Mitigating environmental impact of waste glass materials: review of the existing reclamation options and future outlook

The environmental impact of waste glass (WG) is one of the major challenges crippling sustainable waste management and mitigation. Reclamation of recycled materials from waste glass remains a tedious task amidst complex technological approaches. The challenge as seen in the global containment measures increase the proportion of waste glass and minimize the existing capacity of landfill space. In many works, findings have shown how best to minimize the impact of waste glass as evidenced in their inclusion as building materials such as cement, mortars, concretes and blocks. The concept of this paper is to appraise previous studies carried out on the use of waste glass as key contributing factor in structural building. The scope of this paper will be broaden to include various successes recorded in the evolution of concrete mixtures containing different proportion of recycle glass. Part of the setbacks noted in the inclusion of these recycled materials as matrix, filler or fibre are also reported in this paper. Also discussed is the durability of glass materials in varying conglomerate involving cement in reinforcement of building and structures. Thermal insulating properties of recycled glass are also considered in this work where considerable energy is saved due to their low thermal conductivity. Based on the analysis of various studies and other factors considered in this paper, it is established that recycled glass materials can be accommodated in structural buildings, while continuous research is necessary to adapt waste glass to high pH value of Portland cement.

     

Waste recycling of cathode ray tube glass through industrial production of transparent ceramic frits

ABSTRACT

Cathode ray tube (CRT) glass contains significant amounts of alkali and alkaline earth oxides, making it a useful by-product for use in the ceramics industry. Among the various alkali oxides present, those of strontium (SrO), calcium (CaO), and magnesium (MgO) are well known flux materials used widely in the ceramics industry. The most effective flux, SrO, is also a limited resource. In this study, we aimed to develop an environmentally friendly, low-cost method for recycling CRT waste by using it to produce transparent ceramic frits on an industrial scale. Four different samples were fabricated containing between 13 and 25 wt.% CRT panel glass. The color values, sintering behaviors, phases, and microstructural properties of the corresponding samples were analyzed and compared. The results indicate that a composition containing 25 wt.% CRT panel glass could pass the ISO 10545 test. Thus, the results confirm that CRT glass can be used to inexpensively produce transparent ceramic frits at an industrial scale.

Implications: The recycling of electronic waste (e-waste), including CRT waste, has increased by high rates of computer and TV consumption. This increase in consumption is likely to increase the rate at which CRTs are discarded. However, CRTs cannot be recycled in the desired amount. Owing to the high silicate, barium and strontium content of CRTs, it has great potential for glass ceramics such as frits. CRT panel glass to produce commercial transparent frit at low cost through an industrial production route for use in single-fire sintered products. Thus, CRT wastes can be recycled cost-effective, sustainable and environmentally friendly.     

A mass transfer model for simulating VOC sorption on building materials

The sorption of volatile organic compounds (VOCs) by different building materials can significantly affect VOC concentrations in indoor environments. In this paper, a new model has been developed for simulating VOC sorption and desorption rates of homogeneous building materials with constant diffusion coefficients and material–air partition coefficients. The model analytically solves the VOC sorption rate at the material–air interface. It can be used as a “wall function” in combination with more complex gas-phase models that account for non-uniform mixing to predict sorption process. It can also be used in conjunction with broader indoor air quality studies to simulate VOC exposure in buildings.     

A novel one-step synthesis for carbon-based nanomaterials from polyethylene terephthalate (PET) bottles waste

Nowadays our planet suffers from an accumulation of plastic products that have the potential to cause great harm to the environment in the form of air, water, and land pollution. Plastic water bottles have become a great problem in the environment because of the large numbers consumed throughout the world. Certain types of plastic bottles can be recycled but most of them are not. This paper describes an economical solvent-free process that converts polyethylene terephthalate (PET) bottles waste into carbon nanostructure materials via thermal dissociation in a closed system under autogenic pressure together with additives and/or catalyst, which can act as cluster nuclei for carbon nanostructure materials such as fullerenes and carbon nanotubes. This research succeeded in producing and controlling the microstructure of various forms of carbon nanoparticles from the PET waste by optimizing the preparation parameters in terms of time, additives, and amounts of catalyst.

Implications: Plastic water bottles are becoming a growing segment of the municipal solid waste stream in the world; some are recycled but many are left in landfill sites. Recycling PET bottles waste can positively impact the environment in several ways: for instance, reduced waste, resource conservation, energy conservation, reduced greenhouse gas emissions, and decreasing the amount of pollution in air and water sources. The main novelty of the present work is based on the acquisition of high-value carbon-based nanomaterials from PET waste by a simple solvent-free chemical technique. Thus, the prepared materials are considered to be promising, cheap, eco-friendly materials that may find use in different applications.     

Evidence of recycling of lead battery waste into highly leaded jewelry

Inexpensive highly leaded jewelry, much of it imported from China, remains widely available in the United States. The source materials for these items are unknown. Due to the low cost of much of this trinket jewelry, it seems likely that scrap materials may be used in their manufacture. Thirty-nine jewelry items previously determined to contain 90% or more lead by weight were analyzed for antimony content. The average antimony content of these thirty-nine items was 3.0%. The range of antimony content in the samples was from 0.3% to 6.2% antimony by weight, with twenty-seven of the samples in the range of 2-4% antimony by weight. By comparison, battery lead standard reference material obtained from the US National Institute of Standards and Technology contains 2.95% antimony by weight. While the evidence is circumstantial, the similarity in composition of these samples to battery lead is striking and supports the hypothesis that some battery lead is being recycled into highly leaded jewelry items. These results suggest that the recycling of this waste in China needs to be investigated, as the use of lead battery waste as a source material for children's jewelry poses a clear threat to children's health.     

Recycling of nickel smelter slag for arsenic remediation—an experimental study

In this study, recycled Ni smelter slag has been used as a reactive medium for arsenic (As) removal from aqueous solutions. The results of the study showed that 10.16–11.43-cm long columns containing 451–550 g of slag operated for at least 65 days were able to remove 99–100 % As species from continuously flowing contaminated water at an initial As concentration of 10 mg/L. The removal capacities were found to be 1.039 to 1.054 mg As per g of slag. X-ray photoelectron spectroscopy (XPS) and Raman spectroscopy data also showed that electrostatic attraction and oxidation–reduction reactions between As species and mixed iron oxides present in the slag were the main mechanisms for the removal of arsenic from aqueous solutions. Theoretical multiplet analysis of XPS data revealed that the amount of goethite in the slag increased from 22 to 60 % during arsenic removal by adsorption and the percentage of magnetite decreased from 50 to 40 %. These changes indicate that redox-mediated reactions occurred as part of the As(V) removal process. Raman spectroscopy studies confirmed that, in addition to surface reactions, internal interactions between the slag and arsenic also occurred. The findings of the study suggest that recycled Ni smelter slag could be an effective low-cost reactive medium for a subsurface remediation system, such as a permeable reactive barrier. Recycling of waste material (slag) for the removal of another waste (arsenic) can significantly reduce the environmental footprint of metallurgical operations and hence contribute to sustainable development. Such recycling also decreases slag disposal costs and eliminates the need to purchase commercial reactive material or obtain expensive natural material for remediation purposes.     

Ceramic tiles with black pigment made from stainless steel plant dust: Physical properties and long-term leaching behavior of heavy metals

Stainless steel plant dust is a hazardous by-product of the stainless steelmaking industry. It contains large amounts of Fe, Cr, and Ni, and can be potentially recycled as a raw material of inorganic black pigment in the ceramic industry to reduce environmental contamination and produce value-added products. In this paper, ceramic tiles prepared with black pigment through recycling of stainless steel plant dust were characterized in terms of physical properties, such as bulk density, water absorption, apparent porosity, and volume shrinkage ratio, as well as the long-term leaching behavior of heavy metals (Cr, Ni, Pb, Cd, and Zn). The results show that good physical properties of ceramic tiles can be obtained with 8% pigments addition, sample preparation pressure of 25 MPa, and sintering at 1200 ºC for 30 min. The major controlling leaching mechanism for Cr and Pb from the ceramic tiles is initial surface wash-off, while the leaching behavior of Cd, Ni, and Zn from the stabilized product is mainly controlled by matrix diffusion. The reutilization process is safe and effective to immobilize the heavy metals in the stainless steel plant dust.

Implications: Stainless steel plant dust is considered as a hazardous material, and it can be potentially recycled for black pigment preparation in the ceramic industry. This paper provides the characteristics of the ceramic tiles with black pigment through recycling stainless steel plant dust, and the long-term leaching behavior and controlling leaching mechanisms of heavy metals from the ceramic tile. The effectiveness of the treatment process is also evaluated.     

膨胀石墨在环境污染治理中的应用

膨胀石墨是一种新型的多孔碳质吸附材料.它具有发达的孔结构,对于大分子的物质具有超大的吸附能力.膨胀石墨作为新型纳米功能材料,广泛应用于石油、化工、冶金、机械和环保等领域.在概述膨胀石墨的吸附性能和机理的基础上,介绍了其在海洋溢油污染、水中微量油污染、印染废水和有毒气体治理等方面的应用,并对膨胀石墨的最新合成方法和应用发展趋势进行了展望和预测.     

The fermentative production of L-lysine as an animal feed additive

A new and innovative process for the biotechnological production of L-lysine is presented, exemplified here by the fermentative production of the feed additive Biolys60. The novel feature of this product is that the entire manufacturing concept, i.e. the production strain, the raw materials, all process stages and the product specifications have been systematically tailored for optimal environmental compatibility and for minimum resource depletion and waste. The process completely dispenses with the need to discharge residual and waste material and reduces the handling of hazardous materials to a minimum. Since only a few process stages are involved, the method is economical to use and investment outlay is reduced. The process, which also leads to a higher grade product, is thus highly attractive in both ecological and economical terms. By boosting the nutrient value of the plant-based feedstuffs, the product itself makes an cost-effective contribution towards a more sustainable form of animal feeding and by reducing nitrogen emission levels promotes a more environmentally compatible form of animal husbandry.     

Evaluating carbon emissions of China’s waste management strategies for building refurbishment projects: contributing to a circular economy

This study evaluates carbon emissions of construction and demolition (C&D) waste generated by building refurbishment, using a life cycle assessment approach through a case study project in China. Three waste management scenarios were developed for a building refurbishment project in the city of Suzhou. Scenario 1 is under the business-as-usual C&D waste management practice in China; scenario 2 is based on the open-ended 3R strategy, which focuses on the downstream impact of waste; and scenario 3 considers both the upstream and downstream impact of waste. The results reveal that the composition of the waste generated from building refurbishment projects is different from construction and demolition projects. In the life cycle of C&D waste management of building refurbishment projects, the refurbishment material stage generates the highest carbon emissions compared to the dismantlement, refurbishment construction, and refurbishment material end of life stages. Scenario 1 produces higher carbon emissions than scenario 2, but the difference is not significant in the whole life cycle of the building refurbishment project, whereas carbon emissions for scenario 3 are significantly less than both scenario 1 and scenario 2. The study finds the reason for this difference is that scenario 1 and scenario 2 are based on a linear economy that relies on unsustainable demand for raw materials, whereas scenario 3 is based on a circular economy that uses upcycled materials to substitute for raw materials and considers waste management from a cradle to cradle perspective. This study fills a research gap by evaluating carbon emissions of different waste management strategies for building refurbishment projects, which are expected to be an increasing portion of overall construction activity in China for the foreseeable future.

     

Analysis of flame retarded polymers and recycling materials

Recycling activities on polymeric materials are increasing and becoming more and more important in recent years. For polymers containing no flame retardants, suitable recycling strategies already exist. In order to investigate the recyclability of flame retarded polymers that contain brominated flame retardants, a number of samples were analysed as received from a recycling company. Following the identification and sorting of the samples according to type of polymers and flame retardants, material recycling was tested for the flame retarded polymers identified to occur most frequently. The reactivity of the flame retardants during the recycling procedure was studied by analysing for brominated dioxins and furans. The results demonstrate that flame retarded polymers can be recycled under certain experimental conditions.     

The release of lindane from contaminated building materials

The release of the organochlorine pesticide lindane (γ-hexachlorocyclohexane) from several types of contaminated building materials was studied to assess inhalation hazard and decontamination requirements in response to accidental and/or intentional spills. The materials included glass, polypropylene carpet, latex-painted drywall, ceramic tiles, vinyl floor tiles, and gypsum ceiling tiles. For each surface concentration, an equilibrium concentration was determined in the vapour phase of the surrounding air. Vapor concentrations depended upon initial surface concentration, temperature, and type of building material. A time-weighted average (TWA) concentration in the air was used to quantify the health risk associated with the inhalation of lindane vapors. Transformation products of lindane, namely α-hexachlorocyclohexane and pentachlorocyclohexene, were detected in the vapour phase at both temperatures and for all of the test materials. Their formation was greater on glass and ceramic tiles, compared to other building materials. An empiric Sips isotherm model was employed to approximate experimental results and to estimate the release of lindane and its transformation products. This helped determine the extent of decontamination required to reduce the surface concentrations of lindane to the levels corresponding to vapor concentrations below TWA.     

脱水污泥制备聚合物合成"木材"的研究

以污水处理厂脱水污泥和废塑料为主要原料 ,通过污泥处理、聚合物改性 ,采用热塑复合法可以制备出聚合物复合材料及对应的微孔材料 ,影响材料性能的主要因素有污泥形态、废塑料种类以及它们之间的质量比等参数。最终材料表现出木材的很多性能 ,是一种使污泥高附加值利用的有效方法。     

Evaluation of biopolymer-modified concrete systems for disposal of cathode ray tube glass

Cathode ray tubes (CRTs) from computer monitors and television sets, which contain significantly high percentage of lead (Pb) by weight, represent an enormous and growing hazardous waste problem in the United States and worldwide. As a result, new technologies are needed to cope with current CRT waste stream and increased hazard and build new markets for its recycled components, developing commercially viable concrete composites, as well as minimizing CRT disposal problems. In this study, commercially available biopolymers, such as xanthan gum, guar gum, and chitosan, were used to encapsulate CRT glass waste, reducing the Pb leachability. The biopolymers utilized contain a number of useful functional groups, such as carboxyl (xanthan), hydroxyl (guar), and amino groups (chitosan), which play important roles in binding and stabilizing Pb onto concrete structures. The use of biopolymers in concrete systems can create a stable interpenetrating cross-linking composite that will last for many years. Results from these new composites show 30% higher compressive strength than standard concrete and a sharp decrease in lead leachability from several thousand milligrams per liter initially to an amount of three-tenths milligrams per liter or lower values (much lower than the U.S. Environment Protection Agency standard for hazardous waste of 5 mg/L by the toxicity characteristic leaching procedure test), and for some of the composites leachability is below even the standard for drinking water. This efficient and cost-effective CRT-biopolymer-concrete composite is a new class of biopolymer-modified material that can potentially perform a significant role in relieving the current CRT issue.     

Evaluation of Biopolymer-Modified Concrete Systems for Disposal of Cathode Ray Tube Glass

Abstract

Cathode ray tubes (CRTs) from computer monitors and television sets, which contain significantly high percentage of lead (Pb) by weight, represent an enormous and growing hazardous waste problem in the United States and worldwide. As a result, new technologies are needed to cope with current CRT waste stream and increased hazard and build new markets for its recycled components, developing commercially viable concrete composites, as well as minimizing CRT disposal problems. In this study, commercially available biopolymers, such as xan-than gum, guar gum, and chitosan, were used to encapsulate CRT glass waste, reducing the Pb leachability. The biopolymers utilized contain a number of useful functional groups, such as carboxyl (xanthan), hydroxyl (guar), and amino groups (chitosan), which play important roles in binding and stabilizing Pb onto concrete structures. The use of biopolymers in concrete systems can create a stable interpenetrating cross-linking composite that will last for many years. Results from these new composites show 30% higher compressive strength than standard concrete and a sharp decrease in lead leachability from several thousand milligrams per liter initially to an amount of three-tenths milligrams per liter or lower values (much lower than the U.S. Environment Protection Agency standard for hazardous waste of 5 mg/L by the toxicity characteristic leaching procedure test), and for some of the composites leachability is below even the standard for drinking water. This efficient and cost-effective CRT–biopolymer-concrete composite is a new class of biopolymer-modified material that can potentially perform a significant role in relieving the current CRT issue.     

Composting and bioremediation process evaluation of wood waste materials generated from the construction and demolition industry

The suitability of using bioremediation and composting techniques for diverting construction and demolition (C&D) waste from landfill has been validated in this study. Different timber products from C&D waste have been composted using various composting approaches. The present work demonstrates the quality of compost produced as a result of composting of mixed board product wood waste, which is frequently obtained from the construction and demolition industry. Three compost mixes were prepared by mixing shredded chip board, medium density fibre, hardboard and melamine. Poultry manure, Eco-Bio mixture and green waste were used as nutrient supplements. The results revealed that compost produced from mixtures of poultry manure and green waste used as nutrient supplements improved the performance in plant growth trials (phytotoxicity tests). Results obtained from the experimental study clearly indicate that the composts produced comply with the criterion suggested in BSI PAS 100 (A specification for compost materials) for use in different applications. Composting can also be demonstrated to be a very practical approach to material management including transport reduction to and from the site. The economic suitability of the process will be improved with the increase in landfill tax. In the current regulatory scenario, it is recommended that these materials should be composted at a centralised facility.     

3D printing filament as a second life of waste plastics—a review

In recent times, the issue of plastic recycling has become one of the leading issues of environmental protection and waste management. Polymer materials have been found an application in many areas of daily life and industry. Along with their extended use, the problem of plastic wastes appeared because, after withdrawal from use, they became persistent and noxious wastes. The possibility of reusing polymeric materials gives a possibility of valorization—a second life—and enables effective waste utilization to obtain consumable products. The 3D printing market is a well-growing sector. Printable filaments can be made from a variety of thermoplastic materials, including those from recycling. This paper focuses on a review of the available literature on the production of filaments for 3D printers from recycled polymers as the alternative to present approach of central selective collection of plastics. The possibility of recycling of basic thermoplastic materials and the impact of processing on their physicochemical and mechanical properties were verified (Lanzotti et al. 2019). In addition, commercially available filaments produced from recycled materials and devices which allow self-production of filaments to 3D printing from plastic waste were reviewed.

     

A decision support system for wet soil cleaning

Newly developed software can predict the essential characteristics of the sand product resulting from the ex-situ washing of contaminated soil, dredging sludge or breaker sand. The system was designed for the Dutch situation and it works on the basis of readily available information. The primary output of the system is an assessment of the reusability of the sand product, which is obtained by comparing the prediction of the residual contamination and engineering quality with accepted levels and standards for building materials. The system also provides a ranking of potential applications for the sand with respect to treatment cost, the amount of recycled material or the environmental quality of the product. The software integrates soil cleaning expertise and unit process modelling in a way that allows varying levels of refinement of input data, ranging from a simple identification of the pollution source to a detailed particle size distribution of the contaminated soil. Tests on a database containing information on 117 processed batches of soil, dredging sludge and breaker sand show an 80% success rate in predicting cleanability, even though the input contamination levels were predominantly taken from (relatively inaccurate) in-situ data.     

Leaded electronic waste is a possible source material for lead-contaminated jewelry

Highly leaded jewelry, often imported from China, remains widely available in the United States. Leaded electronic waste is exported from the United States to several Asian countries where solder is recovered and circuit boards are stripped of parts in small workshops. To assess whether electronic waste is being recycled into the jewelry, lead, tin and copper content of highly leaded jewelry samples were determined by atomic absorption spectrometry. Sixteen jewelry items previously determined to contain 20-80% lead by weight were analyzed. Samples were digested in nitric acid for analysis of lead and copper, and in aqua regia for analysis of tin. Six samples contained significant amounts of tin, from 20.8% to 29.9% by weight. In addition, copper was a significant minor component of five of these samples (up to 4% by weight). Copper (present at 10-40% by weight in circuit boards) was shown to rapidly move into heated lead-tin solder. The combined lead-tin-copper content of these six items ranges from 93.5% to 100%, suggestive of a solder-based source material. These results are consistent with the hypothesis that recycled circuit board solders are being used to produce some of the heavily leaded imported jewelry sold in the United States. Should this hypothesis be substantiated, it suggests that environmental policies to protect children's health must address both proper recycling of source materials as well as restrictions of the lead content in consumer goods.     

Decomposition of paper wastes in presence of ceramics and cement raw material

Paper recycling is an environmental important activity that is carried out in all the countries, but during the recycling process a paper waste is produced. Generally these wastes are placed in landfill sites but it is possible to profit it as secondary fuel and raw material in manufacture furnaces.

In this work the combustion of the waste papers with cement and ceramic raw material has been studied with the objective to analyse the interaction of these substances with the emitted pollutants like PAHs and PCDD/Fs.

The results of the study show that the presence of inorganic material produces an increment in the lighter PAH emission but chlorinated compounds are not affected. The PCDD/F emission level found in the combustion of this waste is quite low compared with other wastes subjected to similar conditions.