RESUMO
The efficiency of linear alkylbenzene sulfonate (LAS) removal from laundry wastewater and the related microbial community was investigated in an anaerobic fluidized bed reactor (AFBR). The AFBR was operated in three stages, in addition to the biomass adaptation stage without LAS (stage I). The stages were differentiated by their supplementary co-substrates: stage II had sucrose plus ethanol, stage III had only ethanol, and stage IV had no co-substrate. The replacement of sucrose plus ethanol with ethanol only for the substrate composition favored the efficiency of LAS removal, which remained high after the co-substrate was removed (stage II: 52 %; stage III: 73 %; stage IV: 77 %). A transition in the microbial community from Comamonadaceae to Rhodocyclaceae in conjunction with the co-substrate variation was observed using ion sequencing analysis. The microbial community that developed in response to an ethanol-only co-substrate improved LAS degradation more than the community that developed in response to a mixture of sucrose and ethanol, suggesting that ethanol is a better option for enriching an LAS-degrading microbial community.
Assuntos
Bactérias/metabolismo , Etanol/metabolismo , Consórcios Microbianos/fisiologia , Sacarose/metabolismo , Tensoativos/metabolismo , Poluentes Químicos da Água/metabolismo , Ácidos Alcanossulfônicos/isolamento & purificação , Ácidos Alcanossulfônicos/metabolismo , Ânions , Bactérias/classificação , Bactérias/isolamento & purificação , Biodegradação Ambiental , Reatores Biológicos/microbiologia , Especificidade da Espécie , Tensoativos/isolamento & purificação , Microbiologia da Água , Poluentes Químicos da Água/isolamento & purificação , Purificação da Água/métodosRESUMO
The aim of this study was to investigate the effect of the support material used for biomass attachment and bed porosity on the potential generation of hydrogen gas in an anaerobic bioreactor treating low-strength wastewater. For this purpose, an upflow anaerobic packed-bed (UAPB) reactor fed with sucrose-based synthetic wastewater was used. Three reactors with various support materials (expanded clay, vegetal coal, and low-density polyethylene) were operated for hydraulic retention time (HRT) of 0.5 and 2 h. Based on the results obtained, three further reactors were operated with low-density polyethylene as a material support using various bed porosities (91, 75, and 50 %) for an HRT of 0.5 h. The UAPB reactor was found to be a feasible technology for hydrogen production, reaching a maximum substrate-based hydrogen yield of 7 mol H2 mol(-1) sucrose for an HRT of 0.5 h. The type of support material used did not affect hydrogen production or the microbial population inside the reactor. Increasing the bed porosity to 91 % provided a continuous and cyclic production of hydrogen, whereas the lower bed porosities resulted in a reduced time of hydrogen production due to biomass accumulation, which resulted in a decreasing working volume.
Assuntos
Bactérias Anaeróbias/metabolismo , Materiais Biocompatíveis/química , Reatores Biológicos/microbiologia , Hidrogênio/metabolismo , Reologia/instrumentação , Sacarose/metabolismo , Aderência Bacteriana , Proliferação de Células , Desenho de Equipamento , Análise de Falha de Equipamento , Hidrogênio/isolamento & purificação , PorosidadeRESUMO
This study evaluated linear alkylbenzene sulfonate removal in an expanded granular sludge bed reactor with hydraulic retention times of 26 h and 32 h. Sludge bed and separator phase biomass were phylogenetically characterized (sequencing 16S rRNA) and quantified (most probable number) to determine the total anaerobic bacteria and methanogenic Archaea. The reactor was fed with a mineral medium supplemented with 14 mg l(-1)LAS, ethanol and methanol. The stage I-32 h consisted of biomass adaptation (without LAS influent) until reactor stability was achieved (COD removal >97%). In stage II-32 h, LAS removal was 74% due to factors such as dilution, degradation and adsorption. Higher HRT values increased the LAS removal (stage III: 26 h - 48% and stage IV: 32 h - 64%), probably due to increased contact time between the biomass and LAS. The clone libraries were different between samples from the sludge bed (Synergitetes and Proteobacteria) and the separator phase (Firmicutes and Proteobacteria) biomass.
Assuntos
Reatores Biológicos , Esgotos , Tensoativos/isolamento & purificação , Ânions , Archaea/genética , Archaea/metabolismo , Bactérias Anaeróbias/genética , Bactérias Anaeróbias/metabolismo , Biomassa , Contagem de Colônia Microbiana , RNA Ribossômico 16S/genéticaRESUMO
Linear alkylbenzene sulfonate (LAS) is an anionic surfactant widely used to manufacture detergents and found in domestic and industrial wastewater. LAS removal was evaluated in a horizontal anaerobic immobilized biomass reactor. The system was filled with polyurethane foam and inoculated with sludge that was withdrawn from an up flow anaerobic sludge blanket reactor that is used to treat swine wastewater. The reactor was fed with easily degradable substrates and a solution of commercial LAS for 313 days. The hydraulic retention time applied was 12h. The system was initially operated without detergent and resulted to 94% reduction of demand. The mass balance in the system indicated that the LAS removal efficiency was 45% after 18 0days. From the 109 th day to the 254 th day, a removal efficiency of 32% was observed. The removal of LAS was approximately 40% when 1500 mg of LAS were applied in the absence of co-substrates suggesting that the LAS molecules were used selectively. Microscopic analyses of the biofilm revealed diverse microbial morphologies and denaturing gradient gel electrophoresis profiling showed variations in the total bacteria and sulfate-reducing bacteria populations. 16S rRNA sequencing and phylogenetic analyses demonstrated that members of the order Clostridiales were the major components of the bacterial community in the last step of the reactor operation.
Assuntos
Ácidos Alcanossulfônicos/metabolismo , Biomassa , Reatores Biológicos , Anaerobiose , Bactérias/classificação , Bactérias/genética , Bactérias/metabolismo , Biofilmes , Clonagem Molecular , Filogenia , Reação em Cadeia da Polimerase , RNA Ribossômico 16S/genética , EsgotosRESUMO
The purpose of this study was to assess the anaerobic degradation of black liquor with and without additional carbon sources. Batch experiments were conducted using black liquor, from an integrated pulp and paper mill adding ethanol, methanol and nutrients. The PCR/DGGE technique was used to characterize the structure of the microbial community. The addition of extra sources of carbon did not significantly influence the degradation of black liquor under the conditions evaluated and the microbial community was similar in all experiments. It was observed an increase in some members of the archaeal in reactors that had the best efficiencies for removal of black liquor (around 7.5%). Either ethanol or methanol can be used as co-substrates because the produce the same quantitative and qualitative effect.
Assuntos
Reatores Biológicos/microbiologia , Resíduos Industriais/prevenção & controle , Papel , Eliminação de Resíduos Líquidos/métodos , Anaerobiose , Archaea/genética , Archaea/metabolismo , Etanol/metabolismo , Metanol/metabolismo , Reação em Cadeia da PolimeraseRESUMO
The purpose of this work was to assess the degradation of linear alkylbenzene sulfonate (LAS) in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor. The reactor was filled with polyurethane foam where the sludge from a sanitary sewage treatment was immobilized. The hydraulic detention time (HDT) used in the experiments was of 12 h. The reactor was fed with synthetic substrate (410 mg l(-1) of meat extract, 115 mg l(-1) of starch, 80 mg l(-1) of saccharose, 320 mg l(-1) of sodium bicarbonate and 5 ml l(-1) of salt solution) in the following stages of operation: SI-synthetic substrate, SII-synthetic substrate with 7 mg l(-1) of LAS, SIII-synthetic substrate with 14 mg l(-1) of LAS and SIV-synthetic substrate containing yeast extract (substituting meat extract) and 14 mg l(-1) of LAS, without starch. At the end of the experiment (313 days) a degradation of approximately 35% of LAS was achieved. The higher the concentration of LAS, the greater the amount of foam for its adsorption. This is necessary because the isotherm of LAS adsorption in the foam is linear for the studied concentrations (2 to 50 mg l(-1)). Microscopic analyses of the biofilm revealed diverse microbial morphologies, while Denaturing Gradient Gel Eletrophoresis (DGGE) profiling showed variations in the population of total bacteria and sulphate-reducing bacteria (SRB). The 16S rRNA gene sequencing and phylogenetic analyses revealed that the members of the order Clostridiales were the major components of the bacterial community in the last reactor operation step.
Assuntos
Ácidos Alcanossulfônicos/metabolismo , Biomassa , Reatores Biológicos , Methanosarcinales/metabolismo , Adsorção , Anaerobiose , Methanosarcinales/genética , Filogenia , RNA Ribossômico 16S/genéticaRESUMO
This paper reports on the adhesion of sulfate-reducing bacteria (SRB) and methanogenic archaea on polyurethane foam (PU), vegetal carbon (VC), low-density polyethylene (PE) and alumina-based ceramics (CE). Anaerobic differential reactors fed with a sulfate-rich synthetic wastewater were used to evaluate the formation of a biofilm. The PU presented the highest specific biomass concentration throughout the experiment, achieving 872 mg TVS/g support, while 84 mg TVS/g support was the maximum value obtained for the other materials. FISH results showed that bacterial cells rather than archaeal cells were predominant on the biofilms. These cells, detected with EUB338 probe, accounted for 76.2% (+/-1.6%), 79.7% (+/-1.3%), 84.4% (+/-1.4%) and 60.2% (+/-1.0%) in PU, VC, PE and CE, respectively, of the 4'6-diamidino-2-phenylindole (DAPI)-stained cells. From these percentages, 44.8% (+/-2.1%), 55.4% (+/-1.2%), 32.7% (+/-1.4%) and 18.1% (+/-1.1%), respectively, represented the SRB group. Archaeal cells, detected with ARC915 probe, accounted for 33.1% (+/-1.6%), 25.4% (+/-1.3%), 22.6% (+/-1.1%) and 41.9% (+/-1.0%) in PU, VC, PE and CE, respectively, of the DAPI-stained cells. Sulfate reduction efficiencies of 39% and 45% and mean chemical oxygen demand (COD) removal efficiencies of 86% and 90% were achieved for PU and VC, respectively. The other two supports, PE and CE, provided mean COD removal efficiencies of 84% and 86%, respectively. However, no sulfate reduction was observed with these supports.
Assuntos
Bactérias Anaeróbias/crescimento & desenvolvimento , Biofilmes/crescimento & desenvolvimento , Reatores Biológicos/microbiologia , Euryarchaeota/crescimento & desenvolvimento , Técnicas Microbiológicas/instrumentação , Óxido de Alumínio , Bactérias Anaeróbias/ultraestrutura , Aderência Bacteriana , Biomassa , Carbono , Euryarchaeota/ultraestrutura , Hibridização in Situ Fluorescente , Indóis/metabolismo , Microscopia Eletrônica de Varredura , Consumo de Oxigênio , Polietileno , Poliuretanos , Sulfatos/metabolismo , Fatores de TempoRESUMO
In this study it is reported the operation of a horizontal-flow anaerobic immobilized biomass (HAIB) reactor under sulfate-reducing condition which was also exposed to different amounts of ethanol and toluene. The system was inoculated with sludge taken from up-flow anaerobic sludge blanket (UASB) reactors treating refuses from a poultry slaughterhouse. The HAIB reactor comprised of an immobilized biomass on polyurethane foam and ferrous and sodium sulfate solutions were used (91 and 550 mg/L, respectively), to promote a sulfate-reducing environment. Toluene was added at an initial concentration of 2.0 mg/L followed by an increased range of different amendments (5, 7, and 9 mg/L). Ethanol was added at an initial concentration of 170 mg/L followed by an increased range of 960 mg/L. The reactor was operated at 30(+/-2) degrees C with hydraulic detention time of 12 h. Organic matter removal efficiency was close to 90% with a maximum toluene degradation rate of 0.06 mg(toluene)/mg(vss)/d. Sulfate reduction was close to 99.9% for all-nutritional amendments. Biofilm microscopic characterization revealed a diversity of microbial morphologies and DGGE-profiling showed a variation of bacterial and sulfate reducing bacteria (SRB) populations, which were significantly associated with toluene amendments. Diversity of archaea remained unaltered during the different phases of this experiment. Thus, this study demonstrates that compact units of HAIB reactors, under sulfate reducing conditions, are a potential alternative for in situ aromatics bioremediation.
Assuntos
Bactérias Anaeróbias/citologia , Bactérias Anaeróbias/metabolismo , Reatores Biológicos/microbiologia , Etanol/farmacocinética , Esgotos/microbiologia , Sulfatos/metabolismo , Tolueno/farmacocinética , Biodegradação Ambiental , Técnicas de Cultura de Células/métodos , Células Imobilizadas/citologia , Células Imobilizadas/metabolismo , Oxirredução , Poluentes Químicos da Água/farmacocinética , Purificação da Água/métodosRESUMO
This work focuses on the influence of the source of organic matter on the process of biomass adhesion on polyurethane foam matrices in fixed-bed anaerobic immobilized-sludge reactors. Five experiments were performed in differential 'gradientless' reactors fed with meat extract (protein), glucose, starch, lipids and complex substrate. The polyurethane foam colonization process was monitored temporally in each experiment to identify the amount of biomass buildup, extracellular polymer production and the morphological characteristics of the cells adhering to the support. Different immobilization patterns were observed for the different substrates used. The morphological variety was found to be dependent on the substrate constituents. Polymer excretion was apparently crucial in the colonization process of the polyurethane matrices and was likely related to cell fixation on the support. The production of extracellular polymeric substances speeded up the initial fixation of microorganisms on the polyurethane surface.
Assuntos
Bactérias Anaeróbias/metabolismo , Biomassa , Carbono/metabolismo , Poliuretanos/metabolismo , Eliminação de Resíduos Líquidos/métodos , Reatores Biológicos , Carboidratos , Matriz Extracelular/química , Lipídeos , Microscopia Eletrônica , Compostos Orgânicos , Oxigênio , Poliuretanos/química , Proteínas , Fatores de TempoRESUMO
The development of appropriate technologies for the treatment of formaldehyde discharged into the environment is important to minimize its impact. Aerobic systems have been employed, although alternative anaerobic treatments have also been widely studied, mainly due to their low energy consumption and sludge production. However, toxic substances can lead to disturbances in anaerobic reactors. Some research has already been developed on formaldehyde anaerobic biological treatment, but no consensus has yet been reached about its behavior nor has the most efficient system been identified. Aiming at finding supporting evidence for this issue, therefore, this study investigated the degradation and toxicity of formaldehyde in a Horizontal-Flow Anaerobic Immobilized Sludge Reactor. Formaldehyde concentrations of 26.2-1158.6 mg HCHO/L were applied in the reactor, resulting in formaldehyde and chemical oxygen demand removal efficiencies of 99.7% and 92%, respectively. Volatile fatty acids with up to five carbons, found during the degradation of formaldehyde, are believed to indicate that the degradation followed routes unlike those suggested in the literature, which reports the formation of intermediates such as methanol and formic acid. The Monod kinetic model adhered to the experimental data well, with apparent kinetic parameters estimated as r(app)max) = 2.79 x 10(-3) mg HCHO/mg SSVh and K (app)(s) = 242.8 mg HCHO/L.
Assuntos
Bactérias Anaeróbias/fisiologia , Reatores Biológicos , Fixadores/metabolismo , Formaldeído/metabolismo , Purificação da Água/métodos , Biomassa , Ácidos Graxos Voláteis/análise , Fixadores/toxicidade , Formaldeído/toxicidade , Esgotos/química , Eliminação de Resíduos Líquidos/métodosRESUMO
Data on the influence of substrate composition on the anaerobic degradation of bovine serum albumin (BSA) in a bench-scale packed-bed reactor are presented and discussed from the standpoint of substrate consumption kinetics. The experiments were carried out in a horizontal-flow anaerobic immobilized biomass (HAIB) reactor fed with BSA based substrates. BSA was the sole carbon source in the first one, while the others were composed of BSA, carbohydrates and lipids. In all the experiments, the HAIB reactor was operated at the hydraulic detention time of 4 hours. The reactor's performance was evaluated based on physicochemical and chromatographic analyses and also on microscopy techniques. A kinetic model of irreversible first-order series-parallel reactions with two intermediate products was proposed, allowing evaluation of the microbial consortium's affinity with the substrates and the metabolic compounds formed. As the first-order kinetic model adhered quite well to the experimental data, the initial protein degradation rates (k) were estimated. The presence of carbohydrates and lipids led the initial protein degradation rate to be reduced. However, the system fed with protein and carbohydrates showed higher process stability.
Assuntos
Reatores Biológicos , Modelos Teóricos , Proteínas/metabolismo , Eliminação de Resíduos Líquidos/métodos , Bactérias Anaeróbias , Biodegradação Ambiental , Cromatografia , Cinética , Movimentos da ÁguaRESUMO
A bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor was assayed aiming to verify its performance in degrading benzene, toluene, ethylbenzene and xylene (BTEX). A 138 ml HAIB reactor filled with polyurethane foam matrices containing immobilized anaerobic biomass was initially fed with synthetic substrate containing protein, carbohydrates and lipids. Thereafter, BTEX degradation was evaluated in the presence of the co-solvents ethanol and lineal alkylbenzene sulphonate (LAS), in two sequential experiments. The inlet BTEX concentration ranged from 1.3 to 27.0 mg/L of each compound and outlet concentrations were lower than 0.1 mg BTEX/L for both the experiments with ethanol and LAS. An active enriched microbial consortium was observed in the reactor, containing BTEX-degraders, and also acetogenic, acetotrophic and hydrogenotrophic microorganisms. The results from the most probable number (MPN) tests indicated a decrease in the number of methanogenic archae, while the number of anaerobic microorganisms in the biofilm was maintained during the experimental period. Methanogenic archae were found to represent less than 0.5 % of the total anaerobic organisms in the biomass inside the reactor.
Assuntos
Bactérias Anaeróbias/fisiologia , Derivados de Benzeno/metabolismo , Reatores Biológicos , Archaea/fisiologia , Biodegradação Ambiental , Biofilmes , Biomassa , Euryarchaeota/fisiologia , Poliuretanos , Dinâmica PopulacionalRESUMO
In this study we investigated the development of anaerobic biofilms in differential reactors and suspension cultures in batch reactors under thermophilic (55 degrees C) conditions. FISH, SEM, chemical and chromatographic analysis were used. The differential reactors reached 99.6%, 92.3% and 6.7% of acetic acid, COD and sulfate removal efficiencies, respectively, after 166 h of incubation time. The batch reactor reached 95.6% and 31.8% of acetic acid and sulfate removal efficiencies after 675 h, respectively. FISH results showed that bacterial cells rather than archaeal cells dominated biofilms. These cells, detected with the Bacteria specific probe (EUB338), accounted for 61.1% (+/-3.6) of the DAPI-stained cells and resembled acetate-oxidizing rods and Desulfotomaculum morphologies. Archaeal cells, which hybridized to the Archaea specific probe (ARC915), were also detected in biofilm but they accounted for 36.7% (+/-2.9) of the DAPI-stained cells. These cells were similar to Methanosaeta-like and hydrogenotrophic methanogen rods. In the suspension culture, archaeal cells (58.0%+/-3.8) morphologically similar to Methanosarcina and hydrogenotrophic methanogen rods were predominant over bacterial cells (41.0%+/-4.5), which resembled acetate-oxidizing rods and Desulfotomaculum morphologies. The percentage of sulfate-reducing bacteria cells (SRB) ranged from 12.2% (+/-2.5) to 21.7% (+/-2.8) in the biofilms and from 13.3% (+/-3.6) to 21.7% (+/-4.3) of the DAPI stained cells in suspension culture.
Assuntos
Archaea , Bactérias Anaeróbias , Reatores Biológicos , Euryarchaeota , Biofilmes , Hibridização in Situ Fluorescente , Microscopia Eletrônica de Varredura , Dinâmica Populacional , TemperaturaRESUMO
A bench-scale horizontal-flow anaerobic immobilized biomass (HAIB) reactor was assayed aiming to verify its potential use for phenol degradation. The HAIB reactor consisted of a bore-silicate tube (100 cm long; 5.04 cm diameter) filled with polyurethane foam matrices containing immobilized anaerobic sludge. Before being subjected to phenol, the reactor was fed with synthetic substrate at the influent chemical oxygen demand (COD) of 1,028 mg.l-1 achieving 98% of COD removal efficiency. Thereafter, phenol as the sole carbon source was added under step-increasing concentrations from 50 to 1,200 mg.l-1. Phenol degradation was evaluated by gas chromatographic analysis of influent and effluent samples. Process monitoring included determinations of pH, volatile acids, alkalinity and COD. The HAIB reactor was operated at a constant hydraulic detention time (HDT) of 12 hours. After 33 days with 50 mg/l of phenol in the influent, the reactor achieved 98% of COD removal efficiency. Successful phenol degradation (efficiency removal of 99%) occurred for influent concentrations of 100, 300, 600, 900 and 1,200 mg.l-1 after 148, 58, 47, 29 and 7 days, respectively. The predominance of Methanosaeta-like, rods and methanogenic cocci could be observed in all the operating conditions, besides the presence of phenol oxidizing microorganisms as irregular rods. The results indicate that phenol degradation at very high rates can be accomplished in HAIB reactors containing acclimatized biomass.