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1.
Sci Total Environ ; 804: 150143, 2022 Jan 15.
Artigo em Inglês | MEDLINE | ID: mdl-34798727

RESUMO

Sulfide partial denitrification (SPD) is an alternative pathway for nitrite production accompanied with elemental sulfur (S0) production for nitrate removal from wastewater with anammox. In this study, the SPD granular sludge was cultivated for the first time in an upflow anaerobic sludge bed (UASB) reactor to reach the efficacy of maximum nitrate-to-nitrite transformation ratio of 92% and an in-situ maximum NO3--N reduction rate of 2.46 kg-N/m3-d, both much higher than literature results. Mature granules had an average particle size of 2.52 mm and hold smooth surface with excess rod bacteria. The elements Ca and S, and proteins in extracellular polymeric substances contributed to granule structure's stability. Enriched Thiobacillus genus was proposed to accumulate nitrite at moderate HRT (2-6 h). The immobilized functional strains assist efficient partial nitrification reactions to be realized with formed S0 as byproduct.


Assuntos
Nitritos , Águas Residuárias , Reatores Biológicos , Desnitrificação , Nitratos , Nitritos/análise , Nitrogênio , Oxirredução , Esgotos , Sulfetos , Águas Residuárias/análise
2.
Bioresour Technol ; 343: 125896, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34649059

RESUMO

This study for the first time bioreduced Te(IV) using elemental sulfur (S0) as electron donor, achieving 91.17%±0.8% conversion with reaction rate of 0.77 ± 0.01 mg/L/h in a 60-day cultivation. Characterization using X-ray photoelectron spectroscopy and X-ray power diffraction analyses confirmed that most removed Te(IV) was reduced to elemental Te(0) deposits, while ion chromatogram analysis showed that most S(0) was oxidized to sulfite and sulfate. High-throughput 16S rRNA gene sequencing indicated that the Te(IV) reduction coupled to S(0) oxidation was mediated synergistically by a microbial consortia with S(0)-oxidizing bacteria (Thiobacillus) to generate volatile fatty acids as metabolites and Te(IV)-reducing bacteria (Rhodobacter) to consume formed volatile fatty acids to yield Te(0). The synergy between these two strains presents a novel bioremediation consortium to efficiently treat Te(IV) wastewaters.


Assuntos
Elétrons , Enxofre , Oxirredução , RNA Ribossômico 16S/genética , Sulfatos
3.
Bioresour Technol ; 343: 125913, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34649060

RESUMO

Biofilm wastewater treatment had been applied in practice. Conventionally the biofilm was modeled as a uniform structure to simplify the analysis. This study for the first time established a three-dimensional biofilm model with distributions separating living cells, Extracellular polymeric substances (EPS) and pores, based on which the local fluid flow velocity and pollutant diffusion and reaction fluxes inside the biofilm were numerically evaluated. Both the uniform structured and previously proposed heterogeneous models had been confirmed to overestimate the performances of a biofilm for wastewater treatment. The survival strategies of living cells in biofilm were discussed. Besides exposing to fresh pollutants for maximizing pollutant uptake, the tendency to form small aggregates of cells for shortening diffusion length so furnishing the pollutant with reduced diffusional resistance to living cells was also for the first time noted. This communication advanced the knowledge to comprehend the detailed processes in biofilm.


Assuntos
Poluentes Ambientais , Biofilmes , Reatores Biológicos , Difusão , Matriz Extracelular de Substâncias Poliméricas
4.
Bioresour Technol ; 343: 126123, 2022 Jan.
Artigo em Inglês | MEDLINE | ID: mdl-34653621

RESUMO

As a clean and renewable energy, bioenergy is one of the most promising alternatives to fossil fuels. Lignocellulose possesses great potential for bioenergy production, but the recalcitrant and heterogeneous structure limits its application. Pretreatment technology offers an effective solution to fractionate the main components of the lignocellulose and uncover the available cellulose. The obtained feedstock can be applied to bioconversion into energy, e.g., bioethanol, biogas, biohydrogen, etc. Here, the current state of lignocellulose pretreatment technologies was comprehensively reviewed, the advances in bioenergy production from pretreated lignocellulose was described, with particular attention to key challenges involved. Several new strategies for overcoming pretreatment barriers to realize highly efficient lignocellulose bioconversion were highlighted. The insights given in this review will facilitate further development on lignocellulosic bioenergy production, towards addressing the global energy crisis and climate change related to the use of fossil fuels.


Assuntos
Biocombustíveis , Lignina , Biomassa , Celulose
5.
Bioresour Technol ; : 126439, 2021 Nov 27.
Artigo em Inglês | MEDLINE | ID: mdl-34848332

RESUMO

In order to sustainably manage wastewater treatment plants and the environment, enhanced biological phosphorus (P) removal (EBPR) was proposed to achieve P recovery through extracting P-rich liquid (i.e., Phostrip) from the bottom of aerobic granular sludge (AGS)-based sequencing batch reactors (SBRs) under no mixing during the anaerobic phase. Results showed both tested bacterial AGS (BAGS) and algal-bacterial AGS (A-BAGS) systems stably produced low effluent P (< 0.05 mg-P/L) with little impact on their organics and NH4+-N removals (> 99%). The collected P-rich liquids (55-83 mg-P/L) from both systems showed great potential for P recovery of about 83.85 ± 0.57 % (BAGS) or 83.99 ± 0.77% (A-BAGS), which were contributed by the influent P (> 95%) and P reserves in granules based on P balance analysis. This study suggests that the AGS-based SBRs coupling the Phostrip holds great potentials for P recovery profit and further reduction in energy consumption.

6.
Bioresour Technol ; : 126321, 2021 Nov 14.
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.

7.
Bioresour Technol ; 344(Pt B): 126263, 2021 Oct 30.
Artigo em Inglês | MEDLINE | ID: mdl-34728359

RESUMO

This review overviewed the current researches on the isolation of novel strains, the development of novel identification protocols, the key enzymes and their synergistic interactions with other functional enzyme systems, and the strategies for enhancing enzymolysis efficiencies. The main obstacle for realizing biorefinery of lignocellulosic biomass to biofuels or biochemicals is the high cost of enzymolysis stage. Therefore, research prospects to reduce the costs for lignocellulose hydrolysis were outlined.

8.
Bioresour Technol ; : 126412, 2021 Nov 24.
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-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.

9.
Bioresour Technol ; : 126411, 2021 Nov 24.
Artigo em Inglês | MEDLINE | ID: mdl-34838630

RESUMO

Wastewater treatment plants are expected to realize not only pollutants removal from wastewater but also resources recovery such as phosphorus (P) and alginate-like exopolysaccharides (ALE) from the produced sludge. In this study, ALE extraction and fractionation from the same activated sludge-derived bacterial aerobic granular sludge (AGS) and algal-bacterial AGS were performed in addition to P fate examination during ALE recovery. Results showed that the ALE content recovered from algal-bacterial AGS was 8.81 ±â€¯0.02 mg/g-volatile suspended solids (VSS), about 2.8 times higher than that from bacterial AGS when fed with the same synthetic wastewater. Moreover, the mannuronic acid to guluronic acid (MG) blocks accounted for the largest proportion of ALE from the two granular sludges. In particular, the extracellular polymeric substances (EPS) extracted from bacterial and algal-bacterial AGS contained about 25.10 ±â€¯1.85 and 19.53 ±â€¯0.04 mg-P/g-SS, respectively, and both granular sludges possessed high P bioavailability of 97-99%.

10.
Bioresour Technol ; : 126419, 2021 Nov 25.
Artigo em Inglês | MEDLINE | ID: mdl-34838966

RESUMO

Aromatic compounds are important fuels and key chemical precursors for organic synthesis, however the current aromatics market are mainly relying on fossil resources which will eventually contribute to carbon emissions. Lignin has been recognized as a drop-in substitution to conventional aromatics, with its values gradually realized after tremendous research efforts in the recent five years. To facilitate the development of a possible lignin economics, this study overviewed the recent advances of various biorefinery techniques and the remaining challenging for lignin valorization. Starting with recent discovery of unexplored lignin structures, the potential functions of lignin related chemical structures were emphasized. The important breakthrough of lignin-first pretreatment, catalytic lignin depolymerization, and the high value products with possible benchmark with modern aromatics were reviewed with possible future targets. Possible retrofit of conventional petroleum refinery for lignin products were also introduced and hopefully paving a way to progressively migrate the industry towards carbon neutrality.

11.
Bioresour Technol ; 342: 126021, 2021 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-34600315

RESUMO

Microbial fermentation of organic matter under anaerobic conditions is currently the prominent pathway for biohydrogen production. Organic matter present in waste residues is regarded as an economic feedstock for biohydrogen production by dark and photo fermentative bacteria. Agricultural residues, fruit wastes, vegetable wastes, industrial wastewaters, and other livestock residues are some of the organic wastes most commonly used for biohydrogen production due to their higher organic content and biodegradability. Appropriate pretreatments are required to enhance the performance of biohydrogen from complex organic wastes. Biohydrogen production could also be enhanced by optimizing operation conditions and the addition of essential nutrients and nanoparticles. This review describes the pathways of biohydrogen production, discusses the effect of organic waste sources used and microbes involved on biohydrogen production, along with addressing the key parameters, advantages, and difficulties in each biohydrogen production pathway.

12.
Bioresour Technol ; 344(Pt A): 126166, 2021 Oct 19.
Artigo em Inglês | MEDLINE | ID: mdl-34678452

RESUMO

Lactic acid (LA) is an essential commodity chemical, with bio-based LA ruling the market share. Macroalgae are a desirable feedstock for LA fermentation due to their high carbohydrate and low lignin content. Ulva sp., Gracilaria sp., and Sargassum cristaefolium were evaluated as a feedstock for LA fermentation. Mild acid-thermal hydrolysis (sulfuric acid concentrations < 5%) resulted in superior reducing sugar recovery. Gracilaria sp. attained maximum reducing sugar recovery (0.39 g/g biomass) and lactate yield (0.94 g/g). LA fermentation of fucose-rich hydrolysate of Sargassum cristaefolium is demonstrated for the first time, with 0.81 g/g LA yield and 0.36 g/g reducing sugars. Ulva sp. attained 0.21 g/g reducing sugars and 0.85 g/g LA yield. The efficiency of macroalgae for lactate bioconversion was in the order: red macroalgae > green macroalgae > brown macroalgae. L. rhamnosus and L. plantarum could efficaciously utilize seaweed sugars for LA production. Macroalgae can potentially replace lignocellulosic biomass as a feedstock in LA fermentation.

13.
Bioresour Technol ; 344(Pt A): 126217, 2021 Oct 26.
Artigo em Inglês | MEDLINE | ID: mdl-34715334

RESUMO

The production of hydrogen-rich syngas from municipal solid waste (MSW) by pyrolysis/gasification is one of the most promising waste-to-energy pathways for realizing a circular bioeconomy. This mini-review provides an overview of current research and development efforts in the field, focusing on the development of syngas upgrades and novel gasification processes, with the ultimate goal of making MSW gasification a sustainable and affordable route for the final disposal of MSW. A graphical assessment protocol is proposed to support comprehension of the main reactions that are involved in the MSW gasification. MSW gasification studies are reviewed with the prospects considered to provide a reference for future work.

14.
Langmuir ; 37(38): 11233-11241, 2021 Sep 28.
Artigo em Inglês | MEDLINE | ID: mdl-34528810

RESUMO

The rebound behaviors of multiple droplets simultaneously impacting a superhydrophobic surface were investigated via lattice Boltzmann method (LBM) simulations. Three rebound regions were identified, i.e., an edge-dominating region, a center-dominating region, and an independent rebound region. The occurrence of the rebound regions strongly depends on the droplet spacing and the associated Weber and Reynolds numbers. Three new rebound morphologies, i.e., a pin-shaped morphology, a downward comb-shaped morphology, and an upward comb-shaped morphology, were presented. Intriguingly, in the edge-dominating region, the central droplets experience a secondary wetting process to significantly prolong the contact time. However, in the center-dominating region, the contact time is dramatically shortened because of the strong interactions generated by the central droplets and the central ridges. These findings provide useful information for practical applications such as self-cleaning, anticorrosion, anti-icing, and so forth.

15.
Biomacromolecules ; 22(10): 4446-4457, 2021 10 11.
Artigo em Inglês | MEDLINE | ID: mdl-34506111

RESUMO

This study provides a significant contribution to the development of multiple hydrogen-bonded supramolecular nanocarrier systems by demonstrating that controlling the hydrogen bond strength within supramolecular polymers represents a crucial factor to tailor the drug delivery performance and enhance the effectiveness of cancer therapy. Herein, we successfully developed two kinds of poly(ethylene glycol)-based telechelic polymers Cy-PEG and UrCy-PEG having self-constituted double and quadruple hydrogen-bonding cytosine (Cy) and ureido-cytosine (UrCy) end-capped groups, respectively, which directly assemble into spherical nanogels with a number of interesting physical characteristics in aqueous solutions. The UrCy-PEG nanogels containing quadruple hydrogen-bonded UrCy dimers exhibited excellent long-term structural stability in a serum-containing biological medium, whereas the double hydrogen-bonded Cy moieties could not maintain the structural integrity of the Cy-PEG nanogels. More importantly, after the drug encapsulation process, a series of in vitro experiments clearly confirmed that drug-loaded UrCy-PEG nanogels induced selective apoptotic cell death in cancer cells without causing significant cytotoxicity to healthy cells, while drug-loaded Cy-PEG nanogels exerted nonselective cytotoxicity toward both cancer and normal cells, indicating that increasing the strength of hydrogen bonds in nanogels plays a key role in enhancing the selective cellular uptake and cytotoxicity of drugs and the subsequent induction of apoptosis in cancer cells.


Assuntos
Hidrogênio , Neoplasias , Portadores de Fármacos/uso terapêutico , Humanos , Hidrogênio/uso terapêutico , Ligação de Hidrogênio , Micelas , Nanogéis , Neoplasias/tratamento farmacológico , Polietilenoglicóis/uso terapêutico
16.
Bioresour Technol ; 339: 125587, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34303094

RESUMO

Biomass recalcitrance hinders efficient utilization of lignocellulosic biomass, making pretreatment process a crucial step for successful biorefinery process. Pretreatment processes have been developed for processing biomass, while technical obstacles including intensive energy requirement, high operational cost, equipment corrosions resulted from currently applied techniques promote the development of new pretreatment process for biomass. The deep eutectic solvent (DES) has been recognized as a promising solvent for biomass pretreatment, although the DES application toward biomass is still in its nascent stage. This review summarized the current researches using DES for biomass pretreatment, focusing particularly on lignin extraction and saccharification enhancement of lignocellulosic biomass. The mechanisms for biomass fractionation using DES as agents are introduced. Prospect and challenge were outlined.


Assuntos
Fracionamento Químico , Lignina , Biomassa , Hidrólise , Solventes
17.
Bioresour Technol ; 338: 125509, 2021 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-34271500

RESUMO

Safe disposal of effluent from palm oil production poses an environmental concern. The highly polluting effluent is customarily treated by unsustainable open ponds with low efficiency, direct emissions, and massive land use. This study looks into an application of integrated anaerobic/oxic/oxic scheme for treatment of high strength palm oil mill effluent. The anaerobic reactors functioned as a prime degrader that removed up to 97.5% of the chemical oxygen demand (COD), while the aerobic reactors played a role of an effluent polisher that further reduced the COD. Their complementing roles resulted in a remarkable removal of 99.7%. Assessment of emission mitigation and biogas energy revealed that yearly energy of 53.2 TJ, emissions reduction of 239,237 tCO2 and revenue of USD 1.40 millions can be generated out of electricity generation and heating. The integrated scheme provides a viable and sustainable treatment of the high strength palm oil mill effluent.


Assuntos
Reatores Biológicos , Óleos Vegetais , Anaerobiose , Análise da Demanda Biológica de Oxigênio , Resíduos Industriais/análise , Óleo de Palmeira , Eliminação de Resíduos Líquidos
18.
Chemosphere ; 282: 131059, 2021 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-34111637

RESUMO

The Z-scheme heterojunction is a photocatalyst with narrow band gap and sufficiently high oxidization and reduction powers for degradation of pollutants in waters. This review firstly summarizes the fundamentals of photocatalysis, and explains the need to develop Z-scheme heterojunctions to harvest energy from sunlight effectively. Secondly, contemporary reports of degradation wastewater pollutants, including organic dyes, antibiotics, and other chemicals are reviewed and discussed. A challenge in the selection of an appropriate Z-scheme for removing a specific pollutant is the lack of available energy levels that are offered by the catalyst and the lack of redox energy levels that are required to break down essential chemical bonds of the pollutants. With reference to the redox energy levels offered by the active photocatalytic species, the redox energy levels of specific pollutants studied in literature are estimated. Challenges and prospects concerning the use of the Z-scheme to degrade recalcitrant pollutants under irradiation by sunlight are outlined at the end of this review.


Assuntos
Poluentes Ambientais , Catálise , Corantes , Águas Residuárias , Água
19.
Artigo em Inglês | MEDLINE | ID: mdl-34145543

RESUMO

The metal hexacyanoferrates with transition metal ions to replace ferric ions in the face center cubic structure of Prussian blue (PB) crystals are candidate adsorbents for radioactive cesium ions in waters. This study for the first time synthesized the shape stable poly(vinyl alcohol) (PVA) hydrogels with immobilized metal hexacynoferrate (PB analogue) that can be stored at dry and can efficiently adsorb cesium ions from waters after rewetting. A total of eight PB analogue particles in two families M3[Fe(III)(CN)6]2 (MFe(III)) or M4[Fe(II)(CN)6]2 (MFe(II)) with M=Zn, Ni, Cu, or Co were synthesized and were immobilized in the PVA hydrogels following boric acid and sulfate crosslinking. The produced PVA-PB analogue hydrogels are all stable in shape after dry and rewet, and the rewet hydrogels can adsorb cesium ions from waters at much higher rates. As predicted by the diffusion-reaction model, the apparent reaction constants for cesium ion adsorption are 4.2×10-4 1/s, 3.4×10-4 1/s, 3.9×10-4 1/s, 4.1×10-4 1/s, 4.1×10-4 1/s, 3.8×10-4 1/s, 1.1×10-3 1/s, and 9.6×10-4 1/s, for ZnFe(III), ZnFe(II), NiFe(III), NiFe(II), CuFe(III), CuFe(II), CoFe(III), and CoFe(II), respectively. The corresponding maximum adsorption capacities based on Langmuir isotherm model at 25 °C are 232.6 mg/g, 389.0 mg/g, 193.9 mg/g, 256.8 mg/g, 388.2 mg/g, 395.1 mg/g, 297.3 mg/g, and 391.2 mg/g, respectively. The use of PVA-CoFe(III) is the candidate for enhanced Cs removal from waters comparing the use of other PB analogues as adsorbent.

20.
Water Res ; 201: 117325, 2021 Aug 01.
Artigo em Inglês | MEDLINE | ID: mdl-34144484

RESUMO

Anaerobic digestion (AD) is a promising technology capable of converting waste matter into bio-energy. Recent studies have reported that microbial electrolysis cell assisted anaerobic digestion (MEC-AD) is an effective system for methane production from organic waste, via enhanced electron transfer. However, little is known about the effects of applied voltage on the AD of proteins. Herein, the mechanism of MEC-AD on protein digestion was investigated using varying concentrations of bovine serum albumin (BSA) as the protein substrate (500 mg/L, 4 g/L, and 20 g/L BSA). Experimental results showed that the applied voltage can not only enhance the methane production rate from 23.8% to 45.6% at low and medium organic loading (BSA concentration of 500 mg/L and 4 g/L), but also improve the methanogenesis efficiency increased by 225.4% at high BSA concentration (20 g/L) with the applied voltage of 0.6 V compared to that with open circuit. Mechanism explorations revealed that the applied voltage significantly enhanced the acidogenesis and methanogenesis processes in the AD of proteins. Microbial community characterization showed that with the applied voltage, the abundance of fermentative bacteria increased by 46.7 % at the anode, while, the abundance of Methanobacterium at the cathode increased from 10.4 to 84.3%, indicating the methanogenesis pathway transformed from acetoclastic to hydrogenotrophic. External circuit electron transfer calculations demonstrated that only 10% of the produced methane could be attributed to direct interspecies electron transfer (DIET). From a thermodynamic perspective, the applied external voltage led to a reduction in the cathodic potential to -0.9 V, which is beneficial for enhanced methane production via mediated interspecies electron transfer (MIET) by enrichment of hydrogenotrophic methanogens. The findings reported here reveal the previously unrecognized contribution of proteins to MEC-AD, while also furthering our understanding of the role of applied voltage in the MEC-AD process.


Assuntos
Eletrólise , Metano , Anaerobiose , Reatores Biológicos , Eletrodos , Transporte de Elétrons
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