Global perspective on microplastics in landfill leachate; Occurrence, abundance, characteristics, and environmental impact

Microplastics in municipal solid waste landfill leachate and their removal in treatment units: A perspective of controlled and uncontrolled landfills

Leachate produced from municipal solid waste landfill serves as a potential pathway for microplastics (MPs) release into the environment with a high potential for soil, surface water, and groundwater contamination. These MPs not only persist for longer duration of time in the landfill but also interact with toxic chemical contaminants. These interactions arise from the hydrophobic characteristics and minuscule size of MPs, which absorb a variety of emerging toxic contaminants present in these systems thereby amplifying the risk to surrounding environment. This study was performed to investigate the abundance, characteristics, and pollution risk of MPs in leachate from two contrasting landfill systems in the cities of Chandannagar and Baidyabati, India. A total of 8 leachate samples from an uncontrolled landfill (UCL), i.e., open dump, and 24 samples from different leachate treatment units (LTUs) of a controlled landfill (CL) were evaluated. Particle sizes of 1-5 mm (41.9%) in UCL and 0.025-0.5 mm (46.2%) in CL were predominant. Seven different types of polymers were identified in untreated leachate samples from UCL having concentration 53.4 ± 6.69 p/L (mean ± standard deviation) and in CL 34.7 ± 4.73 p/L. The predominant shapes were films, fragments, and fibers in UCL, whereas fragments and fibers dominated in CL. Polyethylene and polypropylene were the most frequent types of polymers observed in both sites. In CL, collection well, aeration lagoon, and sedimentation pond were used for LTUs, in which overall 83.3% MPs removal was achieved. High removal in LTUs highlights the importance of engineered systems for leachate management. However, optimization of these units is needed for enhanced removal of particles <0.5 mm. For UCL the findings suggest urgent need for implementing basic containment and treatment systems, particularly given their higher pollution risk indices. Varying landfill designs, waste compositions, and weather conditions of specific locations restrict generalisation of the findings to other regions. Therefore, long-term monitoring studies across different geographical and climatic conditions are recommended to develop more comprehensive management strategies.

Application of novel polymer materials for anti-fouling control of landfills: A comprehensive durability evaluation

The novel polymer material is lightweight, environmentally friendly, and offers excellent anti-seepage properties, making it an ideal candidate as a cutoff wall for emergency isolation in landfills, controlling leachate migration. However, limited studies exist on the comprehensive durability of this material. Laboratory experiments were conducted on polyurethane samples through simulating landfill conditions, particularly using dry-wet cycling experiments to mimic seasonal variations in landfill water levels. Pb(NO₃)₂-Zn(NO₃)₂ and CaCl₂ solutions, as representative components of leachate, were evaluated for their effects on the material. The results indicate that the dry-wet process significantly impacted the anti-seepage performance, with the permeability coefficient increasing by 11.7% compared to immersion in pure leachate. The highest impact on material performance was observed in the Pb(NO₃)₂-Zn(NO₃)₂ mixed solution, which led to a 24.2% increase in permeability compared to distilled water, followed by CaCl₂ solution. Two lifetime prediction models yielded a safe service lifetime over 100 years for the polymer material even with heavy metal exposure, utilizing the Arrhenius equation and the WLF (Williams-Landel-Ferry) equation, and high-density materials were recommended. The study confirms the material's strong potential for long-term use, providing a solid foundation for its application in landfill environments. Furthermore, attention should be paid to the destruction of frequent fluctuations in water levels and heavy metals on the polymer cutoff wall.

Detection and quantification of microplastics in endometrial polyps and their role in polyp formation

With the increasing use of plastics, microplastic (MPs) pollution has garnered significant attention in recent years. Endometrial polyps are prevalent gynecological conditions in women of childbearing age, which impair endometrial receptivity and contribute to female infertility. However, no studies have yet reported the exposure of endometrial polyps to MPs. This study employed pyrolysis-gas chromatography/mass spectrometry and laser direct infrared spectroscopy to detect and compare MPs between normal endometrium and endometrial polyps. Using Py-GC/MS, we identified three main MPs in 14 normal endometrial samples and 16 endometrial polyps. The average abundance of MPs in the endometrial polyp group was significantly higher than in the normal endometrium group. The respective average abundance of polyethylene (PE), polystyrene (PS), and polyvinyl chloride (PVC) in the polyp and normal endometrium groups was 13.66 ± 2.0 vs. 7.132 ± 0.78 μg/g (p = 0.0009), 94.81 ± 10.67 vs. 69.29 ± 6.93 μg/g, and 67.67 ± 11.02 vs. 56.35 ± 6.90 μg/g. LDIR analysis revealed 13 different types of MPs, with polymethylmethacrylate being the most prevalent. Moreover, we discovered that PS microspheres can promote the proliferation and migration of endometrial stromal cells through PI3K/AKT pathway, which may be a key factor in the formation of endometrial polyps. This study is the first to explore the presence of MPs in endometrial polyps, compare the differences in MPs content between normal endometrium and endometrial polyps, and clarify the potential connection between MPs exposure and the formation of endometrial polyps. Further research is required to explore additional potential insights.

Advances and recent trends in plant-based materials and edible films: a mini-review

Plant-based materials and edible films have emerged as promising alternatives to conventional packaging materials, offering sustainable and environmentally friendly solutions. This mini-review highlights the significance of plant-based materials derived from polysaccharides, proteins, and lipids, showcasing their renewable and biodegradable nature. The properties of edible films, including mechanical strength, barrier properties, optical characteristics, thermal stability, and shelf-life extension, are explored, showcasing their suitability for food packaging and other applications. Moreover, the application of 3D printing technology allows for customized designs and complex geometries, paving the way for personalized nutrition. Functionalization strategies, such as active and intelligent packaging, incorporation of bioactive compounds, and antimicrobial properties, are also discussed, offering additional functionalities and benefits. Challenges and future directions are identified, emphasizing the importance of sustainability, scalability, regulation, and performance optimization. The potential impact of plant-based materials and edible films is highlighted, ranging from reducing reliance on fossil fuels to mitigating plastic waste and promoting a circular economy. In conclusion, plant-based materials and edible films hold great potential in revolutionizing the packaging industry, offering sustainable alternatives to conventional materials. Embracing these innovations will contribute to reducing plastic waste, promoting a circular economy, and creating a sustainable and resilient planet.

The stress response of tetracycline resistance genes and bacterial communities under the existence of microplastics in typical leachate biological treatment system

Landfill leachate is an important source of microplastics (MPs) and antibiotic-resistance genes (ARGs). Here, in the presence of polystyrene MPs (PS-MPs) and polyethylene MPs (PE-MPs), the nitrogen and phosphorus removal effect and sludge structure performance were affected in an anaerobic-anoxic-aerobic system, a typical biological leachate treatment process. The abundance of tetracycline-resistance genes (tet genes) in biofilms on the two types of MP was significantly higher than that in the leachate and sludge, and the load on PE-MPs was higher than that on PS-MPs because of the porous structure of PE-MPs. Aging of the MPs increased their surface roughness and abundance of oxygen-containing functional groups and shaped the profile of ARGs in the MP biofilms. The biofilm biomass and growth rate on the two types of MP increased with the incubation time in the first 30 days, and was affected by environmental factors. Structural equation models and co-occurrence network analysis demonstrated that the MPs indirectly affected the spectrum of ARGs by affecting biofilm formation, and, to a lesser extent, had a direct impact on the selective enrichment of ARGs. We discuss the mechanisms of the relationships between MPs and ARGs in the leachate treatment system, which will have guiding significance for future research. Our data on the colonization of microorganisms and tet genes in MPs biofilms provide new evidence concerning the accumulation and transmission of these ARGs, and are important for understanding the mechanisms of MPs in spreading pollution.

Genetic Modifications in Bacteria for the Degradation of Synthetic Polymers: A Review

Synthetic polymers, commonly known as plastics, are currently present in all aspects of our lives. Although they are useful, they present the problem of what to do with them after their lifespan. There are currently mechanical and chemical methods to treat plastics, but these are methods that, among other disadvantages, can be expensive in terms of energy or produce polluting gases. A more environmentally friendly alternative is recycling, although this practice is not widespread. Based on the practice of the so-called circular economy, many studies are focused on the biodegradation of these polymers by enzymes. Using enzymes is a harmless method that can also generate substances with high added value. Novel and enhanced plastic-degrading enzymes have been obtained by modifying the amino acid sequence of existing ones, especially on their active site, using a wide variety of genetic approaches. Currently, many studies focus on the common aim of achieving strains with greater hydrolytic activity toward a different range of plastic polymers. Although in most cases the depolymerization rate is improved, more research is required to develop effective biodegradation strategies for plastic recycling or upcycling. This review focuses on a compilation and discussion of the most important research outcomes carried out on microbial biotechnology to degrade and recycle plastics.

Microplastics in different municipal solid waste treatment and disposal systems: Do they pose environmental risks?

Microplastic (MP) pollution is a significant worldwide environmental and health challenge. Municipal solid waste (MSW) can be an important source of MPs in the environment if treated and disposed of inappropriately, causing potential ecological risks. MSW treatment and disposal methods have been gradually shifting from landfilling/dumping to more sustainable approaches, such as incineration or composting. However, previous studies on MP characteristics in different MSW treatment and disposal systems have mainly focused either on landfills/dumpsites or composts. The lack of knowledge of multiple MSW treatment and disposal systems makes it difficult to ensure effective MP pollution control during MSW treatment and disposal. Therefore, this study systematically summarizes the occurrence of MPs in different MSW treatment and disposal systems (landfill/dumpsite, compost, and incineration) on the Eurasian scale, and discusses the factors that influence MPs in individual MSW treatment and disposal systems. In addition, the paper assesses the occurrence of MPs in the surrounding environment of MSW treatment and disposal systems and their ecological risks using the species sensitivity distribution approach. The study also highlights recommendations for future research, to more comprehensively describe the occurrence and fate of MPs during MSW treatment and disposal processes, and to develop appropriate pollution control measures to minimize MP pollution.

Environmental pitfalls and associated human health risks and ecological impacts from landfill leachate contaminants: Current evidence, recommended interventions and future directions

The improper management of solid waste, particularly the dumping of untreated municipal solid waste, poses a growing global challenge in both developed and developing nations. The generation of leachate is one of the significant issues that arise from this practice, and it can have harmful impacts on both the environment and public health. This paper presents an overview of the primary waste types that generate landfill leachate and their characteristics. This includes examining the distribution of waste types in landfills globally and how they have changed over time, which can provide valuable insights into potential pollutants in a given area and their trends. With a lack of specific regulations and growing concerns regarding environmental and health impacts, the paper also focuses on emerging contaminants. Furthermore, the environmental and ecological impacts of leachate, along with associated health risks, are analyzed. The potential applications of landfill leachate, suggested interventions and future directions are also discussed in the manuscript. Finally, this work addresses future research directions in landfill leachate studies, with attention, for the first time to the potentialities that artificial intelligence can offer for landfill leachate management, studies, and applications.