Methane is an abundant and low-cost gas with high global warming potential and its use as a feedstock can help mitigate climate change. Variety of valuable products can be produced from methane by ...methanotrophs in gas fermentation processes. By using methane as a sole carbon source, methanotrophic bacteria can produce bioplastics, biofuels, feed additives, ectoine and variety of other high-value chemical compounds. A lot of studies have been conducted through the years for natural methanotrophs and engineered strains as well as methanotrophic consortia. These have focused on increasing yields of native products as well as proof of concept for the synthesis of new range of chemicals by metabolic engineering. This review shows trends in the research on key methanotrophic bioproducts since 2015. Despite certain limitations of the known production strategies that makes commercialization of methane-based products challenging, there is currently much attention placed on the promising further development.
•From a wide range of bioproducts synthesized by methanotrophic bacteria the most established are PHAs, methanol and SCP.•Recent progress in the field led to novel methane-based products such as sesquiterpenoids, cadaverine, putrescine.•Low gas-liquid mass transfer and methane uptake remain major technological limitations of methane bioconversions.•Low gas-liquid mass transfer and methane uptake remain major technological limitations of methane bioconversions.
Growing concern regarding non-biodegradable plastics and the impact of these materials on the environment has promoted interest in biodegradable plastics. The intensification of separate biowastes ...collection in most European countries has also contributed to the development of biodegradable plastics, and the subject of their end-of-life is becoming a key issue. To date, there has been relatively little research to evaluate the biodegradability of biodegradable plastics by anaerobic digestion (AD) compared to industrial and home composting. However, anaerobic digestion is a particularly promising strategy for treating biodegradable organic wastes in the context of circular waste management. This critical review aims to provide an in-depth update of anaerobic digestion of biodegradable plastics by providing a summary of the literature regarding process performance, parameters affecting biodegradability, the microorganisms involved, and some of the strategies (e.g., pretreatment, additives, and inoculum acclimation) used to enhance the degradation rate of biodegradable plastics. In addition, a critical section is dedicated to suggestions and recommendations for the development of biodegradable plastics sector and their treatment in anaerobic digestion.
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•Biodegradable plastics will play a key role in the future management of biowastes.•Anaerobic digestion of biodegradable plastics performs better under thermophilic than under mesophilic conditions.•Pretreatment can significantly enhance the biodegradation rate of biodegradable plastics by anaerobic digestion.•The agronomic potential and safety of digestates treating biodegradable plastics streams have not yet been reported.•There is currently a lack of norms and certifications for biodegradability in anaerobic digestion systems.
Abstract Preparation of bioplastics and chitosan with sorbitol plasticizer by varying starch and chitosan in the ratio of 30%: 70%, 40% : 60%, 50% : 50%, 60% : 40%, 70% : 30% and added sorbitol ...plasticizer with variations of 60% and 80%. Characterization was carried out on the composition of starch and chitosan with the addition of sorbitol plasticizer starting with physical and mechanical testing and obtained 2 bioplastics showing the highest elongation and tensile strength data obtained in sample BSB4 in the ratio of starch and chitosan 60%: 40% by adding 60% sorbitol plasticizer showed an elongation value of 21.68898% and a tensile strength of 1.7352 MPa and sample BSC1 with a ratio of starch and chitosan 30%: 70% with the addition of 80% sorbitol plasticizer resulted in an elongation value of 23.6926% and tensile strength of 2.3997 MPa. The biodegradability test on bioplastics showed a mass reduction for 4 weeks or 28 days with the highest percentage of each variation of starch and chitosan by adding sorbitol plasticizer reaching 19.38%. SEM results show that there is still mixing between starch and a less homogeneous solution as evidenced by several points on bioplastics that are still white, and the same groups are obtained between the constituents of bioplastics, namely O-H, C-H, and N-H.
Electronic waste is a growing threat to the global environment and human health, raising particular concerns. Triboelectric devices synthesized from sustainable and degradable materials are a ...promising electronic alternative, but the mechanical mismatch at the interface between the polymer substrate and the electrodes remains unresolved in practical applications. This study uses the sulfhydryl silanization reaction and the chemical selectivity and site specificity of the thiol–disulfide exchange reaction in dynamic covalent chemistry to prepare a tough monolithic‐integrated triboelectric bioplastic. The stress is dissipated by covalent bond adaptation to the interface interaction, which makes the polymer dielectric layer to the conductive layer have a good interface adhesion effect (220.55 kPa). The interfacial interlocking of the polymer substrate with the conductive layer gives the triboelectric bioplastic excellent tensile strength (87.4 MPa) and fracture toughness (33.3 MJ m−3). Even when subjected to a tension force of 10 000 times its weight, it still maintains a stable triboelectric output with no visible cracks. This study provides new insights into the design of reliable and environmentally friendly self‐powered devices, which is significant for the development of flexible wearable electronics.
To solve the problem of mismatch at the dielectric–conductive layer interface in green electronics, this study utilizes dynamic covalent chemistry to synthesize a tough monolithic‐integrated triboelectric bioplastic. The triboelectric bioplastic has tensile strength (87.4 MPa) and toughness (33.3 MJ m−3) and is noncracking after being subjected to a tensile force of 10 000 times its own weight.
Bioplastics have long been publicized as a sustainable plastic packaging alternative; however, their widespread industrialization is still embryonic due to complex challenges spanning multiple ...sectors. This review critically analyses the bioplastic lifecycle and provides a holistic evaluation of both the opportunities and potential trade-offs along their value chain. Their lifecycle is divided into three sectors: 1) resources, extraction, and manufacturing, 2) product consumption which discusses availability, consumer perception, and marketing strategies, and 3) end-of-life (EoL) management which includes segregation, recycling, and disposal. In the production phase, the primary challenges include selection of suitable raw feedstocks and addressing the techno-economic constraints of manufacturing processes. To tackle these challenges, it is recommended to source sustainable feedstocks from innovative, renewable, and waste materials, adopt green synthesis mechanisms, and optimize processes for improved efficiency. The consumption phase encompasses challenges related to market availability, cost competitiveness, and consumer perception of bioplastics. Localizing feedstock sourcing and production, leveraging the economics of scale, and promoting market demand for recycled bioplastics can positively influence the market dynamics. Additionally, dispelling misconceptions about degradability through proper labeling, and employing innovative marketing strategies to enhance consumer perception of the mechanical performance and quality of bioplastics is crucial. During the EoL management phase, major challenges include inadequate awareness, inefficient segregation protocols, and bioplastics with diverse properties that are incompatible with existing waste management infrastructure. Implementing a standardized labeling system with clear representation of suitable EoL techniques and integrating sensors and machine learning-based sorting technologies will improve segregation efficiency. Further, establishing interconnected recycling streams that clearly define the EoL pathways for different bioplastics is essential to ensure circular waste management systems. Finally, designing a comprehensive systems-based policy framework that incorporates technical, economic, environmental, and social drivers is recommended to promote bioplastics as a viable circular packaging solution.
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•Bioplastics must address multisectoral challenges to be viable plastic alternatives.•Identifying viable feedstocks and optimized processing methods are critical factors.•Effective labeling and marketing ideas improve consumer perception of bioplastics.•Design of circular end-of-life management system with clear pathways is suggested.•Systems-based policies with techno-economic and socio-ecological drivers are needed.
Petroleum-based plastics are associated with environmental pollution problems owing to their non-biodegradable and toxic properties. In this context, renewable and biodegradable bioplastics possess ...great potential to replace petroleum-based plastics in mitigating these environmental issues. Fabrication of bioplastic films involves a delicate mixture of the film-forming agent, plasticizer and suitable solvent. The role of the plasticizer is to improve film flexibility, whereas the filler serves as a reinforcement medium. In recent years, much research attention has been shifted toward devising diverse methods for enhancing the performance of bioplastics, particularly in the utilization of environmentally benign nanoparticles to displace the conventional hazardous chemicals. Along this line, this paper presents the emergence of nanofillers and plasticizers utilized in bioplastic fabrication with a focus on starch-based bioplastics. This review paper not only highlights the influencing factors that affect the optical, mechanical and barrier properties of bioplastics, but also revolves around the proposed mechanism of starch-based bioplastic formation, which has rarely been reviewed in the current literature. To complete the review, prospects and challenges in bioplastic fabrication are also highlighted in order to align with the concept of the circular bioplastic economy and the United Nations' Sustainable Development Goals.
Bioplastics are materials that are biobased and/or biodegradable, but not necessarily both. Concerns about environmental plastic pollution are constantly growing with increasing demand for ...substituting fossil-based plastics with those made using renewable resource feedstocks. For many conventional bioplastics to completely decompose/degrade, they require specific environmental conditions that are rarely met in natural ecosystems, leading to rapid formation of micro-bioplastics. As global bioplastic production and consumption/use continue to increase, there is growing concern regarding the potential for environmental pollution from micro-bioplastics. However, the actual extent of their environmental occurrence and potential impacts remains unclear, and there is insufficient mass concentration-based quantitative data due to the lack of quantitative analytical methods. This study developed and validated an analytical method coupling pressurized liquid extraction and pyrolysis–gas chromatography–mass spectrometry combined with thermochemolysis to simultaneously identify and quantify five targeted micro-bioplastics (i.e., polylactic acid (PLA), polyhydroxyalkanoate, polybutylene succinate, polycaprolactone, and polybutylene adipate terephthalate (PBAT)) in environmental samples on a polymer-specific mass-based concentration. The recovery of spiked micro-bioplastics in environmental samples (biosolids) ranged from 74 to 116%. The limits of quantification for the target micro-bioplastics were between 0.02 and 0.05 mg/g. PLA and PBAT were commonly detected in wastewater, biosolids, and sediment samples at concentrations between 0.07 and 0.18 mg/g. The presented analytical method enables the accurate identification, quantification, and monitoring of micro-bioplastics in environmental samples. This study quantified five micro-bioplastic types in complex environmental samples for the first time, filling in gaps in our knowledge about bioplastic pollution and providing a useful methodology and important reference data for future research.
Plastics have been on top of the political agenda in Europe and across the world to reduce plastic leakage and pollution. However, the COVID-19 pandemic has severely disrupted plastic reduction ...policies at the regional and national levels and induced significant changes in plastic waste management with potential for negative impacts in the environment and human health. This paper provides an overview of plastic policies and discusses the readjustments of these policies during the COVID-19 pandemic along with their potential environmental implications.
The sudden increase in plastic waste and composition due to the COVID-19 pandemic underlines the crucial need to reinforce plastic reduction policies (and to implement them into action without delays), to scale up in innovation for sustainable and green plastics solutions, and to develop dynamic and responsive waste management systems immediately. Policy recommendations and future research directions are discussed.
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•Plastic pollution threatens environmental sustainability.•COVID-19 pandemic precautionary measures are reversing some plastic waste directives.•Plastic production should be decoupled from fossil-fuel resources.•Citizen-science approaches to reduce plastic pollution needs to be prioritised.•Sustainable development calls for direct links between policy, industry and research.
Bioplastics are considered sustainable alternatives to conventional microplastics which are recognized as a threat to terrestrial ecosystems. However, little is known about the potential ...ecotoxicological effects of bioplastics on soil fauna and ecosystems. The present study assessed the toxicity of microplastics Polystyrene (PS), Polyethylene (PE) and bioplastics Polyvinyl alcohol (PVA), Sodium polyacrylate (NaPa) on a key soil fauna Oppia nitens, a soil oribatid mite, and investigated the ecological relevance of O. nitens avoidance response as a valuable tool for the risk assessment of contaminated soils such as the Superfund sites. Findings showed that the mites’ net response indicated avoidance behavior such that in most cases as concentrations of micro- and bioplastics increased, so did the avoidance responses. The avoidance EC50 endpoints showed PS < PE < PVA < NaPa, indicating higher deleterious effects of microplastics. High toxicity of PS in soils to O. nitens at EC50 of 165 (±25) mg/kg compared to bioplastics and other known contaminants poses an enormous threat to soil. For bioplastics in this study, there were no significant avoidances at concentrations up to 16,200 mg/kg compared to PS and PE which showed avoidance responses at 300 and 9000 mg/kg respectively, implying that bioplastics might be relatively safer to soil mites compared to conventional microplastics. Also, results indicated that long-term heavy metal pollution such as in contaminated Superfund sites decreased microbial biomass; a useful bioindicator of soil pollution. Furthermore, O. nitens avoidance of heavy metals contaminated sites demonstrated the ecological relevance of avoidance response test when assessing the habitat integrity of contaminated soil. The present study further supports the inclusion of the oribatid mite, O. nitens in the ecological risk assessment of contaminants in soil.
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•Reduced microbial biomass reported in Superfund heavy metal-contaminated sites.•O. nitens preference of contaminant-free soils poses risks to soil ecosystem services.•Soil mites tolerate bioplastics better than microplastics in standard artificial soil.•O. nitens avoidance of Superfund sites support its relevance in soil risk assessments.
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