combination fitting confirmed that most of selenite, selenate and arsenate ions existed in geopolymers through electrostatic interaction. Thus, Al tetrahedrons in geopolymer structure control the charge stability for these oxyanions to a large extent. Differently, as for arsenate ions, they were recrystallized into an arsenate compound (Na3.25(OH)0.25(H2O)12)(AsO4) in geopolymers. The additive of these pollutants has an adverse effect on the compactness of geopolymer, then influencing the leaching performance in turn. However, the changes in leaching results did not follow the variation trend of specific surface areas and pore volumes of geopolymers with different Si/Al ratios. The number and distribution of Al tetrahedron and compactness of geopolymer have a synergistic effect on the immobilization of these oxyanions. Besides, the compressive strengths of geopolymer samples are always higher than 20 MPa, which meets the requirement of safe disposal of hazardous waste.

Radiometrical and physico-chemical characterisation of contaminated glass waste from a glass dump in Sweden.

Around former glass factories in south eastern Sweden, there are dozens of dumps whose radioactivity and physico-chemical properties were not investigated previously. Thus, radiometric and physico-chemical characteristics of waste at Madesjö glass dump were studied to evaluate pre-recycling storage requirements and potential radiological and environmental risks. The material was sieved, hand-sorted, leached and scanned with X-Ray Fluorescence (XRF). External dose rates and activity concentrations of Naturally Occurring Radioactive Materials from 238U, 232Th series and 40K were also measured coupled with a radiological risk assessment. Results showed that the waste was 95% glass and dominated by fine fractions (<11.3 mm) at 43.6%. The fine fraction had pH 7.8, 2.6% moisture content, 123 mg kg-1 Total Dissolved Solids, 37.2 mg kg-1 Dissolved Organic Carbon and 10.5 mg kg-1 fluorides. Compared with Swedish EPA guidelines, the elements As, Cd, Pb and Zn were in hazardous concentrations while Pb leached more than the limits for inert and non-hazardous wastes. With 40K activity concentration up to 3000 Bq kg-1, enhanced external dose rates of 40K were established (0.20 µSv h-1) although no radiological risk was found since both External Hazard Index (Hex) and Gamma Index (Iγ) were <1. The glass dump needs remediation and storage of the waste materials under a safe hazardous waste class 'Bank Account' storage cell as a secondary resource for potential future recycling.

New ternary blend limestone calcined clay cement for solidification/stabilization of zinc contaminated soil.

This study evaluates the potential use of a new limestone calcined clay cement (LC3) for stabilization/solidification of zinc contaminated soil. LC3 is a new ternary blend manufactured by the replacement of 50% cement clinker by locally available two supplementary cementitious materials (SCMs) - limestone and calcined clay. The incorporation of LC3 is evaluated on the soil spiked with 0.5% and 1% of Zinc (Zn) at curing times of 3, 7, 14, 28 and 56 days. pH, strength and leachability properties of the solidified/stabilised soil are measured for both mechanical and environmental conditions. Additionally, sequential extraction procedure (SEP), X-ray diffraction (XRD) analysis and scanning electron microscope (SEM) analysis are performed to elucidate the mechanisms of Zn immobilization in the soil. The results show that the leachable Zn concentrations in the stabilised soil are well below the corresponding hazardous waste management regulatory limit after the curing time of 14 days. The soil pH and unconfined compressive strength of the stabilised soil increase with curing time. The SEP results confirm that LC3 considerably reduces the acid soluble fraction (F1) and increase the residual fraction (F4). The XRD and SEM results indicate that formation of Tri-calcium Silicate 3CaO·SiO2, Portlandite Ca(OH)2, Ettringite Ca6Al2(SO4)3(OH)12.26 H2O and Wulfingite Zn(OH)2 are the primary mechanisms for the immobilization of Zn in the LC3 stabilised soil.