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1.
Environ Monit Assess ; 193(1): 39, 2021 Jan 07.
Artigo em Inglês | MEDLINE | ID: mdl-33409667

RESUMO

Synthetic household chemical products (HCP) are used in various household activities. An average urban household was estimated to consume ~ 3 kg HCP per month while discarding 212-387 mg/L HCP in sewage comprising > 265 different chemical compounds. The high sorption properties of HCP and their antimicrobial resistance lead to their long-term persistence in the environment. The intrusion of HCPs and their breakdown products into food chain causes detrimental effects on health and ecology. HCPs comprise mostly of a mixture of xenobiotics, organic and inorganic compounds resulting in an impaired biodegradation. Yet, the biodegradability of HCPs is seldom assessed. Therefore, this research proposes a modified Gompertz model approach to analyze BMP data in order to classify commercially available HCPs into seven groups based on the observed levels of recalcitrance and is in turn coined "Anaerobic Biodegradability Index" (ABI, beginning from ABI-VI to ABI-0 wherein ABI-VI represents the highest degradability and ABI-0 the least). This approach emulates "Energy-Star" ratings of electrical appliances classified based on electrical efficiency. Results of such a classification indicated that HCPs containing ≥ 10% anionic surfactants such as laundry detergents, handwash gel, dishwasher chemicals, and creosote surface cleaner, exhibit lowered anaerobic degradability and were therefore categorized between ABI-0 and ABI-II. Whereas the highly degradable HCP such as toothpaste, shower gel, and hair shampoo were categorized in ABI-V and ABI-VI categories. We perceive that the weightages and concentrations can be used in the future to define the capability of various wastewater treatment systems and their tolerance to various ABI classes.


Assuntos
Monitoramento Ambiental , Esgotos , Anaerobiose , Biodegradação Ambiental , Características da Família , Metano
2.
Ecotoxicol Environ Saf ; 208: 111598, 2021 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-33396119

RESUMO

Within the domain of phytoremediation research, the proper disposal of harvestable plant parts, that remove pollutants from contaminated soil, has been attracted extensive attention. Here, the bioenergy generation capability of trace metals (Cu, Pb, Zn, Cd, Mn, and As) polluted plants was assessed. The biogas production potential of accumulators or hyperaccumulator plants, Elsholtzia haichowensis, Sedum alfredii, Solanum nigrum, Phytolacca americana and Pteris vittata were 259.2 ± 1.9, 238.7 ± 4.2, 135.9 ± 0.9, 129.5 ± 2.9 and 106.8 ± 2.1 mL/g, respectively. The presence of Cu (at approximately 1000 mg/kg) increased the cumulative biogas production, the daily methane production and the methane yield of E. haichowensis. For S. alfredii, the presence of Zn (≥500 mg/kg) showed a significant negative impact on the methane content in biogas, and the daily methane production, which decreased the biogas and methane yield. The biogas production potential increased when the content of Mn was at 5 000-10,000 mg/kg, subsequently, decreased when the value of Mn at 20,000 mg/kg. However, Cd (1-200 mg/kg), Pb (125-2000 mg/kg) and As (1250-10,000 mg/kg) showed no distinctive change in the cumulative biogas production of S. nigrum, S. alfredii and P. vittata, respectively. The methane yield showed a strong positive correlation (R2 =0.9704) with cumulative biogas production, and the energy potential of the plant residues were at 415-985 kWh/ton. Thus, the anaerobic digestion has bright potential for the disposal of trace metal contaminated plants, and has promising prospects for the use in energy production.


Assuntos
Anaerobiose , Biocombustíveis , Poluentes do Solo/análise , Oligoelementos/análise , Biodegradação Ambiental , Poluentes Ambientais , Metano , Plantas , Pteris/química , Sedum
3.
J Environ Sci (China) ; 100: 158-166, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33279028

RESUMO

Evaluating anaerobic biodegradability of sludge and then identifying the stabilization of digestate is necessary in sludge treatment and disposal. 48 sludge samples from 24 typical waste water treatment plants (WWTPs) in 11 provinces in China were selected to investigate the relationship between Biochemical Acidogenic Potential (BAP) test and Biochemical Methane Potential (BMP) test. The volatile fatty acid (VFA) production obtained from BAP tests was found linearly related to the ultimate methane production from corresponding BMP tests. Satisfying results were obtained with Pearson correlation coefficient as 0.929 and R2 value as 0.76. Furthermore, the physio-chemical characteristics (FCI, SUVA254, E4/E6) of supernatant, which were associated with humic-like substances (HS), were investigated before and after BMP tests. Through which a new criterion (FCI>1.50, SUVA254>1.10, E4/E6<4.0) was proposed to evaluate the stabilization level of anaerobic digested sludge.


Assuntos
Esgotos , Eliminação de Resíduos Líquidos , Anaerobiose , Reatores Biológicos , China , Metano/análise
4.
Sci Total Environ ; 755(Pt 1): 142940, 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33348487

RESUMO

Cow manure represents a surplus manure waste in agricultural food sectors, which requires proper disposal. Anaerobic digestion, in this regard, has raised global interest owing to its apparent environmental benefits, including simultaneous waste diminishment and renewable energy generation. However, dedicated intensifications are necessary to promote the degradation of recalcitrant lignocellulosic components of cow manure. Hence, this manuscript presents a review of how to exploit cow manure in anaerobic digestion through different incentives extensively at lab-scale and full-scale. These strategies comprise 1) co-digestion; 2) pretreatment; 3) introduction of additives (trace metals, carbon-based materials, low-cost composites, nanomaterials, and microbial cultures); 4) innovative systems (bio-electrochemical fields and laser irradiation). Results imply that co-digestion and pretreatment approaches gain the predominance on promoting the digestion performance of cow manure. Particularly, for the co-digestion scenario, the selection of lignin-poor co-substrate is highlighted to produce maximum synergy and pronounced removal of lignocellulosic compounds of cow manure. Mechanical, thermal, and biological (composting) pretreatments generate mild improvement at laboratory-scale and are proved applicable in full-scale facilities. It is noteworthy that the introduction of additives (Fe-based nanomaterials, carbon-based materials, and composites) is acquiring more attention and shows promising full-scale application potential. Finally, bio-electrochemical fields stand out in laboratory trials and may serve as future reactor modules in agricultural anaerobic digestion installations treating cow manure.


Assuntos
Biocombustíveis , Esterco , Anaerobiose , Animais , Reatores Biológicos , Bovinos , Feminino , Laboratórios , Metano
5.
Water Res ; 189: 116552, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33166921

RESUMO

A novel granular activated carbon-synergized anaerobic membrane bioreactor (GAC-AnMBR), consisted of four expanded bed anaerobic bioreactors with GAC carriers and a membrane tank, was established in pilot scale (10 m3/d) to treat real municipal wastewater (MWW) at ambient temperature seasonally fluctuating from 35 to 5 °C. It showed sound organic removal over 86% with the permeate COD less than 50 mg/L even at extremely low temperatures below 10 °C. COD mass balance analysis revealed that membrane rejection (with a contribution rate of 10%-20%) guaranteed the stable organic removal, particularly at psychrophilic temperature. The methane yield was over 0.24 L CH4 (STP)/g COD removed at mesophilic temperature and 0.21 L CH4 (STP)/g COD removed at 5-15 °C. Pyrosequencing of microbial communities suggested that lower temperature reduced the abundance of the methane producing bacteria, but the methane production was enhanced by selectively enriched Methanosaeta, syntrophic Syntrophobacter and Smithella and exoelectrogenic Geobacter for direct interspecies electron transfer (DIET) on the additive GAC. Compared with previously reported pilot-scale AnMBRs, the GAC-AnMBR in this study showed better overall performance and higher stability in a wide temperature range of 5-35 °C. The synergistic effect of GAC on AnMBR guaranteed the robustness of GAC-AnMBR against temperature, which highlighted the applicational potential of GAC-AnMBR, especially in cold and temperate climate regions.


Assuntos
Carvão Vegetal , Eliminação de Resíduos Líquidos , Anaerobiose , Reatores Biológicos , Metano , Estações do Ano , Temperatura , Águas Residuárias
6.
Water Res ; 189: 116645, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33227607

RESUMO

Poly ferric sulfate (PFS), one of the typical inorganic flocculants widely used in wastewater management and waste activated sludge (WAS) dewatering, could be accumulated in WAS and inevitably entered in anaerobic digestion system at high levels. However, knowledge about its impact on methane production is virtually absent. This study therefore aims to fill this gap and provide insights into the mechanisms involved through both batch and long-term tests using either real WAS or synthetic wastewaters as the digestion substrates. Experimental results showed that the maximum methane potential and production rate of WAS was respectively retarded by 39.0% and 66.4%, whereas the lag phase was extended by 237.0% at PFS of 40 g per kg of total solids. Mechanism explorations exhibited that PFS induced the physical enmeshment and disrupted the enzyme activity involved in anaerobic digestion, resulting in an inhibitory state of the bioprocess of hydrolysis, acidogenesis, and methanogenesis. Furthermore, PFS's inhibition to hydrogenotrophic methanogenesis was much severer than that to acetotrophic methanogenesis, which could be supported by the elevated abundances of Methanosaeta sp and the dropped abundances of Methanobacterium sp in PFS-present digester, and probably due to the severe mass transfer resistance of hydrogen between the syntrophic bacteria and methanogens, as well as the higher hydrogen appetency of PFS-induced sulfate reducing bacteria. Among the derivatives of PFS, "multinucleate and multichain-hydroxyl polymers" and sulfate were unveiled to be the major contributors to the decreased methane potential, while the "multinucleate and multichain-hydroxyl polymers" were identified to be the chief buster to the slowed methane-producing rate and the extended lag time.


Assuntos
Reatores Biológicos , Esgotos , Anaerobiose , Compostos Férricos , Metano
7.
Water Res ; 189: 116624, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33242788

RESUMO

Growing evidence shows that riverine networks surrounding urban landscapes may be hotspots of riverine greenhouse gas (GHG) emissions. This study strengthens the evidence by investigating the spatial variability of diffusive GHG (N2O, CH4, CO2) emissions from river reaches that drain from different types of landscapes (i.e., urban, agricultural, mixed, and forest landscapes), in the Chaohu Lake basin of eastern China. Our results showed that almost all the rivers were oversaturated with dissolved GHGs. Urban rivers were identified as emission hotspots, with mean fluxes of 470 µmol m-2d-1 for N2O, 7 mmol m-2d-1 for CH4, and 900 mmol m-2d-1 for CO2, corresponding to ~14, seven, and two times of those from the non-urban rivers in the Chaohu Lake basin, respectively. Factors related to the high N2O and CH4 emissions in urban rivers included large nutrient supply and hypoxic environments. The factors affecting CO2 were similar in all the rivers, which were temperature-dependent with suitable environments that allowed rapid decomposition of organic matter. Overall, this study highlights that better recognition of the influence that river networks have on global warming is required-particularly when it comes to urban rivers, as urban land cover and populations will continue to expand in the future. Management measures should incorporate regional hotspots to more efficiently mitigate GHG emissions.


Assuntos
Gases de Efeito Estufa , Dióxido de Carbono/análise , China , Monitoramento Ambiental , Gases de Efeito Estufa/análise , Lagos , Metano/análise , Óxido Nitroso/análise , Rios
8.
Water Res ; 189: 116654, 2021 Feb 01.
Artigo em Inglês | MEDLINE | ID: mdl-33242789

RESUMO

The evasions of methane (CH4) and carbon dioxide (CO2) from inland waters represent substantial fluxes of greenhouse gases into the atmosphere, offsetting a large part of the continental carbon sink. However, the CH4 and CO2 emissions from urban inland waters are less constrained. In particular, ebullitive CH4 emissions from these waters are poorly understood. Here, we measured the concentrations and fluxes of CH4 and CO2 in rivers and lakes in the megacity of Beijing, China, between 2018 and 2019. The CH4 concentration ranged from 0.08 to 70.2 µmol L-1 with an average of 2.5 ± 5.9 µmol L-1. The average CH4 ebullition was 11.3 ± 30.4 mmol m-2 d-1 and was approximately 6 times higher than the global average. The average total CH4 flux (14.2 ± 35.1 mmol m-2 d-1) was 3 times higher than the global average, with ebullition accounting for 80% of the flux. The high surface water CH4 concentrations and ebullitive fluxes were caused by high sediment organic carbon/dissolved organic carbon contents, high aquatic primary productivity and shallow water depths in the urban inland waters. The CH4 emissions accounted for 20% of CO2 emissions in terms of the carbon release and were 1.7 times higher in terms of CO2 equivalent emissions from Beijing inland waters. Furthermore, the CH4 ebullition and its contribution to the total carbon gas emissions increased exponentially with the water temperature, suggesting a positive feedback probably occurs between the greenhouse gas emissions from urban inland waters and climate warming. This study confirms the major role of CH4 ebullition from urban inland waters in the global carbon budget under the rapid progress of global urbanization.


Assuntos
Gases de Efeito Estufa , Pequim , Dióxido de Carbono/análise , China , Lagos , Metano/análise
9.
Chemosphere ; 264(Pt 2): 128516, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33038733

RESUMO

Anaerobic digestion is the preferred method for treating sewage sludge because of its ability to reduce sludge volume and produce biogas. However, conventional anaerobic digestion has a long retention time and low degradation rate. In recent years, hydrothermal treatment has been used to improve the hydrolysis of sewage sludge and biogas production. This process tends to focus on maximizing biogas production. However, very little research has been done on anaerobic digestion residues. In this study, batch experiments were conducted to investigate the effect of hydrothermal temperature on methane production and the contents of liquid fraction after anaerobic digestion (centrate). Experimental conditions were designed using a response surface method and central composite model. A quadratic equation was used to interpret the individual and interactive effects of hydrothermal conditions on anaerobic digestion. Given the maximum biogas production and the minimum concentrate concentration, the optimal operating condition was determined by a 186 °C hydrothermal temperature and a reaction time of 106 min. Under these conditions, the following results could be obtained: methane production (200.5 ± 7.7 mL-CH4/gVSadded), TCOD (16,572 ± 348 mg/L), sCOD (1240 ± 65 mg/L), sTN (658.9 ± 8.0 mg/L) and ammonia (525 ± 27 mg/L).


Assuntos
Reatores Biológicos , Esgotos , Anaerobiose , Biocombustíveis , Metano
10.
Sci Total Environ ; 755(Pt 2): 142578, 2021 Feb 10.
Artigo em Inglês | MEDLINE | ID: mdl-33038809

RESUMO

The increasing trend of adopting organic fertilization in rice production can impact grain yields and soil methane (CH4) emissions. To simulate these impacts in the absence of long-term field data, a process-based biogeochemical model, Denitrification and Decomposition (DNDC version 9.5) was used. The model was calibrated against a single year greenhouse study and validated using a previously published one-year field trial from 1990, both comparing varying fertilization systems in rice production in southeast Texas, USA. In both the greenhouse and the field studies, lower grain yield and greater soil CH4 emissions were observed in organically fertilized systems. Calibrated model simulations of the greenhouse study correlated with the observed daily CH4 emissions (conventional r2 = 0.87; organic r2 = 0.91) and SOC (r2 = 0.83); but, the model overestimated yield of conventional systems (slope = 1.2) and underestimated yield of organic systems (slope = 0.68). For the field study, agreement between simulated and observed yields and CH4 emissions resulted in slopes close to 1. A simple organic system with urea and straw amendment from the field study was an input available in DNDC whereas the slow release, pelletized organic fertilizer used in the greenhouse study, Nature Safe, was not modeled well by DNDC. The validated model was used to simulate 22 years of rice production and predicted that the differences in yield and CH4 emissions between treatments would diminish with time. In the model simulations, the overall soil health was enhanced when managed with organic fertilization compared to conventional inorganic fertilizers. Model simulations could be improved further by including site-specific calibration of soil organic C, and soil carbon dioxide (CO2) emissions.


Assuntos
Metano , Oryza , Agricultura , Fertilização , Fertilizantes/análise , Óxido Nitroso/análise , Solo , Texas
11.
Chemosphere ; 264(Pt 2): 128564, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33065325

RESUMO

Recently, the production of renewable biogas such as biohydrogen and biomethane from wastewaters through anaerobic fermentation has gained worldwide attention. In the present study, a mobile bioenergy generation station had been constructed based on a high-efficiency hydrogenesis & methanogenesis technology (HyMeTek) developed by Feng Chia University, Taiwan. The substrate was a beverage wastewater having chemical oxygen demand (COD) concentration of 1200 mg/L. This bioenergy station had a feedstock tank (3.8 m3), a nutrient tank (0.8 m3), an acidogenesis tank (AT, 2 m3), two methanogenesis tanks (MT, 4 m3 for each), a membrane bioreactor and a control room. Biogas production rate, methane concentration, COD removal efficiencies, energy efficiency and economical interest of the plant were assessed. The peak total methane production rates for AT (at hydraulic retention time, HRT, 4 h) and MT (at HRT 8 h) were 430 and 7 mL/L·d, respectively. A strategy of shortening HRT was a promising method to enhance biogas quality and energy efficiency. This mobile bioenergy system has commercial potential because it could bring good economic benefit of initial rate of return (58.84%) and payback time (2.68 y).


Assuntos
Biocombustíveis , Águas Residuárias , Anaerobiose , Bebidas , Reatores Biológicos , Metano , Taiwan , Eliminação de Resíduos Líquidos
12.
Chemosphere ; 263: 128047, 2021 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-33297060

RESUMO

Anaerobic digestion is a promising waste-to-energy alternative technology. However, the efficiency upgrading for conventional mesophilic digestion of organic solid waste is always indispensable. Employing hyperthermophilic or thermophilic microbial community is one of the viable upgrading alternatives. Given the unavailability of the superior microbial communities, mesophilic digested sludge was used as inoculum, and instantly controlled at 70 °C and 55 °C for acclimation of hyperthermophilic and thermophilic inocula, respectively. Waste activated sludge was continuously and synchronously fed into two digesters. After one round, thermophilic digester achieved stable biogas production rate at 0.22 L L-1 d-1, with a methane proportion over 60%, whereas fluctuation was observed in the hyperthermophilic digester, and approximately triple time was needed to reach a relatively stable biogas production rate 0.12 L L-1 d-1. Nevertheless, higher hydrolysis ratio 24.4% was observed in the hyperthermophilic digester despite the lower biogas production. Therefore, methanogenesis step limited the whole anaerobic process for the hyperthermophilic digestion, and digestion at 70 °C was appropriate as a pre-fermentation stage to enhanced hydrolysis. The genus Methanothrix proportion in the thermophilic digester gradually decreased, while another acetoclastic genus Methanosarcina ultimately was acclimated to the dominant methanogen. In addition to Methanothrix, hydrogenotrophic archaea became competitive in the hyperthermophilic digester, with Methanothermobacter dominant at 22.6%. The genus Psychrobacter, affiliated to the phylum Proteobacteria could survive better than the others at 70 °C, with a final proportion of 62.5%.


Assuntos
Microbiota , Esgotos , Anaerobiose , Archaea , Reatores Biológicos , Metano , Temperatura
13.
Bioresour Technol ; 321: 124206, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33257165

RESUMO

This study investigated the anaerobic bioconversion efficiency of rice straw in continuously stirred tank reactor (CSTR) applying longer hydraulic retention time (HRT) and higher load. Two HRT distributions and two loads were studied and compared for one-stage and two-stage CSTR systems. The results indicated that the two system with longer HRT (60d) and higher load (160g TS·L-1) obtained 11.06% and 14.28%, 15.24% and 19.38%, more biogas and methane productions than those of one-stage system with HRT (50d) and load (140g TS·L-1), respectively, while maintained stable operation at higher loads. It was also found that the microbial richness, diversity, and bacterial and archaeal community compositions showed some differences between two systems with different HRTs and loads, which was thought to be one of reasons leading to the differences in bioconversion efficiencies. The study indicated that two-stage system applying longer HRT and higher load could be one of the effective methods for more bioenergy recovery from rice straw.


Assuntos
Reatores Biológicos , Oryza , Anaerobiose , Biocombustíveis , Metano
14.
Bioresour Technol ; 321: 124398, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33257167

RESUMO

Given the difficulties valorizing methane (CH4) via catalytic routes, this study explores use of CH4-oxidizing bacteria ("methanotrophs") for generating electricity directly from CH4. A preconditioned methanotrophic biofilm on 3D nickel foam with reduced graphene oxide (rGO/Ni) was used as the anode in two-compartment microbial fuel cells (MFCs). This study demonstrates a proof of concept for turning CH4 into electricity by two model methanotrophs including Methylosinus trichosposium OB3b and Methylococcus capsulatus (Bath). Both OB3b (205 mW.m-2) and Bath (110 mW.m-2) strains yielded a higher electricity from CH4 when grown on rGO/Ni compared to graphite felt electrodes. Based on electrochemistry tests, molecular dynamics simulations, genome annotations and interaction analysis, a mechanistic understanding of reasons behind enhanced performance of methanotrophs grown on rGO/Ni are presented.


Assuntos
Methylococcus capsulatus , Methylosinus trichosporium , Bactérias , Eletricidade , Metano , Oxigenases
15.
Bioresour Technol ; 321: 124427, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33264745

RESUMO

Anaerobic digestion of animal manure show a maximum of ca. 50% conversion of volatile solids due to recalcitrance of lignin and crystalline cellulose under anaerobic conditions. The aim of this study is to evaluate different pretreatments on anaerobic digestion of manure fibers after anaerobic digestion. Physical, chemical, thermal, and thermal combined with alkaline pretreatments using sodium hydroxide were tested on manure fiber fraction separated out after anaerobic digestion of cow manure. The anaerobic digestion after pretreatment along with untreated controls were done in semi-continuous anaerobic bioreactors. All pretreatments showed positive effect and the highest increase in VS conversion (42.4%) and methane yield (ca. 127%) was found for 3% NaOH pretreated sample at 180 °C. Composition analysis showed that cellulose, hemicellulose and lignin in digested manure fibers were optimally reduced by 24.8, 29.1 and 9.5% respectively during pretreatment and 76.5% of cellulose and 84.9% of hemicellulose was converted to methane during AD.


Assuntos
Biocombustíveis , Esterco , Anaerobiose , Animais , Lignina/metabolismo , Metano
16.
Bioresour Technol ; 321: 124437, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33271363

RESUMO

Microbial pretreatments have been identified as a compatible and sustainable process with anaerobic digestion compared to energy-intensive physicochemical pretreatments. In this study, barley straw and hay co-substrate was pretreated with a microaerobic barley straw-adapted microbial (BSAM) consortium prior to anaerobic digestion. The improved digestibility was investigated through 16S rRNA gene sequencing, microbial counts and C:N ratios. BSAM pretreatment resulted in 15.2 L kg-1 TS of methane yield after 35 days, almost 40 times more than the control. The methane content in total biogas produced were 58% (v/v) and 10% (v/v) in BSAM and control, respectively. This research demonstrated that BSAM-based pretreatment significantly increased the digestibility and surface area of the lignocellulosic material and considerably enhanced biomethanation. This study generates new potential bio-research opportunities in the emerging field of lignocellulosic anaerobic digestion-biorefineries.


Assuntos
Hordeum , Consórcios Microbianos , Anaerobiose , Biocombustíveis , Lignina , Metano , RNA Ribossômico 16S/genética
17.
Bioresour Technol ; 321: 124456, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33276207

RESUMO

Cow manure (CM) generation in large volumes has for long been considered a waste management challenge. However, the organic content of CM signals opportunities for the production of value-added bioproducts such as volatile fatty acids (VFAs) through anaerobic digestion (AD). However, a robust VFAs fermentation process requires effective methane formation inhibition and enhance VFAs recovery. In this study, thermal pretreatment was applied to inhibit methanogens for enhanced VFAs production and an immersed membrane bioreactor (iMBR) for in situ recovery of VFAs in a semi-continuous AD. Maximal VFAs yield of 0.41 g VFAs/g volatile solids (VS) was obtained from thermally-treated CM without inoculum addition. The CM was further fed to the iMBR operating at organic loading rates of 0.8-4.7 gVS/L.d. The VFAs concentration increased to 6.93 g/L by rising substrate loading to 4.7 g VS/L.d. The applied iMBR set-up was successfully used for stable long-term (114 days) VFAs production and recovery.


Assuntos
Reatores Biológicos , Esterco , Anaerobiose , Animais , Bovinos , Ácidos Graxos Voláteis , Feminino , Fermentação , Metano
18.
Bioresour Technol ; 321: 124454, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33285502

RESUMO

Hydrothermal pretreatment (HTP) conditions were optimized for continuous mesophilic (MAD) and thermophilic (TAD) anaerobic digestion of high-solid sludge (10-11% total solids). COD solubilization increased with prolonged HTP durations, and became not significant after 210 min. According to the methane production rate and energy consumption, the optimal HTP temperature was determined at 160 °C. Regarding continuous operation without HTP, TAD achieved higher methane yield and volatile solids (VS) reduction, at 0.12 L/g VSadded and 23.9%, respectively. After HTP, methane yield and VS reduction in MAD and TAD were increased by 400% and 191% (MAD), 67% and 72% (TAD), respectively. TAD was limited due to the inhibition from about 2800 mg/L of NH4+-N concentration. The methanogenic activity of MAD was enhanced, whereas TAD displayed a reduced value owing to ammonia inhibition. Ultimately, MAD with HTP and TAD without HTP achieved the higher energy balance, 5.25 and 3.27 kJ/g VS, respectively.


Assuntos
Metano , Esgotos , Amônia , Anaerobiose , Reatores Biológicos , Temperatura
19.
Bioresour Technol ; 321: 124429, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33285504

RESUMO

This study aimed to investigate the synergistic effect and microbial community changes between chicken manure (CM) and cardboard (CB) during anaerobic co-digestion. Meanwhile, the energy balance of biogas engineering was extrapolated based on the batch tests. In batch tests, co-digestion system achieved the highest improvement (14.2%) and produced 319.62 mL CH4/gVS with a 65:35 ratio of CB: CM. More extracellular polymeric substance secretion promoted the electron transfer for acidogenesis and more hydrolase was provided with 31.6% improvement. The microbial analysis illustrated that higher acetoclastic Methanosaeta abundance was achieved, leading to 211% enhancement of acetoclastic pathway. Moreover, associated network illustrated that the higher methane production was mainly achieved through matching of hydrolytic bacteria and acidogenesis bacteria. As for energy balance, the synergistic effect increased the energy output by 38% and energy recovery to 46.4%.


Assuntos
Esterco , Microbiota , Anaerobiose , Animais , Biocombustíveis , Reatores Biológicos , Galinhas , Digestão , Matriz Extracelular de Substâncias Poliméricas , Metano
20.
Bioresour Technol ; 321: 124444, 2021 Feb.
Artigo em Inglês | MEDLINE | ID: mdl-33285505

RESUMO

Biomethanation of CO2 has been proven to be a feasible way to produce methane with the employment of H2 as electron source. Subject of the present study is a custom-made membrane biofilm reactor for hydrogenotrophic methanation by archaeal biofilms cultivated on membrane surfaces. Reactor layout was adapted to allow for in situ biofilm analysis via optical coherence tomography. At a feeding ratio of H2/CO2 of 3.6, and despite the low membrane surface to reactor volume ratio of 57.9 m2 m-3, the maximum methane production per reactor volume reached up to 1.17 Nm3 m-3 d-1 at a methane content of the produced gas above 97% (v/v). These results demonstrate that the concept of membrane bound biofilms enables improved mass transfer by delivering substrate gases directly to the biofilm, thus, rendering the bottleneck of low solubility of hydrogen in water less drastic.


Assuntos
Reatores Biológicos , Metano , Biofilmes , Hidrogênio
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