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1.
Environ Monit Assess ; 193(5): 277, 2021 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-33861359

RESUMEN

The moisture content of the municipal solid waste (MSW) is a physical characteristic that plays a fundamental role in the stability and settlement of landfills. However, this physical index is difficult to monitor within the mass of landfilled MSW because it undergoes great variation due, mainly, to the heterogeneity and biodegradation of the waste. Brazilian MSW generally has a large amount of organic matter, that when biodegraded, generates a considerable volume of gases and fluids, aggravated by climatic conditions, such as high rainfall and temperatures. Hence, the importance of obtaining and evaluating the distribution of moisture content in the MSW mass over time. Currently, the electrical resistivity properties have been presented as an interesting approach to obtain the moisture content in landfills indirectly. This study aimed to apply geoelectrical methods as a tool to obtain and evaluate the moisture content distribution in an experimental cell of a sanitary landfill using Archie's law, which correlates the volumetric moisture content and electrical resistivity. Moisture content values were obtained in laboratory tests with MSW samples collected in two vertical holes and electrical resistivity measurements by means of vertical electrical sounding. The moisture content and the resistivity values of the samples were used to calculate the parameters a and m of Archie's law. This allowed to convert the resistivity tomography to moisture content tomography. The good correlation achieved between the moisture content calculated by Archie's law and that obtained from samples indicates that the use of electrical resistivity methods is useful to assess and monitor quantitatively the moisture content in landfills using Archie's law.


Asunto(s)
Eliminación de Residuos , Brasil , Monitoreo del Ambiente , Residuos Sólidos/análisis , Instalaciones de Eliminación de Residuos
2.
Environ Monit Assess ; 193(5): 278, 2021 Apr 16.
Artículo en Inglés | MEDLINE | ID: mdl-33861382

RESUMEN

The municipal solid waste (MSW) dump in Boragaon, Guwahati, lies on the fringe areas of the wetland, Deepor Beel, which is a Ramsar site. The study was undertaken to analyze the impact the solid waste dump has on the adjoining wetland. Five sampling locations (S1, S2, S3, S4 and S5) in the wetland were selected within a distance of 3000 m from the MSW dump for the continuous monitoring of the surface water and sediment of the wetland. Nineteen physicochemical parameters (pH, EC, air and water temperature, total hardness, alkalinity, turbidity, DO, free CO2, TDS, BOD, Na+, K+, Ca2+, Cl-, NO3-, HCO3-, PO43-, SO42-) were analysed in the surface water, and 7 physicochemical parameters (pH, EC, %OC, %N, PO43-, K+, Na+) were analysed in sediment. Heavy metals Cu, Ni, Cd, Cr, Mn, Zn and As were analysed in surface water and sediment samples. The results of the principal component analysis (PCA) and cluster analysis (CA) applied on the surface water data have aptly described the source of contamination in the study area to be from the adjoining MSW dump site. The surface spread of contamination from the MSW dump towards the wetland was evident from the regression equations drawn from the sediment data. The mean concentration of Mn, Cr, Ni, Cd and As in surface water exceeded the MPL (maximum permissible limit) of WHO 2011 (World Health Organization). The pollution load index (PLI) of sediment in the wetland shows that the study area is under the category of "progressive deterioration".


Asunto(s)
Metales Pesados , Eliminación de Residuos , Contaminantes Químicos del Agua , Monitoreo del Ambiente , India , Metales Pesados/análisis , Residuos Sólidos , Agua , Contaminantes Químicos del Agua/análisis , Humedales
3.
Environ Monit Assess ; 193(5): 281, 2021 Apr 18.
Artículo en Inglés | MEDLINE | ID: mdl-33866429

RESUMEN

The present study explored the effect of local meteorology on the dispersion of PM2.5 from a 30-year open municipal solid waste (MSW) dumpsite in Chennai, India. The spatial monitoring was conducted in and around the dumpsite to understand the impacts of dumpsite activities on the nearby residential area. Results showed that dumpsite activities are responsible for deteriorating local air quality. The 24-h average PM2.5 concentrations were 50, 43.7, and 34 µg m-3 during stagnation, recirculation, and ventilation events, respectively. Spearman's correlation showed an inverse relationship between PM2.5 and temperature; wind speed indicated dispersion of fine aerosols. The observed inverse relationship between PM2.5 and relative humidity indicated the hygroscopic growth of fine aerosols in the study area. We used AERMOD to simulate the dispersion of 1-h, 8-h, and 24-h PM2.5 emissions from open waste burning in the dumpsite. The 1-h, 8-h, and 24-h simulated results showed the maximum concentration of 247, 136, and 53.4 µg m-3 in the dumpsite, and concentration levels ranged between 50-60, 30-50, and 10-20 µg m-3 were observed in the nearby residential area. The AERMOD predictions indicated that open waste burning could be a significant contributor to high PM2.5 concentration in an adjacent residential area of the dumpsite.


Asunto(s)
Contaminantes Atmosféricos , Contaminación del Aire , Contaminantes Atmosféricos/análisis , Contaminación del Aire/análisis , Monitoreo del Ambiente , India , Material Particulado/análisis , Estaciones del Año , Residuos Sólidos/análisis
4.
Bioresour Technol ; 331: 125023, 2021 Jul.
Artículo en Inglés | MEDLINE | ID: mdl-33798857

RESUMEN

Anaerobic co-digestion of organic fraction of municipal solid waste with solid content greater than 20% and chicken manure was investigated using leach-bed reactors in the framework of Middle East and North African countries. The objectives of the experiments were to determine the optimal ratio of organic fraction, chicken manure and solid inoculum, to compare temperature conditions and usage of liquid inoculum or water in percolation process. The highest specific methane yield (SMY) (236 LN ∙ kg-1 VS) was received in the reactors with 20/80 organic fraction/solid inoculum ratio under thermophilic conditions with liquid inoculum percolation. Under the same conditions but mesophilic temperature, SMY dropped by 12%. Replacing liquid inoculum by water led to 172 LN ∙ kg-1 VS. Addition of chicken manure to the substrate mixture positively influences a start-up phase and keeps pH in optimal range 6.5-8, despite the high ammonia concentration.


Asunto(s)
Eliminación de Residuos , Residuos Sólidos , Anaerobiosis , Reactores Biológicos , Digestión , Estiércol , Metano
5.
Environ Monit Assess ; 193(5): 288, 2021 Apr 22.
Artículo en Inglés | MEDLINE | ID: mdl-33886016

RESUMEN

In Santo Domingo de los Tsa'chilas province, Ecuador, the population grows proportionally to the territorial extension in urban and rural parishes; therefore, the conception of domestic solid waste has increased exponentially. In this context, in recent years, the distribution of routes for waste collection has not been dealt with or technically explored. The research objective is to apply the theory of graphs to the sector and use the exact method of the Travel Agent Problem (TSP) in dynamic programming to generate optimal routes by sectors. In addition to measuring the variables longitudinally, we test the researcher's hypothesis using parametric techniques for independent samples in the variable's travel time and distance between the usual route and the new route in the Río Verde parish of Santo Domingo Canton.


Asunto(s)
Monitoreo del Ambiente , Residuos Sólidos , Algoritmos , Ecuador , Viaje
6.
Artículo en Inglés | MEDLINE | ID: mdl-33799750

RESUMEN

The inadequate management of municipal solid waste (MSW) in fast-developing nations is a major public health problem. Trash collection is often inconsistent, leaving residents to use unsafe disposal methods such as incineration or unregulated dumping. The issue is especially pronounced in marginalized communities, where public service provision is scarce. Past research has identified factors that perpetuate harmful disposal practices. The current study expanded on previous work by exploring how individuals' perceptions of political, spatial, and economic marginalization affected their agency with regards to waste management. Researchers focused on a marginalized community in the Dominican Republic known as Esfuerzo de Paraíso. There, they conducted semi-structured interviews to explore residents' perceptions of marginalization at the individual, interpersonal, community, and institutional levels, and its effects on their agency. A qualitative coding process revealed that most community members were discontent with their trash disposal practices, but that long-standing marginalization left them feeling ill equipped to generate change at the individual level. Interviewees believed that change should be initiated at the community level and implemented with the support of institutional-level actors, namely the municipal government. Residents did not identify any non-governmental organizations as possible sources of help, which may suggest a limited view of institutional support networks.


Asunto(s)
Eliminación de Residuos , Actitud , República Dominicana , Humanos , Incineración , Residuos Sólidos
7.
J Environ Manage ; 288: 112475, 2021 Jun 15.
Artículo en Inglés | MEDLINE | ID: mdl-33823445

RESUMEN

The necessity for landfill leachate treatment is a requisite to reduce the environmental impact related to municipal solid waste landfills and different aspects must be considered while deciding for an appropriate treatment process. For example, it was demonstrated that the landfill leachate stabilization in tropical regions is achieved right after its first year of operation, requiring technologies capable of treating leachates of a higher recalcitrant character if compared to those leachates from temperate regions and same landfill age. In view of its complexity and variability, stand-alone processes (either biological or physicochemical) are often ineffective in attaining the threshold values for its discharge in receiving bodies. Due to that fact, full-scale facilities have adopted integrated routes, harvesting the benefits of both biological and physicochemical processes. The implementation of membrane bioreactors followed by polishing membrane separation process (nanofiltration and reverse osmosis) seems to be a trend in leachate treatment by full-scale treatment plants. This technology is widely employed in China, European countries, and tropical countries as Brazil, generally with a treatment cost lower than the costs related to its disposal in domestic effluent collection systems. From the technologies already employed by full-scale facilities, four integrated routes were proposed for a sensitive analysis considering the treatment of a landfill leachate of different physicochemical characteristics. From all routes, those employing the membrane separation process as a polishing step had a better efficacy in attaining the threshold values for leachate disposal, being that an interesting alternative for leachate polishing by full-scale facilities.


Asunto(s)
Eliminación de Residuos , Contaminantes Químicos del Agua , Brasil , China , Europa (Continente) , Residuos Sólidos/análisis , Instalaciones de Eliminación de Residuos , Contaminantes Químicos del Agua/análisis
8.
Artículo en Inglés | MEDLINE | ID: mdl-33806374

RESUMEN

In the case of sewage sludge, as direct landfilling was recently prohibited, it is treated through incineration. Among the air pollutants discharged through the incineration of sewage sludge, NOx and SOx are considered secondary substances of PM2.5 and are being managed accordingly. However, NH3, another of the secondary substances of PM2.5, is not well managed, and the amount of NH3 discharged from sewage sludge incineration facilities has not been calculated. Therefore, in this study, we sought to determine whether NH3 is discharged in the exhaust gas of a sewage sludge incineration facility, and, when discharged, the NH3 emission factor was calculated, and the necessity of the development of the emission factor was reviewed. As a result of the study, it was confirmed that the amount of NH3 discharged from the sewage sludge incineration facility was 0.04 to 4.47 ppm, and the emission factor was calculated as 0.002 kg NH3/ton. The NH3 emission factor was compared with the NH3 emission factor of municipal solid waste proposed by EMEP/EEA (European Monitoring and Evaluation Programme/European Environment Agency) because the NH3 emission factor of the sewage sludge incineration facility had not been previously determined. As a result of the comparison, the NH3 emission factor of EMEP/EEA was similar to that of municipal solid waste, confirming the necessity of developing the NH3 emission factor of the sewage sludge incineration facility. In addition, the evaluation of the uncertainty of the additionally calculated NH3 emission factor was conducted quantitatively and the uncertainty range was presented for reference. In the future, it is necessary to improve the reliability of the NH3 emission factor of sewage sludge incineration facilities by performing additional analysis with statistical representation. In addition, the development of NH3 emission factors for industrial waste incineration facilities should be undertaken.


Asunto(s)
Incineración , Aguas del Alcantarillado , Amoníaco , Reproducibilidad de los Resultados , Residuos Sólidos
9.
Artículo en Inglés | MEDLINE | ID: mdl-33801915

RESUMEN

As municipal solid waste severely threatens human health and the ecological environment, since 2019, China has started to fully practice MSW sorting in all prefecture-level cities. In this paper, we apply the event study and difference-in-difference methods to investigate how China's green policy of promoting MSW sorting influences listed waste sorting companies from the perspective of investors' short-term and long-term reactions. This paper finds that investors are not sensitive to the introduction of MSW sorting in the short term, the new environmental policy does not relieve the financing constraints of related enterprises in the long run, and the financing constraints of private enterprises are stricter than those of state-owned enterprises. These findings indicate that China's current encouragement of garbage sorting is not efficient enough as it has not brought benefits to the waste classification industry yet. More measures need to be taken to eliminate uncertainties in urban waste sorting. Our paper enriches the research on China's waste sorting practices and provides new evidence of the effects of environmental policy on related firms from the perspective of green industry.


Asunto(s)
Política Ambiental , Residuos Sólidos , China , Ciudades , Humanos , Industrias , Residuos Sólidos/análisis
10.
Huan Jing Ke Xue ; 42(5): 2413-2421, 2021 May 08.
Artículo en Chino | MEDLINE | ID: mdl-33884812

RESUMEN

The organic fraction of municipal solid waste (OFMSW) has become one of the sources and reservoirs of antibiotic resistance genes (ARGs). It is essential to explore the fate of ARGs during biological treatment of OFMSW. Therefore, the changes in several types of ARGs and integron genes during anaerobic digestion of the OFMSW were analyzed by quantitative PCR. Furthermore, the effects of different particle sizes of activated carbon on the behaviors of the target genes and the potential microbial mechanisms of ARGs dynamics were investigated. The results showed that the total ARGs in the initial system were reduced after anaerobic digestion with or without the presence of activated carbon. The removal rate of the absolute abundance of total ARGs was 29.95%-63.40%. In the final system of anaerobic digestion of the OFMSW, the abundance of total ARGs in powdered activated carbon (PAC) groups was significantly higher than that in the control group (P<0.05). The supplementation of PAC inhibited the reduction of ARGs, and the supplementation of granular activated carbon had no significant effect on the change in ARGs. The potential host bacteria of ARGs were mainly Clostridia, Bacteroidia, and Synergistia during anaerobic digestion. The enrichment of host bacteria caused by PAC addition was the main reason for the increase in the target genes. Moreover, Clostridia might have been the main driving factor for the growth and decline of ARGs. These results will help us to understand the dissemination of ARGs and the impacts of activated carbon addition on ARGs during anaerobic digestion of the OFMSW.


Asunto(s)
Antibacterianos , Residuos Sólidos , Anaerobiosis , Antibacterianos/farmacología , Carbón Orgánico , Farmacorresistencia Microbiana , Genes Bacterianos/genética
11.
Waste Manag ; 124: 314-324, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33647557

RESUMEN

Municipal solid waste (MSW) management is an important challenge in developing and emerging countries, where two realities co-exist. On the one hand, their metropolitan cities exhibit an integrated MSW system with a specialized fleet for the collection and landfills for the final disposal, concentrating on environmental initiatives such as municipal recycling programs. On the other hand, their regional cities show an MSW system based on adapted transports for collection and open dumps for final disposal. Besides, they face other environmental problems due to local conditions. This research proposes a life cycle assessment (LCA) approach to close the gap between these two realities. In particular, we study the city of Valdivia (Chile), one of the main regional capitals of South America, which shares similarities with other southern regional cities in the Global South. This city disposes 95% of its MSW in open dumps and presents one of the highest environmental pollution rates in Latin America. We analyze the greenhouse gas (GHG) emissions and energy performance of six scenarios, seeking a solution for these problems. The results obtained show that a waste-to-energy scenario would generate savings of GHG emission and particulate matter, reaching 11.3% and 21.8%, respectively. Using our LCA approach, we can provide environmental evidence to highlight the importance of improving MSW management in regional cities, closing the gap with MSW management in metropolitan cities, and contributing to national targets such as United Nations Sustainable Development Goals and Nationally-Determined Contributions.


Asunto(s)
Eliminación de Residuos , Administración de Residuos , Animales , Ciudades , Países en Desarrollo , Estadios del Ciclo de Vida , Residuos Sólidos/análisis , América del Sur
12.
J Environ Manage ; 286: 112140, 2021 May 15.
Artículo en Inglés | MEDLINE | ID: mdl-33652254

RESUMEN

The COVID-19 pandemic has imposed a global emergency and also has raised issues with waste management practices. This study emphasized the challenges of increased waste disposal during the COVID-19 crisis and its response practices. Data obtained from the scientific research papers, publications from the governments and multilateral organizations, and media reports were used to quantify the effect of the pandemic towards waste generation. A huge increase in the amount of used personal protective equipments (facemasks, gloves, and other protective stuffs) and wide distribution of infectious wastes from hospitals, health care facilities, and quarantined households was found. The amount of food and plastic waste also increased during the pandemic. These factors caused waste treatment facilities to be overwhelmed, forcing emergency treatment and disposals (e.g., co-disposal in a municipal solid waste incinerator, cement kilns, industrial furnaces, and deep burial) to ramp up processing capacity. This paper discussed the ways the operation of those facilities must be improved to cope with the challenge of handling medical waste, as well as working around the restrictions imposed due to COVID-19. The study also highlights the need for short, mid, and longer-term responses towards waste management during the pandemic. Furthermore, the practices discussed in this paper may provide an option for alternative approaches and development of sustainable strategies for mitigating similar pandemics in the future.


Asunto(s)
Eliminación de Residuos Sanitarios , Eliminación de Residuos , Administración de Residuos , Humanos , Pandemias , Residuos Sólidos/análisis
13.
Bioresour Technol ; 329: 124889, 2021 Jun.
Artículo en Inglés | MEDLINE | ID: mdl-33662854

RESUMEN

The study aims to investigate the feasibility of anaerobic co-landfilling of effluent treatment plant sludge (ETPS) from paper mill and municipal solid waste (MSW) in prismoidal shaped simulated anaerobic landfill bioreactors. Both ETPS and MSW were co-disposed in 0:100 (R1), 25:75 (R2), 50:50 (R3) and 75:25 (R4) ratios. Periodic assessments of leachate characteristics and biomethane production were carried out for 300 days. ETPS co-disposal with MSW showed considerable reduction in biochemical oxygen demand of leachate (R2: 95.9%, R3: 97.5% and R4: 93.2%). Moreover, cumulative methane gas generations were 2.974, 6.085 and 4.653 times more in R2, R3 and R4 bioreactors as compared to R1. Gompertz growth model was found in well-fitting for methane generation with the observed data. Correlogram plotted among leachate parameters exhibited exclusive relationships and justified leachate trends. This simulation of co-landfilling could be baseline study for the implementation of technology at pilot scale.


Asunto(s)
Eliminación de Residuos , Contaminantes Químicos del Agua , Anaerobiosis , Reactores Biológicos , Descontaminación , Metano , Aguas del Alcantarillado , Residuos Sólidos , Instalaciones de Eliminación de Residuos , Contaminantes Químicos del Agua/análisis
14.
J Environ Manage ; 287: 112257, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33690013

RESUMEN

The economic developments around the globe resulted in the increased demand of energy, which overburdened the supply chain sources of energy. Fossil fuel reserves are exploited to meet the high demand of energy and their combustion is becoming the main source of environmental pollution. So there is dire need to find safe, renewable and sustainable energy resources. Waste to energy (WtE) may be viewed as a possible alternate source of energy, which is economically and environmentally sustainable. Municipal solid waste (MSW) is a major contributor to the development of renewable energy and sustainable environment. At present the scarcity of renewable energy resources and disposal of MSW is a challenging problem for the developing countries, which has generated a wide ranging socioeconomic and environmental problems. This situation stimulates the researchers to develop alternatives for converting WtE under a variety of scenarios. Herein, the present scenario in developing the WtE technologies such as, thermal conversion methods (Incineration, Gasification, Pyrolysis, Torrefaction), Plasma technology, Biochemical methods, Chemical and Mechanical methods, Bio-electrochemical process, Mechanical biological treatment (MBT), Photo-biological processes for efficacious energy recovery and the challenges confronted by developing and developed countries. In this review, a framework for the evaluation of WtE technologies has been presented for the ease of researchers working in the field. Furthermore, this review concluded that WtE is a potential renewable energy source that will partially satisfy the demand for energy and ensure an efficient MSW management to overcome the environmental pollution.


Asunto(s)
Eliminación de Residuos , Administración de Residuos , Biomasa , Incineración , Residuos Sólidos , Tecnología
15.
J Environ Manage ; 287: 112238, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33714044

RESUMEN

Increasing amounts of municipal solid waste (MSW) has gained widely concern on reduction, utilization and minimizing environmental impacts associated with waste management. Life cycle assessment (LCA) has been used to evaluate total environmental impact of municipal waste management (MSWM) options in strategy-planning and decision-making process. The exiting LCA studies have covered a large range of detailed focus from waste treatment technology to applied modelling methods in LCA of MSWM, yet an important concern for stakeholders, the relationship between practical management strategies and their LCA results, has not been comprehensively summarized. This paper reviews recent LCA studies focusing on MSWM system in 45 cases from both developing and developed regions to promote evolution of the MSWM system through modification of waste management strategies. Selected literatures conducted LCA with system boundary covering the whole MSWM system rather than single treatment process or specific type of waste. This review has explored distribution and evolution of LCA studies in waste management field and summarized critical parameters (system boundary, functional unit, assessment approach and data uncertainty) for conducting LCA of MSWM system. Comparison results from 45 worldwide cases indicated 33%-154% environmental benefit in Global warming potential (GWP) impact with implement of integrated solid waste management system to replace single landfill, incineration, or open dumping treatment. Key issues with upgrading of MSWM system have been highlighted to raise concern, i.e., the importance of targeted management strategy on organic and recyclable waste, the growing contribution of waste collection and transportation to the total environmental impact, as well as promoting multi-impacts assessment for MSWM system to achieve environmentally effective, economically affordable, and socially acceptable. Rather than focus on technical factors, results from this study indicated the key influences from understanding local limitation, environmental concern, management chain and comprehensive impact, providing useful strategies on improving MSWM with generalization results of LCA studies.


Asunto(s)
Eliminación de Residuos , Administración de Residuos , Animales , Ciudades , Incineración , Estadios del Ciclo de Vida , Residuos Sólidos
16.
J Environ Manage ; 287: 112320, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33725658

RESUMEN

Information on the spatial extent of potential impact areas near disposal sites is vital to the development of a sustainable natural resource management policy. Eight Canadian landfills of various sizes and shapes in different climatic conditions are studied to quantify the spatial extent of their bio-thermal zone. Land surface temperature (LST) and normalized difference vegetation index (NDVI) are examined with respect to different Land Use Land Cover (LULC) classes. Within 1500 m of the sites, LST ranged from 18.3 °C to 29.5 °C and 21.3 °C-29.7 °C for forest land and agricultural land, respectively. Linear regression shows a decreasing LST trend in forest land for five out of seven landfills. A similar trend, however, is not observed for agricultural land. Both the magnitude and the variability of LST are higher in agricultural land. The size of the bio-thermal zone is sensitive to the respective LULC class. The approximate bio-thermal zones for forest class and agricultural classes are about 170 ± 90 m and 180 ± 90 m from the landfill perimeter, respectively. For the forest class, NDVI was negatively correlated with LST at six out of seven Canadian landfills, and stronger relationships are observed in the agricultural class. NDVI data has a considerably larger spread and is less consistent than LST. LST data appears more appropriate for identifying landfill bio-thermal zones. A subtle difference in LST is observed among six LULC classes, averaging from 23.9 °C to 27.4 °C. Geometric shape makes no observable difference in LST in this study; however, larger landfill footprint appears to have higher LST.


Asunto(s)
Monitoreo del Ambiente , Residuos Sólidos , Canadá , Bosques , Temperatura , Instalaciones de Eliminación de Residuos
17.
Waste Manag ; 124: 348-355, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33662766

RESUMEN

Temperatures as high as 100 °C have been reported at a few municipal solid waste (MSW) landfills in the U.S. A recently published model describing landfill heat accumulation identified reactions that contribute significant heat to landfills including the hydration and carbonation of Ca-containing wastes such as ash from MSW and coal combustion. The objective of this study was to develop a method to measure heat release from Ca-containing ash by isothermal calorimetry. The method was confirmed by comparing measured heat release from hydration and carbonation of pure CaO and Ca(OH)2 to the theoretical heat. Theoretical heat release was determined by characterizing test materials before and after experiments using thermogravimetric analysis (TGA) and X-ray diffraction (XRD). Heat recovery efficiencies with both water and synthetic leachate ranged from 79 to 90% for CaO hydration and between 65 and 74% for Ca(OH)2 carbonation, with no effect attributable to leachate. Additionally, simultaneous hydration and carbonation of CaO/Ca(OH)2 mixtures resulted in efficiencies of 65 to 74%. The developed method was applied to eight samples that were excavated from a landfill and known to contain coal ash, and the ratio of measured to theoretical heat was 0.5 to 4. Thus, calculation of theoretical heat release from XRD data was not a good predictor of the experimentally measured heat release. The developed method can be used by landfill operators to evaluate the heat potential of a waste, thereby facilitating decisions on the quantity of a waste that can be buried in consideration of landfill temperatures.


Asunto(s)
Eliminación de Residuos , Ceniza del Carbón , Calor , Residuos Sólidos , Instalaciones de Eliminación de Residuos
18.
Waste Manag ; 124: 368-376, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33662768

RESUMEN

Many methods have been applied to monitor fugitive methane gas from landfills. Recently, there have been suggestions to use a framework utilizing an unmanned aerial vehicle (UAV) for landfill gas monitoring, and several field campaigns have proved that a rotary UAV-based measurement has advantages of ease of control and high-resolution concentration mapping on the target planes. However, research on the evaluation of error-inducing factors in the suggested system is limited so far. This study prepared a measurement system with a lightweight methane detector and a rotary UAV to support the applicability of rotary UAV in landfill gas monitoring. Then, the validity of the system was tested experimentally and theoretically. In the detector reliability test, the methane detector had sufficient resolution for field application. The critical UAV velocity required was obtained to ensure the credibility of the proposed measurement system. When spatial interpolators were applied to field data from the measurement system, the empirical Bayesian kriging demonstrated the best prediction of methane concentrations at unmeasured points. With the verifications provided in this study, this proposed method may contribute to reducing uncertainty in estimating fugitive landfill gas emission.


Asunto(s)
Contaminantes Atmosféricos , Eliminación de Residuos , Contaminantes Atmosféricos/análisis , Teorema de Bayes , Monitoreo del Ambiente , Metano/análisis , Reproducibilidad de los Resultados , Residuos Sólidos , Instalaciones de Eliminación de Residuos
19.
Waste Manag ; 124: 385-402, 2021 Apr 01.
Artículo en Inglés | MEDLINE | ID: mdl-33662770

RESUMEN

Artificial neural networks (ANNs) have recently attracted significant attention in environmental areas because of their great self-learning capability and good accuracy in mapping complex nonlinear relationships. These properties of ANNs benefit their application in solving different solid waste-related issues. However, the configurations, including ANN framework, algorithm, data set partition, input parameters, hidden layer, and performance evaluation, vary and have not reached a consensus among relevant studies. To address the current state of the art of ANN application in the solid waste field and identify the commonalities of ANNs, this critical review was conducted by focusing on a modeling perspective and using 177 relevant papers published over the last decade (2010-2020). We classified the reviewed studies into four categories in terms of research scales. ANNs were found to be applied widely in waste generation and technological parameter prediction and proven effective in solving meso-microscale and microscale issues, including waste conversion, emissions, and microbial and dynamic processes. Given the difficulty of data collection in many solid waste-related issues, most studies included a data size of 101-150. For mathematical optimization, dividing the data into training-validation-test sets is preferable, and the training set is supposed to account for ~70%. A single hidden layer is usually sufficient, and the optimal numbers of hidden layer nodes most likely range from 4 to 20. This review is supposed to contribute basic and comprehensive knowledge to the researchers in general waste management and specialized ANN study on solid waste-related issues.


Asunto(s)
Residuos Sólidos , Administración de Residuos , Algoritmos , Redes Neurales de la Computación , Residuos Sólidos/análisis
20.
Sci Total Environ ; 771: 144891, 2021 Jun 01.
Artículo en Inglés | MEDLINE | ID: mdl-33736128

RESUMEN

Microalgae residue was efficiently converted into lactic acid with a high yield (33.9%) under mild reaction conditions (210 °C, 2 h) over a Fe-Sn-Beta catalyst. Under the action of homogeneous H3O+ and distinct Lewis acid sites on the catalyst, the production of lactic acid from microalgae residue underwent three main reaction steps: hydrolysis, isomerization, and retro-aldol condensation. Results demonstrated that the lipid component had a strong inhibitory effect on the production of lactic acid due to the formation of aromatics, esters, and complex nitrogenous heterocyclic compounds, which covered or poisoned the Lewis acid sites of the catalyst. The protein component acted as a chemical buffer that enhanced the production of lactic acid by controlling the release of monosaccharides from the carbohydrate fraction of microalgae and maintaining the catalytic activity of the catalyst. Thus, microalgae residue demonstrated great promise for the production of value-added chemicals.


Asunto(s)
Microalgas , Catálisis , Hidrólisis , Ácido Láctico , Residuos Sólidos
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