Search

Packaging accounts for the largest demand for global plastic consumption and around 60% is for food and beverage packaging. The amount of packaging is increasing rapidly due to the expansion of retailer industries, especially in supermarkets and convenience stores. Plastic recycling strategies for food packaging in retailer industries need to be developed, but the current consumption and recycling status is not clear. To address this knowledge gap, this study quantifies the food packaging generation from major supermarket and convenience store chains in Taipei, Taiwan. We focus on the composition, recycling habit, and the recycling status to evaluate the packaging recyclability and major pathways for material losses. Based on our field survey and analysis, the total amount of plastic packaging generation was 21846.04 tons in 2020 with 64.99% of it being recycled. We defined the recycling rates as the continued product of Recyclable Content Ratio of the packaging itself, Sorting Accuracy Ratio of consumers, and Re-granulated Ratio in the final treatment facilities. These three ratios for major food categories were also presented to identify the hotspots of material losses. Our results suggest that to promote plastic food packaging recycling, identifying the limitations in different stages and designing corresponding strategies is crucial.

Riverbanks are an important source of plastic pollution. However, the current assessment methods for riverbank litter are based on a point-based sampling which is time consuming and limited in scope. To quickly assess hotspot areas and litter compositions in larger areas, this study developed a new citizen science bicycle survey for riverine debris. Covering 281.5 km of the Tamsui river system in Taiwan, the new methodology was tested at one of the most plastics polluted rivers in the world. The results revealed an average litter density of 15.3 m3/km at the river mouth and of 0.2 m3/km to 2.8 m3/km along the riverbanks further upstream. The coastline was mainly polluted by derelict fishing gear whereas single-use plastics and illegally dumped waste dominated the upstream areas. A correlation between litter and population density could not be identified, but it was noted that litter hotspots occur at cut banks and near mangrove vegetation. Overall, the new methodology proved suitable to collect large quantities of data for scientific purposes and to quickly detect litter accumulations prior to clean-up activities.

An optimum treatment system for the waste electronic home appliance in remote area by local pre-processing and outsourcing post-processing is proposed. The cost reduction potential of the proposed treatment system is presented for main four types of electronic home appliances by the case study of Kinmen, Taiwan. Implementation of local pre-processing in Kinmen, Taiwan can provide 42, 54, 32, and 41 TWD unit cost reduction for television, washing machine, refrigerator, and air conditioner, respectively, comparing to the current treatment system. The different treatment characteristics according to the type of the appliances are the major factors for the applicability and cost reduction potential of the local pre-processing system. The application of this system to other cases is presented by sensitivity analysis with relative labor cost and transportation distance as the parameters. The results and the analysis process can be applied to the domestic systems with regions without recycling facilities, and also the international systems under the extended producer responsibility concept to take back the products for recycling.

Transparent gallium-doped zinc oxide films were deposited on large area (117 mm × 185 mm) glass substrates by atmospheric pressure plasma jet method, using two different enclosure conditions—with and without side opening boundary. The opening allows gas exchange between the growth ambient and outside atmosphere. The spatial resistivity distribution was apparently influenced by the air flow field. The case with side opening has higher overall non-uniformity, and the film near the opening has the highest resistivity, caused by considerable reduction in carrier concentration (−32%) and mobility (−15%). Computer fluid dynamics simulations show that air was drawn in, through the side opening, from outside atmosphere, resulting in a much higher oxygen mass fraction (+50%) near the opening. As such, the film near the opening was deposited in O-rich conditions. The degradation of electrical conductivity in O-rich conditions cannot be explained by oxygen vacancies. We suggest that it is due to the formation of dopant-defect complex GaZn−VZn (the lowest formation energy) and reduction of hydrogen impurity (reduced hydrogen partial pressure) in O-rich conditions. Therefore, the tool enclosure, gas flow field, and scanning trajectory must be carefully designed to achieve minimum resistivity non-uniformity on large-area substrates.

Waste management is more challenging in small islands due to islands’ special characteristics. For small islands where energy recovery by incineration is difficult due to smaller waste generation amount with large seasonal fluctuations, waste shipments outside of island can make energy recovery possible. This study evaluated the cost effectiveness and environmental performance of waste shipments for energy recovery in case of small islands. The results shown that the direct shipment for incineration is expensive, but the emission prevention by energy recovery can surpass the emission from waste transportation. Waste shipments in the form of refused derived fuel (RDF) can reduce the transportation and incineration cost, but the high fossil fuel consumption in RDF production process resulted in high greenhouse gas emissions. The shipping distance, RDF gate fee, and emission from RDF production process have high influence on the cost effectiveness and environmental performance of the waste treatment process. The results of this study revealed the cost effective and environmental beneficial choosing criteria of waste shipments’ destination.

The abandoned end-of-life vehicle (ELV) problem in small islands has negative effects on local sustainable development, and the treatment of ELVs in island scale is usually difficult. This study presents the investigation of the material flows and economic analysis on the ELVs in small islands by the case study of Kinmen, Taiwan. The ELVs generation amount is estimated using the population balance model (PBM) and the results showed a steep increase in the future for both automobiles and motorcycles. The insufficient ELV treatment capacity has resulted in the significant informal treatment flow, which will be the total weight of 1906 tons of items with market value, with a potential economic gain of 16.9 million TWD in 2050. The results of the economic characterization of the local dismantling business clarified that profitability is the main hindrance for the development of new dismantling business due to high transportation costs. Our results suggested that implementation of the different subsidy rate according to the treatment area under the current policy or creation of a new treatment flow with a direct shipment of ELVs for treatment is necessary to improve the utilization of the stocked materials from untreated ELVs.

The effect of main gas flow rate and gas type of carrier gas on the electrical and optical properties of Ga-doped ZnO films deposited by atmospheric pressure plasma jet was investigated. Adding Ar and H 2 in the carrier gas reduces the sheet resistance of the films from 230 to 90 Ω/□ and increases the deposition rate by 38% due to the incorporation of hydrogen as a shallow donor and the lower breakdown potential of Ar, respectively. The effect of the main gas flow rate is less significant compared with the gas type of the carrier gas, but a proper flow rate is required to produce the film with lower resistivity. The lowest resistivity of 1.25 × 10 − 3 Ω cm was achieved with a carrier gas mixture percentage of 75% and a main gas flow rate of 30 slm at a substrate temperature of 180 °C in open air. All the samples presented in this study exhibit average transmittance above 80% in the visible region and low haze below 5.5%.

Large area (117 mm × 185 mm) gallium-doped zinc oxide (GZO) films are prepared on glass substrates by atmospheric pressure plasma jet (APPJ) technique. The uniformity of material properties, in particular the electrical resistivity, of the deposited film is of great importance in reducing design complexity of the electron devices. We investigate the effects of scanning trajectory recipe (speed, pitch and number of passes) on structural and electrical properties of GZO thin films. We find that the trajectory has significant effects on the magnitude and uniformity of sheet resistance over the glass substrates. For single pass, the resistance appears higher at the starting part of spray, whereas, for cases of multiple passes, the highest resistance appears in the central part of the substrate. XRD, SEM, Hall measurement and residual stress are used to study the film properties and identify root causes of the nonuniform distribution of sheet resistance. We conclude that annealing time is the dominant root cause of the nonuniform resistance distribution, and other factors such as residual stress and structural characteristics may also have contributions.