Journal of the Air & Waste Management Association最新文献

Thermal treatment is a mainstream technique to separate plastic components from waste crystalline silicon (c-Si) photovoltaic (PV) modules. In this study, the thermogravimetric analysis (TGA) was conducted for a better understanding of the characteristics of plastic components mainly poly(ethylene-co-vinyl) acetate (EVA) binder and polyfluoroethylene composite membrane (TPT) backsheet in waste c-Si PV panels through thermal treatment at four different heating rates (5-20°C·min^-1) under nitrogen and air conditions, respectively. The thermal process of the EVA binder whether in a nitrogen or air atmosphere could be divided into two phases, which were 300-400°C and 400-515°C in nitrogen with the total weight loss reached 99.64%; the two phases in the air were 270-405°C and 405-570°C with the total weight loss was 99.68%. The thermal weight loss of TPT in nitrogen has only one phase occured between 380°C and 520°C, and the weight loss rate is about 83%. There are two weight loss phases in the air atmosphere, which the first phase starts from 265°C to 485°C and the second phase ends at 635°C with a final weight loss reaching 97%. Furthermore, the Kissinger-Akahira-Sunose (KAS) method was chosen to calculate the pyrolysis kinetic parameters. The activation energy for EVA in nitrogen (261.16 kJ·mol^-1) was higher than in air (209.04 kJ·mol^-1), also the TPT in nitrogen (188.28 kJ·mol^-1) higher than in air (172.21 kJ·mol^-1). That indicated that the thermal decomposition of EVA binder was accelerated at first phase in nitrogen, but there is little difference in air atmosphere. Moreover, the activation energy of PVF of the TPT backsheet in the first phase was lower than that in the second phase. This study provides the fundamental basis to develop efficient thermal separation for the plastic components EVA and TPT in waste PV panels.Implications: This study mainly aims to explore the thermal separation of plastic components of waste c-Si panels for heating treatment, so that developing an accurate heat treatment approach that is efficient to implement for the separation of secondary raw material i.e., glass and silicon wafer from end-of-life PV panels. Therefore, this research findings have significant implications for providing the basic data support for waste PV panels management recycling standards, specifications, or policy documents.

Fugitive dust emissions play an important role in urban air quality. Much research on fugitive dust's effects has focused on human health and societal impacts, with limited work investigating effects on other species. The endangered Apodemia mormo langei butterfly is endemic to the Antioch Dunes, a small area on the south bank of the San Joaquin River in northern California, largely protected as a National Wildlife Refuge. Between the two protected portions of the dunes is a gypsum processing facility. Deposition of gypsum dust may adversely affect endangered insects, especially in their vulnerable larval life stage. Persistent westerly winds blow from the western section of the refuge, across the industrial facility, to the eastern protected dune area. Ambient particulate matter (PM) was collected at 30 sites in both sections of the refuge using passive samplers deployed at times matching the butterfly life cycle. The prevailing wind maintained upwind-downwind sampling orientation throughout the study. PM samples were analyzed for total mass, and elemental composition via X-ray fluorescence. Downwind concentrations of gypsum-related elements were between 4 (strontium) and 12 (sulfur) times higher than upwind loadings, suggesting deposition of PM from the gypsum facility. The effect of fugitive emissions was strongest at the industrial facility's fenceline, closest to a conveyor belt that loads gypsum. Combined with documented reductions in insect larval longevity when exposed to gypsum dust, the results suggest that gypsum deposition may be affecting the ecosystem and endangered species in the downwind unit of the Antioch Dunes National Wildlife Refuge.Implications: Fugitive dust has impacts not only on humans, but on other organisms. The Antioch Dunes National Wildlife Refuge (ADNWR) in California, set aside to protect the endangered Apodemia mormo langei butterfly, consists of two land units separated by a gypsum processing facility in between them. In this study, we demonstrate fugitive gypsum dust deposition on the downwind unit of the ADNWR, which may impact the endangered butterfly and its ecosystem.

Particulate matter (PM) concentrations have decreased dramatically over the past 20 years, thus lower method detection limits (MDL) are required for these measurements. Energy-dispersive X-ray fluorescence (XRF) spectroscopy is used to quantify multiple elements simultaneously in the U.S. Environmental Protection Agency (EPA) Chemical Speciation Network (CSN). Inductively-coupled plasma mass spectrometry (ICP-MS) is an alternative analysis with lower MDL for elements. Here, we present a side-by-side comparison of XRF and ICP-MS for elements in PM_2.5 samples collected via the EPA's CSN. For ICP-MS, a simple extraction and ICP-MS analysis technique was applied to a wide variety of samples to minimize effort and cost and serve as a feasibility test for a large monitoring network. Filter samples (N = 549) from various urban locations across the US were analyzed first analyzed via XRF at UC Davis and then ICP-MS at RTI International. Both methods measured 29 of the same elements out of the 33 usually reported to CSN. Of these 29, 14 elements (Na, Mg, Al, K, Ca, Ti, V, Cr, Mn, Fe, Ni, Cu, Zn, Pb) were found to be frequently detected (i.e. had more than 10% of values above both XRF and ICP-MS MDL). ICP-MS was found to have lower MDL for 26 out of 29 elements, namely Na, Mg, Al, Ca, Ti, V, Cr, Mn, Fe, Co, Ni, Cu, As, Se, Rb, Sr, Zr, Ag, Cd, In, Sn, Sb, Cs, Ba, Ce, Pb; conversely, XRF had lower MDL for 3 elements, namely, P, K, Zn. Intra-method quality checks using (1) inter-elemental inspection of scatter plots using a priori knowledge of element sources and (2) scatter plots of routine versus collocated measurements reveal that ICP-MS exhibits better measurement precision. Lower detection limits for element measurements in nationwide PM monitoring networks would benefit human-health and source apportionment research.Implications: We demonstrate that ICP-MS with adilute-acid digestion method would significantly improve the element detection rates and thus be avaluable addition to the current analysis techniques for airborne PM samples in anationwide monitoring network. In this paper, we show that a hybrid method of elemental analysis for airborne particulate matter (PM) would significantly improve the detection rates for elements in PM. This would be a valuable addition to the current analysis techniques for airborne PM samples in nationwide and other large-scale monitoring networks, such as the EPA's Chemical Speciation Network (CSN). The techniques explored in this study (i.e., X-ray Fluorescence Spectroscopy or XRF and Inductively Coupled Plasma-Mass Spectrometry or ICP-MS) are relevant to the PM monitoring and regulatory community audience of JAWMA, especially agencies and states that are already involved in CSN. In addition, our results outline considerations that give insight on factors to consider for other large-scale and long-term ambient air monitoring efforts.

The growth, reproduction, and metabolic activities of microorganisms can lead to blockages within porous media, a phenomenon commonly observed in landfill engineering. Termed as microbial plugging, this phenomenon is significantly influenced by the inherent permeability characteristics of the system. In this study, we propose a simulation model based on the Monod equation to elucidate the clogging process caused by microorganisms in one-dimensional pore channels. Our primary focus is on the application of this model in landfill bioreactor systems. We demonstrate that microbial clogging in these systems is predominantly affected by factors such as the maximum environmental carrying capacity and pore size. These factors are directly influenced by the presence of solid waste within the landfill. By offering a theoretical foundation for mitigating microbial clogging in pore channels of landfill bioreactor systems, this research has the potential to contribute to the development of more efficient and effective waste management practices.Implications: Microbial plugging is a hot research topic in the field of environmental geotechnical engineering. Previous papers often only considered the reduction of pore volumes, while neglecting the role of clogging and the uneven distribution of permeability. In this paper, we established a permeability model for porous media that considers microbial growth and plugging. This model can reflect the temporal variation of permeability with microbial growth and predict the spatial distribution of permeability. This paper can promote on the utilization of microbial plugging technology in landfills or solid waste.

To explore the characteristic of competitive adsorption of formaldehyde (HCHO) and benzene(C₆H₆) on activated carbon, the slit models of activated carbon with different pore sizes of 1 nm, 2 nm and 4 nm were constructed by using the Visualizer module of Materials Studio molecular simulation software. The adsorption of single-component C₆H₆ and HCHO at three different temperatures of 288.15K,293.15K and 323.15K were conducted by the method of grand canonical Monte Carlo. Experiments were carried out to verify the accuracy of simulation results. For the single-compound adsorption, the adsorption amount of C₆H₆ varied little at different temperature conditions, while the pore size had a significant effect on the adsorption amount of C₆H₆, and the adsorption capability increased as the pore size goes up. The adsorption capacity of HCHO decreased as the temperature goes up, and the adsorption capacity of both 1 nm and 4 nm pore size activated carbon was less than that of 2 nm pore size. As for the competitive adsorption, HCHO has a better adsorption effect by activated carbon when the pore is in small size like 1 nm, while the competitive adsorption ability of C₆H₆ is much better than HCHO as the pore size goes up to 2 nm or 4 nm.Implications: (1) Understanding the equilibrium process of activated carbon adsorption at the molecular level based on the co-existence of multi-component VOCs. (2) The effects of concentration, temperature and humidity factors on the coupling of the dynamic equilibrium of competing adsorption of benzene and formaldehyde were analyzed. (3) The accuracy of the molecular simulations was verified using an experimental approach.

Cement solidification is essential to reduce heavy metal leaching from industrial sludge and make it recyclable. This paper studied the effect of aggregate grading optimized by sludge containing heavy metal of different particle sizes on the performance of baking-free sludge bricks, which was mixed with industrial sludge cured by both micro-silica fume and cement. First, the gradation of fine natural aggregates was adjusted according to the Fuller curve. Fine aggregates in baking-free bricks were replaced by artificially processed sludge with particle sizes of 0.15 mm ~0.3 mm and 2.36 mm ~4.75 mm. In this case, a mixed proportion scheme was designed. Then, the strength, water absorption, porosity, and heavy metal leaching were measured. With the help of nuclear magnetic resonance (NMR) and scanning electron microscopy (SEM), the phase and pore structures were observed. The test results showed that: (1) Sludge can replace part of the fine aggregates to make baking-free bricks, resulting in the reduction of the strength of baking-free bricks, but the strength still meets the standard strength requirements of GB/T 21,144-2007. (2) When fine aggregates are partly replaced by sludge with finer particle sizes, baking-free sludge bricks exhibit higher strength, lower water absorption, better pore structures and microphase structure, and stronger solidification of heavy metals, the leaching number of heavy metals meets the standard requirements of GB5085.3-2007, which will be provided support for actual industrial production.Implications: Cement solidification is an essential means to reduce the heavy metal leaching from industrial sludge and make it recyclable. This paper studied sludge containing heavy metal of different particle sizes on the performance of baking-free sludge bricks. This paper analyzed the compressive strength, porosity and water absorption of baking-free bricks mixed with sludge of different partical sizes, and adopted the NMR to characterize the pores of baking-free bricks, and the SEM to observe the baking-free bricks resultants and the interfacial transition zone (ITZ). The heavy metal leaching test verified the environmental benefits of baking-free bricks mixed with sludge instead of aggregates. There not only make full use of solid wastes, but also thus minimizing pollution to the environment, which provide support for actual industrial production and a reference for studying industrial sludge recycling technology.

Poor air quality is linked to numerous adverse health effects including strokes, heart attacks, and premature death. Improving energy efficiency in the industrial sector reduces air emissions and yields health benefits. One of these strategies, replacing an existing grid boiler (GB) with a combined heat and power (CHP) system, can improve a facility's energy efficiency but can also increase local air emissions, which in turn can affect health outcomes. Previous studies have considered air-emissions and health outcomes of CHP system installation at a single location, but few studies have investigated the regional air quality and health impacts of replacing an existing GB with new CHP system. This study estimates the emission changes and associated health impacts of this shift in 14 regions in the US, representing different electricity generation profiles. It assumes that one manufacturing facility in each region switches from an existing GB to a CHP system. The monetized annual US health benefits of shifting a single GB to a CHP in each of the 14 regions range from $-5.3 to 0.55 million (2022 USD), while including CHP emission control increases the benefits by 100-170% ($9,000 to 1.15 million (2022 USD)). This study also includes a sensitivity analysis, which suggests that the facility location (region, state, and county), boiler efficiency, and emission control of the CHP are key factors that would determine whether shifting from a GB to CHP system would result in health benefits or burdens.Implications: Combined heat and power (CHP) systems offer industrial facilities the opportunity to improve their energy efficiency and reduce greenhouse gas emissions. However, CHP systems also combust more fuel on site and can also increase local air emissions. This study evaluates how converting an existing grid boiler (GB) system to a CHP system (with or without emission control) affects local (from combustion) and regional emissions (from electricity consumption) and the associated health burdens in different US regions. A facility can use this study's analysis as an example for estimating the tradeoffs between local emission changes, regional emission changes, and health effects. It also provides a comparison between the incremental cost of adding SCR (compared to uncontrolled CHPs) and the NPV of the monetized health benefits associated with adding the SCR.

With the goal of corroborating existing emissions inventories of volatile organic compounds (VOCs), a statistical analysis was undertaken on measured ambient VOC concentrations in Maricopa County, Arizona. The Chemical Mass Balance (CMB) model was used to generate emissions source contribution estimates based on ambient VOC concentrations collected at the JLG Supersite in Phoenix, Arizona, and emissions source profiles obtained from EPA's SPECIATE database. With trial-and-error, optimal model performance using a combination of emissions source profiles yielded source contribution estimates which could be compared to existing regulatory engineering-based emissions inventories. The ultimate objective of this study is to offer a comparison to the "top-down" emissions modeling via CMB and the "bottom-up" modeling traditionally used in preparing emission inventories to identify possible discrepancies and help direct future investigations to better understand local air quality. The methods used to develop the "bottom-up" inventory rely upon sound modeling developed to accurately capture emissions from various source categories. The results show discrepancies between the "bottom-up" and "top-down" emission inventory for VOC emissions from biogenic and natural gas combustion sources, suggesting that the emission strength from these source categories should be further investigated.Implications: The following implication statement has been prepared for the manuscript titled Source Apportionment of Measured Volatile Organic Compounds in Maricopa County, Arizona. The purpose of preparing such a study was to independently corroborate the findings of Maricopa County Air Quality Department (MCAQD) on source contribution estimates of VOC emissions as published in their 2020 Periodic Emissions Inventory for Ozone Precursors. The goal of preparing the findings in the study was to provide additional commentary on the significance of various VOC emissions sources to tropospheric ozone formation in Maricopa County through an alternate air quality modeling approach. The findings from this study are significant to the environment and health of Maricopa County as they offer additional insights into the pathways by which tropospheric ozone may form.

Exposure to air pollution is a fundamental obstacle that makes it complex to realize the Sustainable Development Goals (SDGs 3) for good health and wellbeing. It is for this reason that air pollution has been characterized as the global environmental health risk facing the current generation. The risks of air pollution on morbidity, and life expectancy are well documented. This feeds directly to the substantial body of the literature that exists regarding the burden of diseases associated with ambient air pollution. However, the bulk of this literature originates from developed countries. Whilst most of the sub-Saharan African studies extrapolate literature from developed countries to contextualize the risks of elevated air pollution exposure levels associated with the burden of disease. However, extrapolation of epidemiological evidence from developed countries is problematic given that it disregards the social vulnerability. Therefore, given this observation, it is ideal to evaluate if the monitoring executions of hazardous particulate matter and nitrogen dioxide do take into consideration the concerted necessary efforts to associate monitored air pollution exposure levels with the burden of disease. Therefore, based on this background, the current meta-analysis evaluated air quality monitoring associated with the burden of disease across sub-Saharan Africa. To this extent, the current meta-analysis strictly included peer-reviewed published journal articles from the sub-Saharan African regions to gain insight on air quality monitoring associated with the burden of disease. The collected meta-analysis data was captured and subsequently analyzed using Microsoft Excel 2019. This program facilitated the presentation of the meta-analysis data in the form of graphs and numerical techniques. Generally, the results indicate that the sub-Saharan Africa is characterized by a substantial gap in the number of regional studies that evaluate the burden of disease in relation with exposure to air quality.Implications: The work presented here is an original contribution and provides a comprehensive yet succinct overview of the monitoring associated with the burden of disease in sub-Saharan Africa. The author explores if the monitoring executions of hazardous particulate matter and nitrogen dioxide do take into considerations the concerted necessary efforts to associate monitored air pollution exposure levels with the burden of disease. The manuscript includes the most relevant and current literature in a field of study that has not received a deserving degree of research attention in recent years. This is especially true in sub-Saharan Africa, characterized by insufficient monitoring of air quality exposure concentrations.