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"Acid Disposal"
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Sustainable gold mining wastewater treatment by sorption using low-cost materials
Sorption technique was employed to remove heavy metals from gold mining effluent using natural and plant materials for sustainability. An assessment of the effluent quality of a gold mining company in Ghana indicated that arsenic, copper and cyanide were the major pollutants in the process effluent. Arsenic and copper were successfully removed from the effluent by the studied materials. The research showed that the down-flow fixed-bed treatment configuration is an ideal system for the simultaneous removal of copper and arsenic from low concentration gold mining effluent, in addition to other heavy metals present in very low concentrations.
Book
Bridging methodological gaps in forensic science: A study of hydrochloric acid and human dentition
The use of acid to obscure human remains is a tactic frequently associated with criminal activity, yet research on its effects on human dentition remains inconsistent. Dental tissues, among the body's most durable components, play a vital role in forensic identification. However, existing studies on acid dissolution of dentition often lack standardized methods, resulting in findings that are difficult to reproduce or generalize. This study addresses these gaps by examining the effects of hydrochloric acid (HCl) on permanent maxillary molars under controlled conditions, using a replicable methodology that incorporates experimental controls and evaluates the impact of handling techniques such as removal, rinsing, and drying. Five permanent maxillary molar samples were submerged in HCl (37 %) under varied handling conditions. Findings reveal that undisturbed samples dissolved more slowly than those subjected to periodic removal and rinsing, which accelerated dissolution rates by over 100 %. This highlights the significant influence of handling techniques on experimental outcomes. The study also identifies inconsistent reporting and the absence of standardized protocols in prior research as critical barriers to reproducibility. By providing a clear and replicable framework, this study advances understanding of the dissolution process and emphasizes the importance of methodological rigor in forensic science. These findings have broader implications for improving the reliability of forensic evidence and ensuring its applicability in criminal investigations. Addressing these issues is essential for enhancing public trust in forensic methods and strengthening their role in the justice system.
•Clear, replicable research is critical to maintaining credibility in forensic applications.•Variability in dentition studies reveals critical gaps in forensic science's methodological rigor.•Introducing controls in forensic research can significantly improve the accuracy of findings.•It found that handling methods, like periodic rinsing, accelerate tooth dissolution compared to undisturbed conditions.•This study explores how hydrochloric acid affects human molars using a controlled, replicable approach.
Journal Article
Environmental Impact Assessment of the Dismantled Battery: Case Study of a Power Lead–Acid Battery Factory in China
With the increase in battery usage and the decommissioning of waste power batteries (WPBs), WPB treatment has become increasingly important. However, there is little knowledge of systems and norms regarding the performance of WPB dismantling treatments, although such facilities and factories are being built across the globe. In this paper, environmental performance is investigated quantitively using life cycle assessment (LCA) methodology for a dismantled WPB manufacturing process in Tongliao city of Inner Mongolia Province, China. The functional unit was selected to be one metric ton of processed WPB, and the average data of 2021 were used. The results indicated that WPB dismantling treatments are generally sustainable in their environmental impacts, because the life cycle environmental effects can be neutralized by the substitution of virgin products with recycled counterparts. Of all the processes of dismantlement, Crude Lead Making, Refining, and Preliminary Desulfurization, were the top three contributors to the total environmental burden. The results of the sensitivity analysis showed that increasing photovoltaic power, wind power, and natural gas usage may significantly reduce the burden on the environment. On the basis of our findings, some suggestions are put forward for a policy to promote environmental green growth of WPB treatment. Although this paper is aimed at the power lead–acid battery, the research method is also of significance for the power lithium-ion battery, and we will conduct relevant research on the disassembly process of the power lithium-ion battery in the future.
Journal Article
Sustainably sourced components to generate high-strength adhesives
Nearly all adhesives
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are derived from petroleum, create permanent bonds
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, frustrate materials separation for recycling
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and prevent degradation in landfills. When trying to shift from petroleum feedstocks to a sustainable materials ecosystem, available options suffer from low performance, high cost or lack of availability at the required scales. Here we present a sustainably sourced adhesive system, made from epoxidized soy oil, malic acid and tannic acid, with performance comparable to that of current industrial products. Joints can be cured under conditions ranging from use of a hair dryer for 5 min to an oven at 180 °C for 24 h. Adhesion between metal substrates up to around 18 MPa is achieved, and, in the best cases, performance exceeds that of a classic epoxy, the strongest modern adhesive. All components are biomass derived, low cost and already available in large quantities. Manufacturing at scale can be a simple matter of mixing and heating, suggesting that this new adhesive may contribute towards the sustainable bonding of materials.
We present a sustainably sourced adhesive system, with performance comparable to that of current industrial products, made from epoxidized soy oil, malic acid and tannic acid, all biomass derived, low cost and readily available.
Journal Article
Alginate beads provide a beneficial physical barrier against native microorganisms in wastewater treated with immobilized bacteria and microalgae
When the freshwater microalga Chlorella sorokiniana and the plant growth-promoting bacterium Azospirillum brasilense were deployed as free suspensions in unsterile, municipal wastewater for tertiary wastewater treatment, their population was significantly lower compared with their populations in sterile wastewater. At the same time, the numbers of natural microfauna and wastewater bacteria increased. Immobilization of C. sorokiniana and A. brasilense in small (2-4 mm in diameter), polymer Ca-alginate beads significantly enhanced their populations when these beads were suspended in normal wastewater. All microbial populations within and on the surface of the beads were evaluated by quantitative fluorescence in situ hybridization combined with scanning electron microscopy and direct measurements. Submerging immobilizing beads in wastewater created the following sequence of events: (a) a biofilm composed of wastewater bacteria and A. brasilense was created on the surface of the beads, (b) the bead inhibited penetration of outside organisms into the beads, (c) the bead inhibited liberation of the immobilized microorganisms into the wastewater, and (d) permitted an uninterrupted reduction of ammonium and phosphorus from the wastewater. This study demonstrated that wastewater microbial populations are responsible for decreasing populations of biological agents used for wastewater treatment and immobilization in alginate beads provided a protective environment for these agents to carry out uninterrupted tertiary wastewater treatment. [PUBLICATION ABSTRACT]
Journal Article
Biotechnology of Rhodococcus for the production of valuable compounds
Bacteria belonging to Rhodococcus genus represent ideal candidates for microbial biotechnology applications because of their metabolic versatility, ability to degrade a wide range of organic compounds, and resistance to various stress conditions, such as metal toxicity, desiccation, and high concentration of organic solvents. Rhodococcus spp. strains have also peculiar biosynthetic activities that contribute to their strong persistence in harsh and contaminated environments and provide them a competitive advantage over other microorganisms. This review is focused on the metabolic features of Rhodococcus genus and their potential use in biotechnology strategies for the production of compounds with environmental, industrial, and medical relevance such as biosurfactants, bioflocculants, carotenoids, triacylglycerols, polyhydroxyalkanoate, siderophores, antimicrobials, and metal-based nanostructures. These biosynthetic capacities can also be exploited to obtain high value-added products from low-cost substrates (industrial wastes and contaminants), offering the possibility to efficiently recover valuable resources and providing possible waste disposal solutions. Rhodococcus spp. strains have also recently been pointed out as a source of novel bioactive molecules highlighting the need to extend the knowledge on biosynthetic capacities of members of this genus and their potential utilization in the framework of bioeconomy.Key points• Rhodococcus possesses promising biosynthetic and bioconversion capacities.• Rhodococcus bioconversion capacities can provide waste disposal solutions.• Rhodococcus bioproducts have environmental, industrial, and medical relevance.
Journal Article
Biodegradation of polyurethane by the microbial consortia enriched from landfill
Polyurethanes (PU) are one of the most used categories of plastics and have become a significant source of environmental pollutants. Degrading the refractory PU wastes using environmentally friendly strategies is in high demand. In this study, three microbial consortia from the landfill leachate were enriched using PU powder as the sole carbon source. The consortia efficiently degraded polyester PU film and accumulated high biomass within 1 week. Scanning electron microscopy, Fourier transform infrared spectroscopy, and contact angle analyses showed significant physical and chemical changes to the PU film after incubating with the consortia for 48 h. In addition, the degradation products adipic acid and butanediol were detected by high-performance liquid chromatography in the supernatant of the consortia. Microbial composition and extracellular enzyme analyses revealed that the consortia can secrete esterase and urease, which were potentially involved in the degradation of PU. The dominant microbes in the consortia changed when continuously passaged for 50 generations of growth on the PU films. This work demonstrates the potential use of microbial consortia in the biodegradation of PU wastes.Key points• Microbial consortia enriched from landfill leachate degraded polyurethane film.• Consortia reached high biomass within 1 week using polyurethane film as the sole carbon source.• The consortia secreted potential polyurethane-degrading enzymes.
Journal Article
Degradation of dibutyl phthalate by Paenarthrobacter sp. Shss isolated from Saravan landfill, Hyrcanian Forests, Iran
Phthalic acid esters are predominantly used as plasticizers and are industrially produced on the million ton scale per year. They exhibit endocrine-disrupting, carcinogenic, teratogenic, and mutagenic effects on wildlife and humans. For this reason, biodegradation, the major process of phthalic acid ester elimination from the environment, is of global importance. Here, we studied bacterial phthalic acid ester degradation at Saravan landfill in Hyrcanian Forests, Iran, an active disposal site with 800 tons of solid waste input per day. A di-n-butyl phthalate degrading enrichment culture was established from which Paenarthrobacter sp. strain Shss was isolated. This strain efficiently degraded 1 g L–1 di-n-butyl phthalate within 15 h with a doubling time of 5 h. In addition, dimethyl phthalate, diethyl phthalate, mono butyl phthalate, and phthalic acid where degraded to CO2, whereas diethyl hexyl phthalate did not serve as a substrate. During the biodegradation of di-n-butyl phthalate, mono-n-butyl phthalate was identified in culture supernatants by ultra-performance liquid chromatography coupled to electrospray ionization quadrupole time-of-flight mass spectrometry. In vitro assays identified two cellular esterase activities that converted di-n-butyl phthalate to mono-n-butyl phthalate, and the latter to phthalic acid, respectively. Our findings identified Paenarthrobacter sp. Shss amongst the most efficient phthalic acid esters degrading bacteria known, that possibly plays an important role in di-n-butyl phthalate elimination at a highly phthalic acid esters contaminated landfill.
Journal Article
Innovations in applications and prospects of bioplastics and biopolymers: a review
Non-biodegradable plastics are continually amassing landfills and oceans worldwide while creating severe environmental issues and hazards to animal and human health. Plastic pollution has resulted in the death of millions of seabirds and aquatic animals. The worldwide production of plastics in 2020 has increased by 36% since 2010. This has generated significant interest in bioplastics to supplement global plastic demands. Bioplastics have several advantages over conventional plastics in terms of biodegradability, low carbon footprint, energy efficiency, versatility, unique mechanical and thermal characteristics, and societal acceptance. Bioplastics have huge potential to replace petroleum-based plastics in a wide range of industries from automobiles to biomedical applications. Here we review bioplastic polymers such as polyhydroxyalkanoate, polylactic acid, poly-3-hydroxybutyrate, polyamide 11, and polyhydroxyurethanes; and cellulose-based, starch-based, protein-based and lipid-based biopolymers. We discuss economic benefits, market scenarios, chemistry and applications of bioplastic polymers.
Journal Article
Molecular distribution and compound-specific stable carbon isotopic composition of dicarboxylic acids, oxocarboxylic acids and α-dicarbonyls in PM2.5 from Beijing, China
This study investigates the seasonal variation, molecular distribution and stable carbon isotopic composition of diacids, oxocarboxylic acids andα-dicarbonyls to better understand the sources and formation processes of fine aerosols (PM2.5) in Beijing. The concentrations of total dicarboxylic acids varied from 110 to 2580 ng m-3, whereas oxoacids (9.50–353 ng m-3) and dicarbonyls (1.50–85.9 ng m-3) were less abundant. Oxalic acid was found to be the most abundant individual species, followed by succinic acid or occasionally by terephthalic acid (tPh), a plastic waste burning tracer. Ambient concentrations of phthalic acid (37.9 ± 27.3 ng m-3) and tPh (48.7 ± 51.1 ng m-3) were larger in winter than in other seasons, illustrating that fossil fuel combustion and plastic waste incineration contribute more to wintertime aerosols. The year-round mass concentration ratios of malonic acid to succinic acid (C3 / C4) were relatively low by comparison with those in other urban aerosols and remote marine aerosols. The values were less than or equal to unity in Beijing, implying that the degree of photochemical formation of diacids in Beijing is insignificant. Moreover, strong correlation coefficients of major oxocarboxylic acids and α-dicarbonyls with nss-K+ suggest that biomass burning contributes significantly to these organic acids and related precursors. The meanδ13C value of succinic acid is the highest among all species, with values of -17.1 ± 3.9 ‰ (winter) and -17.1 ± 2.0 ‰ (spring), while malonic acid is more enriched in13C than others in autumn (-17.6 ± 4.6 ‰) and summer (-18.7 ± 4.0 ‰). The δ13C values of major species in Beijing aerosols are generally lower than those in the western North Pacific atmosphere, the downwind region, which indicates that stable carbon isotopic compositions of diacids depend on their precursor sources in Beijing. Therefore, our study demonstrates that in addition to photochemical oxidation, high abundances of diacids, oxocarboxylic acids andα-dicarbonyls in Beijing are largely associated with anthropogenic primary emissions, such as biomass burning, fossil fuel combustion and plastic waste burning.
Journal Article