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1.
J Environ Qual ; 49(2): 509-515, 2020 Mar.
Artigo em Inglês | MEDLINE | ID: mdl-33016413

RESUMO

Organic waste materials are sources of anthropogenic methane (CH4 ) emissions. Anaerobic digestion (AD) is a technology that produces biogas from organic waste materials, and CH4 is the primary component of biogas. Unintended emission of CH4 from biogas facilities could undercut the environmental benefits of this technology. The objective of this study was to determine if the implementation of an AD system affected ambient CH4 concentrations ([CH4 ]) on a commercial dairy farm over 5 yr, from before installation into full operation. Concentrations at 4.5-m height on a tower receiving wind that originated from various directions, comprising components of the dairy farm such as the AD facility, crop fields, or main barn, were measured using a closed-path tunable diode laser trace-gas analyzer. In 2012 and 2013, the first 2 yr of AD operation, [CH4 ] was not significantly different than pre-AD levels in 2011 (2.04 ± 0.01 µl L-1 ). However, mean [CH4 ] increased to 2.47 ± 0.03 and 2.48 ± 0.04 µl L-1 in 2014 and 2015, respectively, and the occurrence of high [CH4 ] (>10 µl L-1 ) increased from <0.05% in Year 1 (pre-AD) to 12% in Years 4 and 5. These elevated concentrations were related to an increased use of food waste feedstocks over time and suggest that the biogas system was a source of fugitive CH4 emissions. Food waste materials have a high biogas potential and are a valuable resource that require appropriate facility design and management to fully harness their benefits.


Assuntos
Metano , Eliminação de Resíduos , Anaerobiose , Fazendas , Alimentos
2.
Sci Total Environ ; 741: 140513, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32887002

RESUMO

The dynamics of microbial necromass of municipal solid waste over long-term landfill remain unknown. This study presents the first investigation on the dynamics of bacterial and fungal necromass of municipal sludge in non-aeration versus alternating aeration landfill bioreactors by using amino sugar biomarkers. Results showed that under non-aeration treatment, the decomposition rate of muramic acid derived from bacteria is higher than that of fungal-derived glucosamine. The relative change in glucosamine and muramic acid in the early period of landfills under the alternating aeration treatment is consistent with that under non-aeration treatment. However, with the increase in alternating aeration cycles, bacterial necromass muramic acid exerts a lower decomposition rate than fungal necromass glucosamine. Throughout the entire landfill period, galactosamine is the amino sugar with the slowest decomposition rate under non-aeration mode but the amino sugar with the fastest decomposition rate under alternating aeration mode. The present work fills the knowledge gap of microbial necromass dynamics of municipal solid waste in landfills.


Assuntos
Eliminação de Resíduos , Esgotos , Amino Açúcares , Bactérias , Biomarcadores , Reatores Biológicos , Instalações de Eliminação de Resíduos
3.
Sci Total Environ ; 741: 140502, 2020 Nov 01.
Artigo em Inglês | MEDLINE | ID: mdl-32887006

RESUMO

Landfill leachate contains high concentrations of complex organic matter (OM) that can severely impact the ecological environment. If landfill leachate is to be treated using a combined "biological + advanced treatment" process, the molecular information of OM must be investigated to optimize the operation parameters of the combined process and maximize the removal of organic pollutants. This study applied ultra-high resolution mass spectroscopy to investigate the degradation and transformation characteristics of refractory OM in mature landfill leachate at the molecular level (m/z = 150-800) during biological treatment (i.e., semi-aerobic aged refuse biofilter, SAARB) and subsequent chemical oxidation (i.e., the Fenton process and ozonation). After SAARB treatment, the polycyclic aromatics (aromatic index, AI > 0.66) and polyphenol (0.66 ≥ AI > 0.50) contents increased, and the highly unsaturated phenolic compounds (AI ≤ 0.50 and H/C < 1.5), which have a high bioavailability, were mostly removed. Compared with raw leachate, SAARB effluent (i.e., SAARB leachate) contained fewer organics with short carbon chains, more organics with long carbon chains, an elevated condensation degree for organics and, thus, a considerably reduced biodegradability. Although both the Fenton and ozonation processes could remove many of the polycyclic aromatics and polyphenols, ozone produced considerable amounts of aliphatic compounds with high bioavailability. Compared to ozonation, the Fenton process utilized the hydroxyl radical to non-selectively react with OM and produced better mineralization results.


Assuntos
Resíduos de Alimentos , Ozônio , Eliminação de Resíduos , Poluentes Químicos da Água/análise , Peróxido de Hidrogênio , Oxirredução
4.
Water Sci Technol ; 82(2): 227-241, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32941165

RESUMO

The wastewater industry is undergoing a paradigm shift from focusing solely on treatment to incorporating concepts aimed at mitigating environmental impacts such as energy and nutrient recovery and water reuse. This study uses life cycle assessment and life cycle cost analysis to investigate the effect of expanding anaerobic digestion (AD) capacity and adding combined heat and power on environmental and cost indicators at a mid-sized wastewater treatment facility (WWTF) in Massachusetts, USA. Since 2014, Massachusetts has banned the disposal of organic waste from commercial organizations producing more than one ton of material per week. The WWTF's additional digester capacity allows the co-digestion of municipal solids with a food-based engineered bioslurry due to this ban. Study data were compiled for several AD feedstock quantity and performance scenarios, and compared to a baseline scenario representative of historic plant operations prior to co-digestion. Reductions in environmental impact are demonstrated for six of eight environmental impacts, including global climate change potential and cumulative energy demand. Eutrophication potential increases by 10 percent and 24 percent across assessed scenarios. Water use remains relatively constant across scenarios. Facility energy production increases dramatically with co-digestion, satisfying 100 percent of the WWTF's thermal energy requirement and producing surplus electricity assuming full AD capacity utilization.


Assuntos
Eliminação de Resíduos , Águas Residuárias , Anaerobiose , Análise Custo-Benefício , Alimentos
5.
Waste Manag Res ; 38(10): 1161-1175, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32907525

RESUMO

Quantification, measurement of quality, post-treatment, and leachate control has been a significant problem due to the dumping of waste in an unscientific manner across the globe, and especially in developing countries like India. In this context, the objective of this study was to investigate the degradation of fresh mixed municipal solid waste (MSW) in an anaerobic landfill reactor operated with rainfall addition in laboratory conditions. Experiments were carried out in a landfill reactor of 1 m length × 1 m width × 1.1 m height. The reactor was simulated with 50 years weighted average actual rainfall rate of India. It contained the waste composition of 73% wet waste (food and kitchen) and 27% dry waste (paper, plastic, wood, textiles, and others). The leachate parameters were continually monitored for 39 weeks. In the fresh MSW landfill reactor it was evident that concentrations of leachate parameters were high initially, and there was a significant decrease in BOD5 (7041-39310 mg L-1), COD (15692-71630 mg L-1) and TS (9077-33200 mg L-1) in leachate. Therefore, rainfall had a direct influence on leachate quality. The developed first-order decay models were used for BOD5, COD, and total solids with adjusted R2 of 0.83, 0.92, and 0.96, respectively. Therefore, this model can be applied for leachate strength estimation at any given time from the period of deposition of waste under similar rainfall and waste compositions, and is largely applicable in India and tropical areas. This study is expected to be a good simulation for cities with the waste composition of high wet waste (>70%) as the estimations of important design parameters such as BOD5, COD, VFA, and NH4+-N were studied in this research. As the importance of moisture (precipitation) has been established in this study, some moisture additions can be designed in areas with low rainfall, such as arid zones.


Assuntos
Eliminação de Resíduos , Poluentes Químicos da Água , Anaerobiose , Reatores Biológicos , Índia , Resíduos Sólidos/análise , Instalações de Eliminação de Resíduos , Poluentes Químicos da Água/análise
6.
Waste Manag Res ; 38(10): 1153-1160, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32907527

RESUMO

The performances of an integrated system based on mechanical biological treatment and bioreactor landfill with leachate recirculation for managing the mixed municipal solid waste generated in a given Italian district were investigated. In the mechanical biological treatment the municipal solid waste was mechanically sorted into two main streams: a dry and a mechanically sorted organic fraction consisting of 45,000 tonnes year-1. After being sorted the mechanically sorted organic fraction was aerobically pretreated before being disposed of in the 450,000 m3 bioreactor landfill. Experimental runs showed that an aerobic pretreatment period ranging from 15 to 30 days was able to maximize the methane generated by the mechanically sorted organic fraction once landfilled up to 10 Nm3 tonne-1. The aerobic pretreatment leads to a significant volatile solids reduction in the first 30 days, after which the volatile solids concentration remained quite constant. Similarly the potential dynamic respirometer index was significantly reduced in the first 15 days of the aerobic pretreatment decreasing from about 5,000 to about 3,500 mgO2kgVS-1h-1. The whole amount of electrical energy producible by the landfill ranged from 18.5 kWh tonne-1 to 21 kWh tonne-1, depending on the strategies adopted for the activation in bioreactor mode of each landfill cell by the leachate recirculation.


Assuntos
Eliminação de Resíduos , Gerenciamento de Resíduos , Reatores Biológicos , Itália , Resíduos Sólidos/análise , Instalações de Eliminação de Resíduos
7.
J Environ Public Health ; 2020: 4609164, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32733576

RESUMO

Air pollution has been a major challenge worldwide particularly in the developing world. Improper waste disposal and management may result in microbial air pollution. In advanced countries, landfill sites are far from neighborhoods; however, the opposite is observed for landfill sites in the developing world. In Accra, some landfill sites are 100 meters from neighborhoods. The aim of this study was to assess the microbial air quality and associated environmental health hazards of landfill sites in selected districts in the Greater Accra Region of Ghana. A random sampling method was employed to select sampling sites across the dry and wet seasons from landfills and their corresponding neighborhoods. Results obtained showed a higher total count (CFU/m3) of bacteria and fungi in the air at the landfill sites than neighborhoods. Statistically significant variation (p < 0.05) in bacterial and fungal concentrations over two seasons was found for both landfills and neighborhoods. However, bacterial concentrations were significantly higher than fungal concentrations (p < 0.05) across seasons for all locations. Staphylococcus epidermidis was the highest (15.6 %) occurring microbe at both landfill sites and neighborhoods. This was followed by Staphylococcus aureus (12.7%). Other bacteria and fungi of public health importance such as Pseudomonas aeruginosa, Escherichia coli, Aspergillus flavus, and Aspergillus niger were also isolated from the study sites, above the WHO recommended levels. In conclusion, the landfill waste disposal and its close proximity to neighborhoods as observed in this study pose a potential environmental health risk, with dire implications for public health and safety. The government must enact and implement policies to regulate waste management and to ensure public safety.


Assuntos
Microbiologia do Ar , Poluentes Atmosféricos/análise , Instalações de Eliminação de Resíduos , Poluentes Atmosféricos/normas , Bactérias/classificação , Bactérias/isolamento & purificação , Monitoramento Ambiental , Fungos/classificação , Fungos/isolamento & purificação , Gana , Saúde Pública , Eliminação de Resíduos , Medição de Risco
8.
Sci Total Environ ; 746: 141086, 2020 Dec 01.
Artigo em Inglês | MEDLINE | ID: mdl-32750579

RESUMO

In order to evaluate microbial community structure dominated metabolic function profiles in large-scale food waste (FW) biotreatment systems, bacterial, archaeal and fungal community associated with metabolic function in high-temperature aerobic fermentation (AF) and anaerobic co-digestion (AcoD) processes were comprehensively investigated in this study. The qPCR results showed the higher gene copies of bacteria and fungi in initial and AF-treated FW compared with AcoD-treated FW, as well as bacteria and archaea in AcoD-treated FW were highly abundant among detected samples. Furthermore, the total abundances of archaea ((1.18-4.88) × 106 copies/ng DNA) in AcoD system were 2-3 orders of magnitude higher than that in other samples (P < 0.01), indicating active archaeal activity in AcoD system. Correlation analysis of microbial community and metabolic function indicated that the higher abundances of Kazachstania, Pyrobaculum, Sulfophobococcus, Lactobacillus and Candida in initial FW had close linkages with lipid metabolism (P < 0.05). Abundant Aspergillus, Staphylococcus, Pelomonas, Corynebacterium, Faecalibacterium, Methanobacterium and Xeromyces in AF system were positively and significantly correlated with high metabolic activities of energy metabolism, carbohydrate metabolism, amino acid metabolism, fatty acid metabolism, glycosaminoglycan degradation, sulfur metabolism and nitrogen metabolism. As for AcoD system, dominant genera Methanosaeta, Methanoculleus, Methanobacterium, Fastidiosipila, Rikenellaceae RC9, Bifidobacterium and Xeromyces had close relationships with metabolism of cofactors and vitamins, energy metabolism, methane metabolism, carbohydrate metabolism and glycosaminoglycan degradation (P < 0.05). These results are expected to improve the metabolic efficiency by functional microorganism in different large-scale FW treatment systems.


Assuntos
Microbiota , Eliminação de Resíduos , Anaerobiose , Archaea/genética , Reatores Biológicos , Alimentos , Metano , Esgotos
9.
Bioresour Technol ; 317: 123948, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32799075

RESUMO

This study aimed to analyze the relationship between food components and food waste aerobic fermentation efficiency. Different food wastes were designed to be reflective of different dietary regimes, including formulated (R1), high oil/fat and salt (R2), high oil/fat and sugar (R3), and vegetarian (R4) diets, after which the physicochemical properties, enzyme activity, and structural characteristics of food waste microbial communities were examined to explore the potential mechanisms of food waste degradation under different dietary regimes. The main results of this study demonstrated that the physicochemical properties and hydrolase activity of different food waste were significantly different. The species richness in R2 and R3 food waste was higher than that of R1 and R4, whereas the community diversity of R1 and R4 food waste was higher than that of R2 and R3. At the genus level, the dominant bacteria in the four food waste types were Bacillus, Thermoactinomyces, Paenibacillus, and Cohnella.


Assuntos
Microbiota , Eliminação de Resíduos , Reatores Biológicos , Fermentação , Alimentos
10.
Bioresour Technol ; 317: 124016, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32822892

RESUMO

In this study, batch experiments were conducted to compare the effect of temperature and substrate source on microbial communities in the anaerobic digestion of kitchen waste. The results showed that the microbial communities of anaerobic digestion were not sensitive to varied sources of waste, but shifted with the change in operating temperatures. In the reactors operated at mesophilic conditions, Levilinea, Syntrophomonas, Methanothrix, and Methanosphaerula, etc. were the dominant microbes during the process. While in thermophilic reactors, Levilinea, Ornatilinea, Methanosphaerula and Methanomassiliicoccus, etc. prevailed. Meanwhile, an enrichment in Coprothermobacter, Defluviitoga, Defluviitalea, Tepidimicrobium, Lutispora and Fonticella were observed as the temperature changed from mesophilic to thermophilic, suggesting these genera could be selectively enriched at thermophilic conditions. The results provided fundamental understanding of the microbiology that could support the scale up of food waste anaerobic digestion.


Assuntos
Microbiota , Eliminação de Resíduos , Anaerobiose , Reatores Biológicos , Alimentos , Metano , Esgotos , Temperatura
11.
Bioresour Technol ; 317: 123994, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32836034

RESUMO

The effects of long-term acclimatization on the optimum food waste to cow manure ratio (FW/CM) and substrate to inoculum ratio (S/I) in anaerobic codigestion with FW and CM were investigated by batch trials. For the unacclimated sludge, the highest CH4 yields of 646.6 and 653.4 mL/g VS were achieved under the optimum FW/CM (2.5 VS/VS) and S/I (0.07 VS/VS) ratios, respectively. After more than 550 days of acclimatization, the optimum FW/CM and S/I of the acclimated sludge were improved to 3.4 and 0.68 VS/VS with more anaerobic digestion enzymes and lignocellulose, respectively. Based on high-throughput sequencing analysis, the microbial community structures of bacteria, fungi, and archaea were changed, which was the main reason for the change in the optimum FW/CM and S/I. Therefore, the FW/CM and S/I should be periodically optimized during the long-term operation of codigestion to improve the codigestion efficiency for biogas production.


Assuntos
Esterco , Eliminação de Resíduos , Aclimatação , Anaerobiose , Animais , Biocombustíveis , Reatores Biológicos , Bovinos , Feminino , Alimentos , Metano
12.
J Environ Manage ; 271: 110978, 2020 Oct 01.
Artigo em Inglês | MEDLINE | ID: mdl-32778277

RESUMO

Geosynthetic clay liners (GCL) are increasingly being used as a major component of barrier systems replacing compacted clay liners due to their very low permeability and speed of installation. Researchers and practitioners have identified the critical role of the GCL overlap that presents constant challenges encountered in maintaining the designed hydraulic conductivity. This study presents a series of flow box tests conducted to evaluate and improve understanding of the combined effect of each of the four contributing factors, namely, overlap width, supplemental bentonite applied at the overlap, the overburden confining stress, and the hydraulic head acting on the GCL overlap. The findings reveal that the overlap width is the most significant parameter affecting the design hydraulic conductivity. The application of a minimum overburden stress to maintain the designed hydraulic performance is also recognised as important. The effect of confinement due to higher hydraulic heads is of interest to practitioners. The supplemental bentonite has the least effect on the GCL overlap hydraulic performance even though it enhances the function of the overlap seam. This knowledge addresses the inadequacy of published GCL overlap experimental data comparing the effect of different factors affecting its hydraulic performance. It also assists industry practitioners to design and specify the overlap criterion for a specific application depending on the product specifications and site conditions. The results of this research will help minimise failures of liner systems in barrier applications such as landfills, mines, tailing dams substantially to reduce the potential risk of groundwater contamination.


Assuntos
Argila , Eliminação de Resíduos , Silicatos de Alumínio , Condutividade Elétrica , Instalações de Eliminação de Resíduos
13.
Waste Manag Res ; 38(9): 1047-1063, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32755279

RESUMO

From the chronological analytical review regarding municipal solid waste management (MSWM) and governance optimisation progress in Hong Kong since 2002, it is noted that the policy outcomes have seriously deviated from the original policy goals under the hitherto lack of effective development in bureaucratic and economic policy cultures in municipal solid waste (MSW) strategies formulation and related programmes implementation. The policy analysis specially stated that although the MSW recycling ratio (30%) is not particularly poor, the recovered percentage of plastics, glass and food waste in Hong Kong are extremely low. Based on the unfavourable outcomes and consequences for MSWM and governance in Hong Kong, a conclusion of negative correlation between the per capita MSW disposal rate and bureaucratic policy culture development, as well as positive correlation between recycling rate of low value items and economic policy culture development, can be made. With considering the key factors of benchmark indicators, socio-economic factors, driving force, and communication of MSW policy, conducive options and prospects are also developed for the attempt to provide insights to restructure MSWM and governance in Hong Kong in the next decade. First, the government can build up strategic innovation from a global benchmark case - MSWM and governance improvement from the South Korea case. Second, to create opportunities and conditions to develop high value biofuel from waste through flexible local environmental policies formulation and implementation. Third, shifting a front-line MSWM for governance structure reform.


Assuntos
Eliminação de Resíduos , Gerenciamento de Resíduos , Cidades , Alimentos , Hong Kong , República da Coreia , Resíduos Sólidos/análise
14.
Waste Manag ; 116: 120-130, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32795643

RESUMO

Municipal Solid Waste (MSW) landfills are sources of physical, chemical and microbiological processes and as a result, gases and heat are generated as by-products. The generated heat flows from the higher to lower temperature regions within the landfill. Specific heat and thermal conductivities are two important properties that determine heat flow in MSW landfills. The goal of this study was to determine the thermal conductivity and specific heat capacity of MSW samples of Indian origin and to study its effect on landfill fires. Thermal conductivity and specific heat capacity of waste samples collected from dumpsite at Bhandewadi landfill, Nagpur & Bellahalli landfill, Bangalore (India) and the synthetic MSW (prepared in the lab) were determined using newly designed and fabricated experimental set-up. Results showed that moisture and organic content of MSW are directly proportional to specific heat capacity and indirectly proportional to thermal conductivity. Thermal conductivity of MSW is directly proportional to its density and specific heat is indirectly proportional to the density of MSW. MSW with specific heat and thermal conductivity in the range 0.003 J/g. K - 0.47 J/g. K and 0.35-3.6 J/s. m. K, respectively were found between 30 and 75 °C with 5% to 25% moisture content. As the temperature increases above 75 °C, decrease in thermal conductivity & increase in specific heat was observed and thermal conductivity of 0.07 J/s. m. K was observed at 130-140 °C. As a result of this, heat does not flow and gets concentrated in that region leading to landfill fire.


Assuntos
Fogo , Eliminação de Resíduos , Temperatura Alta , Índia , Resíduos Sólidos/análise , Condutividade Térmica , Instalações de Eliminação de Resíduos
15.
Waste Manag ; 116: 100-111, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32799092

RESUMO

In recent years, a growing number of investigations have examined food waste in the food service sector, in which the catering of individual events received little attention. We aimed to contribute to fill this knowledge gap by presenting insights from a case study based on data from 239 event caterings. The case study presents findings about the influences of four variables, namely event type, season, event size, and menu prices, on buffet leftovers. We used a waste tracking system that allowed kitchen staff to quantify buffet leftovers for 4 years: from the beginning of 2014 until the end of 2017. Among the studied variables, the event size demonstrated the strongest influence on the generation of buffet leftovers in the case study. Buffet leftovers showed a trend of decreasing quantities relative to the number of guests for increasing event sizes. For instance, smaller events with less than 100 participants recorded the highest quantities of approximately 280 g of buffet leftovers per guest, and larger events of more than 500 participants recorded the lowest quantities of approximately 74 g per guest. In addition, we found that three food product groups-meat & poultry, finger food, and side dishes-caused approximately 54% of the overall quantity of buffet leftovers and approximately 65% of the corresponding monetary equivalents. Our findings emphasize that further research is necessary on food waste reduction strategies.


Assuntos
Serviços de Alimentação , Eliminação de Resíduos , Alimentos , Humanos , Estações do Ano
16.
Waste Manag ; 116: 179-189, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32805553

RESUMO

This study proposes a design of a household waste collection system based on a two-stage procedure. First, the bin location-allocation problem is solved by selecting collection sites from a set of potential sites, and determining the type and number of bins at each selected collection site. Second, bin-to-bin waste collection routes are obtained for a fleet of homogeneous vehicles that are restricted by either work shift duration or vehicle capacity. Mixed integer linear programming (MILP) models are proposed for both stages, considering the particular characteristics of the problem. The models are applied to a real-world instance in the commune of Renca in Santiago, Chile. The results of first stage indicate an important preference for small bins since they have a lower unitary cost. Due to the large size of the real instance, a Large Neighborhood Search (LNS) heuristic is used in the second stage to find good feasible vehicle routing solutions in a reasonable period of time. The results for the routing phase suggest a larger number of routes in the morning work shift since these routes have shorter distances. The LNS heuristic presents a satisfactory behavior when compared to the MILP model with small instances. The proposed bin-to-bin household waste collection vehicle routing presents a more efficient solution than the existing door-to-door waste collection in the commune of Renca with respect to the total daily traveled distance and the average work shift duration. Finally, a sensitivity analysis is presented and discussed for both models.


Assuntos
Eliminação de Resíduos , Gerenciamento de Resíduos , Chile
17.
Bioresour Technol ; 316: 123900, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32739578

RESUMO

The influence of co-hydrothermal carbonization (co-HTC) on the hydrochar properties and nutrients distribution derived from food waste (FW) and woody sawdust (WS) blend was assessed. The carbon retention, surface functional groups and morphology features involved in hydrochar were evaluated to study the interaction effects. Results suggested that hydrochar yield consistently decreased with increase of both FW ratio and HTC temperature. C retention from 260 °C hydrochar was low (approximately 65%), but more microsphere structures was formed due to the enhanced carbonization degree of hydrochar. Hydrochar obtained at high FW blend ratio and temperature resulted in weaken oxygen-containing groups like OH and CO with enhanced CC and C(O, N). 10.43-60.45% of N and 82-94% of P were retained in hydrochar. NH4+-N (6.63%-15.63%) and organic nitrogen (70.4%-87.7%) were identified as main N-containing species in liquid phase, while total P content (14-166 mg/L) depended more on FW ratio.


Assuntos
Alimentos , Eliminação de Resíduos , Carbono , Nutrientes , Temperatura , Madeira
18.
Bioresour Technol ; 316: 123901, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32739579

RESUMO

The enhancement of zerovalent iron (ZVI) on anaerobic digestion (AD) has been proved, but there are still some problems that constrain the large-scale application of ZVI, such as the destruction of cell membrane and the inhibition of methanogenesis led by rapid H2 accumulation. Aiming at these problems, sulfidated microscale zerovalent iron (S-mZVI) was employed to evaluate its effect on anaerobic co-digestion (AcoD) of waste activated sludge (WAS) and food waste (FW). Experimental results showed that S-mZVI promoted the direct interspecies electron transfer (DIET) between specific bacteria and methanogens, resulting in higher methane yield. At S-mZVI 10 g/L, the cumulative methane yield and ETS activity reached 264.78 mL/g-VS and 24.62 mg INTF/(g-TS h), which was 1.33 and 1.83 times that of blank. Microbiological analysis demonstrated that the abundance of DIET-related microorganisms such as Syntrophomonas, Methanosarcina and Methanobacterium increased with the increasing dosage of S-mZVI.


Assuntos
Eliminação de Resíduos , Esgotos , Anaerobiose , Reatores Biológicos , Elétrons , Alimentos , Ferro , Metano
19.
Bioresour Technol ; 316: 123929, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32763805

RESUMO

This research presents the tangerine seed activated carbon (TSAC), obtained from food waste (tangerine seed) by one-step pyrolysis method and applied to remove carbamate pesticides (CMs) from complex solutions. The effects of carbonization temperature and time on adsorption performance were studied. Structural properties of TSAC were determined by Fourier Transform Infrared Spectrometer, X-ray diffraction analysis, Raman spectroscopy, scanning electron microscope and nitrogen adsorption/desorption methods and compared with that of tangerine seed. The TSAC exhibited a specific surface area of 659.62 m2/g, a total pore volume of 0.6203 cc/g and a pore diameter of 1.410 nm. The influences of initial pesticide concentration, adsorption temperature and contact time were investigated through batch experiments. Pseudo-second-order kinetic model and Langmuir isotherm model were more suitable for CMs adsorption process onto TSAC. Furthermore, the thermodynamic research indicated that this adsorption process was spontaneous and exothermic.


Assuntos
Praguicidas , Eliminação de Resíduos , Poluentes Químicos da Água/análise , Adsorção , Carbamatos , Carvão Vegetal , Concentração de Íons de Hidrogênio , Cinética , Sementes/química , Espectroscopia de Infravermelho com Transformada de Fourier , Termodinâmica , Água
20.
Bioresour Technol ; 316: 123946, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32769001

RESUMO

The agri-food waste (AW) require amendments for composting to adjust nutritional and physicochemical deficiencies. The theoretical mixtures formulation is difficult to reach on an industrial scale. The main objective of this work was to evaluate to what extent the composition of AW-based mixtures determines the quality of the final compost produced at the industrial scale. Raw materials having the same AW share characteristics, irrespectively of the amendments added, but their compost were different. All the materials were biological stable at the cooling phase, and mature enough at the end, although the degree of humification did not match with the absence of phytotoxicity. The final compost had sufficient quality even though the AW-based raw materials have a low C/N ratio (<20) and other characteristics such as high electrical conductivity (13 mS·cm-1) and pH (<8.5) that are unfavorable for composting. The management operations during industrial composting correct the deficiencies of raw materials.


Assuntos
Compostagem , Eliminação de Resíduos , Carbono , Alimentos , Resíduos Industriais/análise , Nitrogênio/análise , Solo
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