RESUMO
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
The performance of a sewage treatment system consisting of a settler followed by an Upflow Anaerobic Sludge Bed (UASB) reactor is described. Mean ambient and sewage temperature were 16.5 and 21.6 degrees C, respectively. Total Chemical Oxygen Demand (CODt) concentration averaged 224.2 and 152.6 mg/L, for raw and settled sewage, respectively. The effluent concentration was 68.5 mgCODt/L. Total and suspended COD removal efficiencies of approximately 70 and 80%, respectively, have been observed in the system at a mean Hydraulic Retention Time (HRT) of 2 + 5 h. Maximum COD removal efficiency was achieved in the UASB reactor when upflow velocity (Vup) was 0.43 m/h (HRT = 6 h). Mean Specific Methanogenic Activity (SMA) and Volatile Suspended Solids (VSS) concentration in the granular sludge bed were 0.11 gCOD-CH4/gVSS.d and 30.0 gVSS/Lsludge, respectively. SMA was inversely related to VSS concentration, and both parameters varied along the sludge bed height. The Solids Retention Time (SRT) in the reactor was 450 days. Sludge characteristics have not been affected by changes of up to one month in Vup in the range 0.28-0.85 m/h (HRT 3-9 h). This system or two UASB reactors in series could be an alternative for sewage treatment under moderate temperature conditions.
Assuntos
Bactérias Anaeróbias/fisiologia , Reatores Biológicos , Euryarchaeota/fisiologia , Esgotos/microbiologia , Oxigênio/química , Projetos Piloto , Esgotos/química , Temperatura , Clima Tropical , Eliminação de Resíduos Líquidos/métodosRESUMO
Aerobic and methanogenic consortia were evaluated as inocula for laboratory scale denitrifying reactors, fed with a synthetic wastewater with acetate as the main electron donor. The denitrifying microflora of inocula and reactors was evaluated by specific denitrifying activity, enumeration and isolation of denitrifiers, which were screened by amplified ribosomal DNA restriction analysis. Reactor performance was monitored by COD and nitrate removal efficiencies and granule size. The aerobic sludge failed to form granules, probably due to the development of a filamentous, nitrate-reducing organism which was characterised by 16SrDNA sequencing as Bacillus cereus. The methanogenic sludge showed denitrifying activity and adapted very rapidly to denitrifying conditions in the two reactors seeded with granules of different sizes. Denitrifiers grew around the granules, increasing the specific denitrifying activity of the sludge over 10-fold. Exopolymer-forming organisms, belonging to the same species, were isolated from both reactors. Granule size increased during operation, but flotation of the aggregates, related to gas retention was observed.
Assuntos
Bacillus cereus/fisiologia , Bactérias Aeróbias/fisiologia , Reatores Biológicos , Euryarchaeota/fisiologia , Eliminação de Resíduos Líquidos/métodos , Acetatos/metabolismo , DNA Bacteriano/análise , Nitratos/metabolismo , Tamanho da Partícula , Polímeros , RNA Ribossômico 16S/análiseRESUMO
The present research aimed at evaluating pentachlorophenol (PCP) degradation in a hybrid reactor supplied with a mixture of fatty acids (propionic, butyric, acetic and lactic) and methanol. The performance of the reactor is remarkably stable and efficient during PCP additions at range of 2.0 to 21.0 mg/L. The reduction of chemical oxygen demand (COD) was around 97% and methane was found to be 88% in the biogas production. The efficiency of volatile fatty acids breakdown was 93%, 64% and 74% respectively for butyric, propionic and acetic. PCP total removal of more than 99% was reached by granular sludge activities formed during 21 months of reactor operation. Methanogenic microorganisms predominance was noticed with 10(5) to 10(6) cells/mL during enumeration on methanol or lactate added to sulfate culture media. The removal rate was 1.07 mg PCP.g-1 VS.d-1 during the highest PCP concentration addition.
Assuntos
Bactérias Anaeróbias/fisiologia , Euryarchaeota/fisiologia , Inseticidas/metabolismo , Pentaclorofenol/metabolismo , Reatores Biológicos , Ácidos Graxos/metabolismo , Gases , Cinética , Metanol/metabolismo , Oxigênio/metabolismo , VolatilizaçãoRESUMO
The degradation of of lineal alkylbenzene sulphonate (LAS) was studied in a two-stage anaerobic system where the acidogenic reactor was bioaugmented with a strain of Pseudomonas aeruginosa (M113). This is a strain, which under aerobic and denitrifying conditions uses LAS as carbon source. Results show that LAS was only degraded within the acidogenic stage while in the methanogenic reactor there was no degradation and eventually there was an inhibition due to a LAS accumulation in the sludge. During the experiment, the M113 strain remained in the acidogenic conglomerate (at around 10(4) CFU/mL) although there is no evidence of their involvement in LAS degradation.
Assuntos
Ácidos Alcanossulfônicos/metabolismo , Pseudomonas aeruginosa/fisiologia , Tensoativos/metabolismo , Biodegradação Ambiental , Reatores Biológicos , Indústria Química , Euryarchaeota/fisiologia , Resíduos Industriais , Nitrogênio/metabolismo , Eliminação de Resíduos Líquidos/métodos , Purificação da Água/métodosRESUMO
This paper reports on the influence of the material porosity on the anaerobic biomass adhesion on four different inert matrices: polyurethane foam, PVC, refractory brick and special ceramic. The biofilm development was performed in a fixed-bed anaerobic reactor containing all the support materials and fed with a synthetic wastewater containing protein, lipids and carbohydrates. The data obtained from microscopic analysis and kinetic assays indicated that the material porosity has a crucial importance in the retention of the anaerobic biomass. The polyurethane foam particles and the special ceramic were found to present better retentive properties than the PVC and the refractory brick. The large specific surface area, directly related to material porosity, is fundamental to provide a large amount of attached biomass. However, different supports can provide specific conditions for the adherence of distinct microorganism types. The microbiological exams revealed a distinction in the support colonization. A predominance of methanogenic archaeas resembling Methanosaeta was observed both in the refractory brick and the special ceramic. Methanosarcina-like microorganisms were predominant in the PVC and the polyurethane foam matrices.
Assuntos
Euryarchaeota/fisiologia , Eliminação de Resíduos Líquidos/métodos , Bactérias Anaeróbias/fisiologia , Biofilmes , Biomassa , Reatores Biológicos , Metabolismo dos Carboidratos , Cinética , Metabolismo dos Lipídeos , Poliuretanos/química , Proteínas/metabolismoRESUMO
A trial was carried out in a continuous regimen, using a completely stirred tank reactor, at acidogenic phase, and a hybrid reactor (upflow anaerobic sludge blanket + fixed bed) at methanogenic phase at room temperature. The residue to be treated came from a flour and cassava meal industry, and the reactors operated for 300 d with affluent chemical oxygen demand (COD) concentrations of 7500, 9000, 11,000, and 14,000 mg/L. The final results showed a biogas production with a content of 80% methane and an average reduction of COD and free cyanide of nearly 96 and 98%, respectively. The separation of phases selected bacterial groups. At acidogenic phase, a predominance of propionic, n-butyric, and n-valeric acids, as well as a biomass composed of 95% fermentative bacilli, which were responsible for a 90% reduction in free cyanide concentration, was observed. At methanogenic phase, a predominance of methanogenic bacteria that came only from the Methanothrix genus was observed. The bacteria were responsible for high levels of organic matter removal and methane production.