Journal of the Air & Waste Management Association最新文献

The selection of the appropriate composting system, climate conditions, and duration of the composting process are important parameters for municipal solid waste composting. Therefore, this research aimed to design, test, and evaluate two different static composting systems under two different climate regions, Palestine and India, following a multi-criteria approach. A forced-aeration composting system was designed for use in Palestine, and a naturally aerated one was used in India. Three experiments were conducted, two of them in Palestine and one in India. The operational parameters were controlled and monitored during the composting process, while the physio-chemical and biological parameters were tested to evaluate the compost end quality. The results showed that both systems provide good efficiency toward formation of final compost (39-43 days in Palestine, and 31 days in India), and the average materials' volume reduction was almost 60%. The physio-chemical analysis showed that most of the parameters comply with the threshold limits specified by the Palestinian Standards Institution (PSI) and Indian Fertilizer Control Order (FCO) except for minor deviations. Both systems provided a high fertility index (4.3, 4.7, and 4.8), and a high clean index (4.6, 5.0, and 4.7). However, the results of the biological parameters showed that all the experiments met PSI, but none of them met FCO, suggesting that the outer edges of the composting system didn't heat enough to inactivate pathogenic microbes, therefore, developing the system by adding turning option could overcome this shortcoming. It was concluded that the forced aeration system is suitable for Palestine, while the natural aeration system is suitable for India.Implications: Municipal solid waste management is facing technical and financial challenges worldwide due to the increasing generation of solid waste following the population growth. The current improper management of this waste stream through landfilling is adding pressure on the environment as a result of methane emissions and landfill leachate. Therefore, composting of the organic fraction through selection of an appropriate composting system can solve many waste management problems and contribute to environmental sustainability. This research focuses on design, test and evaluate two composting systems in two regions with different climatic conditions, Palestine and India as both are facing waste management problems. The outcome of this research optimized the composting process which can be replicated and scaled up in other countries worldwide with similar climatic conditions.

The release of toxic gases into the atmosphere may reach concentrations that can cause undesirable health, economic, or aesthetic effects. It is therefore important to monitor the amounts of pollutants injected into the atmosphere from various sources. Most countries have a ground network with multiple measuring sites and instruments, that can measure the air quality index (AQI). However, the main challenge with the networks is the low spatial coverage. In this work, satellite data is used to calculate for the first time the spatial distribution of AQI and pollutant concentration over South Africa. The TROPOspheric Monitoring Instrument (TROPOMI) onboard Sentinel-5P data is used to calculate AQI from carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O₃), and sulfur dioxide (SO₂) gases. The results that the month of June has the worst air quality distribution throughout the country, while March has the best air quality distribution. Overall, the results clearly show that TROPOMI has the capability to measure air quality at a country and city level.Implications: In this work, satellite data is used to calculate for the first time the spatial distribution of the air quality index (AQI) and pollutant concentration over South Africa. The TROPOspheric Monitoring Instrument (TROPOMI) onboard Sentinel-5P data is used to calculate AQI from carbon monoxide (CO), nitrogen dioxide (NO₂), ozone (O3), and sulfur dioxide (SO₂) gases. Currently, South Africa has a ground network of instruments that measure AQ, however, the network does not cover the whole country. In this work, we show that the use of TROPOMI can compliment the current network and provide data for the areas not covered.

Real-time measurements of short-chain (C < 8) per- and polyfluoroalkyl substances (PFAS) were performed in Central New Jersey air using chemical ionization mass spectrometry (CIMS). The CIMS was calibrated for C₂-C₆ perfluorinated carboxylic acids, and 4:2 and 6:2 fluorotelomer alcohols. Of these, only trifluoroacetic acid (TFA) was detected in ambient air above instrumental detection limits. However, instrumental sensitivities (and thus ambient mixing ratios) were estimated for other detected PFAS including C₃H₂F₆O and C₆HF₁₁O₃. TFA mixing ratios reached up to 0.7 parts-per-trillion by volume (pptv). Estimated C₃H₂F₆O and C₆HF₁₁O₃ mixing ratios reached the single pptv level. These latter two formulas are consistent with hexafluoroisopropanol (HFIP) and hexafluoropropylene oxide dimer acid (HFPO-DA), respectively, though they may potentially represent multiple isomers. Diel profiles of detected PFAS along with local meteorological data can provide information on potential local sources of these compounds. However, only limited discussion of potential sources was provided here given the sparse detection of these compounds above instrument detection limits. These results demonstrate the potential of online CIMS instrumentation for measuring certain PFAS in ambient outdoor air in real time at or below the pptv level. This technique also has potential for fenceline monitoring and other near-source applications.Implications: Online chemical ionization mass spectrometry (CIMS) has potential for fast, real-time measurements of certain airborne per- and polyfluoroalkyl substances (PFAS). Three short-chain (C < 8) PFAS were detected by CIMS in Central New Jersey ambient air near or above the parts-per-trillion by volume (pptv) level. This technique also has potential for fenceline monitoring and other near-source applications for airborne PFAS.

Efficient solid waste management is crucial for urban health and welfare in the midst of fast industrialization and urbanization. In this changing environment, government authorities have a significant role in addressing and reducing the effects of solid waste. While waste separation at the source simplifies processes, manual sorting is a consequence of ignorance in numerous regions, which endangers the health of waste pickers. This study addresses the challenges by introducing the MSW-Net model, a hierarchical stacking model designed for the automated classification of municipal solid waste (MSW). Customized Convolutional Neural Network (custom CNN) and Bayesian-Optimized MobileNet models serve as the base models, with Gradient Boosting employed as the meta-classifier. The MSW-Net model, as proposed, exhibits exceptional performance, attaining 99%, 95%, and 96.43% accuracy rates over training, validation, and testing, respectively. Additionally, the model achieves precision, recall, and F1 scores of 96.42%, 96.43%, and 96.42% during the testing phase. Therefore, the proposed MSW-Net model performs better than the other existing models in sorting the waste. This could also aid the municipal authorities in classifying the waste with minimal human intervention.Implications: The MSW-Net model, featuring a hierarchical stacking approach with custom CNN and Bayesian-Optimized MobileNet base models, and Gradient Boosting as the meta-classifier, achieves remarkable accuracy in automated municipal solid waste classification. With performance metrics of 99% accuracy in training, 95% in validation, and 96.43% in testing, alongside precision, recall, and F1 scores around 96.42%, the MSW-Net model significantly outperforms existing models. This advancement promises to aid municipal authorities in efficient waste management, reducing reliance on manual sorting and thereby improving the health and safety of waste pickers.

Communities near transportation sources can be impacted by higher concentrations of particulate matter (PM) and other air pollutants. Few studies have reported on air quality in complex urban environments with multiple transportation sources. To better understand these environments, the Kansas City Transportation and Local-Scale Air Quality Study (KC-TRAQS) was conducted in three neighborhoods in Southeast Kansas City, Kansas. This area has several emissions sources including transportation (railyards, vehicles, diesel trucks), light industry, commercial facilities, and residential areas. Stationary samples were collected for 1-year (October 24, 2017, to October 31, 2018) at six sites using traditional sampling methods and lower-cost air sensor packages. This work examines PM less than 2.5 μm in diameter (PM_2.5), black carbon (BC), and trace metals data collected during KC-TRAQS. PM_2.5 filter samples showed the highest 24-h mean concentrations (9.34 μg/m³) at the sites located within 20-50 m of the railyard. Mean 24-h PM_2.5 concentrations, ranging from 7.96 to 9.34 μg/m³, at all sites were lower than that of the nearby regulatory site (9.83 μg/m³). Daily maximum PM_2.5 concentrations were higher at the KC-TRAQS sites (ranging from 25.31 to 43.76 μg/m³) compared to the regulatory site (20.50 μg/m³), suggesting short-duration impacts of localized emissions sources. Across the KC-TRAQS sites, 24-h averaged PM_2.5 concentrations from the sensor package (P-POD) ranged from 3.24 to 5.69 µg/m³ showing that, out-of-the-box, the PM sensor underestimated the reference concentrations. KC-TRAQS was supplemented by elemental and organic carbon (EC/OC) and trace metal analysis of filter samples. The EC/OC data suggested the presence of secondary organic aerosol formation, with the highest mean concentrations observed at the site within 20 m of the railyard. Trace metals data showed daily, monthly, and seasonal variations for iron, copper, zinc, chromium, and nickel, with elevated concentrations occurring during the summer at most of the sites.Implications: This work reports on findings from a year-long air quality study in Southeast Kansas City, Kansas to understand micro-scale air quality in neighborhoods impacted by multiple emissions sources such as transportation sources (including a large railyard operation), light industry, commercial facilities, and residential areas. While dozens of studies have reported on air quality near roadways, this work will provide more information on PM_2.5, black carbon, and trace metals concentrations near other transportation sources in particular railyards. This work can also inform additional field studies near railyards.

Volatile Particulate Matter (vPM) emissions are challenging to measure and quantify, since they are not present in the condensed form at the engine exit plane and they evolve to first form in the aircraft plume and then continue to grow and change as they mix and dilute in the ambient atmosphere. To better understand the issues associated with the initial formation and growth of vPM, a modeling study has been undertaken to examine several key parameters that affect the formation and properties of the vPM that is created in the initial cooling and dilution of the aircraft exhaust. A modeling tool (Aerosol Dynamic Simulation Code, ADSC) that was developed and enhanced over a series of past research projects supported by NASA, DoD's SERDP/ESTCP, and FAA was used to perform a parametric analysis of vPM. The parameters of fuel sulfur content (FSC), emitted condensable hydrocarbon (HC) concentrations, and the species profile of the HCs were used to construct a computational matrix that framed a wide range of expected parameter values. This computational matrix was executed for two representative commercial aircraft engines at ground idle and results were obtained for distances of 250 m and 1000 m downstream. From prior results, the most significant vPM emissions occur at the lowest power settings, so an engine power condition of 7% rated thrust was used. A primary goal of the parametric study is to develop an updated vPM modeling methodology and also to help interpret data collected in experimental campaigns. The parameterization proposed here allows the vPM emission composition and particle numbers to be estimated in greater detail than current methods. The aim is to provide additional understanding on how the vPM properties vary with fuel and engine parameters to increase the utility of vPM predictions.Implications: Volatile Particulate Matter (vPM) is an important contribution to the total PM emitted by aviation engines. While vPM is not currently a part of engine emissions certification regulations, vPM is used in aviation environmental impact assessments and for air quality modeling in and around airports. Current methods in use, such as FOA, were developed before many recent advances in experimental data acquisition and in understanding of vPM processes. The parameterization proposed here allows the vPM emission composition and particle numbers to be estimated in greater detail than current methods. These estimates can be used to develop inventories and provide a better estimate of total emission for most aviation engines. Its use in international regulatory tools can inform possible future regulatory actions regarding vPM.

To quantitatively investigate the transboundary behaviors and source attributions of ozone (O₃) and its precursor species over East Asia, we utilize the adjoint technique in the CMAQ modeling system (the CMAQ adjoint). Our focus is on the Seoul Metropolitan Area (SMA) in South Korea, which is the receptor region of this study. We examine the contributions of both local and transported emissions to an O₃ exceedance episode observed on June 3, 2019, estimating up to four days in advance. By using the CMAQ adjoint, we can determine the sensitivity of O₃ remaining in the SMA to changes in O₃ precursor emissions (emissions-based sensitivity) and concentrations (concentrations-based sensitivity) along the long-range transport pathways and emission source regions overseas. These include Beijing-Tianjin-Hebei (BTH), Shandong, Yangtze River Delta (YRD), and Central China. CMAQ adjoint-derived source attributions suggest that overseas precursor emissions and O₃ contributed significantly to the O₃ exceedance event in SMA. The emissions-based sensitivities revealed that precursor emissions originating from Shandong, YRD, Central China, and BTH contributed 11.42 ppb, 4.28 ppb, 1.24 ppb, 0.9 ppb, respectively, to the O₃ exceedance episode observed in the SMA. Meanwhile, Korean emissions contributed 31.1 ppb. Concentrations-based sensitivities indicated that 19.3 ppb of contributions originated in regions beyond eastern China and directly affected the O₃ level in the SMA in the form of background O₃. In addition to capturing the transboundary movements of air parcels between the source and receptor regions, we performed HYSPLIT backward trajectory analyses. The results align with the trajectories of O₃ and its precursors that we obtained from the adjoint method. This study represents a unique effort in employing the adjoint technique to examine the impacts of regional O₃ on South Korea, utilizing a combination of emissions-based and concentrations-based sensitivities.Implications: This research brings to light the critical role of both local and regional precursor emissions in contributing to an ozone (O₃) exceedance event in the Seoul Metropolitan Area (SMA), South Korea. Utilizing the CMAQ adjoint technique, a novel approach in the context of South Korea's O₃ investigations, we were able to delineate the quantitative contributions of different regions, both within South Korea and from overseas areas such as Beijing, Shandong, Shanghai, and Central China. Importantly, the results underscore the substantial influence of transboundary pollutant transport, emphasizing the need for international collaboration in addressing air quality issues. As metropolitan areas around the globe grapple with similar challenges, the methodology and insights from this study offer a potent tool and framework for regions seeking

Polychlorinated biphenyls (PCBs), including all 209 congeners, are designated as persistent organic pollutants (POPs) due to their high toxicity and bioaccumulation in human bodies and the ecosystem. The need for PCB remediation still remains long after their production ban. In this study, a catalytic hydro-dechlorination (HDC) method was employed to dechlorinate 2,4,4'-trichlorobiphenyl (PCB 28), a congener found ubiquitously in multiple environmental media. The HDC of PCB 28 was experimentally studied at mild temperatures viz. ~20, 50, and ~77°C and atmospheric pressure. Et₃N (triethylamine) was added as a co-catalyst. The dechlorination rates increased with temperature as well as Et₃N dosage, and the HDC pathway was hypothesized based on the product and intermediates observed. The less chlorinated intermediates suggested that the position of the chlorine strongly impacted HDC rates, and the preference of HDC at para positions can be orders of magnitudes higher than the ortho. The activation energy was estimated in the range of 12.4-13.9 kJ/mole, indicating a diffusion-controlled HDC system.Implications: The remediation need for polychlorinated biphenyls (PCBs) still remains long after their production ban around the world. The development of low-cost methods is highly desirable, especially for developing countries, in response to the Stockholm Convention. In this study, the dechorination of a ubiquitously present PCB congener was studied using a catalytic hydro-dechlorination (HDC) method in low temperatures up to ~77°C and was able to achieve near 100% dechlorination in 6 hr. Results indicated that the HDC process can be performed under mild temperatures and atmospheric conditions and can be a potential solution to real world PCB contamination issues.

This study partially replaced the clay with sewer sludge (SS) and rice husk (RH-SS) to make fired bricks. The brick samples were examed in terms of shrinkage, water absorption, and compressive strength. Besides, they were analyzed via XRD and metal extraction to determine the heavy metal residuals in the products. The results showed that it was possible to fabricate fired bricks using sewer sludge or rice husk-blended sludge with up to 30% by weight. These brick samples complied with the technical standard for clay brick production, in which the compressive strength was more than 7.5 MPa, water absorption was from 11-16%, and the linear shrinkage was all less than 5%. The rice husk addition helped mitigate the heavy metal residuals in the bricks and leaching liquid, in which all the values were lower than the US-EPA maximum concentration of contaminants for toxicity characteristics.Implications: Previous studies have proved the possibility of mixing sewage sludge from different origins (sewage sludge, river sediment, canal sediment, sewer sediment, etc.) with clay and some wastes to make bricks. In which, mostof the studies used sewage sludge from wastewater treatment plants, very fewdealt with lake/river or sewer sediment. This study shall be the first to study the possibility of employing sewer sediments with the addition of rice husk powder to achieve two targets, including (1) the reuse of biowaste and sludge for brick fabrication and (2) the reduction of heavy metals in final calcined bricks. Different ratios of the rice-husk blended sewer sludge (RH-SS) - clay mixture shall be tested to find the optimized compositions. The results showed that it was possible to fabricate fired bricks using sewer sludge or rice husk-blended sludge with up to 30% by weight, which meant reduce 30% of clay in the brick production. The final products were proved to meet the quality standard in terms of compressive strength (more than 10 MPa), water absorption(from 11-16%), and the linear shrinkage (less than 5%). Larger scale of this study can be an evident to recommend for policy change in the waste reuse in construction field.