Relationship between recycling rate and air pollution: Waste management in the state of Massachusetts

Household waste management in Singapore and Shanghai: Experiences, challenges and opportunities from the perspective of emerging megacities

Due to rapid economic development and urbanisation, emerging megacities with dense populations have witnessed a significant increase in waste generation. Megacities face challenges in developing sustainable waste management systems. Considerable heterogeneity exists across megacities in management strategies. The two selected emerging megacities, Singapore (a city-state) and Shanghai, have similar developmental characteristics, but their waste management modes differ strikingly. This study assessed the two modes in terms of management strategies, environmental effects, economic costs, and social outcomes. Environmental footprint analysis and cost quantification were employed for the assessment based on public data. The research results would permit a deeper understanding of the long-term sustainability of each mode while considering the feasibility of implementation across different contexts. It was found that the waste management system in Singapore had a relatively lower environmental impact than Shanghai before Shanghai's new waste segregation and recycling policy in 2019. However, when the effect of fossil fuel substitution is taken into account, the environmental burden in Shanghai can be lowered more substantially than the one in Singapore. Although Shanghai had more economic burden for the waste segregation at source, it tended to implement the circular economy principles (e.g., reduce, reuse, and recycling) better and improve its sense of community significantly. Based on the practical experiences from the two representative megacities, suggestions for better waste management practices were provided for Singapore, Shanghai, and other emerging megacities with similar circumstances. In addition, challenges and opportunities related to household waste segregation and recycling were identified to guide future practices in emerging megacities.

Relationship between economic growth and mismanaged e-waste: Panel data evidence from 27 EU countries analyzed under the Kuznets curve hypothesis

The volumes of waste electrical and electronic equipment are rapidly increasing worldwide. While the relationship between e-waste generation and economic growth has previously been studied, mismanaged e-waste has received little attention. This study examines the environmental Kuznets curve (EKC) hypothesis between economic growth and mismanagement e-waste for 27 European countries over the period 2008-2016. Previous studies on ECK employed waste generation as a proxy for environmental degradation, while this work uses mismanaged e-waste, namely uncollected and non-recycled/non-reused e-waste. Two different econometric methods (dynamic and static) are applied; the first method uses Fully Modified Ordinary Least Square (FMOLS) and Dynamic Ordinary Least Square (DOLS) as panel integration estimation, while the second method employs traditional Pooled Ordinary Least Square (OLS) and Robust Least Squares (MM-estimation). The advantages of the first method are its ability to avoid the problems of endogeneity and serial correlation, while the second method is applied to check the robustness of the results and to disclose whether the data set suffers from outliers. All estimators used consistently identified the inverted U-shaped relationship between economic growth and mismanaged e-waste, as postulated by the EKC hypothesis: quantities of mismanaged e-waste increase along economic growth up to a certain economic development stage (turning point), but then mismanaged e-waste quantities decline while economy continues to grow. A unidirectional causality relationship running from economic growth to uncollected and non-recycled/non-reused e-waste was found. Furthermore, the results reveal that mismanaged e-waste increases with higher credit to private sector.

Characterizing municipal solid waste component densities for use in landfill air space estimates

Understanding the densities of individual waste materials in landfills as a function of landfill overburden pressure can provide a means to estimate the space occupied by these materials when they are landfilled. A compression device was used to simulate the overburden pressures in a landfill to determine the densities associated with 14 material categories. The materials with the greatest density were food waste, yard waste, and glass, ranging from 1302 to 1865 kg m^-3. The lowest density was associated with aluminum and steel/tin cans at 206 and 389 kg m^-3, respectively. Some materials did not exhibit a large variation in density when the load increased, indicating that their density was mostly independent of the overburden pressure. The data gathered from this research can be used as lifecycle assessment impact categories, where the functional unit of interest is 1 tonne of a material and the impact is measured as m³ of landfill space occupied.

Association of Ambient Air Pollution with Nasopharyngeal Carcinoma Incidence in Ten Large Chinese Cities, 2006-2013

Large cities in China are experiencing severe ambient air pollution. Although China accounts for more than 45% of new cases of nasopharyngeal carcinoma worldwide in 2018, few studies have examined the association between ambient air pollution and the high nasopharyngeal carcinoma (NPC) incidence in China. Thus, we aim to investigate whether exposure to ambient air pollution (including nitrogen dioxide, sulfur dioxide, and PM10) would significantly affect NPC incidence in large Chinese cities. We collected panel data of ten Chinese provincial cities about local NPC incidence, air pollution level, meteorology, and city profiles during 2006 to 2013 to construct a two-way fixed-effects model to explore the association between ambient air pollution and NPC incidence, as well as possible regional and gender differences behind the association. We found that NO2 had the strongest association with NPC incidence, and the relative risks were 2.2995 (95% CI, 1.2567-4.2075) for males and 1.3010 (95% CI, 0.8212-2.0620) for females, respectively. Under cumulative exposure, it was still NO2 that had the strongest association with NPC incidence, with a relative risk of 1.8836 (95% CI, 1.2416-2.8577), compared to 1.0857 (95% CI, 0.9474-1.2450) and 1.0547 (95% CI, 0.8790-1.2663) for SO2 and PM10, respectively. In addition, males were found more sensitive to ambient air pollution than females. We also found that southern Chinese cities were more sensitive to NO2 than northern cities, which might be related to a higher humidity there. Our study reveals that exposure to ambient air pollutants like SO2, PM10, and particularly NO2, is significantly positively associated with NPC incidence in China.

Environmental impact of biogas: A short review of current knowledge

The social acceptance of biogas is often hampered by environmental and health concerns. In this study, the current knowledge about the impact of biogas technology is presented and discussed. The survey reports the emission rate estimates of the main greenhouse gases (GHG), namely CO₂, CH₄ and N₂O, according to several case studies conducted over the world. Direct emissions of gaseous pollutants are then discussed, with a focus on nitrogen oxides (NO_x); evidences of the importance of suitable biomass and digestate storages are also reported. The current knowledge on the environmental impact induced by final use of digestate is critically discussed, considering both soil fertility and nitrogen release into atmosphere and groundwater; several case studies are reported, showing the importance of NH₃ emissions with regards to secondary aerosol formation. The biogas upgrading to biomethane is also included in the study: with this regard, the methane slip in the off-gas can significantly reduce the environmental benefits.