Search Results (122)

In the environment, plastic waste degrades into small particles known as microplastics and nanoplastics (MNPLs), depending on their size. Given the potential harmful effects associated with MNPL exposure, it is crucial to develop environmentally representative particles for hazard assessment. These so-called true-to-life MNPLs are generated through in-house degradation of real-world plastic products. In this study, we produced titanium-doped nanoplastics (NPLs) from opaque polyethylene terephthalate (PET) milk bottles, which contain titanium dioxide as a filler. The resulting PET(Ti)-NPLs were thoroughly characterized using scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), mass spectrometry (MS), dynamic light scattering (DLS), ζ-potential measurements, transmission electron microscopy (TEM), and Fourier-transform infrared (FTIR) spectroscopy. Human-derived THP-1 monocytes were employed to investigate particle uptake kinetics, dosimetry, and genotoxicity. A combination of flow cytometry and inductively coupled plasma mass spectrometry (ICP-MS) enabled the quantification of internalized particles, while the comet assay assessed DNA damage. The results revealed dose- and time-dependent effects of PET(Ti)-NPLs on THP-1 cells, particularly in terms of internalization. Titanium doping facilitated detection and influenced genotoxic outcomes. This study demonstrates the relevance of using environmentally representative nanoplastic models for evaluating human health risks and underscores the importance of further mechanistic research. Full article

Recycling plastic waste has emerged as one of the most pressing environmental challenges of the 21st century. One of the biggest challenges in polyethylene terephthalate (PET) recycling is the requirement to return bottles in their original, undeformed state. This necessitates storing large volumes of waste and takes up substantial space. Therefore, this paper seeks to address this issue and introduces a novel AIoT-based infrastructure that integrates the PET Bottle Identification Algorithm (PBIA), which can accurately recognize bottles regardless of color or condition and distinguish them from other waste. A detailed study of Azure Custom Vision services for PET bottle identification is conducted, evaluating its object recognition capabilities and overall performance within an intelligent waste management framework. A key contribution of this work is the development of the Algorithm for Citizens’ Trust Level by Recycling (ACTLR), which assigns trust levels to individuals based on their recycling behavior. This paper also details the development of a cost-effective prototype of the AIoT system, demonstrating its low-cost feasibility for real-world implementation, using the Asus Tinker Board as the primary hardware. The software application is designed to monitor the collection process across multiple recycling points, offering Microsoft Azure cloud-hosted data and insights. The experimental results demonstrate the feasibility of integrating this prototype on a large scale at minimal cost. Moreover, the algorithm integrates the allocation points for proper recycling and penalizes fraudulent activities. This innovation has the potential to streamline the recycling process, reduce logistical burdens, and significantly improve public participation by making it more convenient to store and return used plastic bottles. Full article

The quality of water and its impact on consumers’ health has been studied extensively, along with concerns surrounding the use of polyethylene terephthalate (PET) packaging. This research aimed to analyze consumer behavior regarding water consumption patterns, with a focus on sustainability, packaging preferences, and perceptions of drinking water quality. Two surveys, conducted in 2019 and 2024, used a 23-question structured questionnaire to assess the public willingness to prevent water waste in the context of the circular economy. The surveys addressed consumer identification, drinking water preferences, the awareness of alternative consumption methods, and the openness to sustainable solutions such as water filters. Key quantitative findings showed a 10.4% increase in the amount of bottled water purchased in a single trip and a 12.1% rise in the frequency of weekly purchases, particularly among women and younger consumers. Simultaneously, a 4% increase in the preference for PET packaging over glass raised concerns about environmental sustainability, while the preference for tap water dropped by 5%, correlated with a 4.2% decline in the perceived tap water quality. The brand preference also shifted notably, with Aqua Carpatica rising to 38% and Borsec declining from 37% to 16%, reflecting the influence of purity-focused marketing. The novelty of the approach lay in identifying emerging trends related to sustainability, health, and circular economy principles. A comparative analysis of Romanian citizens’ responses over time highlighted changing perceptions of water use and waste reduction. To support the analysis, 13 statistical indicators were evaluated, a Spearman correlation test was applied to 13 criteria, descriptive statistics were computed, and a t-test was conducted across eight hypotheses. Full article

The widespread use of polyethylene terephthalate (PET) in bottled water packaging remains significant and is expected to increase further in the coming years. This trend raises concerns due to the generation of large amounts of waste. The degradation of PET leads to the release of low-molecular-weight substances and microplastic particles, which contaminate food products and the environment. This work highlights the significance of microplastic pollution, summarizes the mechanisms of PET degradation, and discusses methods for microplastic detection. A key section of the paper explores potential degradation management strategies, focusing on their applications and existing limitations. The study underscores the need for coordinated action among the scientific community, industry, and policymakers to mitigate this pressing environmental challenge. Full article

Microplastics (MPs), defined as plastic particles smaller than 5 mm, are an emerging global environmental and health concern due to their pervasive presence in aquatic ecosystems. This systematic review synthesizes data on the distribution, shapes, materials, and sizes of MPs in various water sources, including lakes, rivers, seas, tap water, and bottled water, between 2014 and 2024. Results reveal that river water constitutes the largest share of studies on MP pollution (30%), followed by lake water (24%), sea water (19%), bottled water (17%), and tap water (11%), reflecting their critical roles in MP transport and accumulation. Seasonal analysis indicates that MP concentrations peak in the wet season (38%), followed by the dry (32%) and transitional (30%) seasons. Spatially, China leads MP research globally (19%), followed by the USA (7.8%) and India (5.9%). MPs are predominantly composed of polyethylene (PE), polypropylene (PP), and polyethylene terephthalate (PET), with fibers and fragments being the most common shapes. Sub-millimeter MPs (<1 mm) dominate globally, with significant variations driven by anthropogenic activities, industrial discharge, and environmental factors such as rainfall and temperature. The study highlights critical gaps in understanding the long-term ecological and health impacts of MPs, emphasizing the need for standardized methodologies, improved waste management, and innovative mitigation strategies. This review underscores the urgency of addressing microplastic pollution through global collaboration and stricter regulatory measures. Full article

Waste polyethylene terephthalate (PET) bottles represent 12% of global plastic waste; however, only 9% are recycled. Hydrothermal processing presents the opportunity to upcycle waste PET into its monomers, particularly, terephthalic acid (TPA). In this study, post-consumer PET sparkling water bottles were neutrally hydrolysed via a hydrothermal process operating within a temperature range of 220–270 °C, a residence time of 30–90 min, and autogenous pressure of 25–90 bar. Under these conditions, the TPA yield varied between 7.34 and 81.05%, and the maximum TPA yield was obtained at 250 °C, 90 min, and 40 bar. The process temperature had a more profound impact on the PET conversion and TPA yield than the residence time. The values of the environmental factor (EF) were found to be 0.017–0.106, which were comparable to those of bulk chemicals (EF < 1). With the chosen operating conditions, the environmental energy impact (EEI) of TPA production was estimated to be 5.29 × 10⁴ °C min. The findings demonstrate that neutral hydrolysis is a feasible approach for converting PET polymers into monomers under mild environmental conditions. In addition, a GCMS analysis of the aqueous-phase product revealed a notable increase in the secondary degradation products of TPA, such as benzoic acid, rising from 66.4% to 75.7% as the process temperature increased from 220 °C to 270 °C. The degradation mechanisms of PET were found to be decarboxylation, dehydration, and oxidation. The dominant mechanism was found to be a decarboxylation reaction. Full article

Chlorella sp. was cultivated in a closed system using PET bottles (5 L) and with the continuous injection of air and commercial gas (98% CO₂) and in simulated conditions (15% CO₂, 73% N₂, and 12% O₂). The culture medium was prepared using well water and mining wastewater, the cultivation period occurred in a 10-day cycle, and the cell growth curves were evaluated through cell counting using a Neubauer chamber. The cultivation was carried out under the following conditions: temperature at 22 °C to 25 °C; aeration rate with commercial and simulated CO₂ gas at 0.01 vvm; and synthetic air containing 0.042% CO₂. The dry biomass productivity was 0.81 g·L⁻¹·day⁻¹ and the maximum CO₂ fixation rate was 0.90 g·L⁻¹·day⁻¹ when the microalgae were cultivated with a continuous flow of simulated waste gas and a culture medium composed of wastewater. The percentages of macromolecules obtained in the biomass cultivated in wastewater reached 20.95%, 26.48%, and 9.3% for lipids, proteins, and carbohydrates, respectively. Full article

In recent years, several plastic-degrading enzymes with efficient depolymerization abilities for PET have been reported. Here, we report a bioprocess for mixed PET waste depolymerization using crude extracellularly expressed enzymes in E. coli. The enzymes, namely FastPETase, LCC, and LCC^ICCG, were screened to depolymerize amorphous PET powder and films of different sizes and crystallinity. FastPETase, LCC, and LCC^ICCG achieved approximately 25, 34, and 70% depolymerization, respectively, when applied to 13 g L⁻¹ of PET film, powder, or mixed waste in optimized enzyme conditions without any pH control. The yield of terephthalic acid in the hydrolytic process was maximum for LCC^ICCG followed by LCC and FastPETase. Finally, extracellular LCC^ICCG-producing E. coli cells were cultivated using minimal media supplemented with 0.1% ammonium chloride and 1% glycerol as nitrogen and carbon sources in a bioreactor with a final protein content and specific activity of 119 ± 5 mg L⁻¹ and 1232 ± 18 U mg⁻¹, respectively. Nearly complete depolymerization of 13 g L⁻¹ PET and 23.8 g L⁻¹ post-consumer PET was achieved in 50 h using crude LCC^ICCG supernatant, without enzyme purification, at 62 °C. A bioprocess was thus developed to depolymerize 100 g L⁻¹ mixed PET trays and bottle waste (MW1 and MW2), reaching 78% and 50% yield at 62 °C with a crude enzyme loading of 2.32 mg g⁻¹ PET in 60 h. The results demonstrate an easy PET depolymerization strategy that could be exploited in large-scale facilities for efficient plastic waste treatment. Full article

Unmanaged waste can cause environmental pollution, as well as hygiene and health problems. Sitimulyo Piyungan Bantul at the coordinates of −7.86409, 110.42888 was established in 1994 and is the final waste repository area in Yogyakarta, and it is now completely closed; consequently, causing joblessness in the surrounding community. There are activities that can be undertaken to recycle waste such as managing rubbish. Waste can be divided into four categories scrapping, composting, and producing maggot food. However, unmanaged and useful waste, namely, inorganic and hazardous waste, remains a big problem. This research work aims to solve the problem by re-engineering and making an initial simulation using computational fluid dynamics of an incinerator to complete unmanaged inorganic and hazardous rubbish. The incinerator was produced to process non-organic solid and medical waste, which should be combusted at temperatures higher than 800 °C to reduce combustible rubbish that can no longer be recycled, and toxic chemicals, to kill bacteria and viruses. The main incinerator frame is made of an iron elbow. Construction of the incinerator is divided into the chamber, recirculation zone, and chimneys. The wall of the incinerator machine is made of refractory stone and insulators. To measure and control the temperature, thermocouples and a thermocontrol are placed at the inner wall of the incinerator machine. The function of the incinerator machine was tested, and it ran normally. Initial operation of an incinerator for solid hazardous waste such as infusion bottles, pets, glass bottles, pampers, and expired medicines was undertaken. The performance showed that the achieved temperature was 705 °C during the process of the operation, and all of the hazardous waste became ash and the recycled material became a paving block that is economically worthwhile. Hence, the incinerator can be operated as a household industrial tool for a solid medical waste processing apparatus. An initial computational study of the incinerator was also carried out briefly using the student version of commercial software. Full article

Waste recycling is critical for the development of smart cities. Local authorities are responsible for the disposal of waste plastics, but the extent of material recycling is insufficient, and much of the waste generated is incinerated. This conflicts with the trend of decarbonisation. Of particular note are the effects of the COVID-19 pandemic, during and after which large quantities of waste plastics, such as plastic containers and packaging, were generated. In order to develop a sustainable smart city, we need an effective scheme where we can separate materials before they are taken to the local authorities and recyclers. In other words, if material identification can be performed at the place of disposal, the burden on recyclers can be reduced, and a smart city can be created. In this study, we developed and demonstrated smart material identification equipment for waste plastic materials made of PET, PS, PP, and PE using GaP THz and sub-THz wavelengths. As basic information, we used a GaP terahertz spectrometer to sweep frequencies from 0.5 THz to 7 THz and measure the spectrum, and the transmittance rate was measured using the sub-THz device. The sub-THz device used a specific frequency below 0.14 THz. This is a smaller, more carriable, and less expensive semiconductor electronic device than the GaP. Moreover, the sub-terahertz device used in the development of this equipment is compact, harmless to the human body, and can be used in public environments. As a result, smart equipment was developed and tested in places such as supermarkets, office entrances, and canteens. The identification of materials can facilitate material recycling. In this study, we found that measuring devices designed to identify the PET and PS components of transparent containers and packaging plastics, and the PP and PE components of PET bottle caps, could effectively identify molecular weights, demonstrating new possibilities for waste management and recycling systems in smart cities. With the ability to collect and analyse data, these devices can be powerful tools for pre-sorting. Full article

The growing production of plastic waste and its recycling, from a circular economy perspective, faces challenges in finding solutions that are easy to implement, cheap in labor and energy during recycling, and locally implementable to avoid transportation. This work developed and validated a methodology to address these challenges. Designed for small-scale use at home or in schools following a Do It Yourself (DIY) approach, it transforms water bottles into plastic strips, which, after passing through an extruder nozzle, become filaments with a diameter of 1.75 mm. These can replace commercially available thermoplastic filaments. Specimens produced by additive manufacturing with recycled PET (rPET) and commercial PETG showed similar mechanical properties and can serve as alternatives to commercial PETG. PETG shows higher strength (30 MPa) compared to rPET (24 MPa), a slightly higher Young’s modulus of 1.44 GPa versus 1.43 GPa, and greater strain at failure with 0.03 mm/mm against 0.02 mm/mm, making it stiffer and more ductile. This simple and widely applicable local solution may absorb a considerable amount of bottle waste, offering an economical, sustainable alternative to commercial filaments. Full article

In the work presented here, we explore the upcycling of polyethylene terephthalate (PET) that was derived from water bottles. The material was granulated and extruded into a filament compatible with fused filament fabrication (FFF) additive manufacturing platforms. Three iterations of PET combined with a thermoplastic elastomer, styrene ethylene butylene styrene with a maleic anhydride graft (SEBS-g-MA), were made with 5, 10, and 20% by mass elastomer content. The elastomer and specific mass percentages were chosen based on prior successes involving acrylonitrile butadiene styrene (ABS), in which the maleic anhydride graft enabled compatibility between different materials. The rheological properties of PET and the PET/SEBS blends were characterized by the melt flow index and dynamic mechanical analysis. The addition of SEBS-g-MA did not have a significant impact on mechanical properties, as determined by tensile and impact testing, where all test specimens were manufactured by FFF. Delamination of the tensile specimens convoluted the ability to discern differences in the mechanical properties, particularly % elongation. Annealing of the specimens enabled the observation of the effect of elastomer content on the mechanical properties, particularly in the case of impact testing, where the impact strength increased with the increase in SEBS content. However, annealing led to shrinkage of the specimens, detracting from the realized benefits of the thermal process. Scanning electron microscopy of spent tensile specimens revealed that, in the non-annealed condition, SEBS formed nodules that would detach from the PET matrix during the tensile test, indicating that a robust bond was not present. The addition of SEBS-g-MA did allow for shape memory property characterization, where deformation of tensile specimens occurred at room temperature. Specimens from the 20% by mass elastomer content sample group exhibited a shape fixation ratio on the order of 99% and a shape recovery ratio on the order of 80%. This work demonstrates a potential waste reduction strategy to tackle the problem of polymer waste by upcycling discarded plastic into a feedstock material for additive manufacturing with shape memory properties. Full article

The rising challenge of polyethylene terephthalate (PET) waste necessitates efficient collection methods to mitigate environmental impacts. The Analytic Hierarchy Process (AHP) is one of the Multi-Criteria Decision Analysis (MCDA) approaches utilized in this study. The Technique for Order of Preference by Similarity to the Ideal Solution (TOPSIS) was used to rank each alternative according to the objective weight that AHP had produced. Also, sensitivity analysis was performed to determine how robust the findings were when considering equal weights and entropy weights to maximize PET waste collection techniques. The alternative achieved the objective of obtaining the best collection method, Threshold Plastic Bottle Waste Collection (T_pbw), out of all the three alternatives considered. Another MCDA approach, VIseKriterijumska Optimizacija I Kompromisno Resenje (VIKOR), was used to compare the results and validate the ranking result achieved by the TOPSIS method. The VIKOR technique’s validation of the TOPSIS approach showed that the outcomes were highly consistent. Data for the study were gathered from the archives of waste management companies on possible practices of plastic waste collection, addressing costs, environmental impacts, social acceptance, feasibility, and efficiency. The findings provide a prioritized framework for enhancing PET waste collection strategies, contributing to sustainable waste management. Many criteria are considered when deciding the best collecting method for PET waste recycling, making it challenging. By using criteria importance, MCDA was applied in this study, and the objective weight of the criteria was determined using the AHP. The five criteria considered in this study are Initial investment cost, operational cost, transportation cost, environmental risk, employment potential, and the objective weights allocated to them. AHP results 0.4952, 0.1997, 0.1565, 0.0870, and 0.0616 are, respectively, determined. Full article

In Japan, when people take their waste bottle caps to designated recycling companies, JPY 5/kg is donated to developing countries for polio vaccine dissemination activities. The waste volume of plastic bottles and caps is increasing every year, and there is not a day that goes by that we do not see more bottles and caps. PET bottles are more easily recycled, as the bottle body is made of a single material. However, bottle caps are made of two different materials (PP and PE), which are difficult to identify perfectly when utilising the existing NIR technology in the recycling field. This is because the designs and colours of PP and PE bottle caps are becoming more diverse, with black and dark-coloured caps being difficult to sort using NIR technology. In addition, their specific gravity is almost the same; therefore, it is difficult to separate them by their water-based specific gravity, which is an approach commonly used by recyclers. Unidentified caps are sent for thermal recycling, which runs counter to the need for decarbonisation. They may also be mixed with identified caps and sold as recycled raw material, resulting in a reduction in the purity of the recycled plastic. If PP and PE caps can be identified using simple technology, it is expected to promote high resource recycling. Therefore, in order to develop such a sorting process, this study proposes a new method for the material identification of waste caps using terahertz waves. Therefore, this research aims to identify a new identification method for waste plastic caps, which has been a challenge both domestically and internationally. Specifically, we describe the limitations of the conventional methods for identifying PP and PE bottle caps according to their weight, specific gravity, and melting point and propose an identification method using terahertz waves, demonstrating its measurement-related merits and high identification accuracy. Full article

With Japan facing workforce shortages and the need for enhanced recycling systems due to an aging population and increasing environmental challenges, automation in recycling facilities has become a key component for advancing sustainability goals. This study presents the development of an automated sorting robot to replace manual processes in beverage container recycling, aiming to address environmental, social, and economic sustainability by optimizing resource efficiency and reducing labor demands. Using artificial intelligence (AI) for image recognition and high-speed suction-based grippers, the robot effectively sorts various container types, including PET bottles and clear and colored glass bottles, demonstrating a pathway toward more sustainable waste management practices. The findings indicate that stabilizing items on the sorting line may enhance acquisition success, although clear container detection remains an AI challenge. This research supports the United Nation’s 2030 Agenda for Sustainable Development by advancing recycling technology to improve waste processing efficiency, thus contributing to reduced pollution, resource conservation, and a sustainable recycling infrastructure. Further development of gripper designs to handle deformed or liquid-containing containers is required to enhance the system’s overall sustainability impact in the recycling sector. Full article