Your browser doesn't support javascript.
loading
Mostrar: 20 | 50 | 100
Resultados 1 - 20 de 6.720
Filtrar
1.
Artigo em Inglês | MEDLINE | ID: mdl-33477308

RESUMO

Municipal solid waste (MSW) must be managed to reduce its impact on environmental matrices and population health as much as possible. In particular, the variables that influence the production, separate waste collection, and costs of MSW must be understood. Although many studies have shown that such factors are specific to an area, the awareness of these factors has created opportunities to implement operations to enable more effective and efficient MSW management services, and to specifically respond to the variables that have the most impact. The deep learning approaches used in this study are effective in achieving this goal and can be used in any other territorial context to ensure that the organizations that deal with these issues are more aware and create useful plans to promote the circular economy. Our findings indicate the important influence of number of rooms in a residential buildings and construction years on MSW production, the combination of services such as municipal collection centers and door-to-door service for separate MSW collection and the characteristics of the residential buildings in the municipalities on MSW management costs.


Assuntos
Aprendizado Profundo , Eliminação de Resíduos/economia , Resíduos Sólidos/economia , Gerenciamento de Resíduos/economia , Cidades , Custos e Análise de Custo , Humanos , Itália , Eliminação de Resíduos/métodos
2.
Artigo em Inglês | MEDLINE | ID: mdl-33477392

RESUMO

Environmental pollution and ecological damage caused by human activities have attracted widespread attention in recent years, and while citizens' environmental awareness and intentions have increased, their actions may not necessarily change accordingly. This study aims to understand the intention-behavior gap, based on the theory of planned behavior (TPB), by exploring the relationship between intention and pro-environmental behavior on the new waste sorting policy in China. The structural model of extended TPB was tested using sample data from 3113 residents of Changsha, each of whom was asked to complete a two-stage survey. Results demonstrated that perceived policy effectiveness and actual behavioral control positively affect behavioral intention, implementation intention, and pro-environmental behavior. Among them, the actual behavioral control of residents was found to be the most influential factor on behavioral intention and implementation intention, followed by residents' perceived policy effectiveness. Moreover, behavioral intention and implementation intention mediate the relationship between antecedents and pro-environmental behavior. These findings imply that people with high-level perceptions of policy effectiveness, strong control over actual behavior, strong behavioral intentions, and strong implementation intentions are more likely to engage in pro-environmental behavior. The findings suggest that factors such as perceived policy effectiveness and actual behavioral control should be considered when implementing new policies and campaigns for waste sorting and management.


Assuntos
Atitude , Intenção , Teoria Psicológica , Eliminação de Resíduos/métodos , China , Feminino , Humanos , Masculino , Política Pública , Responsabilidade Social , Inquéritos e Questionários , Gerenciamento de Resíduos
3.
Ecotoxicol Environ Saf ; 211: 111913, 2021 Mar 15.
Artigo em Inglês | MEDLINE | ID: mdl-33493721

RESUMO

Effective management of municipal solid waste (MSW) is essential for the conservation of ecosystems in the Qinghai-Tibetan Plateau (QTP). Considering the landfill is the major method of MSW management, the factors influencing groundwater contamination near MSW landfill sites in the QTP were studied, based on field investigations, environmental impact assessment, and meteorological and hydrogeological analyses. Results indicated that the groundwater was contaminated heavily by nitrate (PI = 7.5), particularly in the landfill without an anti-seepage system, followed by nitrite (PI = 3.5) and heavy metals including arsenic (PI = 4.1) and hexavalent chromium (PI = 2.8). Total hardness, total dissolved solids, nitrate, and lead in the groundwater near the investigated landfill sites were significantly different between the monsoon and the cold seasons. Both the rainfall infiltration and the leachate infiltration were considerably limited by environmental characteristics in the QTP, including high evaporation, low rainfall, and the presence of permafrost. Soil sample contamination near landfill sites was considered as moderate (28.6% of the soil samples) and moderate to heavy (71.4% of the soil samples), based on the geoaccumulation index of mercury. However, comparatively low generation and concentrations of leachate and good topsoil quality (PI = 0.84) reduced the quantity of pollutants infiltrating into the groundwater. The alkaline leachate (pH = 7.45-9.23) and soil (pH = 7.08-8.72) also considerably decreased the concentrations of contaminants dissolved in the infiltrated rainfall and leachate. Additionally, low groundwater level can delay preferential flow and enhance attenuation. Therefore, the groundwater contamination near the landfill sites was simply point pollution, which was influenced by leachate, soil, climate, and hydrogeology characteristics in the QTP. The anti-seepage system is a potential strategy for use in the prevention of groundwater contamination by MSW landfills in the QTP.


Assuntos
Monitoramento Ambiental , Água Subterrânea/química , Instalações de Eliminação de Resíduos , Poluentes Químicos da Água/análise , Ecossistema , Água Subterrânea/análise , Metais Pesados/análise , Nitratos/análise , Eliminação de Resíduos/métodos , Estações do Ano , Solo , Resíduos Sólidos/análise , Tibet , Gerenciamento de Resíduos
4.
Ecotoxicol Environ Saf ; 208: 111596, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396117

RESUMO

The surge in solid waste (SW) has become major issues in the fields of public health and ecological environment fuelled by the rapid development of social economy. The fate of nitrogen contained in SW (SWN) varies with different treatment methods, which will affect the environment to varying degrees. It is of great practical and guiding significance to comprehensively evaluate the sources, fate and its cascading effects of SWN. Here, a systematic SWN flow evaluation of the generation, treatment and emissions in China from 2008 to 2017 was established. During this period, the SWN flow and the N pollution emissions from SW treatment increased by 19.7% and 27.6% respectively, with the domestic garbage being the largest contributor. This shows that it is particularly important to reinforce the classified of domestic garbage and resource recycling in China. Landfill was the main treatment, accounting for 51.8% of the total SWN. Landfill and incineration were the main sources of pollution N emissions, while compost treatment has the lowest contribution rate. It highlights the urgency of changing the waste treatment methods in China. About 92.3% of the N pollution emissions was lost to the atmosphere and 7.7% to the groundwater. NH3 and NOx were the main pollutants to the atmosphere. Special attention is paid to the reduction and control of NH3 in landfill, dumping and compost processes, while NOx in incineration. This study provides scientific basis for management and disposal of SW, so as to reduce its impact on the ecological environment and develop more sustainable policies for China and other developing countries.


Assuntos
Nitrogênio/análise , Eliminação de Resíduos/métodos , Resíduos Sólidos/análise , China , Meio Ambiente , Poluição Ambiental , Incineração/métodos , Reciclagem , Instalações de Eliminação de Resíduos
5.
Chemosphere ; 262: 127906, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32799154

RESUMO

Pulping and paper industries using non-woody feedstocks face the challenge of its notorious waste disposal problem. To resolve this problem, in this study, we evaluated a variety of properties of solid residues reclaimed from the effluents of both wheat straw ammonium sulfate and Kraft pulping processes as organic fertilizers. The results show that both residues from the ammonium sulfate (RAS) and Kraft pulping (RKP) processes possess desirable C/N ratios, appropriate nutritional compositions, and low levels of harmful heavy metals. The high solubilities (>35 g/L) of both residues allow their use for fertigation or foliar applications. The salt index (30-50) is within the range of commercial chemical fertilizers such as potassium sulfate (42.6) and magnum sulfate (44). The E3/E5 ratios of residues suggest that the residues have small molecular sizes, which are similar to fulvic acids. Overall, wheat straw pulping residues demonstrate the potential as the sustainable organic fertilizers and the beneficial soil amendments. This work has the potential to resolve the severer effluent disposal problem faced by the non-woody pulping and papermaking industries, open a door to effectively utilize residues as value-added byproducts, and lead to both environmental sustainability and economic benefits.


Assuntos
Fertilizantes , Poluentes do Solo/análise , Monitoramento Ambiental , Metais Pesados , Eliminação de Resíduos/métodos , Solo/química , Triticum
6.
Chemosphere ; 262: 127924, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32805661

RESUMO

Cr(VI) compounds at high temperature usually tend to decompose and reduce into Cr(III) due to thermodynamically instability for Cr(VI). This study found Cr(VI) could be reduced into Cr(V) instead of Cr(III) in the presence of CaO during heating solid waste containing Cr(VI). CaCrO4 is prepared and mixed with CaO as simulated solid waste containing Cr(VI). It was found that CaCrO4 reacted with CaO and formed a new product Ca5(CrO4)3O0.5 at temperature range of 800 and 1000 °C. The valence state of Cr in Ca5(CrO4)3O0.5 is determined to be +5 b y XPS analysis, and the color for new formed Cr(V) is observed in green, similar to Cr(III) compounds. The temperature and CaO are two keys to arouse the reduction reaction of Cr(VI) into Cr(V). In particular, the reduction of Cr(VI) into Cr(V) is strongly depended on temperature (800-1000 °C), this reaction can be balanced within 10 min, while prolonging sintering time has little help for promoting the reduction of Cr(VI) to Cr(V). Additionally, it was found Cr(V) can keep stable and not be re-oxidized into Cr(VI) at 800-1000 °C. Above results offers some new understanding and knowledge about the formation of Cr(V) in presence of much CaO or CaCO3 during heating solid waste containing Cr(VI).


Assuntos
Cromo/química , Eliminação de Resíduos/métodos , Hidróxido de Cálcio/química , Calefação , Temperatura Alta , Oxirredução , Resíduos Sólidos , Temperatura
7.
Chemosphere ; 263: 127974, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-32828060

RESUMO

CaCr2O4 (Cr (III)), mainly generated through the decomposition of CaCrO4 (Cr (VI)), is a significant intermediate for toxic Cr (VI) formation during solid fuel combustion. In this study, the formation, oxidation and sulfation kinetics of CaCr2O4 were analyzed to forecast the potential of CaCr2O4 oxidation during co-firing of coal and solid waste in a circulating fluidized bed boiler. The results indicated that the formation and oxidation of CaCr2O4 were fitted to a single step nucleation and growth model while CaCr2O4 sulfation was fitted to a shrinking core model. CaCr2O4 formation through CaCrO4 decomposition was favored in oxygen-lean atmosphere and considerably suppressed in the presence of oxygen. In contrast, CaCr2O4 oxidation was mainly determined by the contacts between CaCr2O4 and CaSO4/CaO, which influenced not only oxidation rates but also the product species. Moreover, the oxidation reactivity of CaCr2O4 was higher in the presence of CaO than that of CaSO4. On the other hand, CaCr2O4 sulfation can occur more easily than CaCr2O4 oxidation, the reaction rate of which was deeply affected by sulfate product layer. Findings in this study suggested that spraying calcium in furnace for desulphurization may increase the risk of CaCr2O4 oxidation. Measures including the adjustment of Ca/S ratio in blended fuel (with added limestone) and operating conditions (such as temperature and local atmosphere) in co-firing system could be taken to control CaCr2O4 formation and oxidation.


Assuntos
Cromo/química , Carvão Mineral/análise , Eliminação de Resíduos/métodos , Resíduos Sólidos , Leitos , Cromo/análise , Cinza de Carvão , Oxirredução , Oxigênio , Sulfatos , Temperatura
8.
Bull Environ Contam Toxicol ; 105(5): 784-789, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32979083

RESUMO

Properly disposing of unused pharmaceuticals is essential to minimize emissions of active pharmaceutical ingredients (APIs). The aim of this study was to determine whether disposing of unused pharmaceuticals in household solid waste is a cost-effective way of attenuating pharmaceutical emissions. We calculated attenuation rates (ARs) for unused pharmaceuticals by performing mass balance calculations for disposal to landfill. The results indicated that the average ARs for disposal as household solid waste reached 63% to 100% for our investigated pharmaceuticals at the worst scenario, indicating that disposal as household solid waste strongly attenuated emissions of APIs. Disposing of unused pharmaceuticals as household solid waste could be a cost-effective disposal method from the view of reducing APIs emission, but should be used with caution.


Assuntos
Preparações Farmacêuticas/análise , Eliminação de Resíduos/métodos , Resíduos Sólidos/análise , Instalações de Eliminação de Resíduos , China
9.
PLoS One ; 15(8): e0231933, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32818952

RESUMO

Financing municipal solid waste (MSW) services is one of the key challenges faced by cities in developing countries. This study used plastic waste, a constituent of MSW, to explore the possibility of generating revenue for financing MSW management in the municipalities of Nepal. The results of this study suggest that plastic material recovery could generate revenue, which is equivalent to 1.38 times of the plastic-waste-related management cost when collection efficiency reaches 66.7%. An increase in 1% of recovery rate and collection efficiency could cover an additional 4.64% and 2.06% of the costs of managing plastic waste, respectively. In addition, an increase in tax on imported plastic materials could also motivate recovery of plastic waste for recycle and reuse. An additional 1% tax on plastic imports would be sufficient to cover plastic-related waste management when plastic waste recovery and collection efficiency rates are low. This plastic recovery- revenue exercise could be expanded to other materials such as paper and metal to fully understand the possibility of sustainable financing of MSW management and reducing environmental harm in developing countries like Nepal.


Assuntos
Reciclagem/métodos , Resíduos Sólidos/economia , Gerenciamento de Resíduos/métodos , Cidades , Países em Desenvolvimento , Nepal , Plásticos/análise , Plásticos/química , Reciclagem/economia , Eliminação de Resíduos/economia , Eliminação de Resíduos/métodos , Resíduos Sólidos/análise , Gerenciamento de Resíduos/economia
10.
Chemosphere ; 261: 127754, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32738714

RESUMO

In this study, different organic acids-such as citric, acetic, lactic, propionic, and butyric acid-were evaluated to ascertain the optimum leaching solvent for dechlorinating fly ash. Results suggest that the acid type, concentration, and interactions between both parameters contributed significantly to the variations in the efficiency of fly ash dechlorination. Simple main-effect analysis suggested that a higher acid concentration yields better dechlorination efficiency. However, improvements in dechlorination efficiency did not necessarily yield a low chlorine content leaching residue because in a specific acid concentration region, the increased acid concentration may also accelerate the mass reduction rate of the leaching residue. Experimental results also demonstrate that citric and acetic acid yield the highest dechlorination efficiency, followed by propionic and butyric acid. The least dechlorination efficiency of lactic acid could be attributed to the formation of precipitate (i.e. calcium lactate) which might cover the chlorides and reduce the contact area of intimal chlorides with the leaching solvent. Therefore, a specific concentration of organic matter fermentation broth rich in citric and acetic radicals may present itself as an ideal water substitute for fly ash dechlorination.


Assuntos
Ácidos Acíclicos/química , Cloretos/análise , Cinza de Carvão/análise , Eliminação de Resíduos/métodos , Resíduos Sólidos/análise , Solventes/química , Ácido Acético/química , Ácido Cítrico/química , Concentração de Íons de Hidrogênio , Material Particulado/análise
11.
Chemosphere ; 260: 127524, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32693254

RESUMO

Trace metals concentrations of 25 elements were determined for 22 subcomponents of biodegradable and non-biodegradable waste samples representing the United States municipal solid waste (MSW) stream collected during three separate waste sorts. The subcomponent trace metal concentrations and estimated composition results were used to predict trace metal concentrations present in the overall MSW stream along with MSW compost and waste to energy (WTE) ash, which were compared to health-based standards (i.e., US EPA regional screening levels) and to values previously reported in the literature. These estimates for potentially problematic elements like As and Sb could be attributed to abundant base materials in MSW, while other elements, such as Pb, were calculated at much lower concentrations than other published studies. This suggests that trace metals measured in actual MSW compost and WTE ash could originate not only from MSW base components but also from other sources, such as highly concentrated low-mass wastes (e.g., e-waste). While the removal of small quantity components with high metal concentrations may reduce concentrations of some potentially problematic metals (e.g., Pb), others (e.g., As and Sb) are likely to persist in quantities that impede reuse and recycling since they are present in the more abundant base MSW components (e.g., papers, plastics, organics). Promoting meaningful reductions in potentially problematic trace metals in MSW-derived materials may require reevaluating their presence in higher-volume, lower-concentrated MSW components such as paper, plastics, and organics.


Assuntos
Metais/análise , Plásticos/análise , Reciclagem , Eliminação de Resíduos/métodos , Resíduos Sólidos/análise , Oligoelementos/análise , Estados Unidos
12.
J Environ Public Health ; 2020: 5157046, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32587623

RESUMO

An increase in urban population and the rising demand for food and other essentials perpetuate a rise in the amount of waste being generated daily by each household. In Ethiopia, this waste is eventually thrown into open dump sites. It can cause severe impact on soil and surface water quality. As a result, it becomes the probable source of human health risk through food chain. Therefore, this study was aimed at assessing the effect of a solid waste dump site on surrounding soil and river water quality in Tepi town, Southwest Ethiopia. Three surface water, one leachate, and four soil samples were collected and analyzed. Six heavy metals for surface water and leachate samples and four heavy metals for soil samples were measured by flame atomic absorption spectroscopy. In addition, physiochemical parameters were analyzed using standard methods. The data were analyzed statistically using Origin pro version 8.0 computer software packages. The pH of soil was slightly basic ranging from 8 ± 0.1 to 8.7 ± 0.21. Electrical conductivity was lower at 60 meters (1800 ± 0.5 µs/cm) and higher in the other sample sites (3490 ± 0.66-4920 ± 1.04 µs/cm). The concentration of heavy metals in soil samples revealed cadmium (0.53 ± 0.01-2.26 ± 0.02 mg/kg), zinc (623.93 ± 0.29-859.41 ± 0.02 mg/kg), lead (3.26 ± 0.25-57.560.26 mg/kg), and copper (204.06 ± 0.06-337.11 ± 0.01 mg/kg). Lead, cadmium, manganese, nickel, copper, and zinc were found in the leachate water; nickel and manganese were found in the nearby river water; BOD5 and COD for both leachate and stream water samples were found to be higher than standard guideline values. The finding suggested that solid waste open dump site adversely affects soil and water quality in the study area and becomes a probable source of risk for human health via the food chain.


Assuntos
Eliminação de Resíduos/métodos , Rios/química , Solo/química , Resíduos Sólidos/análise , Poluentes Químicos da Água/análise , Cidades , Monitoramento Ambiental , Etiópia , Metais Pesados/análise , Medição de Risco
13.
Chemosphere ; 251: 126414, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32443252

RESUMO

The disposal of municipal solid waste (MSW) in landfills generates leachate, a highly polluting liquid to the aquatic environment. Leachate composition become a challenge to choose the best treatment process. Then, detailed techniques to determine the organic content, in terms of refractability, composition, sources and biodegradability in landfill leachate can help to choose the appropriate treatment and improve landfill management. In this sense, the aim of this study is to apply conventional and non-conventional parameters through inert chemical oxygen demand (COD) analyses and spectroscopic techniques of fluorescence and UV-vis absorbance for the characterization of municipal landfill leachate. Results indicated that physicochemical characterization cannot provided enough detailed information about leachate composition, which becomes the treatment process fragile. Inert COD, besides have high time to execution (∼30 days), presented additional information on potential of biological treatability in anaerobic conditions. Dissolved organic matter (DOM) characterization showed transitions between labile and refractory organic matter compounds. Moreover, the cost estimated showed that non-conventional parameters analysis have lower investment than conventional, being their implementation feasible. In conclusion, the synergy between conventional and non-conventional parameters, and the detailed information provided by inert COD and DOM characterization, shown a useful tool to the landfill management and, consequently, improving treatment process and its efficiency.


Assuntos
Biodegradação Ambiental , Poluentes Químicos da Água/análise , Compostos Orgânicos , Eliminação de Resíduos/métodos , Resíduos Sólidos/análise , Instalações de Eliminação de Resíduos
14.
Chemosphere ; 252: 126570, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32443266

RESUMO

Hydrotalcite precipitation is a promising technology for the on-site treatment of acid mine drainage (AMD). This technology is underpinned by the synthesis of hydrotalcite that can effectively remove various contaminants. However, hydrotalcite precipitation has only limited capacity to facilitate sulfate removal from AMD. Therefore, the feasibility of coupling biological sulfate reduction with the hydrotalcite precipitation to maximize sulfate removal was evaluated in this study. AMD emanating from a gold mine (pH 4.3, sulfate 2000 mg L-1, with various metals including Al, Cd, Co, Cu, Fe, Mn, Ni, Zn) was first treated using the hydrotalcite precipitation. Subsequently, biological treatment of the post-hydrotalcite precipitation effluent was conducted in an ethanol-fed fluidized bed reactor (FBR) at a hydraulic retention time (HRT) of 0.8-1.6 day. The hydrotalcite precipitation readily neutralized the acidity of AMD and removed 10% of sulfate and over 99% of Al, Cd, Co, Cu, Fe, Mn, Ni, Zn. The overall sulfate removal increased to 73% with subsequent FBR treatment. Based on 454 pyrosequencing of 16S rRNA genes, the identified genera of sulfate-reducing bacteria (SRB) included Desulfovibrio, Desulfomicrobium and Desulfococcus. This study showed that sulfate-rich AMD can be effectively treated by integrating hydrotalcite precipitation and a biological sulfate reducing FBR.


Assuntos
Hidróxido de Alumínio/química , Hidróxido de Magnésio/química , Eliminação de Resíduos/métodos , Sulfatos/química , Ácidos , Reatores Biológicos/microbiologia , Concentração de Íons de Hidrogênio , Metais , Mineração , Oxirredução , RNA Ribossômico 16S
15.
Chemosphere ; 255: 126929, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32402877

RESUMO

Using the biogas generated from organic waste anaerobic treatment to produce polyhydroxyalkanoates (PHAs) has emerged as an attractive alternative to heat and power generation (CHP) in waste treatment plants. The sustainability of biogas combustion for CHP, biogas bioconversion into PHA and a combination of both scenarios was compared in terms of environmental impact, process economics and social responsibility according to the IChemE Sustainability Metrics. Although PHA production presented higher investment and operational costs, a comparable economic performance was observed in all biogas valorization scenarios regarding net present value (0.77 M€) and internal rate of return (6.4 ± 0.2%) due to the higher market value of biopolymers. The PHA production entailed a significant reduction of atmospheric acidification and odor emissions compared to CHP despite showing higher land, water, chemicals and energy requirements. Job creation associated to biopolymer industry and the increasing public demand for bioproducts were identified as fundamental aspects for enhancing social and local acceptance of waste processing facilities. This study demonstrated that PHA production from biogas constitutes nowadays a realistic alternative to CHP in waste treatment plants and that PHA can be produced at a competitive market price when biogas is used for internal energy provision (4.2 €·kg-1 PHA).


Assuntos
Poli-Hidroxialcanoatos/química , Eliminação de Resíduos/métodos , Biocombustíveis , Biopolímeros , Reatores Biológicos , Conservação dos Recursos Naturais
16.
Artigo em Inglês | MEDLINE | ID: mdl-32397281

RESUMO

A one-stage anaerobic ammonium oxidation (ANAMMOX) reactor can be quickly started within 40 days by mixing partial nitrifying sludge with ANAMMOX granular sludge with an average temperature of 30 °C. After 70 days of nitrogen load acclimation, Acinetobacter, including Candidatus Kuenenia, became the dominant strain of the system within the reactor, which exhibited high efficiency and a stable nitrogen removal performance. At an influent chemical oxygen demand (COD), NH4+-N content, total nitrogen (TN) content, hydraulic retention time (HRT), temperature, and reactor dissolved oxygen (DO) content of 100, 60, and 70 mg/L, 6 h, 30 ± 1 °C, and below 0.6 mg/L, respectively, the one-stage ANAMMOX reactor could effectively treat domestic sewage on campus. The removal rates of COD, NH4+-N, and TN were approximately 89%, 96.7%, and 70%, respectively.


Assuntos
Compostos de Amônio , Reatores Biológicos/microbiologia , Eliminação de Resíduos/métodos , Esgotos , Acinetobacter , Anaerobiose , Nitrogênio , Oxirredução
17.
Chemosphere ; 255: 126805, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32387911

RESUMO

Large amounts of agricultural solid wastes (ASWs) and animal dung are produced annually causing serious environmental problem that requires proper treatment. The present study proposes a strategy for optimizing the anaerobic co-digestion of ASWs and cow dung (CD), identifies the key factors governing the co-digestion performance and evaluates the effect of NaHCO3 alkalinity treatment on improving the economy and performance of anaerobic digestion (AD). The results revealed that the highest cumulative methane production (CMP) of 297.99 NL/kgVS can be generated by co-digestion of ASWs and CD at a ratio of 60:40. Further improvement was achieved via alkalinity treatment with 1.0 g of NaHCO3/gVS leading to decrease in lignin, cellulose, and hemicellulose contents of feedstock by 3.5%, 10.5% and 15.9%, respectively, converting them to soluble fractions and improving the CMP by 11.2-29.7% based on substrate quality. The improved CMP in the chemically treated substrates reflects a 19% increase in the generated revenue. The kinetics of the AD process was successfully fitted to modified Gompertz model with very low standard deviation residuals (SDR) ≤ 5.21 and R2 ≥ 0.979. Results confirm that the proposed strategy is an effective method for producing biogas from co-digestion of ASWs and CD.


Assuntos
Agricultura , Biocombustíveis , Eliminação de Resíduos/métodos , Anaerobiose , Animais , Reatores Biológicos , Bovinos , Celulose , Cinética , Lignina/química , Metano/biossíntese , Resíduos Sólidos/análise
18.
Chemosphere ; 256: 127116, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32460161

RESUMO

Anaerobic digestion (AD) of lignocellulosic biomass is appealing because of the abundance and ease of obtaining the biomass locally. However, the recalcitrance of lignocellulosic biomass presents an obstacle in the hydrolysis step of AD and lowers the process efficiency. In this study, sunflower, which is a model lignocellulosic biomass, was pretreated by thermal (hydrothermal pretreatment, HTP) and non-thermal (milling) methods; the methane yield and biodegradability of the pretreated biomass were determined using a series of batch tests. The thermal pretreatment method showed a significantly higher methane yield (213.87-289.47 mL g-1 VS) and biodegradability (43-63%) than those of the non-thermally pretreated biomass, and the optimum pretreatment effect was observed at an HTP temperature of 180 °C. However, at an HTP temperature exceeding 200 °C, the induced formation of 5-hydroxymethylfurfural and furfural significantly lowered the methane yield and biodegradability. This study revealed that the HTP temperature is closely related to the formation of lignocellulosic biomass-degrading byproducts, which potentially hinder the methanogenesis step in AD; severe HTP conditions may have the opposite effect on the AD performance of lignocellulosic biomass.


Assuntos
Biocombustíveis/análise , Temperatura Alta , Lignina/química , Metano/análise , Eliminação de Resíduos/métodos , Anaerobiose , Biodegradação Ambiental , Biomassa , Hidrólise
19.
Chemosphere ; 250: 126269, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32126330

RESUMO

MSWI(Municipal solid waste incineration) fly ash as hazardous wastes usually is treated properly with OPC(ordinary Portland cement) based binders prior to being disposed in security landfill, but some toxic elements present poor stability in its highly alkaline environment. This study developed a novel solidification/stabilization technology based on MgO-SiO2-H2O (M-S-H) cementious material with compatibility with contaminants for MSWI fly ash encapsulation. Compressive strength and leaching toxicity tests were undertaken to evaluate the immobilization effect of MSWI fly ash treated with M-S-H matrix. And TAM, XRD, DTA/TGA and SEM techniques were employed to explore hydration process and microstructure morphology of M-S-H solidified body. Results demonstrated that M-S-H cement matrix played a positive impact on the immobilization of heavy metals, and the immobilization rate of Cd, Pb and Zn was 97.5%, 99.8% and 98.7%, which was far more than that fixed in Portland cement. The incorporation of MSWI fly ash inhibited the hydration process of M-S-H matrix on the whole, which was mainly due to its poor pozzolanic activity. Moreover, there were some new hydration phases including CdSiO3, Ca3PbSiO6 and Zn(OH)2 generated and some MSWI fly ash embedded in the core-shell structure of M-S-H matrix in depth. These results suggested that heavy metals of MSWI fly ash were mainly fixed in M-S-H solidified bodies by physical encapsulation, isomorphous replacement and chemical precipitation. Overall, this study demonstrated that M-S-H matrix is a promising candidate that can serve as low-carbon and high-efficient materials for hazardous MSWI fly ash.


Assuntos
Incineração , Carbono/química , Força Compressiva , Materiais de Construção , Resíduos Perigosos , Óxido de Magnésio/química , Metais Pesados/análise , Material Particulado/química , Eliminação de Resíduos/métodos , Dióxido de Silício/química , Resíduos Sólidos/análise
20.
Chemosphere ; 252: 126436, 2020 Aug.
Artigo em Inglês | MEDLINE | ID: mdl-32182511

RESUMO

Ash products from coal and municipal solid waste combustion constitute a waste stream with characteristics that, unless recycled, require specific disposal practices. Although traditional disposal involves ash placement in a cell dedicated solely for the ash (monofill), new regulations for the management of coal combustion residues in the US might lead to more co-disposal of these residues with unburned municipal solid waste (MSW) that has not been combusted or otherwise processed. Both monofill and co-disposal practices are currently utilized for MSW incineration ash in the US. Column tests were performed using landfill leachate as a leaching solution to simulate co-disposal conditions of ash with MSW, while DI water was used to simulate monofilling. Mobility of As, B and V from coal fly ash was enhanced in the presence of landfill leachate in both batch and column tests, and a similar trend was observed for Cd and Mo release from MSW incineration ash. For several elements, release was greater with the column procedure relative to the batch procedure. The results suggest that long-term implications of co-disposal should be factored into decisions regarding which disposal scenario to pursue.


Assuntos
Incineração/métodos , Oligoelementos/análise , Eliminação de Resíduos/métodos , Resíduos Sólidos/análise , Água , Poluentes Químicos da Água/análise
SELEÇÃO DE REFERÊNCIAS
DETALHE DA PESQUISA
...