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1.
Nat Commun ; 11(1): 3803, 2020 07 30.
Artigo em Inglês | MEDLINE | ID: mdl-32732991

RESUMO

Microbial communities comprised of phototrophs and heterotrophs hold great promise for sustainable biotechnology. Successful application of these communities relies on the selection of appropriate partners. Here we construct four community metabolic models to guide strain selection, pairing phototrophic, sucrose-secreting Synechococcus elongatus with heterotrophic Escherichia coli K-12, Escherichia coli W, Yarrowia lipolytica, or Bacillus subtilis. Model simulations reveae metabolic exchanges that sustain the heterotrophs in minimal media devoid of any organic carbon source, pointing to S. elongatus-E. coli K-12 as the most active community. Experimental validation of flux predictions for this pair confirms metabolic interactions and potential production capabilities. Synthetic communities bypass member-specific metabolic bottlenecks (e.g. histidine- and transport-related reactions) and compensate for lethal genetic traits, achieving up to 27% recovery from lethal knockouts. The study provides a robust modelling framework for the rational design of synthetic communities with optimized growth sustainability using phototrophic partners.


Assuntos
Bacillus subtilis/metabolismo , Escherichia coli/metabolismo , Processos Heterotróficos/fisiologia , Processos Fototróficos/fisiologia , Synechococcus/metabolismo , Yarrowia/metabolismo , Aldeídos/metabolismo , Bacillus subtilis/genética , Reatores Biológicos/microbiologia , Escherichia coli/genética , Etanol/metabolismo , Formaldeído/metabolismo , Metanol/metabolismo , Microbiota/fisiologia , Modelos Biológicos , Ácido Succínico/metabolismo , Synechococcus/genética , Yarrowia/genética
2.
Chemosphere ; 260: 127581, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758787

RESUMO

Forward osmosis membrane bioreactor (FOMBR) is an integrated physical-biological treatment process that has received increased awareness in treating municipal wastewater for its potential to produce high effluent quality coupled with its low propensity for fouling formation. However, reverse salt diffusion (RSD) is a major issue and so far limited studies have reported long-term FOMBR operation under the elevated salinity conditions induced by RSD. This study investigated the performance of a FOMBR in treating municipal wastewater under a controlled saline environment (6-8 g L-1 NaCl) using two separate sodium chloride draw solution (NaCl DS) concentrations (35 and 70 g L-1) over 243 days. At 35 g L-1 NaCl DS, the water flux performance dropped from 6.75 L m-2 h-1 (LMH) to 2.07 LMH after 72 days of operation in the first experimental stage, when no cleaning procedure was implemented. In the subsequent stage, the DS concentration was increased to 70 g L-1 and a weekly physical cleaning regime introduced. Under stable operation, the water flux performance recovery was 67% after 21 cycles of physical cleaning. For the first time in FOMBR studies, a shortcut nitrogen removal via the nitrite pathway was also achieved under the elevated salinity conditions. At the end of operation (day 243), the ammonia-oxidising bacteria (Nitrosomonas sp.) was the only nitrifier species in the system and no nitrite oxidising bacteria was detected. The above study proves that a FOMBR system is a feasible process for treating municipal wastewater.


Assuntos
Membranas Artificiais , Nitrogênio/metabolismo , Eliminação de Resíduos Líquidos/instrumentação , Eliminação de Resíduos Líquidos/métodos , Aerobiose , Reatores Biológicos/microbiologia , Desnitrificação , Desenho de Equipamento , Nitrificação , Nitritos/metabolismo , Nitrosomonas/metabolismo , Osmose , Salinidade , Águas Residuárias/química
3.
Chemosphere ; 260: 127600, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32758769

RESUMO

Granules initiation and development is the backbone of aerobic granular sludge technology. Feed composition can notably affect initiation and development of aerobic granules, and yield aerobic granules with distinct microbial community, morphology and structure. This paper reports an unexpected formation of aerobic granules in an aspartic acid fed SBR under unfavorable hydrodynamic selection conditions. Detailed characteristics of these aerobic granules were investigated in terms of morphology, structure, bioactivity and EPS. The results showed that due to the absence of favorable hydrodynamic selection pressure, the formed aerobic granules had an irregular shape with a rough outline and loose internal structure, which was quite different from mature aerobic granules. Bacteria in these aerobic granules were mainly presented in the form of microcolony with calcium and ß-polysaccharides responsible for its mechanical stability. The high N/C ratio of aspartic acid enabled the enrichment of significant amount of nitrifiers within aerobic granules and thus resulted in high nitrification activity of these aerobic granules. The negatively charged and hydrophilic aspartic acid also induced the bacteria to secrete more exopolysaccharides for contributing to more neutral and hydrophilic surface of the aerobic granules, which was beneficial for aspartic acid capture. As a result, polysaccharides, rather than proteins, became the major components of EPS in these aerobic granules. This paper provides us a foundation to better understand the granulation potential of proteinaceous substrates that is frequently encountered in industrial wastewaters.


Assuntos
Ácido Aspártico/química , Reatores Biológicos/microbiologia , Esgotos/microbiologia , Purificação da Água/métodos , Aerobiose , Análise da Demanda Biológica de Oxigênio , China , Matriz Extracelular de Substâncias Poliméricas/química , Hidrodinâmica , Microbiota , Modelos Teóricos , Nitrificação , Proteobactérias/isolamento & purificação , Esgotos/química , Propriedades de Superfície , Águas Residuárias/química
4.
PLoS One ; 15(8): e0238386, 2020.
Artigo em Inglês | MEDLINE | ID: mdl-32853235

RESUMO

Moving Bed Biofilm Reactors (MBBRs) can efficiently treat wastewater by incorporating suspended biocarriers that provide attachment surfaces for active microorganisms. The performance of MBBRs for wastewater treatment is, among other factors, contingent upon the characteristics of the surface area of the biocarriers. Thus, novel biocarrier topology designs can potentially increase MBBR performance in a significant manner. The goal of this work is to assess the performance of 3-D-printed biofilter media biocarriers with varying surface area designs for use in nitrifying MBBRs for wastewater treatment. Mathematical models, rendering, and 3D printing were used to design and fabricate gyroid-shaped biocarriers with a high degree of complexity at three different levels of specific surface area (SSA), generally providing greater specific surface areas than currently available commercial designs. The biocarriers were inoculated with a nitrifying bacteria community, and tested in a series of batch reactors for ammonia conversion to nitrate, in three different experimental configurations: constant fill ratio, constant total surface area, and constant biocarrier media count. Results showed that large and medium SSA gyroid biocarriers delivered the best ammonia conversion performance of all designs, and significantly better than that of a standard commercial design. The percentage of ammonia nitrogen conversion at 8 hours for the best performing biocarrier design was: 99.33% (large SSA gyroid, constant fill ratio), 94.74% (medium SSA gyroid, constant total surface area), and 92.73% (large SSA gyroid, constant biocarrier media count). Additionally, it is shown that the ammonia conversion performance was correlated to the specific surface area of the biocarrier, with the greatest rates of ammonia conversion (99.33%) and nitrate production (2.7 mg/L) for manufactured gyroid biocarriers with a specific surface area greater than 1980.5 m2/m3. The results suggest that the performance of commercial MBBRs for wastewater treatment can be greatly improved by manipulation of media design through topology optimization.


Assuntos
Biofilmes/crescimento & desenvolvimento , Reatores Biológicos/microbiologia , Águas Residuárias/análise , Águas Residuárias/microbiologia , Amônia/química , Bactérias/crescimento & desenvolvimento , Meios de Comunicação de Massa , Nitratos/química , Nitrificação/fisiologia , Nitrogênio/química , Impressão Tridimensional , Eliminação de Resíduos Líquidos/métodos
5.
Chemosphere ; 259: 127474, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32603962

RESUMO

Anaerobic digestion (AD) is the biological preferred treatment applied to Slaughterhouse wastewaters (SWW) due to its effectiveness. The aim of the study is to investigate the effect of different percentages of fats, oil and grease (FOG) on biomethane production in anaerobic co-digestion with slaughterhouse wastewater using BMP tests under mesophilic conditions (35 °C). For this purpose, three percentages of FOG from 1% to 10% were tested. Biodegradability, biomethane production and the microbial population were studied. In addition, settling capacity has been evaluated at different conditions: i) before and after anaerobic co-digestion; ii) at different temperature 25 °C and 35 °C. The settling rates as well as the characterization of the digestate were recorded. Experimental results showed that all the co-digestion mixtures (FOG percentages = 1-10%) enhanced biomethane production and biodegradability compared to AD of sole SWW. The best conditions were achieved at 5-10% of FOG, showing biodegradability of 66-70% CODtremoval and specific biomethane productions of 562 and 777 mLCH4·g-1CODsremoved, respectively. Regarding microbial dynamics, Eubacteria was reduced with the increase in %FOG but Acetate utilizing methanogens was increased. Regarding settling capacity, mesophilic temperatures (35 °C) increased the settling rate of digestate in 1.76 times and reduced the lag-phase to 0.92 min; obtaining a more concentrated sludge and leaving a clarified whose TSS represent only 8% of TS.


Assuntos
Matadouros , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias , Anaerobiose , Bactérias , Biodegradação Ambiental , Reatores Biológicos/microbiologia , Gorduras , Hidrocarbonetos , Metano , Esgotos/química
6.
Chemosphere ; 260: 127514, 2020 Dec.
Artigo em Inglês | MEDLINE | ID: mdl-32688309

RESUMO

The main aim of this study was to evaluate the performance of an air membrane bioreactor (aMBR) for the treatment of gas-phase methanol. A laboratory-scale hollow fiber aMBR was operated for 150 days, at inlet methanol concentrations varying between 2 and 30 g m-3 and at empty bed residence times (EBRT) of 30, 10 and 5 s. Under steady-state conditions, a maximum methanol removal efficiency (RE) of 98% was obtained at an EBRT of 30 s and a decrease in RE of methanol was observed at lower EBRTs. On increasing the inlet loading rate, some portion of gas-phase MeOH was stripped into the liquid phase due to its solubility in water. Under transient conditions, the MeOH removal efficiency dropped from an average value of 95%-90% after 5 h of 10-fold shock load and dropped from an average value of 95%-88% under 5-fold increase in shock load. During transient-state tests, the aMBR performed well under different upset loading conditions and a drop in RE of ∼ 5-10% was observed. However, the aMBR performance was restored within 1-2 days when pre-shock conditions were restored. The results from microbial structure analysis revealed a big shift of the dominant methanol degrader, from Candida boidinii strain TBRC 217 to Xanthobacter sp. and Fusicolla sp., respectively.


Assuntos
Poluentes Atmosféricos/análise , Reatores Biológicos/microbiologia , Membranas Artificiais , Metanol/análise , Biodegradação Ambiental , Biofilmes/crescimento & desenvolvimento , Candida/crescimento & desenvolvimento , Desenho de Equipamento , Filtração/métodos , Xanthobacter/crescimento & desenvolvimento
7.
Chemosphere ; 258: 127271, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535444

RESUMO

Water and soil contamination by industrial wastes is a global concern. Biological treatment of industrial wastewater using bioreactors allows the removal of organic matter and nutrients and enables either reuse or safe discharge. Wastewater bioremediation depends in part on the microbial communities present in the bioreactor. To ascertain which communities may play a role in the remediation process, the present study investigates the microbial community structure and diversity of microorganisms found in a full-scale membrane bioreactor (MBR) for industrial wastewater treatment. The study was carried out using high-throughput data observations following a failure (crash) of the MBR and during the extended recovery of the process. Results revealed a positive correlation between the MBR's ability to remove organic matter and its microbial community richness. The significant changes in relative microbial abundance between crash and recovery periods of the MBR revealed the important role of specific bacterial genera in wastewater treatment processes. A whole-genome metagenomics based comparison showed a clear difference in microbial makeup between two functional periods of MBR activity. The crash period was characterized by abundance in bacteria belonging to Achromobacter, Acinetobacter, Halomonas, Pseudomonas and an uncultured MBAE14. The recovery period on the other hand was characterized by Aquamicrobium and by Wenzhouxiangella marina. Our study also revealed some interesting functional pathways characterizing the microbial communities from the two periods of bioreactor function, such as Nitrate and Sulfate reduction pathways. These differences indicate the connection between the bacterial diversity of the MBR and its efficiency to remove TOC.


Assuntos
Reatores Biológicos/microbiologia , Microbiota/efeitos dos fármacos , Águas Residuárias , Purificação da Água/métodos , Biodegradação Ambiental , Gammaproteobacteria/efeitos dos fármacos , Gammaproteobacteria/genética , Resíduos Industriais/análise , Membranas Artificiais , Metagenômica , Microbiota/genética , Esgotos/microbiologia , Águas Residuárias/química , Águas Residuárias/microbiologia
8.
Chemosphere ; 257: 127269, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32531490

RESUMO

Various sole and mixed electron donors were tested to promote the denitrification rate and nitrate removal efficiency in biofilter systems with high phosphate and ammonia removal efficiency (92.6% and 95.3% respectively). Compared to sole electron donors, complex organic carbon (bits of wood and straw) substantially improved the denitrification rate and nitrate removal efficiency (from 6.3%-18.5% to35.4%) by shifting the denitrifying microbial community composition, even though the relative abundance of functional genes mediating denitrification decreased. The mixed electron donor combining complex organic carbon with sulfur, iron and CH4 further promoted nitrate removal efficiency by 37.2%. The significantly higher abundance and diversity of bacteria mediating organic carbon decomposition in the treatments with complex organic carbon indicated the continuous production of organic carbon with small molecular weights, which provided sustainable and effective electron donor for denitrification. However, sole sulfur or iron did not effectively promote the denitrification rate and nitrogen removal efficiency, even though the related microbial community had been formed.


Assuntos
Reatores Biológicos/microbiologia , Desnitrificação/fisiologia , Microbiota , Bactérias , Carbono , Elétrons , Metagenoma , Nitratos , Nitrogênio , Óxidos de Nitrogênio , Enxofre
9.
Chemosphere ; 257: 127272, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32534299

RESUMO

A hybrid biofilter was established on Fe-C supported carriers aimed to enhance nitrogen removal from polluted water of low Carbon/Nitrogen (C/N) ratio. Effects of organic loadings, hydraulic retention time (HRT), additional electron donor (Fe2+) supplementation and operation mode on the performance of the biofilter were investigated. Results showed that up-flow operation mode was better than down-flow mode in terms of nitrate and total nitrogen (TN) removal at low COD/N. The average removal of NO3--N, NH4+ -N and TN attained 83.1%, 84.7% and 81.2%, respectively, under the conditions of influent COD/NO3--N = 1.5-3.6, HRT = 10 h and up-flow operation. When the biofilter was operated under autotrophic conditions without organic compounds in influent as electron donors, the biofilter achieved a NO3--N removal of 46% and TN removal of 56% depending on the innate electron donors provided by the Fe-C carriers. Supplementation of Fe2+ in influent further promoted autotrophic denitrifying process, and the removal of NO3--N and TN increased to 96.3% and 84.7%, respectively, at the mol ratio of Fe2+/NO3- = 10 and HRT = 10 h. The microbial community was analyzed for the biofilm samples enriched under heterotrophic and autotrophic conditions. The Fe-C biofilter boosted the growth of a large population of mixotrophic denitrifying bacteria including Gallionella, heterotrophic denitrifying bacteria Denitratisoma, and autotrophic denitrifying bacteria Thiobacillus and Thioalkalispira. On the whole, the biofilter coupled with Fe-C micro-electrolysis provides a novel strategy to treat polluted water of low C/N under both heterotrophic and autotrophic conditions.


Assuntos
Reatores Biológicos/microbiologia , Nitrogênio/metabolismo , Processos Autotróficos , Bactérias , Carbono , Desnitrificação , Poluentes Ambientais , Processos Heterotróficos , Nitratos , Águas Residuárias , Água
10.
Ecotoxicol Environ Saf ; 201: 110860, 2020 Sep 15.
Artigo em Inglês | MEDLINE | ID: mdl-32563162

RESUMO

The biodegradation of naphthalene using low-density polyethylene (LDPE) immobilized Exiguobacterium sp. RKS3 (MG696729) in a packed bed bioreactor (PBBR) was studied. The performance of a continuous PBBR was evaluated at different inlet flow rates (IFRs) (20-100 mL/h) under 64 days of operation. The maximum naphthalene removal efficiency (RE) was found at low IFR, and it further decreased with increasing IFRs. In a continuous PBBR, the external mass transfer (EMT) aspect was analysed at various IFRs, and experimental data were interrelated between Colburn factor (JD) and Reynolds number (NRe) as [Formula: see text] . A new correlation [Formula: see text] was obtained to predict the EMT aspect of naphthalene biodegradation. Andrew-Haldane model was used to evaluate the bio-kinetic parameters of naphthalene degradation, and kinetic constant νmax, Js, and Ji were found as 0.386 per day, 13.6 mg/L, and 20.54 mg/L, respectively.


Assuntos
Reatores Biológicos/microbiologia , Naftalenos/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Bacillales/crescimento & desenvolvimento , Bacillales/metabolismo , Biodegradação Ambiental , Células Imobilizadas/microbiologia , Cinética , Polietileno/química
11.
Chemosphere ; 256: 127092, 2020 Oct.
Artigo em Inglês | MEDLINE | ID: mdl-32559887

RESUMO

Although nitrogen removal from wastewater is essential to prevent eutrophication, the biological processes employed to this end are characterized by several disadvantages, including high energy consumption and the production of large quantities of sludge. Thus, in this study, the organic matter and nitrogen removal efficiencies of the new sulfate reduction, denitrification/anammox and partial nitrification (SRDAPN) process were examined using an anaerobic-anoxic-oxic biofilter reactor. The results showed that the organic matter removal efficiency of the new process at loading rate 1.0 kg COD/m3 per day was 97%. With a circulation flow from the oxic to the anoxic column that was 3 times influent, the nitrogen removal efficiency of the sulfur denitrification and nitrification (SRDN) process without anammox, was 66%, while that of the SRDAPN process with anammox was 76%. Additionally, nitrogen consumption by the anammox reaction in the anoxic column was 13.8% for nitrite-nitrogen and 10.5% for ammonium-nitrogen, and the withdrawal of excess sludge was not required throughout the 170 days of operation. Microbial community analysis showed that acetogenic sulfate reducing bacteria and acetoclastic methanogens coexisted in the anaerobic column, and in the anoxic column, the total relative abundance of anammox bacteria, including Candidatus Brocadia, which coexisted with heterotrophic denitrifying bacteria and sulfur denitrifying bacteria, was 17-18%. Thus, this study established the SRDAPN process as an energy saving and high removal efficiency process.


Assuntos
Sulfatos/química , Eliminação de Resíduos Líquidos/métodos , Compostos de Amônio , Bactérias , Reatores Biológicos/microbiologia , Desnitrificação , Nitrificação , Nitritos , Nitrogênio , Oxirredução , Esgotos/microbiologia , Enxofre , Águas Residuárias/química , Águas Residuárias/microbiologia
13.
Int J Syst Evol Microbiol ; 70(7): 4269-4279, 2020 Jul.
Artigo em Inglês | MEDLINE | ID: mdl-32584751

RESUMO

A strictly anaerobic bacterial strain designated EA1T was isolated from an enrichment culture inoculated with biogas reactor content. Cells of strain EA1T are spore-forming rods (1-3×0.4-0.8 µm) and stain Gram-negative, albeit they possess a Gram-positive type of cell-wall ultrastructure. Growth of strain EA1T was observed at 30 and 37 °C and within a pH range of pH 5-9. The major components recovered in the fatty acid fraction were C14:0, C16:0, C16:0 DMA (dimethyl acetal) and C16:1 ω7c. Strain EA1T fermented several mono- and disaccharides. Metabolic end products from fructose were acetate, butyrate, caproate and lactate. Furthermore, ethanol, CO2 and H2 were identified as products. The genome consists of a chromosome (3.9 Mbp) with 3797 predicted protein-encoding genes and a G+C content of 51.25 mol%. Phylogenetic analysis based on 16S rRNA gene sequences indicated that strain EA1T represents a novel taxon within the family Oscillospiraceae. The most closely related type strains of EA1T, based on 16S rRNA gene sequence identity, are Caproiciproducens galactitolivorans BS-1T (94.9 %), [Clostridium] leptum DSM 753T (93.8 %), [Clostridium] sporosphaeroides DSM 1294T (91.7 %) and Ruminococcus bromii ATCC 27255T (91.0 %). Further phenotypic characteristics of strain EA1T differentiate it from related, validly described bacterial species. Strain EA1T represents a novel genus and novel species within the family Oscillospiraceae. The proposed name is Caproicibacter fermentans gen. nov., sp. nov. The type strain is EA1T (DSM 107079T=JCM 33110T).


Assuntos
Reatores Biológicos/microbiologia , Caproatos/metabolismo , Clostridiales/classificação , Filogenia , Bactérias Anaeróbias/classificação , Técnicas de Tipagem Bacteriana , Composição de Bases , Clostridiales/isolamento & purificação , DNA Bacteriano/genética , Ácidos Graxos/química , Fermentação , RNA Ribossômico 16S/genética , Análise de Sequência de DNA
14.
Chemosphere ; 258: 127363, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32554017

RESUMO

Grey water (GW) containing high levels of linear alkylbenzene sulfonates (LAS) can be a threat to the human health and organisms in the environment if not treated properly. Although aerobic treatment may achieve high GW treatment efficacy, conventional aeration can lead to serious foaming. Here, we firstly and systematically evaluated an oxygen-based membrane biofilm reactor (O2-MBfR) for its capacity to simultaneous remove organics and nitrogen from greywater with high LAS levels and carbon/nitrogen (C/N) ratios. After a five-day startup period, multifarious microorganisms formed multifunctional biofilms and the MBfR achieved high removal rates of chemical oxygen demand (COD), LAS, and total nitrogen (TN) of 88.4%, 95.6%, and 80%, respectively, with a hydraulic retention time of 7.86 h. Higher organics loading (5.53 g TCOD/m2-day) caused cell lysis and damaged the O2-MBfR system, leading to a discernible and continuous decline of the reactor performance. The O2-MBfR design completely eliminated foaming formation. LAS -biodegrading-rich genus containing Clostridium, Parvibaculum, Dechloromonas, Desulfovibrio, Mycobacterium, Pseudomonas, and Zoogloea enable the nearly complete removal of LAS even under high C/N conditions. Results demonstrated that the O2-MBfR technology is feasible for treating GW containing high LAS and C/N ratio, while remaining free of foaming formation, and at a low cost due to high O2 utilization rates.


Assuntos
Ácidos Alcanossulfônicos/análise , Biofilmes/crescimento & desenvolvimento , Reatores Biológicos/microbiologia , Carbono/análise , Nitrogênio/análise , Oxigênio/química , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/análise , Biodegradação Ambiental , Biofilmes/efeitos dos fármacos , Análise da Demanda Biológica de Oxigênio , Membranas Artificiais
15.
Chemosphere ; 258: 127146, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32531298

RESUMO

Tetramethylammonium hydroxide (TMAH) was often used as developer in the high-tech industries. Information regarding biological treatment of high TMAH-containing wastewater is limited. This study investigated aerobic degradation of high TMAH, its impacts on nitrification, and microbial community in a sequencing batch reactor (SBR). The initial TMAH concentrations of SBR gradually increased from 200 to 4666 mg L-1 (equivalent to 31 to 718 mg-N L-1) to enrich microbial community for aerobic TMAH degradation and nitrification. The results indicated that the aerobic specific TMAH degradation rates followed the Monod-type kinetics with a maximum specific TMAH degradation rate of 2.184 mg N hour-1 g volatile suspended solid (VSS)-1 and the half-saturation coefficient of 175.1 mg N L-1. After TMAH degradation and ammonia release, the lag time for the onset of nitrification highly correlated with initial TMAH fed for the SBR. According to the microbial community analysis using next generation sequencing (NGS), potential aerobic TMAH-degraders including Mycobacterium sp. and Hypomicrobium sp. were enriched in the aerobic SBR. The results of real-time quantitative polymerase chain reaction (qPCR) and reverse transcript (RT)-qPCR indicated that Hyphomicrobium sp. may be able to utilize both TMAH and its degradation intermediates such as trimethylamine (TMA), while Thiobacillus sp. can only utilize TMAH. The qPCR and RT-qPCR results suggested that TMAH may inhibit nitrification by inactive expression of amoA gene and the intermediates of TMAH degradation may compete ammonia monooxygenase (AMO) enzyme with ammonia for nitrification inhibition.


Assuntos
Microbiota/fisiologia , Compostos de Amônio Quaternário/metabolismo , Eliminação de Resíduos Líquidos/métodos , Poluentes Químicos da Água/metabolismo , Aerobiose , Amônia/metabolismo , Biodegradação Ambiental , Reatores Biológicos/microbiologia , Sequenciamento de Nucleotídeos em Larga Escala , Microbiota/genética , Mycobacterium/genética , Mycobacterium/metabolismo , Nitrificação , Compostos de Amônio Quaternário/química , Reação em Cadeia da Polimerase em Tempo Real , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Thiobacillus/metabolismo , Eliminação de Resíduos Líquidos/instrumentação , Águas Residuárias/química , Poluentes Químicos da Água/química
16.
Chemosphere ; 258: 127148, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535434

RESUMO

Tetrahydrofuran (THF) is a common highly toxic cyclic aliphatic ether that frequently exists in waste gases. Removal of gaseous THF is a serious issue with important environmental ramifications. A novel three-phase airlift bioreactor (TPAB) loaded with immobilized cells was developed for efficient THF removal from gas streams. An effective THF-degrading transformant, Pseudomonas oleovorans GDT4, which contains the pTn-Mod-OTc-gfp plasmid and was tagged with a green fluorescent protein (GFP), was constructed. Continuous treatment of THF-containing waste gases was succeeded by the GFP-labelled cells immobilized with calcium alginate and activated carbon fiber in the TPAB for 60 days with >90% removal efficiency. The number of fluorescent cells in the beads reached 1.7 × 1011 cells·g-1 of bead on day 10, accounting for 83.3% of the total number of cells. The amount further increased to 3.0 × 1011 cells·g-1 of bead on day 40. However, it decreased to 2.5 × 1011 cells·g-1 of bead with a substantial increase in biomass in the liquid because of cell leakage and hydraulic shock. PCR-DGGE revealed that P. oleovorans was the dominant microorganism throughout the entire operation. The maximum elimination capacity was affected by empty bed residence time (EBRT). The capacity was only 25.9 g m-3·h-1 at EBRT of 80 s, whereas it reached 37.8 g m-3·h-1 at EBRT of 140 s. This work provides an alternative method for full-scale removal of gaseous THF and presents a useful tool for determining the biomass of a specific degrader in immobilized beads.


Assuntos
Reatores Biológicos/microbiologia , Furanos/metabolismo , Pseudomonas oleovorans/metabolismo , Gerenciamento de Resíduos/métodos , Alginatos/química , Biodegradação Ambiental , Biomassa , Fibra de Carbono , Células Imobilizadas/metabolismo , Carvão Vegetal , Desenho de Equipamento , Gases , Proteínas de Fluorescência Verde/genética , Microbiota , Microrganismos Geneticamente Modificados , Pseudomonas oleovorans/citologia , Pseudomonas oleovorans/genética , Gerenciamento de Resíduos/instrumentação
17.
Chemosphere ; 258: 127289, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535447

RESUMO

Anammox-based processes and microbial consortia have drawn extensive attention for their use in high-efficiency wastewater treatment technologies. Metals substantially affect the activity of anammox consortia and the quality of wastewater treatment plant effluent. Here, we explored the role of anammox consortia in terms of metals complexation in both single and multi-metal systems. Adsorption edges of single metal cations indicate that the adsorption preference was in the order: Pb(II) > Cd(II) > Cr(VI). A competitive effect was observed in multi-metal cations systems, with Pb(II) being preferably adsorbed and the degree of adsorption somewhat reduced in the presence of either Cd(II) or Cr(VI), while Cd(II) and Cr(VI) were easily exchanged and substituted by other metals. Fourier transform infrared (FTIR) and X-ray photoelectron spectroscopy (XPS) further suggest that the adsorption of Pb(II) and Cd(II) are as inner-sphere ion-exchange mechanisms, while Cr(VI) adsorption is mainly by outer-sphere complexation. Density functional theory (DFT) calculations highlight that Cd(II) and Pb(II) have different binding sites compared to Cr(VI), and the order of binding energy (Ebd) of three metal cations were Pb(II) > Cd(II) > Cr(VI). These calculations support the adsorption data in that Pb forms more stable complexes with anammox bacterial surface ligands. Surface complexation modelling (SCM) further predicted both the sorption of single metal cations and competitive adsorption of the three metals to anammox consortia, the exception being Cd at higher loadings. The results of this study highlight the potential role of anammox consortia in removing metal cations from wastewater in treatment systems.


Assuntos
Amônia/metabolismo , Reatores Biológicos/microbiologia , Metais Pesados/química , Consórcios Microbianos/fisiologia , Adsorção , Anaerobiose , Cátions , Teoria da Densidade Funcional , Metais Pesados/metabolismo , Oxirredução , Espectroscopia Fotoeletrônica , Espectroscopia de Infravermelho com Transformada de Fourier , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Poluentes Químicos da Água/química , Poluentes Químicos da Água/metabolismo
18.
Chemosphere ; 258: 127290, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535448

RESUMO

Biomass segregation between granules/biofilm and flocs is widespread in anammox-based processes. The segregation of biomass allows for easy control of processes stability. The goal of this study is to understand the biomass segregation in two anoxic anammox reactors respectively operated in nitrite-limited (RNO2) and ammonium-limited (RNH4) modes treating low-strength wastewater at 20 °C. Results showed that size-based biomass segregation was developed in both reactors. But the functional and population heterogeneity was more significant in the ammonium-limited anammox reactor. The activity and abundance of anammox bacteria in large granules were significantly higher than that in flocs under the ammonium-limited conditions. The large granules played a major role in nitrogen removal in RNH4. By contrast, both large granules and small flocs contributed significantly to the nitrogen loss in the nitrite-limited anammox reactor, since a large number of anammox bacteria existed in both granules and flocs. Besides, a number of Nitrospira-like NOB were also detected in both anoxic anammox reactors, which primarily inhabited in flocs seemingly droved by the availability of oxygen. But the abundance of Nitrospira in RNH4 was much higher than that in RNO2. All these results suggested that selective flocs removal would be necessary for RNH4 to improve its anammox performance but non-essential for RNO2. The two anammox reactors shared the predominant anammox species with the closest relative to Ca. Brocadia sp. 40 (98%). Unexpectedly, the anammox species grew faster in RNH4. But the microbial diversity and evenness was much greater in RNO2, suggesting its higher functional stability.


Assuntos
Compostos de Amônio/metabolismo , Reatores Biológicos/microbiologia , Nitritos/metabolismo , Eliminação de Resíduos Líquidos/métodos , Águas Residuárias/química , Bactérias/metabolismo , Biofilmes , Biomassa , Nitrogênio/metabolismo , Oxirredução , Eliminação de Resíduos Líquidos/instrumentação
19.
Pol J Microbiol ; 69(2): 193-203, 2020 Sep.
Artigo em Inglês | MEDLINE | ID: mdl-32548988

RESUMO

Microbial populations within the rhizosphere have been considered as prosperous repositories with respect to bioremediation aptitude. Among various environmental contaminants, effluent from textile industries holds a huge amount of noxious colored materials having high chemical oxygen demand concentrations causing ecological disturbances. The study was aimed to explore the promising mycobiome of rhizospheric soil for the degradation of azo dyes to develop an efficient system for the exclusion of toxic recalcitrants. An effluent sample from the textile industry and soil samples from the rhizospheric region of Musa acuminata and Azadirachta indica were screened for indigenous fungi to decolorize Congo red, a carcinogenic diazo dye, particularly known for its health hazards to the community. To develop a bio-treatment process, Aspergillus terreus QMS-1 was immobilized on pieces of Luffa cylindrica and exploited in stirred tank bioreactor under aerobic and optimized environment. Quantitative estimation of Congo red decolorization was carried out using UV-Visible spectrophotometer. The effects of fungal immobilization and biosorption on the native structure of Luffa cylindrica were evaluated using a scanning electron microscope. A. terreus QMS-1 can remove (92%) of the dye at 100 ppm within 24 h in the presence of 1% glucose and 1% ammonium sulphate at pH 5.0. The operation of the bioreactor in a continuous flow for 12 h with 100 ppm of Congo red dye in simulated textile effluent resulted in 97% decolorization. The stirred tank bioreactor was found to be a dynamic, well maintained, no sludge producing approach for the treatment of textile effluents by A. terreus QMS-1 of the significant potential for decolorization of Congo red.Microbial populations within the rhizosphere have been considered as prosperous repositories with respect to bioremediation aptitude. Among various environmental contaminants, effluent from textile industries holds a huge amount of noxious colored materials having high chemical oxygen demand concentrations causing ecological disturbances. The study was aimed to explore the promising mycobiome of rhizospheric soil for the degradation of azo dyes to develop an efficient system for the exclusion of toxic recalcitrants. An effluent sample from the textile industry and soil samples from the rhizospheric region of Musa acuminata and Azadirachta indica were screened for indigenous fungi to decolorize Congo red, a carcinogenic diazo dye, particularly known for its health hazards to the community. To develop a bio-treatment process, Aspergillus terreus QMS-1 was immobilized on pieces of Luffa cylindrica and exploited in stirred tank bioreactor under aerobic and optimized environment. Quantitative estimation of Congo red decolorization was carried out using UV-Visible spectrophotometer. The effects of fungal immobilization and biosorption on the native structure of Luffa cylindrica were evaluated using a scanning electron microscope. A. terreus QMS-1 can remove (92%) of the dye at 100 ppm within 24 h in the presence of 1% glucose and 1% ammonium sulphate at pH 5.0. The operation of the bioreactor in a continuous flow for 12 h with 100 ppm of Congo red dye in simulated textile effluent resulted in 97% decolorization. The stirred tank bioreactor was found to be a dynamic, well maintained, no sludge producing approach for the treatment of textile effluents by A. terreus QMS-1 of the significant potential for decolorization of Congo red.


Assuntos
Aspergillus/metabolismo , Reatores Biológicos/microbiologia , Vermelho Congo/isolamento & purificação , Microbiologia Industrial/métodos , Luffa/microbiologia , Microbiologia Industrial/economia , Rizosfera
20.
Chemosphere ; 258: 127228, 2020 Nov.
Artigo em Inglês | MEDLINE | ID: mdl-32535438

RESUMO

Urea hydrolysis in partial nitritation process forming nitrite and ammonia is advantageous to subsequent treatment with ANAMMOX for total nitrogen removal. In this study, stable partial nitritation for urea wastewater with urea increasing from 250 to 2000 mg L-1 were achieved in an aerobic SBR. Urea removal efficiency and nitrite accumulation percentage both kept above 98%, with nitrite production rate about 0.985 kg N·m-3·d-1. Urea hydrolysis mechanism in this aerobic system was described as, (1) massive urea in the bulk was absorbed into cell, (2) urea was hydrolyzed by intracellular urease inside cell, (3) produced ammonia then slowly diffused into the bulk through membrane, which is later converted by ammonia-oxidizing bacteria (AOB) into nitrite. Due to this mechanism, the activity of AOB could not be inhibited by high FA (free ammonia) value under high urea concentration condition while nitrite-oxidizing bacteria (NOB) remained to be inhibited. An uncultured genus belonging to poorly characterized phylum Gemmatimonadetes was found enriched in this process and became dominant genus. This genus was speculated to have same energy pathway like ureaplasma, by absorbing excessive urea from environment and utilize urea hydrolysis to generate energy. So it was believed to be responsible for urea hydrolysis mechanism mentioned above. This SBR showed stable partial nitritation and high urea removal efficiency for treating urea wastewater, which was obviously feasible as the pretreatment process for subsequent ANAMMOX.


Assuntos
Amônia/análise , Reatores Biológicos/microbiologia , Nitritos/análise , Ureia/análise , Poluentes Químicos da Água/análise , Purificação da Água/métodos , Aerobiose , Amônia/metabolismo , Bactérias/metabolismo , Hidrólise , Nitritos/metabolismo , Nitrogênio/análise , Nitrogênio/metabolismo , Oxirredução , Ureia/metabolismo , Águas Residuárias/química , Poluentes Químicos da Água/metabolismo
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