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1.
J Environ Manage ; 304: 114253, 2022 Feb 15.
Artigo em Inglês | MEDLINE | ID: mdl-35021584

RESUMO

BioH2 production from cheese whey (CW) was evaluated in two acidogenic reactors, UASB and structured fixed-bed (FB), without pH adjustment, under mesophilic conditions, and OLR of 25-90 g COD/L.d. Stage 1 was conducted as a control experiment using sucrose. BioH2 production occurred under pH < 3.0 with maximum yields of 5.8 and 3.0 mol H2/mol sucroseconsumed for UASB and FB reactors, respectively. In Stage 2, CW was the only substrate and a negligible bioH2 production was observed. Nevertheless, a maximum lactic acid concentration of 9.6 g/L was obtained, indicating that pH adjustment can be non-essential for lactic acid production from CW. In Stage 3, a strategy to enrich hydrogenogenic biomass was conducted by initially feeding the reactors with sucrose and gradually replacing it by CW. This strategy brought better bioH2 results compared to Stage 2, but it could not bear over the long-term, as non-hydrogen producing bacteria became predominant.


Assuntos
Queijo , Soro do Leite , Anaerobiose , Reatores Biológicos , Fermentação , Hidrogênio , Metano
2.
Environ Monit Assess ; 194(2): 50, 2022 Jan 04.
Artigo em Inglês | MEDLINE | ID: mdl-34984556

RESUMO

Wetlands are emitters of greenhouse gases. However, many of the wetlands remain understudied (like temperate, boreal, and high-altitude wetlands), which constrains the global budgets. Himalayan foothill is one such data-deficient area. The present study reported (for the first time) the greenhouse gas fluxes (CO2, CH4, N2O, and H2O vapor) from the soils of the Nakraunda wetland of Uttarakhand in India during the post-monsoon season (October 2020 to January 2021). The sampling points covered six different types of soil within the wetlands. CO2, CH4, N2O, and H2O vapor emissions ranged from 82.89 to 1052.13 mg m-2 h-1, 0.56 to 2.25 mg m-2 h-1, 0.18 to 0.40 mg m-2 h-1, and 557.96 to 29,397.18 mg m-2 h-1, respectively, during the study period. Except for CO2, the other three greenhouse gas effluxes did not show any spatial variability. Soils close to "swamp proper" emitted substantially higher CO2 than the vegetated soils. Soil temperature exhibited exponential relationships with all the greenhouse gas fluxes, except for H2O vapor. The Q10 values for CO2, CH4, and N2O varied from 3.42 to 4.90, 1.66 to 2.20, and 1.20 to 1.30, respectively. Soil moisture showed positive relationships with all the greenhouse gas fluxes, except for N2O. The fluxes observed from Nakraunda were in parity with global observations. However, this study showed that wetlands experiencing lower temperature regime are also capable of emitting a substantial amount of greenhouse gases and thus, requires more study. Considering the seasonality of greenhouse gas fluxes should improve global wetland emission budgets.


Assuntos
Dióxido de Carbono , Áreas Alagadas , Dióxido de Carbono/análise , Monitoramento Ambiental , Metano/análise , Óxido Nitroso/análise , Solo
3.
Appl Microbiol Biotechnol ; 106(2): 743-754, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34982194

RESUMO

Nitrite-dependent anaerobic methane oxidation (n-damo) acts as a crucial link between biogeochemical carbon and nitrogen cycles. Nevertheless, very few studies have characterized n-damo microorganisms in high-latitude permafrost regions. Therefore, this study investigated the vertical distribution and diversity of n-damo bacterial communities in soil from three forest types in the permafrost regions of the Daxing'an Mountains. A total of 11 and 8 operational taxonomic units (OTUs) of n-damo 16S rRNA and pmoA genes were observed, respectively. Remarkable spatial variations in n-damo bacteria community richness, diversity, and structure were observed at different soil depths. Moreover, the abundances of n-damo bacteria (16S rRNA and pmoA genes) varied between 1.55 × 104 to 1.47 × 105 and 1.31 × 103 to 3.11 × 104 copies g-1 dry soil (ds), as demonstrated by quantitative PCR analyses. 13CH4 stable isotope tracer assays indicated that the potential n-damo rates varied from 0 to 1.26 nmol g-1 day-1, with the middle layers (20-40 cm and 40-60 cm) exhibiting significantly higher values than the upper (0-20 cm) and deeper layers (80-100 cm) in all three forest types. Redundancy analyses (RDA) indicated that total organic carbon (TOC), nitrate (NO3--N), and nitrite (NO2--N) were key modulators of the distribution of n-damo bacterial communities. This study thus demonstrated the widespread occurrence of n-damo bacteria in cold and high-latitude regions of forest ecosystems and provided important insights into the global distribution of these bacteria. KEY POINTS: • This study detected n-damo bacteria in soil samples obtained from the permafrost region of three forest types in the Daxing'an Mountains. • The community composition of n-damo bacteria was mainly affected by soil depth and not forest type. • The abundances of n-damo bacteria first increased and then decreased at higher soil depths.


Assuntos
Nitritos , Pergelissolo , Anaerobiose , Bactérias/genética , Ecossistema , Metano , Oxirredução , RNA Ribossômico 16S/genética
4.
J Environ Manage ; 302(Pt B): 114061, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34800769

RESUMO

Scots pine bog edge woodland is a type of habitat typical on raised bogs where trees cohabitate with bog vegetation to form a low-density stand. Even though nowadays this habitat does not cover large areas, in a future scenario it is possible that this environment will expand, either naturally (drier climate) or anthropogenically, as the result of the application of new restoration strategies that could increase net landscape carbon benefits from both peatland and woodland environments. This study is the first reported investigation in Scotland exploring carbon flux dynamics from sparse woodlands on raised bogs. We examined how Scots pine trees directly or indirectly affected soil temperature and moisture, ground vegetation, and consequently carbon dioxide (CO2) and methane (CH4) soil fluxes. Soil CO2 and CH4 were measured at different distance from the tree and thereafter assessed for both spatial and temporal variability. Our results showed that these low-density trees were able to modify the ground vegetation composition, had no effect on soil temperature, but did affect the soil moisture, with soils close to tree roots significantly drier (0.25 ± 0.01 m3 m-3) than those on open bog (0.39 ± 0.02 m3 m-3). Soil CO2 fluxes were significantly higher in the vicinity of trees (34.13 ± 3.97 µg CO2 m-2 s-1) compared to the open bog (24.34 ± 2.86 µg CO2 m-2 s-1). On the opposite, CH4 effluxes were significantly larger in the open bog (0.07 ± 0.01 µg CH4 m-2 s-1) than close to the tree (0.01 ± 0.00 µg CH4 m-2 s-1). This suggests that Scots pine trees on bog edge woodland may affect soil C fluxes in their proximity primarily due to the contribution of root respiration, but also as a result of their effects on soil moisture, enhancing soil CO2 emissions, while reducing the CH4 fluxes. There is, however, still uncertainty about the complete greenhouse gas assessment, and further research would be needed in order to include the quantification of soil nitrous oxide (N2O) dynamics together with the analysis of complete gas exchanges at the tree-atmosphere level.


Assuntos
Dióxido de Carbono , Metano , Dióxido de Carbono/análise , Florestas , Óxido Nitroso/análise , Solo , Áreas Alagadas
5.
Waste Manag ; 137: 294-303, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34823136

RESUMO

A key environmental sustainability requirement for the treatment of organic waste via anaerobic digestion (AD) is the prevention of unwanted methane emissions in the production chain whenever possible. Identifying and quantifying these emissions has been frequently investigated, particularly in Europe. However, the challenges of climate change are also becoming vitally important in Australia. This novel study presents the results from emission measurement campaigns carried out at two biogas plants and one landfill site in Australia. An on-site approach consisting of leakage detection and emission quantification by a static chamber method was applied. Twenty-nine leakages were detected predominantly on the digesters (gastight covered anaerobic lagoons) of the biogas plants. Ten emission hot spots were found on the surface cover of a landfill site. Methane emission rates of 9.9 ± 2.3 kg h-1 (10.5 ± 2.4% CH4) for biogas plant A, 3.0 ± 1.9 kg h-1 (8.1 ± 5.2% CH4) for biogas plant B and 41-211 g h-1 for the two largest emission hot spots from the landfill were measured. Since not every single leakage or hot spot could be quantified separately, the stated overall emission rates had to be extrapolated. Importantly, the emission rates from the landfill should be interpreted carefully due to the limited overall area which could be practicably investigated. Leakages occurred at common components of the covered anaerobic lagoons such as the membrane fixation or concrete walls. Repairing these parts would increase the plant safety and mitigate negative environmental effects.


Assuntos
Poluentes Atmosféricos , Eliminação de Resíduos , Gerenciamento de Resíduos , Poluentes Atmosféricos/análise , Austrália , Biocombustíveis , Metano/análise , Instalações de Eliminação de Resíduos
6.
Bioresour Technol ; 344(Pt B): 126177, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34699963

RESUMO

The development of biogas projects feed by lignocellulosic biomass has been constrained by the high cost of pre- and post-treatment. In this study, a novel strategy for pretreatment by using two by-products, i.e., CO2 and liquid digestate (LD), generated from anaerobic digestion (AD) was developed to overcome these shortcomings. Results showed that corn straw pretreated in LD pressurized under 1 Mpa CO2 at 55 â„ƒ resulted in increased glucose and xylose contents and a 9.80% decrease in cellulose crystallinity. After 45 days of AD conversion, the methane yield increased by 50.97% compared with untreated straw. However, pretreatment in LD pressurized under 1 Mpa CO2 at 170 â„ƒ produced 5-hydroxymethylfurfural and furfural, which led to a decrease in methane production from the straw in the subsequent AD conversion. The alteration of the microbial community in the pretreated slurry at 55 °C was another potential contributor to the enhanced performance of AD.


Assuntos
Biocombustíveis , Zea mays , Anaerobiose , Biomassa , Lignina/metabolismo , Metano , Zea mays/metabolismo
7.
Bioresour Technol ; 344(Pt B): 126173, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34728354

RESUMO

Long-term semi-continuous experiments were carried out under three feedstock conditions to study the effects of mixing ratio and total solids (TS) content on temperature-phased anaerobic codigestion of rice straw (RS) and pig manure (PM). The results showed that biohythane only produced from the mixture with 6% TS content and its average content were 12.83 ± 1.19% (hydrogen) and 23.68 ± 1.12% (methane). Increasing mixture TS content and decreasing its RS ratio increased biohythane production and organic matter removal by creating a suitable process pH and increasing the anaerobic reaction rates. The highest biohythane production of the mixture reached 73.09 ± 3.03 ml/g VS (hydrogen) and 235.81 ± 9.30 ml/g VS (methane) at a mixing ratio of 5:1 and TS content of 6%. A variety of hydrogen-producing bacteria were found in the thermophilic reactor and Clostridium_sensu_stricto_1 played an important role. Butyric acid fermentation is the main hydrogen-producing pathway. Methanobacterium and Methanosaeta were dominant archaea in the mesophilic reactor.


Assuntos
Esterco , Oryza , Anaerobiose , Animais , Biocombustíveis , Reatores Biológicos , Metano , Suínos , Temperatura
8.
Bioresour Technol ; 344(Pt B): 126244, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34732374

RESUMO

Tofu processing residues (TPR) have received more attention as a source of bioenergy. However, their low solubility has hindered biohythane generation. Consequently, the ultrasonic and H2SO4 pretreatments were combined and compared for the first time to improve the hydrolysis of organic matter and carbohydrate and increase free amino nitrogen generation from TPR. Besides, the impact of pretreatments on biohythane generation was investigated. Under the optimal conditions of 7.54% substrate level, 8% H2SO4 concentration, 80 °C and 50 min, the coincident ultrasonic-H2SO4 pretreatment enriched the contents of soluble chemical oxygen demand, reducing sugar, and free amino nitrogen to 49675 mg/L, 26 g/L, and 1721 mg/L, respectively, greater than individual pretreatments. Also, Biohythane yield increased by 4.24-13.61% over control (389.42 ± 23.7 ml/g-VSfed). Furthermore, hydrogen yield at 42.5 ± 2.08 and 28.1 ± 1.07 ml/g-VSfed and sulfate removal efficiency at 93 and 92% were significantly improved with ultrasonic-H2SO4 and H2SO4 pretreatments, respectively, indicating acidogenic and sulfidogenic activity enhancement.


Assuntos
Alimentos de Soja , Ultrassom , Anaerobiose , Análise da Demanda Biológica de Oxigênio , Hidrogênio , Metano
9.
Bioresour Technol ; 344(Pt B): 126243, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34737136

RESUMO

The mechanisms underlying the advanced performance in anaerobic co-digestion (AcoD) are crucial but remain elusive. This study conducted AcoD of swine manure, rice straw and apple waste (AW, mainly consisting of labile carbon) or fructose (a pure labile carbon), and monitored microbial community abundances, activities and transcriptional profiles in the digestate and on straw. The transformation efficiencies of manure (not straw) to CH4 were promoted in AcoD co-fed manure and AW (by 39 ± 13%) or fructose (by 65 ± 14%), compared to the control mono-fed manure, implying labile carbon could trigger a priming effect underlying AcoD advantage. Although digestate-associated and straw-associated communities existed in a same bioreactor, the priming effect mainly linked to the former and was attributed to enhancements in deterministic turnover of active communities, in activities of Firmicutes taxa involved in substrate hydrolysis, and in acetoclastic methanogenesis. These findings provide novel insights to elaborate AcoD processes.


Assuntos
Biocombustíveis , Metano , Anaerobiose , Animais , Carbono , Esterco , Suínos
10.
Bioresour Technol ; 344(Pt B): 126270, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34740796

RESUMO

The effect of organic bulking agents on CO2, NH3, N2O and CH4 emission and related genes was evaluated in 40 days sludge composting with wood chip, wheat straw and rice husk, respectively. The results showed wood chip had the highest C/N of 111.3, total porosity of 93.13% and aeration porosity of 78.98% among three bulking agents. Wheat straw had the highest water-holding porosity of 25.62%, which could be critical factor increasing CH4 production and reducing NH3 emission. Moreover, there was no significant difference in N2O emission rates in three composting systems with three bulking agents. RDA analysis showed a negative correlation between mcrA and NH + 4-N. Nitrate content in raw feedstock was dominant factor limiting N2O yield due to low amoA. The continuous increase of oxidation-reduction potential was significantly positive correlated with pmoA and negative correlation with nirK and norB, which reduced N2O and CH4 production in the curing period.


Assuntos
Compostagem , Gases de Efeito Estufa , Amônia/análise , Gases de Efeito Estufa/análise , Metano/análise , Óxido Nitroso/análise , Esgotos , Solo
11.
Bioresour Technol ; 344(Pt B): 126238, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34743991

RESUMO

The treatment of a dewatered liquid of dry fermentation via the anammox process was investigated in the present study. Fast acclimation was established: within 2-months of operation, nitrogen removal rate reached 5 times (5.5 g-N/L/d) higher than it was at startup, which was achieved by inoculation with cold-stored HAP-anammox granules and inhibition control. The specific anammox activity of the dewatered liquid was highly improved and quite comparable to that of synthetic wastewater. Ca. Kuenenia with the relative abundance of 31.1% was revealed to be the only anammox genre and maintained its dominance throughout the operation. Simultaneously, Ca. D. denitrificans was proliferated, with its relative abundance increasing from 1.5% to 14.9%. The microbial co-occurrence network of HAP-anammox granules developed during the treatment of the dewatered liquid of dry fermentation. The experience of this work provides valuable strategies facilitating fast acclimation of the anammox process for the treatment of high-strength wastewater.


Assuntos
Compostos de Amônio , Desnitrificação , Aclimatação , Reatores Biológicos , Fermentação , Metano , Nitrogênio , Oxirredução , Esgotos , Simbiose , Águas Residuárias
12.
Bioresour Technol ; 344(Pt B): 126311, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34780910

RESUMO

The status, recent trends and future perspectives in modelling and optimisation of anaerobic co-digestion is investigated. Areas that can be focused on and those which need further research towards enhancing biogas production are pointed out. Co-digestion, modelling and optimisation of anaerobic digestion as well as techno-economic aspects are reviewed in this paper. It was noted that co-digestion requires more research into a variety of bio-resources and their specific blend proportions. Modelling and optimisation of co-digestion with substrate seasonal fluctuations has not been addressed in previous studies. Controlling key process factors including temperature, pH, and carbon to nitrogen ratio is critical in improving biogas yield. Biogas hybridisation is yet to be explored in depth. The majority of researches are focused on mono-digestion, feedstock co-digestion, modelling, and optimisation of anaerobic digestion needs significant further investigations. A multi-objective approach taking all technical and economic parameters in the modelling and optimization is essential.


Assuntos
Biocombustíveis , Nitrogênio , Anaerobiose , Biomassa , Reatores Biológicos , Digestão , Metano
13.
Bioresour Technol ; 344(Pt B): 126321, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34785334

RESUMO

Anaerobic digestion has been recognized as promising technology for bioenergy production, while the bottlenecks including long start up times, low methane contents, and susceptibility toward environmental change attenuate the process benefits. Integrating microbials electrolysis cell (MEC) with anaerobic digestion (AD) has been recognized as a promising strategy for alleviate the performance bottleneck. This review summarized and updated the current researches that utilize MEC-AD for enhanced methane production from biomass. The integrated AD-MEC was first elucidated, followed by illustrations on strategies for process performance enhancements, parameters effects, and the associated applications. Finally, the challenges and prospects were outlined in this work.


Assuntos
Reatores Biológicos , Eletrólise , Anaerobiose , Biomassa , Metano
14.
Bioresour Technol ; 344(Pt B): 126309, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34798247

RESUMO

The efficiency of anaerobic digestion could be increased by promoting microbial retention through biofilm development. The inclusion of certain types of biofilm carriers has differentiated existing AD biofilm reactors through their respective mode of biofilm growth. Bacteria and archaea engaged in methanogenesis during anaerobic processes potentially build biofilms by adhering or attaching to biofilm carriers. Meta-analyzed results depicted varying degrees of biogas enhancement within AD biofilm reactors. Furthermore, different carrier materials highly induced the dynamicity of the dominant microbial population in each system. It is suggested that the promotion of surface contact and improvement of interspecies electron transport have greatly impacted the treatment results. Modern spectroscopy techniques have been and will continue to give essential information regarding biofilm's composition and structural organization which can be useful in elucidating the added function of this special layer of microbial cells.


Assuntos
Biocombustíveis , Reatores Biológicos , Anaerobiose , Biofilmes , Metano
15.
Bioresour Technol ; 344(Pt B): 126226, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34798250

RESUMO

To improve the efficiency of methane production from chicken manure (CM) anaerobic digestion, the mechanism of coal slime (CS) as an additive on methane production characteristics were investigated. The results showed that adding an appropriate amount of CS quickened the start of the fermentation and effectively increased the methane yield. In addition, the pH changed in a stable manner in the liquid phase, and the concentrations of total ammonia nitrogen (TAN) and free ammonia nitrogen (FAN) were reduced. Moreover, organic matter was decomposed and volatile fatty acids (VFAs) were consumed effectively. The abundance of Bacteroides in the bacterial community and Methanosarcina in the archaea was increased. In addition, the reduction of CO2 was the main methanogenic pathway, and adding CS raised the abundance of genes for key enzymes in metabolic pathways during methane metabolism. The results provide a novel method for the efficient methane production from CM.


Assuntos
Esterco , Metano , Anaerobiose , Animais , Reatores Biológicos , Galinhas , Carvão Mineral
16.
Bioresour Technol ; 344(Pt B): 126353, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34798256

RESUMO

This study evaluated the effects of bio-based carbon materials on methane production by anaerobic digestion. The results showed that biochar and hydrochar can promote cumulative methane yield by 15% to 29%. However, there was no statistical significance (p > 0.05) between hydrochar and biochar produced at different temperature on methane production. 16S rRNA gene sequencing and bioinformatics analysis showed that biochar and hydrochar enriched microorganism that might participate in direct interspecies electron transfer (DIET) such as Pseudomonadaceae, Bacillaceae, and Clostridiaceae. The the surface properties of the modified biochar were characterized with BET, Raman, FTIR and XPS. Bio-based carbon materials with uniform dispersion provided a stable environment for the DIET of microorganisms and electrons are transferred through aromatic functional groups on the surface of materials. This study reveals bio-based carbon materials surface properties on methane production in anaerobic digestion and provides a new approach to recycling spent coffee grounds.


Assuntos
Reatores Biológicos , Grafite , Anaerobiose , Carbono , Carvão Vegetal , Etanol , Metano , RNA Ribossômico 16S/genética
17.
Water Res ; 208: 117839, 2022 Jan 01.
Artigo em Inglês | MEDLINE | ID: mdl-34801819

RESUMO

Low economic gains from biogas drive research on shifting to volatile fatty acid (VFA) production during anaerobic sludge digestion. pH control and methanogenesis inhibition are widely used strategies for VFA production via anaerobic digestion of sludge. However, these strategies require perpetual dosing of chemicals, increasing cost and operation complexity. Here, we applied electrochemical pretreatment (EPT) (12 V/30 min) for VFA production during anaerobic sludge digestion. The underlying mechanisms of the VFA production induced by EPT were explored systematically through analyses of the changes in the EPT operation parameters, the sludge characteristics, and the microbial community structure and functional enzymes involving in the subsequent sludge digestion. EPT with carbon-based electrodes selectively inhibited methanogenesis by down-regulating heterodisulfide reductase without affecting enzymatic acidogenesis and hydrolysis, resulting in accumulation of VFAs (up to 389±12 mg acetic acid equivalent/L). Propionate and acetate were, respectively enriched to 89 and 75% of the total VFAs after carbon- and graphite- EPT. Titanium-EPT produced lower levels of VFA; instead, biogas yield increased by ∼20%. We anticipate that EPT will advance VFA recovery from diverse organic wastes to meet the global challenge of resource supply and waste management.


Assuntos
Biocombustíveis , Esgotos , Anaerobiose , Reatores Biológicos , Digestão , Ácidos Graxos Voláteis , Concentração de Íons de Hidrogênio , Metano
18.
Bioresour Technol ; 344(Pt B): 126350, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34813924

RESUMO

Anaerobic digestion (AD) is a technique that can be used to treat high concentrations of various organic wastes using a consortium of functionally diverse microorganisms under anaerobic conditions. Methane gas, a beneficial by-product of the AD process, is a renewable energy source that can replace fossil fuels following purification. However, detailed functional roles and metabolic interactions between microbial populations involved in organic waste removal and methanogenesis are yet to be known. Recent metagenomic approaches based on advanced high-throughput sequencing techniques have enabled the exploration of holistic microbial taxonomy and functionality of complex microbial populations involved in the AD process. Gene-centric and genome-centric analyses based on metagenome-assembled genomes are a platform that can be used to study the composition of microbial communities and their roles during AD. This review looks at how these up-to-date metagenomic analyses can be applied to promote our understanding and improved the development of the AD process.


Assuntos
Reatores Biológicos , Metagenoma , Anaerobiose , Metagenômica , Metano
19.
Bioresour Technol ; 344(Pt B): 126412, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34838626

RESUMO

Biogas upgrading is an essential process for efficient and safe utilization of biogas produced from anaerobic digestion (AD), a cost-effective and environmentally friendly technology for bioenergy recovery from organic wastes. Biogas recirculation in AD reactors has been recently reported as a cost-effective and promising method to enhance methane content in biogas. This review aimed to summarize the state-of-the-art of biogas recirculation-based AD systems to better understand the possible mechanisms and main factors relating to in-situ biogas upgrading. It shows that biogas recirculation in the AD reactor can not only enhance methane content via both physicochemical and biological effects, but also help establish a robust AD system with high buffering capacity for highly efficient treatment of various organic wastes. More research works are demanding for a better understanding of the mechanisms and the optimization of the whole AD system, targeting its further development for high-calorie bioenergy production.


Assuntos
Biocombustíveis , Águas Residuárias , Anaerobiose , Reatores Biológicos , Metano
20.
Sci Total Environ ; 806(Pt 1): 150499, 2022 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-34571221

RESUMO

The off-site effects of agricultural organic soils include the leaching of N, P, and organic carbon (OC) to watercourses and CO2, CH4, and N2O emissions into the atmosphere. The aim of this study was to quantify how the thickness of organic layers affects these loads. A 19.56-ha experimental field drained by subsurface pipes was established in Ruukki, northwestern Finland. Three plots had a 60-80 cm-thick sedge peat layer and three others had a thickness of 20 cm or less. The drainage pipes lie in mineral soil that, in this field, contains sulfidic material. This study documents the experimental settings and reports on the leaching of substances in the first two years, as well as CO2, CH4 and N2O emissions during eight weeks in one summer. Total N (TN) and OC loads were higher from the thicker peat plots. The mean TN loads during a hydrological year were 15.4 and 9.2 kg ha-1 from the thicker and thinner peat plots, respectively, with organic N representing 36% of TN load. Total P (TP) load averaged 0.27 kg ha-1 yr-1. Dissolved P load represented 63 and 36% of TP in the thicker peat area and only 23 and 13% in the thinner peat area, and was thus increased upon peat thickness. These N and P loads through the subsurface drainage system represented roughly 83% of TN and 64% of TP loads from this field. There were no clear differences in greenhouse gas emissions among the plots during the eight-week monitoring period. Slowly oxidizing sulfide in the subsoil resulted in annual leaching of 147 kg S ha-1, almost ten times that of non-sulfidic soils. Our first results emphasize the effect of the peat thickness on the leaching of substances and warn about considering all organic soils as a single group in environmental assessments.


Assuntos
Gases de Efeito Estufa , Dióxido de Carbono/análise , Metano/análise , Óxido Nitroso/análise , Solo
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