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1
Suidan, Makram T., Joseph R. V. Flora, Pratim Biswas i Gregory D. Sayles. "Optimization modelling of anaerobic biofilm reactors". Water Science and Technology 30, nr 12 (1.12.1994): 347–55. http://dx.doi.org/10.2166/wst.1994.0634.
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A rigorous steady state model of acetate-utilizing methanogenic biofilms is developed accounting for the mass transfer of neutral and ionic species, pH changes within the biofilm, pH-dependent Monod kinetics, chemical equilibrium, electroneutrality, gas production within the biofilm, and the presence of a concentration boundary layer (CBL). In contrast to traditional biofilm models where the pH is assumed to be constant within the biofilm, an increase in pH in acetate-utilizing methanogenic biofilms is predicted. Furthermore, significant differences can exist between the flux predictions using the traditional models and when pH changes within the biofilm are taken into account. The optimum pH for acetate-utilizing biofilms is less than the optimum defined for suspended-growth systems. The biofilm model is coupled to a model of a completely-stirred tank reactor (CSTR), and strategies for the optimization of biofilm reactor performance are examined. For a fixed set of operating conditions, an optimum influent pH can be defined that corresponds to the maximum removal efficiency and flux of acetate into the biofilm.
2
Fahmy, M., E. Heinzle i O. M. Kut. "Treatment of Bleaching Effluents in Aerobic/Anaerobic Fluidized Biofilm Systems". Water Science and Technology 24, nr 3-4 (1.08.1991): 179–87. http://dx.doi.org/10.2166/wst.1991.0474.
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Biodegradation of chloroorganic compounds in real industrial bleaching effluents (chlorination and extraction), with adapted biofilm in fluidized sand bed reactors, was studied under aerobic and anaerobic conditions. The effluents were only diluted and supplied with mineral nutrients. Two reactor combinations were compared with a single stage aerobic digestor (AFB). In the anaerobic-aerobic reactors in series (AAS), the effluents were first treated anaerobically followed by an aerobic reactor in a single pass. In the anaerobic-aerobic recycle reactor (AAR), the reactor content was periodically moving back from aerobic to anaerobic fluidized beds. The reactors were running continuously for one year. The most significant differences observed were between aerobic and anaerobic single reactors. Generally anaerobiosis reduced performance in terms of global parameters (COD, NPOC, AOX). With a residence time of 18 h for each reactor, COD and AOX typically decreased by 15-32 % for each aerobic reactor system (AFB, AAS, AAR), whereas a decrease of typically 4-15 % was observed in the purely anaerobic system. From GC and GC/MS analysis it was evident that in the anaerobic reactors, 2,4,6-trichlorophenol was first converted to 2,4-dichlorophenol. In all three systems 2,4,6-trichlorophenol and dichlorophenols were almost completely removed.
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Kennedy, K. J., i R. L. Droste. "Diffusional limitations of anaerobic biofilms". Canadian Journal of Civil Engineering 14, nr 5 (1.10.1987): 631–37. http://dx.doi.org/10.1139/l87-093.
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Using an empirical determination of apparent kinetic parameters in the bulk mixed liquor, the intrinsic kinetic parameters of anaerobic biofilms developed at 35 °C during start-up and steady-state downflow stationary fixed film reactor operation were estimated. The apparent kinetic parameters of anaerobic biofilms are not significantly influenced by internal diffusion limitations. The apparent kinetic parameters of mature biofilms showed no significant trends with increased biofilm thickness up to 2.6 mm and increased apparent Thiele modulus up to 3.1. Key words: anaerobic, biofilm kinetics, Thiele modulus, wastewater, filter.
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Jahren, Sigrun J., i Hallvard Ødegaard. "Treatment of Thermomechanical Pulping (TMP) Whitewater in Thermophilic (55°C) Anaerobic-Aerobic Moving Bed Biofilm Reactors". Water Science and Technology 40, nr 8 (1.10.1999): 81–89. http://dx.doi.org/10.2166/wst.1999.0391.
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Thermomechanical pulping whitewater was treated in an anaerobic followed by an aerobic Kaldnes moving bed biofilm reactor at 55°C. The anaerobic reactor was mixed by gas circulation and the aerobic reactor was mixed by aeration. The anaerobic reactor was started with mesophilic inoculum, while the aerobic reactor was started without inoculation. The reactors were operated on molasses water for one and a half years before the experiment was started. Total biomass concentrations (suspended and attached) were 3.3 g VSS/L in the anaerobic reactor and 1.6 g VSS/L in the aerobic reactor when starting feeding the reactors with TMP whitewater. After 7 months of operation the biomass concentrations had reached 5.5 and 6.5 g VSS/L in the anaerobic and aerobic reactors, respectively. The CODsol removals in the anaerobic reactor were around 30 % at loading rates up to 7 kg CODsol/m3d, and over-all CODsol removals of about 60 % were achieved. The results show that the anaerobic-aerobic moving bed biofilm process could be feasible for the thermophilic treatment of thermomechanical pulping whitewater.
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Liang, Qiaochu, Takahiro Yamashita, Norihisa Matsuura, Ryoko Yamamoto-Ikemoto i Hiroshi Yokoyama. "Community Structure Analyses of Anodic Biofilms in a Bioelectrochemical System Combined with an Aerobic Reactor". Energies 12, nr 19 (24.09.2019): 3643. http://dx.doi.org/10.3390/en12193643.
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Bioelectrochemical system (BES)-based reactors have a limited range of use, especially in aerobic conditions, because these systems usually produce current from exoelectrogenic bacteria that are strictly anaerobic. However, some mixed cultures of bacteria in aerobic reactors can form surface biofilms that may produce anaerobic conditions suitable for exoelectrogenic bacteria to thrive. In this study, we combined a BES with an aerobic trickling filter (TF) reactor for wastewater treatment and found that the BES-TF setup could produce electricity with a coulombic efficiency of up to 15% from artificial wastewater, even under aerobic conditions. The microbial communities within biofilms formed at the anodes of BES-TF reactors were investigated using high throughput 16S rRNA gene sequencing. Efficiency of reduction in chemical oxygen demand and total nitrogen content of wastewater using this system was >97%. Bacterial community analysis showed that exoelectrogenic bacteria belonging to the genera Geobacter and Desulfuromonas were dominant within the biofilm coating the anode, whereas aerobic bacteria from the family Rhodocyclaceae were abundant on the surface of the biofilm. Based on our observations, we suggest that BES-TF reactors with biofilms containing aerobic bacteria and anaerobic exoelectrogenic bacteria on the anodes can function in aerobic environments.
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Boltz, Joshua P., Barth F. Smets, Bruce E. Rittmann, Mark C. M. van Loosdrecht, Eberhard Morgenroth i Glen T. Daigger. "From biofilm ecology to reactors: a focused review". Water Science and Technology 75, nr 8 (2.02.2017): 1753–60. http://dx.doi.org/10.2166/wst.2017.061.
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Biofilms are complex biostructures that appear on all surfaces that are regularly in contact with water. They are structurally complex, dynamic systems with attributes of primordial multicellular organisms and multifaceted ecosystems. The presence of biofilms may have a negative impact on the performance of various systems, but they can also be used beneficially for the treatment of water (defined herein as potable water, municipal and industrial wastewater, fresh/brackish/salt water bodies, groundwater) as well as in water stream-based biological resource recovery systems. This review addresses the following three topics: (1) biofilm ecology, (2) biofilm reactor technology and design, and (3) biofilm modeling. In so doing, it addresses the processes occurring in the biofilm, and how these affect and are affected by the broader biofilm system. The symphonic application of a suite of biological methods has led to significant advances in the understanding of biofilm ecology. New metabolic pathways, such as anaerobic ammonium oxidation (anammox) or complete ammonium oxidation (comammox) were first observed in biofilm reactors. The functions, properties, and constituents of the biofilm extracellular polymeric substance matrix are somewhat known, but their exact composition and role in the microbial conversion kinetics and biochemical transformations are still to be resolved. Biofilm grown microorganisms may contribute to increased metabolism of micro-pollutants. Several types of biofilm reactors have been used for water treatment, with current focus on moving bed biofilm reactors, integrated fixed-film activated sludge, membrane-supported biofilm reactors, and granular sludge processes. The control and/or beneficial use of biofilms in membrane processes is advancing. Biofilm models have become essential tools for fundamental biofilm research and biofilm reactor engineering and design. At the same time, the divergence between biofilm modeling and biofilm reactor modeling approaches is recognized.
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KOZAK, Melike, Serdar GÖÇER, Ahmet DUYAR, İrem AYRANPINAR, Emre Oğuz KÖROĞLU i Kevser CIRIK. "INVESTIGATION OF BIOFILM FORMATION ON KALDNES K1". Kahramanmaraş Sütçü İmam Üniversitesi Mühendislik Bilimleri Dergisi 25, nr 4 (3.12.2022): 565–69. http://dx.doi.org/10.17780/ksujes.1137084.
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The moving bed biofilm reactor (MBBR) has proven to be an effective system for the treatment of municipal and industrial wastewater. The main operating mechanism of moving bed biofilm reactors (MBBR) is the growth of attached biomass in biofilm carriers in the bioreactor with mixing provided by diffusers in aerobic bioreactors or mechanical stirrers in anoxic/anaerobic bioreactors. Biofilm formation is a complex process affected by microbial composition and properties.
In this study, biofilm formation performance on Kaldnes K1 was investigated in two moving bed biofilm reactors (AnMBBR1 and AnMBBR2) using textile wastewater. Both MBBRs with a 40% fill rate were operated with a 6-hour hydraulic retention time (HRT). AnMBBR1 was operated under anaerobic conditions while AnMBBR2 was operated at different aeration rates (0.001-0.004 m3 air/m3reactor). The highest biomass concentration was observed in AnMBBR2 with a reactor aeration ratio of 0.004 m3air/m3reactor, corresponding to 4062 mg/L. The results showed that limited aeration improved biofilm formation on biofilm carriers rather than anaerobic conditions.
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Hirata, Akira, Haeng-Seog Lee, Satoshi Tsuneda i Tomotake Takai. "Treatment of photographic processing wastewater using anaerobic-aerobic biofilm reactor". Water Science and Technology 36, nr 12 (1.12.1997): 91–99. http://dx.doi.org/10.2166/wst.1997.0435.
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Two types of anaerobic-aerobic biofilm processes were applied to the treatment of the photographic processing wastewater. Two-phase fixed bed reactor packed with sponge cubic media and completely mixing three-phase fluidized bed reactor, respectively, were used as an anaerobic and aerobic biofilm reactors. One of the aerobic biofilm reactors was packed with cement balls (CB) made by crushed cement particles, and another packed with biological activated carbon (BAC). The fivefold diluted photographic processing wastewater, from which Ag had been removed previously, was used as an influent (BOD 5,700 g/m3, CODcr 17,000 g/m3, T-N 2,600 g/m3). During long-term continuous biological treatment, BOD values in effluent decreased gradually and reached 280 g/m3, which could fulfill the sewage discharge control value in Japan (BOD < 600 g/m3). It took more than one year to acclimatize the sludge and to get the effective microorganisms for degrading the compounds in the photographic processing wastewater. However, pH values in the aerobic biofilm reactors fell down to 3∼4. This was possibly because thiosulfate (5,700 g/m3) in the photographic processing wastewater was almost oxidized to sulfate by sulfur-oxidizing bacteria. For the purpose of obtaining higher BOD removal efficiency, pH in the aerobic biofilm reactor was adjusted to 7 using pH controller. As a result, BOD removal ratio was gradually improved, and the sewage discharge control value was steadily achieved after 181 days. The number of bacteria in the anaerobic biofilm reactor and the aerobic biofilm reactor with pH controller were 6.0×109 N/mL and 1.1×108 N/mL, respectively.
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Gönenç, I. E., D. Orhon i B. Beler Baykal. "Application of Biofilm Kinetics to Anaerobic Fixed Bed Reactors". Water Science and Technology 23, nr 7-9 (1.04.1991): 1319–26. http://dx.doi.org/10.2166/wst.1991.0584.
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Two basic phenomena, reactor hydraulics and mass transport through biofilm coupled with kinetic expressions for substrate transformations were accounted for in order to describe the soluble COD removal mechanism in anaerobic fixed bed reactors. To provide necessary verification, experimental results from the long term operation of the pilot scale anaerobic reactor treating molasses wastewater were used. Theoretical evaluations verified by these experimental studies showed that a bulk zero-order removal rate expression modified by diffusional resistance leading to bulk half-order and first-order rates together with the particular hydraulic conditions could adequately define the overall soluble COD removal mechanism in an anaerobic fixed bed reactor. The experimental results were also used to determine the kinetic constants for practical application. In view of the complexity of the phenomena involved it is found remarkable that a simple simulation model based on biofilm kinetics is a powerful tool for design and operation of anaerobic fixed bed reactors.
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Comett, I., S. Gonzalez-Martinez i P. Wilderer. "Treatment of leachate from the anaerobic fermentation of solid wastes using two biofilm support media". Water Science and Technology 49, nr 11-12 (1.06.2004): 287–94. http://dx.doi.org/10.2166/wst.2004.0863.
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Biofilms growing on different carrier media have a different response to the nutrients contained in wastewater. Biofilms have proven to be an alternative to the treatment of wastewater containing higher concentrations of contaminants. The main objective of this research was to compare two biofilm support media for the treatment of leachate from the anaerobic fermentation of solid wastes. The removal of organic matter and ammonia was achieved in two fixed bed biofilm reactors containing Kaldnes® and Linpor® support materials with specific surface areas of 490 and 270 m2/m3, respectively, and operating under the sequencing batch procedure during 204 days. The Linpor reactor achieved higher total COD removal than the Kaldnes reactor (47% and 39%, respectively). Linpor was shown to be less sensitive to influent COD changes than Kaldnes. The effluent total COD values of Kaldnes were higher than Linpor. The dissolved COD removal was 21% for both reactors. The average ammonia removal for Linpor was 72% and 42% for Kaldnes. The matrix of Linpor allows higher concentrations of microorganisms (as dry mass) than Kaldnes. The dry mass concentration was related to the "active" exposed surface area of the biofilm. This is considered to be the cause for the better performance of Linpor when compared with Kaldnes.
11
Raskin, Lutgarde, Rudolf I. Amann, Lars K. Poulsen, Bruce E. Rittmann i David A. Stahl. "Use of ribosomal RNA-based molecular probes for characterization of complex microbial communities in anaerobic biofilms". Water Science and Technology 31, nr 1 (1.01.1995): 261–72. http://dx.doi.org/10.2166/wst.1995.0057.
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The use of ribosomal RNA (rRNA) probe technology for the characterization of complex microbial communities is reviewed and illustrated by discussing the results of a long-term study of four anaerobic fixed-bed biofilm reactors. Two distinct approaches were used to characterize the microbial community structure in these biofilm reactors. The first used a collection of phylogenetically defined oligonucleotide rRNA probes for methanogens and sulfate-reducing bacteria (SRB) to quantify their populations. Population abundance was linked to the functional behavior of the biofilm reactor community by determining the effluent concentrations of the substrates, intermediates, and final products of microbial metabolism. This analysis indicated that the presence of SRB (especially Desulfovibrio-species) was not dependent upon the presence of sulfate. Methanobacteriales-species were the major competitors for hydrogen with these SRB in the absence of sulfate. The second approach involved selective amplification, cloning, sequencing, and whole cell hybridization to identify, visualize, and isolate a biofilm community member (strain PT-2). Subsequently, it was determined that the growth rate of strain PT-2 was significantly higher in young biofilms than in established biofilms.
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Chen, Yingwen, Jinlong Zhao, Kai Li i Shitao Xie. "A novel fast mass transfer anaerobic inner loop fluidized bed biofilm reactor for PTA wastewater treatment". Water Science and Technology 74, nr 5 (16.06.2016): 1088–95. http://dx.doi.org/10.2166/wst.2016.285.
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In this paper, a fast mass transfer anaerobic inner loop fluidized bed biofilm reactor (ILFBBR) was developed to improve purified terephthalic acid (PTA) wastewater treatment. The emphasis of this study was on the start-up mode of the anaerobic ILFBBR, the hydraulic loadings and the operation stability. The biological morphology of the anaerobic biofilm in the reactors was also analyzed. The anaerobic column could operate successfully for 46 days due to the pre-aerating process. The anaerobic column had the capacity to resist shock loadings and maintained a high stable chemical oxygen demand (COD) and terephthalic acid removal rates at a hydraulic retention time of 5–10 h, even under conditions of organic volumetric loadings as high as 28.8 kg COD·m−3.d−1. The scanning electron microscope analysis of the anaerobic carrier demonstrated that clusters of prokaryotes grew inside of pores and that the filaments generated by pre-aeration contributed to the anaerobic biofilm formation and stability.
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Mendoza, Marisol Vergara, i Rodrigo Torres Sáez. "Modelling biofilm anaerobic reactor with effluent from hydrolytic/acidogenic reactor as substrate". Water Science and Technology 79, nr 8 (15.04.2019): 1534–40. http://dx.doi.org/10.2166/wst.2019.152.
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Abstract This work presents modelling of an anaerobic biofilm reactor using ceramic bricks as support. The results were compared with the experimental data. It was observed that the substrate concentration curves showed the same tendency. The methane formation curves showed significant differences. The substrate removal efficiency was 83%. In the steady state, the experimental data were higher than the model, from the result the substrate degrading bacteria grew enough to reach biofilm and that the effect of the shear stress was more significant as the biofilm increased in thickness. To the methane production, the model in steady state reached a maximum value of 0.56 m3 CH4/m3 *d and the experimental data reached 0.42 (m3 CH4/m3 * d). The biofilm thickness calculated by the model was 14 μm.
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Fuentes, M., N. J. Scenna, P. A. Aguirre i M. C. Mussati. "ANAEROBIC BIOFILM REACTOR MODELING FOCUSED ON HYDRODYNAMICS". Chemical Engineering Communications 195, nr 6 (13.02.2008): 600–621. http://dx.doi.org/10.1080/00986440701555399.
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McHugh, S., G. Collins, T. Mahony i V. O'Flaherty. "Biofilm reactor technology for low temperature anaerobic waste treatment: microbiology and process characteristics". Water Science and Technology 52, nr 7 (1.10.2005): 107–13. http://dx.doi.org/10.2166/wst.2005.0188.
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The microbial composition, methanogenic activity and architecture of particulate and fixed biofilms within four anaerobic hybrid reactors, R1–R4, operating at psychrophilic temperatures were investigated. The reactors treated low-strength (1 g COD l−1; R1) and high-strength (10 g COD l−1; R2–R4) wastewaters from the food-processing sector (R1, R2 – whey; R3 – sucrose; R4 – volatile fatty acids). Successful start-up and long-term psychrophilic operation was observed for all four reactors, with COD removal efficiencies of 80–99% achieved at 12–20 °C at organic loading rates of 1.3–20 kg COD m−3 d−1. The formation and maintenance of a well-settling granular sludge bed and an attached biofilm were shown to occur under psychrophilic conditions, an important consideration for the successful implementation of low temperature biofilm reactor technology. Culture-independent molecular techniques (terminal restriction fragment length polymorphism, clone library analysis and 16S rRNA gene sequencing) revealed that microbial population structure could be a key factor in reactor performance, with changes in the community structure of the three high-strength reactors preceding granular instability and a subsequent decline in COD removal efficiency. Biomonitoring of microbial population structure and dynamics within anaerobic reactors may, therefore, allow for the early recognition of potential operational problems.
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Araujo, J. C., G. Brucha, J. R. Campos i R. F. Vazoller. "Monitoring the development of anaerobic biofilms using fluorescent in situ hybridization and confocal laser scanning microscopy". Water Science and Technology 41, nr 12 (1.06.2000): 69–77. http://dx.doi.org/10.2166/wst.2000.0243.
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In this study we investigated the development of anaerobic biofilm using a laboratory reactor. We were especially interested in comparing the organization of anaerobic cells (particularly those that are very common in domestic sewage sludge) in a hydrophilic (glass) versus a hydrophobic (polypropylene) surface. Fluorescent in situ hybridization (FISH) with domain and group specific probes directed against 16S ribosomal RNA were used to quantify microbial composition in the biofilm. FISH and confocal laser scanning microscopy (CLSM) were used to elucidate spatial distribution of microbes in the biofilms. Two experiments were carried out, one with pure methanogenic organisms and the other with a microbial anaerobic consortium. The pure methanogen cultures, Methanobacterium formicicum (DSM 1535); Methanosaeta concilli (DSM 3671) and Methanosarcina barkeri (DSM 800) were used to seed the modified Robbins Device (MRD) to allow the development of biofilms on polypropylene and glass surfaces during the 9-days experiment. The results showed that all the three species were colonizing both surfaces after two and nine days of experimental period. In another experiment, with polypropylene coupons only, MRD was seeded with a microbial anaerobic consortium and biofilm formation was studied during 11 days. At the end of this period, the biofilms generated were of uneven thickness with areas of minimal or no surface coverage and areas where the biofilm attained a thickness of 7.0 to 9.0 μm as revealed by CLSM. The results showed that the modified Robbins Device together with the fluorescent in situ hybridization and confocal laser scanning microscopy are suitable tools to study anaerobic biofilm development in different kinds of support materials.
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Jahren, Sigrun J., Jukka A. Rintala i Hallvard Ødegaard. "Anaerobic Thermophilic (55°C) Treatment of TMP Whitewater in Reactors Based on Biomass Attachment and Entrapment". Water Science and Technology 40, nr 11-12 (1.12.1999): 67–75. http://dx.doi.org/10.2166/wst.1999.0696.
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Thermomechanical pulping (TMP) whitewater was treated in thermophilic (55°C) anaerobic laboratory-scale reactors using three different reactor configurations. In all reactors up to 70% COD removals were achieved. The anaerobic hybrid reactor, composed of an upflow anaerobic sludge blanket (UASB) and a filter, gave degradation rates up to 10 kg COD/m3d at loading rates of 15 kg COD/m3d and hydraulic retention time (HRT) of 3.1 hours. The anaerobic multi-stage reactor, consisting of three compartments, each packed with granular sludge and carrier elements, gave degradation rates up to 9 kg COD/m3d at loading rates of 15-16 kg COD/m3d, and HRT down to 2.6 hours. Clogging and short circuiting eventually became a problem in the multi-stage reactor, probably caused by too high packing of the carriers. The anaerobic moving bed biofilm reactor performed similar to the other reactors at loading rates below 1.4 kg COD/m3d, which was the highest loading rate applied. The use of carriers in the anaerobic reactors allowed short HRT with good treatment efficiencies for TMP whitewater.
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Rodgers, M., i D. Burke. "Nitrogen removal using a vertically moving biofilm system". Water Science and Technology 47, nr 1 (1.01.2003): 71–76. http://dx.doi.org/10.2166/wst.2003.0019.
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The aim of this laboratory study was to establish the efficacy of a new experimental biofilm system for the removal of nitrogen from synthetic wastewater. The system consisted of six reactors in series: one anaerobic, one anoxic and four aerobic reactors. In both the anaerobic and anoxic reactors, a plastic cuboid module was repeatedly moved up and down in the wastewater, while being totally submerged at all times. In each of the aerobic reactors, an identical module to that used in the anaerobic and anoxic reactors was intermittently and repeatedly immersed in and lifted out of the wastewater. All the individual reactors had a bulk fluid volume of 28.2 litres and the average temperature of the wastewater was about 10°C. Each module consisted of crossflow corrugated plastic sheets with a surface area of 1.824 m2. The nitrate recycle flow from the fourth aerobic tank to the anoxic tank was twice the inflow to that tank. In the anoxic reactor, filtered COD was removed at an average rate of 2.22 kg COD/m3.d and nitrate-nitrogen was denitrified at a rate of 0.42 kg NO3-N/m3.d. The average nitrification rate in the second aerobic reactor was 0.12 kg NH4-N/m3.d. The new biofilm system was simple to construct and operate.
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García-Morales, J. L., L. I. Romero i D. Sales. "Influence of operational conditions on biofilm specific activity of an anaerobic fluidized bed reactor". Water Science and Technology 47, nr 5 (1.03.2003): 197–200. http://dx.doi.org/10.2166/wst.2003.0318.
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A key parameter in water and wastewater treatment technology is the biomass activity in terms of substrate removal ability. The effects of organic load rate and percentage of bed expansion on biofilm specific methanogenic activity were determined in an anaerobic fluidized bed reactor treating wine-distillery wastes in the thermophilic range (55°C). The proposed activity tests are highly reproducible: an experiment with three identical tests has shown that the standard deviation with respect to the mean values is less than 3%. Specific tests are applied to measure the maximum methanogenic activities of the biomass carrier in lab-scale anaerobic biofilm reactors. These tests have been successfully applied for monitoring the support colonization process and the evolution of biofilm activity in reactors, anaerobic filter and fluidized bed, with different operating conditions. The results show a dependence between the percentage of bed expansion and the specific activity of methanogenic microbiote on biofilm. There is a relationship between the percentage of bed expansion, the shear stress on the biofilm and the hydrodynamic conditions in the system. Initial biofilm detachment can be compensated with the increase of biomass and of its activity due to the reduction of the substrate diffusional limitations to the microorganism growth inside the support pores.
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Mendonça, N. M., C. L. Niciura, E. P. Gianotti i J. R. Campos. "Full scale fluidized bed anaerobic reactor for domestic wastewater treatment: performance, sludge production and biofilm". Water Science and Technology 49, nr 11-12 (1.06.2004): 319–25. http://dx.doi.org/10.2166/wst.2004.0871.
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This paper describes the performance, sludge production and biofilm characteristics of a full scale fluidized bed anaerobic reactor (32 m3) for domestic wastewater treatment. The reactor was operated with 10.5 m.h-1 upflow velocity, 3.2 h hydraulic retention time, and recirculation ratio of 0.85 and it presented removal efficiencies of 71 ± 8% of COD and 77 ± 14% of TSS. During the apparent steady-state period, specific sludge production and sludge age in the reactor were (0.116 ± 0.033) kgVSS. kgCOD-1 and (12 ± 5)d, respectively. Biofilm formed in the reactor presented two different patterns: one of them at the beginning of the colonization and the other of mature biofilm. These different colonization patterns are due to bed stratification in the reactor, caused by the difference in local-energy dissipation rates along the reactor's height, and density, shape, etc. of the bioparticles. The biofilm population is formed mainly of syntrophic consortia among sulfate reducing bacteria, methanogenic archaea such as Methanobacterium and Methanosaeta-like cells.
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Yamashita, T., R. Yamamoto-Ikemoto i E. Sakurai. "Treatment of dye works wastewater using anaerobic–oxic biological filter reactor packed with carbon fibre and aerated with micro-bubbles". Water Science and Technology 53, nr 11 (1.05.2006): 151–61. http://dx.doi.org/10.2166/wst.2006.348.
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A new anaerobic–oxic biological filter reactor, which was packed with carbon fibre and aerated with micro-bubbles, was proposed. The reactor performance was examined using dye works wastewater compared with the activated sludge reactor. Effluent SS from the experimental reactor was significantly lower than that from the activated sludge reactor, and transparency was higher. Temperatures of the activated sludge reactor were over 35 °C and DOC removal ratios were 40–80% depending on the influent wastewater. On the other hand, the DOC removal efficiency of the experimental reactor was over 70%, when the reactor temperature was over 22 °C. In the anaerobic zone, sulphate reduction occurred predominantly and acetate was produced. In the oxic reactor, sulphur oxidation and organic removal occurred. When the amount of sulphate reduction in the anaerobic zone increased, DOC and colour in effluent decreased. The sulphate reducing activity of biofilm at 30 °C was three times higher than those at 20 °C. The sulphate reducing activity of biofilm in the oxic zone was higher than those in the anaerobic zone, meaning that the sulphate reduction-oxidation cycles were established in the biofilm of the oxic zone. Microbial community of sulphate reducing bacteria was examined by in situ hybridisation with 16S rRNA targeted oligonucleotide probes. Desulfobulbus spp. was most common sulphate reducing bacteria in the anaerobic zone. In the oxic zone, Desulfobulbus spp. and Desulfococcus spp. were observed.
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Hosseini Koupaie, E., M. R. Alavi Moghaddam i S. H. Hashemi. "Successful treatment of high azo dye concentration wastewater using combined anaerobic/aerobic granular activated carbon-sequencing batch biofilm reactor (GAC-SBBR): simultaneous adsorption and biodegradation processes". Water Science and Technology 67, nr 8 (1.04.2013): 1816–21. http://dx.doi.org/10.2166/wst.2013.061.
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The application of a granular activated carbon-sequencing batch biofilm reactor (GAC-SBBR) for treatment of wastewater containing 1,000 mg/L Acid Red 18 (AR18) was investigated in this research. The treatment system consisted of a sequencing batch reactor equipped with moving GAC as biofilm support. Each treatment cycle consisted of two successive anaerobic (14 h) and aerobic (8 h) reaction phases. Removal of more than 91% chemical oxygen demand (COD) and 97% AR18 was achieved in this study. Investigation of dye decolorization kinetics showed that the dye removal was stimulated by the adsorption capacity of the GAC at the beginning of the anaerobic phase and then progressed following a first-order reaction. Based on COD analysis results, at least 77.8% of the dye total metabolites were mineralized during the applied treatment system. High-performance liquid chromatography analysis revealed that more than 97% of 1-naphthyalamine-4-sulfonate as one of the main sulfonated aromatic constituents of AR18 was removed during the aerobic reaction phase. According to the scanning electron microscopic analysis, the microbial biofilms grew in most cavities and pores of the GAC, but not on the external surfaces of the GAC.
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Wanner, O., O. Debus i P. Reichert. "Modelling the spatial distribution and dynamics of a xylene-degrading microbial population in a membrane-bound biofilm". Water Science and Technology 29, nr 10-11 (1.10.1994): 243–51. http://dx.doi.org/10.2166/wst.1994.0767.
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In a stirred laboratory reactor a biofilm was grown on a gas-permeable silicone membrane, Xylene was added to the bulk fluid as the only carbon source and oxygen was supplied through the membrane. For 66 days the reactor was operated under varying experimental conditions. The concentrations of five components in the reactor effluent and of two in the gas outlet were measured almost daily, the biofilm thickness was determined several times. The measured time series were used to calibrate a mathematical model which calculates pH, aerobic degradation of xylene, and microbial growth, decay and conversion to inert particulate material. The calibrated model was then used to analyze the spatial distribution and dynamics of the xylene-degrading heterotrophic population in the biofilm. The analysis revealed that as long as oxygen was supplied as air heterotrophic cells only grew within a thin zone of about two hundred micrometers near the membrane. Upon the change from air to pure oxygen this zone shifted instantaneously by half of the biofilm thickness of about two millimeters towards the biofilm surface. The immediate ability of the biofilm to convert xylene in a zone which so far had been strictly anaerobic, indicates the presence of a heterotrophic population in this zone. The conclusion is that this population had been transported from the aerobic to the anaerobic zone and that transport and growth of microbial cells are processes which are equally important in biofilms.
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Kim, I., H. H. Lee, Y. C. Chung i J. Y. Jung. "High-strength nitrogenous wastewater treatment in biofilm and granule anammox processes". Water Science and Technology 60, nr 9 (1.11.2009): 2365–71. http://dx.doi.org/10.2166/wst.2009.133.
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Biofilm and granule reactors were employed to remove nitrogen via an anammox reaction applying synthetic nitrogen wastewater, whose concentration was in the range of 20 to 1,400 mg N/L as total nitrogen. A biofilm reactor was packed with non-woven fabric and a granule reactor was filled with anaerobic granular sludge taken from the brewery wastewater treatment plant. Both reactors were seeded with Planctomycetes KSU-1 and operated for 450 days. The biofilm reactor showed high NH4+-N and NO2−-N removal efficiencies of over 88% and 94%, respectively, until total nitrogen concentration was reached at 800 mg N/L. However, the biofilm reactor showed severe inhibition at over 1,000 mg N/L of total nitrogen due to nitrogen overloading. The granule reactor revealed better nitrogen removal performance than the biofilm reactor, showing high NH4+-N and NO2−-N removal efficiencies of over 90%, even at a total nitrogen concentration of 1,400 mg N/L. However, aggregation of anammox bacteria grown in the sludge bed after long-term operation resulted in the deterioration of nitrogen. The removal ratio of NH4+-N and NO2−-N was close to 1:1, suggesting other reactions related to ammonium oxidation could occur simultaneously. Free ammonia inhibition as well as NO2−-N could be significant when high-strength nitrogenous wastewater was applied.
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Power, M. E., J. C. Araujo, J. R. van der Meer, H. Harms i O. Wanner. "Monitoring sulfate-reducing bacteria in heterotrophic biofilms". Water Science and Technology 39, nr 7 (1.04.1999): 49–56. http://dx.doi.org/10.2166/wst.1999.0326.
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To a laboratory reactor, in which heterotrophic biofilms were grown on stainless steel coupons under aerobic conditions, sulfate-reducing bacteria (SRB) were added in order to elucidate whether and how these microorganisms were going to establish themselves in the biofilm. Polymerase chain reaction for the dissimilatory sulfite reductase gene and in situ hybridization with probes directed against 16S ribosomal RNA were used to detect the SRB in the biofilm. Both methods proved to be suitable tools for monitoring the SRB in these experiments, which lasted seven days. In a first series of experiments, in which the SRB were added after a biofilm had already developed, the SRB could be detected only one day after addition. No evidence was found that the SRB penetrated the biofilm and established themselves in the anaerobic niches which were present. In a second series of experiments, in which the SRB were inoculated together with a seed of aerobic heterotrophic microorganisms, the SRB were present in the biofilm over the whole biofilm depth and for the duration of the experiment. The study suggests that colonization of the steel coupons by the SRB added to the bulk fluid is hampered by the already developed biofilm, even though the heterogeneous biofilm structure and anaerobic zones in the biofilm depth offer the possibility for the SRB to penetrate and establish themselves.
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Kindaichi, Tomonori, Ikuo Tsushima, Yuji Ogasawara, Masaki Shimokawa, Noriatsu Ozaki, Hisashi Satoh i Satoshi Okabe. "In Situ Activity and Spatial Organization of Anaerobic Ammonium-Oxidizing (Anammox) Bacteria in Biofilms". Applied and Environmental Microbiology 73, nr 15 (25.05.2007): 4931–39. http://dx.doi.org/10.1128/aem.00156-07.
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ABSTRACT We investigated autotrophic anaerobic ammonium-oxidizing (anammox) biofilms for their spatial organization, community composition, and in situ activities by using molecular biological techniques combined with microelectrodes. Results of phylogenetic analysis and fluorescence in situ hybridization (FISH) revealed that “Brocadia”-like anammox bacteria that hybridized with the Amx820 probe dominated, with 60 to 92% of total bacteria in the upper part (<1,000 μm) of the biofilm, where high anammox activity was mainly detected with microelectrodes. The relative abundance of anammox bacteria decreased along the flow direction of the reactor. FISH results also indicated that Nitrosomonas-, Nitrosospira-, and Nitrosococcus-like aerobic ammonia-oxidizing bacteria (AOB) and Nitrospira-like nitrite-oxidizing bacteria (NOB) coexisted with anammox bacteria and accounted for 13 to 21% of total bacteria in the biofilms. Microelectrode measurements at three points along the anammox reactor revealed that the NH4 + and NO2 − consumption rates decreased from 0.68 and 0.64 μmol cm−2 h−1 at P2 (the second port, 170 mm from the inlet port) to 0.30 and 0.35 μmol cm−2 h−1 at P3 (the third port, 205 mm from the inlet port), respectively. No anammox activity was detected at P4 (the fourth port, 240 mm from the inlet port), even though sufficient amounts of NH4 + and NO2 − and a high abundance of anammox bacteria were still present. This result could be explained by the inhibitory effect of organic compounds derived from biomass decay and/or produced by anammox and coexisting bacteria in the upper parts of the biofilm and in the upstream part of the reactor. The anammox activities in the biofilm determined by microelectrodes reflected the overall reactor performance. The several groups of aerobic AOB lineages, Nitrospira-like NOB, and Betaproteobacteria coexisting in the anammox biofilm might consume a trace amount of O2 or organic compounds, which consequently established suitable microenvironments for anammox bacteria.
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Prakash, R., i K. J. Kennedy. "Kinetics of an anaerobic fluidized bed reactor using biolite carrier". Canadian Journal of Civil Engineering 23, nr 6 (1.12.1996): 1305–15. http://dx.doi.org/10.1139/l96-939.
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Start-up and steady state operation of anaerobic fluidized bed reactors (AFBRs) with biolite as the inert carrier material was studied. Start-up and concomitant biofilm development of AFBRs was performed using two common start-up techniques, the maximum efficiency profile (MEP) technique and the maximum load profile (MLP) technique. The MEP start-up technique increases the volumetric organic loading rates to the reactor gradually and is tied to the removal efficiency of the process. The MLP start-up technique maintains a moderately high but constant volumetric organic loading rate irrespective of reactor performance. Using sucrose-based wastewater as feed, both start-up techniques led to equally fast biofilm development and start-up times of approximately 5 weeks. However, the MEP technique resulted in more stable controlled reactor operation during the start-up period. The quick start-up confirms the high compatibility of biolite for bio-adhesion and the development of a healthy active biofilm.High concentrations of biofilm biomass achieved in AFBRs (69 g volatile biofilm solids (VBS)/L of expanded bed volume at an organic loading rate of 25 g COD/(Lùd)) allowed the successful treatment of wastewaters at high organic loading rates and organic removal efficiencies. During steady state experiments, organic removal efficiencies over 80% were obtained for organic loading rates as high as 20 g COD/(L∙d). It was found that the dependence of removal efficiency on hydraulic retention time is influenced by substrate concentration. Total biofilm yield was determined to be 0.08 g VBS/g COD removed, demonstrating the low net synthesis of solids in the AFBR. AFBRs had an average solids retention time of 150 days, corresponding to a washout factor of 0.01. Extrinsic kinetics of the AFBRs was determined to be zero order with a maximum specific utilization rate of 0.48 g COD/(g VBS∙d).AFBRs used to treat municipal landfill leachate with a BOD5:COD ratio of 0.86 achieved steady state COD removal efficiencies that ranged from 70% to 87%, depending on the reactor organic loading rate and the concentration of the leachate being treated. During leachate treatment, biofilm biomass gradually became "mineralized" as a result of precipitation of metal sulfides and carbonates. This eventually resulted in a decrease in biofilm microbial activity and the need for higher pumping rates to maintain the same degree of bed expansion. Key words: anaerobic, biological fluidized bed reactor, biolite, landfill leachate, sucrose, modeling, start-up, steady state kinetics.
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Tessele, F., G. Englert i L. O. Monteggia. "Biofilm development in down flow anaerobic fluidised bed reactors under transient conditions". Water Science and Technology 46, nr 1-2 (1.07.2002): 253–56. http://dx.doi.org/10.2166/wst.2002.0485.
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Biofilm development onto polypropylene particles (<4 mm) was studied in a laboratory-scale down flow anaerobic fluidised bed reactor. The reactor was fed with a synthetic solution containing sucrose and nutrients, and operated at 35°C during 65 days at 44% bed expansion rate and 36 h HRT. Scanning electron microscopy (SEM) monitored the biofilm development. Initial adhesion occurred within the first 6 hours and after day 44 biofilm structure was complete. The presence of attached cells morphologically similar to Methanotrix bacilli and Methanosarcina sp. was observed by Scanning Electron Microscopy (SEM). The biofilm and the carrier surface roughness were measured by atomic force microscopy (AFM) and yielded 9.1 and 75 nm respectively. Results also showed good correlation between the SEM characterisation and the conventional anaerobic reactor parameters.
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Ruiz-Treviño, F. A., S. González-Martínez, C. Doria-Serrano i M. Hernández-Esparza. "Phosphorus Release Kinetics in Biofilm Reactors". Water Science and Technology 26, nr 3-4 (1.08.1992): 567–76. http://dx.doi.org/10.2166/wst.1992.0436.
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This paper presents the kinetic analysis, using Generalized Power-Law equations to describe the results of an experimental investigation conducted on a batch submerged biofilm reactor for phosphorus removal under an anaerobic/aerobic cycle. The observed rates and amounts of phosphorus release and organic substrate uptake in the anaerobic phase leads to a kinetic model in which these two variables are dependent on each other with a non-linear behaviour and reach equilibrium values in both cases, at different times and are function of rate constants ratio. The model has a good fit with experimental data except for C uptake at anaerobic contact times longer than four hours, where other kinetics are implied. Kinetic parameters were obtained with different initial substrate concentrations, anaerobic contact cycles, and type of substrates.
30
Helness, H., i H. Ødegaard. "Biological Phosphorus Removal in a Sequencing Batch Moving Bed Biofilm Reactor". Water Science and Technology 40, nr 4-5 (1.08.1999): 161–68. http://dx.doi.org/10.2166/wst.1999.0588.
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Experiments have been carried out with biological phosphorus removal in a sequencing batch moving bed biofilm reactor (SBMBBR) with a plastic biofilm carrier (Kaldnes) suspended in the wastewater. The aim of the research leading to this paper was to evaluate biological phosphorus removal in this type of biofilm process. Biological phosphorus removal can be achieved in a moving bed biofilm reactor operated as a sequencing batch reactor. In order to achieve good and stable phosphorus removal over time, the length of the anaerobic period should be tuned to achieve near complete removal of easily biodegradable COD in the anaerobic period. The total COD-loading rate must at the same time be kept high enough to achieve a net growth of biomass in the reactor. Use of multivariate models based on UV-absorption spectra and measurements of the redox potential show potential for control of such a process.
31
Escalera, C. R., i S. Uchida. "The Performance of a Heat Exchanger Type Anaerobic Biofilm Reactor". Water Science and Technology 24, nr 5 (1.09.1991): 149–61. http://dx.doi.org/10.2166/wst.1991.0121.
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The performance of a heat exchanger-type anaerobic biofilm reactor(HEABR) was theoretically and experimentally studied. The treatment of a relatively low-strength artificial wastewater was experimentally feasible for a range of wall temperatures varying from 25° C to 37° C, inlet temperatures varying from 5° C to 15° C and loading rates varying from 0.2g-C/l.day to 0.8 g-C/l.day. Removal efficiencies in the range of 70–98% were obtained. It was found that the performance of the reactor is strongly dependent on the wall temperatures and the hydraulic retention times and that the inlet temperature effect is smaller. A reactor model was developed which considers that a consecutive reaction occurs both in the biofilm and the bulk liquid where the bacteria exist. The effects of temperature on the reaction and diffusion rates of the primary substrate and the intermediate product are also considered. A good fit between the experimental and calculated results showed the validity of the model.
32
di Biase, A., T. R. Devlin, M. Kowalski i J. A. Oleszkiewicz. "Anaerobic moving bed biofilm reactor treating brewery wastewater". Proceedings of the Water Environment Federation 2016, nr 7 (1.01.2016): 1215–23. http://dx.doi.org/10.2175/193864716819714654.
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Gonçalves, R. F., i F. Rogalla. "Continuous Biological Phosphorus Removal in a Biofilm Reactor". Water Science and Technology 26, nr 9-11 (1.11.1992): 2027–30. http://dx.doi.org/10.2166/wst.1992.0653.
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Mechanisms for biological phosphorus removal from wastewaters in an upflow granular aerated filter are evaluated. The feasibility of excess phosphorus uptake on fixed bacteria is demonstrated on pilot scale and the limiting parameters are established. The influence of the duration of anaerobic and aerobic states and of substrate loadings on phosphorus removal is verified, as well as the impact of alternating aeration on nitrification. Because bacteria are attached, hydraulic retention time of biomass and water can be separated and the exposure of bacteria to anaerobic or aerated conditions can be optimised.
34
Buffière, P., i R. Moletta. "Relations between carbon removal rates, biofilm size and density of a novel anaerobic reactor: the inverse turbulent bed". Water Science and Technology 41, nr 4-5 (1.02.2000): 253–60. http://dx.doi.org/10.2166/wst.2000.0453.
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An anaerobic inverse turbulent bed, in which the biogas only ensures fluidisation of floating carrier particles, was investigated for carbon removal kinetics and for biofilm growth and detachment. The range of operation of the reactor was kept within 5 and 30 kgCOD· m−3· d−1, with Hydraulic Retention Times between 0.28 and 1 day. The carbon removal efficiency remained between 70 and 85%. Biofilm size were rather low (between 5 and 30 μm) while biofilm density reached very high values (over 80 kgVS· m−3). The biofilm size and density varied with increasing carbon removal rates with opposite trends; as biofilm size increases, its density decreases. On the one hand, biomass activity within the reactor was kept at a high level, (between 0.23 and 0.75 kgTOC· kgVS· d−1, i.e. between 0.6 and 1.85 kgCOD·kgVS · d−1).This result indicates that high turbulence and shear may favour growth of thin, dense and active biofilms. It is thus an interesting tool for biomass control. On the other hand, volatile solid detachment increases quasi linearly with carbon removal rate and the total amount of solid in the reactor levels off at high OLR. This means that detachment could be a limit of the process at higher organic loading rates.
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Castillo, P. A., S. González-Martínez i I. Tejero. "Observations during start-up of biological phosphorus removal in biofilm reactors". Water Science and Technology 41, nr 4-5 (1.02.2000): 425–32. http://dx.doi.org/10.2166/wst.2000.0475.
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This research describes the start-up phase of Biological Phosphorus Removal (BPR) processes in two reactors. A Submerged Fix Bed Reactor (SFBR) working with a mixture of synthetic wastewater and domestic sewage and seeded with activated sludge coming from a BPR facility. A second reactor, a Biofilm Membrane Reactor (BMR), was fed with synthetic wastewater and seeded with a mixture of a pure culture of Acinetobacter lwoffi and fresh domestic sewage. It was found that Organic Loading Rates (OLR) above 5 gCOD/m2·d do not guarantee the adequate Mean Cellular Retention Time (MCRT) for the development of Poly-P organisms. Anaerobic periods should not be short during start-up phase or facultative bacteria will efficiently compete for food and, eventually, facing long aerobic periods, the Poly-P organisms may not need the phosphate mechanism to survive short anaerobic periods. Even if COD removal is observed during the anaerobic phase, further P accumulation during the aerobic phase will not be significant, unless the COD removal results in PHB formation. A loss in the BPR capacity of the Poly-P microorganisms was observed after seeding a reactor with active Poly-P organisms. The drop of BPR activity after seeding a reactor with active Poly-P organisms can be caused by the loss of genetic material due to the new environmental conditions and the new influent substrate.
36
Choi, E., Z. Yun, Y. Park, H. Lee, H. Jeong, K. Kim, H. Lee, K. Rho i K. Gil. "Extracellular polymeric substances in relation to nutrient removal from a sequencing batch biofilm reactor". Water Science and Technology 43, nr 6 (1.03.2001): 185–92. http://dx.doi.org/10.2166/wst.2001.0371.
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Experimental investigations were performed to determine the possibility of simultaneous biological nitrogen and phosphorus removal during various biofilm processes in conjunction with biofilm characterisation, especially extracellular polymeric substance (EPS). Since biological nitrogen removal requires an alternating exposure of anaerobic-anoxic-oxic conditions in the bulk liquid that surrounds the biofilm growth media, a sequencing batch reactor (SBR)-type operation was used. Various materials including expanded clay, polystyrene, polyurethane, and acrylic materials were used as the biofilm growth support medium. Simultaneous nitrogen and phosphorus removal was possible with SBR, but it was postulated that nutrient removal efficiencies varied with film thickness. Thinner biofilm promoted nitrification and phosphorus removal, but thicker biofilm enhanced denitrification and reduced phosphorus removal. EPS contents were similar regardless of support media types or biofilm configuration, but EPS contents gradually increased as the film growth continued after backwashing. EPS contents were increased with increased nitrogen removal, but it was difficult to define its relation with phosphorus removal. In addition, suspended solids removal was correlated well with the EPS content in the biofilms.
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Lanthier, M., P. Juteau, F. Lépine, R. Beaudet i R. Villemur. "Desulfitobacterium hafniense Is Present in a High Proportion within the Biofilms of a High-Performance Pentachlorophenol-Degrading, Methanogenic Fixed-Film Reactor". Applied and Environmental Microbiology 71, nr 2 (luty 2005): 1058–65. http://dx.doi.org/10.1128/aem.71.2.1058-1065.2005.
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ABSTRACT We developed a pentachlorophenol (PCP)-degrading, methanogenic fixed-film reactor by using broken granular sludge from an upflow anaerobic sludge blanket reactor. This methanogenic consortium was acclimated with increasing concentrations of PCP. After 225 days of acclimation, the reactor was performing at a high level, with a PCP removal rate of 1,173 μM day−1, a PCP removal efficiency of up to 99%, a degradation efficiency of approximately 60%, and 3-chlorophenol as the main chlorophenol residual intermediate. Analyses by PCR-denaturing gradient gel electrophoresis (DGGE) showed that Bacteria and Archaea in the reactor stabilized in the biofilms after 56 days of operation. Important modifications in the profiles of Bacteria between the original granular sludge and the reactor occurred, as less than one-third of the sludge DGGE bands were still present in the reactor. Fluorescence in situ hybridization experiments with probes for Archaea or Bacteria revealed that the biofilms were composed mostly of Bacteria, which accounted for 70% of the cells. With PCR species-specific primers, the presence of the halorespiring bacterium Desulfitobacterium hafniense in the biofilm was detected very early during the reactor acclimation period. D. hafniense cells were scattered in the biofilm and accounted for 19% of the community. These results suggest that the presence of PCP-dehalogenating D. hafniense in the biofilm was crucial for the performance of the reactor.
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Lanthier, M., B. Tartakovsky, R. Villemur, G. DeLuca i S. R. Guiot. "Microstructure of Anaerobic Granules Bioaugmented with Desulfitobacterium frappieri PCP-1". Applied and Environmental Microbiology 68, nr 8 (sierpień 2002): 4035–43. http://dx.doi.org/10.1128/aem.68.8.4035-4043.2002.
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ABSTRACT Oligonucleotide probes were used to study the structure of anaerobic granular biofilm originating from a pentachlorophenol-fed upflow anaerobic sludge bed reactor augmented with Desulfitobacterium frappieri PCP-1. Fluorescence in situ hybridization demonstrated successful colonization of anaerobic granules by strain PCP-1. Scattered microcolonies of strain PCP-1 were detected on the biofilm surface after 3 weeks of reactor operation, and a dense outer layer of strain PCP-1 was observed after 9 weeks. Hybridization with probes specific for Eubacteria and Archaea probes showed that Eubacteria predominantly colonized the outer layer, while Archaea were observed in the granule interior. Mathematical simulations showed a distribution similar to that observed experimentally when using a specific growth rate of 2.2 day−1 and a low bacterial diffusion of 10−7 dm2 day−1. Also, the simulations showed that strain PCP-1 proliferation in the outer biofilm layer provided excellent protection of the biofilm from pentachlorophenol toxicity.
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Triovanta, Ulfa, i Ridho Rinaldi. "Two-Stage Anaerobic Co-digestion of Landfill Leachate and Starch Wastes Using Anaerobic Biofilm Reactor for Methane Production". Progress in Agricultural Engineering Sciences 15, nr 1 (grudzień 2019): 53–70. http://dx.doi.org/10.1556/446.15.2019.1.4.
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Abstract The study aims to evaluate two-stage anaerobic co-digestion of leachate and starch waste using anaerobic biofilm bioreactor to enhance methane production. The anaerobic digestion process was operated under the mesophilic condition at 35 ± 1 °C. Hydraulic retention time (HRT) applied to the acidogenesis and methanogenesis reactors were 5 and 25 days, respectively. The organic loading rate (OLR) used in the process of acidogenesis was 2.91 gram volatile solid /L.day, while methanogenesis was 0.58 gram volatile solid (VS) per liter per day. Results showed that two-stage process using biofilm was an effective method for operating anaerobic co-digestion of starch waste and landfill leachate in which the system produced higher methane yield at 125.11 mL methane (CH4) per gram volatile solid (VS) added (mL.CH4/g.VS.added) in comparison to the single-stage process (20.57 mL CH4/g.VS.added) and two-stage process (77.60 mL CH4/g.VS.added) without using biofilm. Two-stage process using biofilm also effectively reduced organic matters in the culture in which the system reached 61% BOD removal in comparison to the single-stage process and two-stage process without biofilm that only had 27.6 and 39.3% BOD removal, respectively. This study suggested that the two-stage process using biofilm would be the preferred technique for treating starch waste and landfill leachate.
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Cuba, Renata Medici Frayne, i Francisco Javier Cuba Teran. "CARBOHYDRATE ENHANCED BIOFILM GROWTH IN ANAEROBIC FLUIDIZED BED REACTOR TREATING SYNTHETIC WASTEWATER". Holos Environment 10, nr 1 (24.11.2010): 54. http://dx.doi.org/10.14295/holos.v10i1.2224.
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Biofilm dynamics in anaerobic fluidized bed reactor was studied since start-up during a 600-day operation time. Specific methanogenic activity tests revealed gas production by the anaerobic biomass since 30th operation day. Scanning Electron Microscopy (SEM) micrographs permitted to verify three bacterial development stages depending on the organic loading imposed to the system. Increasing of organic loading caused methanogenic specific activity depletion due to diffusion resistance through anaerobic biofilm. With maximum organic loading of 28.5 kg COD.m-3.day-1, almost 10% of the volatile solids fixed in inert particle surface were detected as polymeric extracellular material.
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Tauber, Joseph, Daniel Möstl, Julia Vierheilig, Ernis Saracevic, Karl Svardal i Jörg Krampe. "Biological Methanation in an Anaerobic Biofilm Reactor—Trace Element and Mineral Requirements for Stable Operation". Processes 11, nr 4 (27.03.2023): 1013. http://dx.doi.org/10.3390/pr11041013.
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Biological methanation of carbon dioxide using hydrogen makes it possible to improve the methane and energy content of biogas produced from sewage sludge and organic residuals and to reach the requirements for injection into the natural gas network. Biofilm reactors, so-called trickling bed reactors, offer a relatively simple, energy-efficient, and reliable technique for upgrading biogas via ex-situ methanation. A mesophilic lab-scale biofilm reactor was operated continuously for nine months to upgrade biogas from anaerobic sewage sludge digestion to a methane content >98%. To supply essential trace elements to the biomass, a stock solution was fed to the trickling liquid. Besides standard parameters and gas quality, concentrations of Na, K, Ca, Mg, Ni, and Fe were measured in the liquid and the biofilm using ICP-OES (inductively coupled plasma optical emission spectrometry) to examine the biofilms load-dependent uptake rate and to calculate quantities required for a stable operation. Additionally, microbial community dynamics were monitored by amplicon sequencing (16S rRNA gene). It was found that all investigated (trace) elements are taken up by the biomass. Some are absorbed depending on the load, others independently of it. For example, a biomass-specific uptake of 0.13 mg·g−1·d−1 for Ni and up to 50 mg·g−1·d−1 for Mg were measured.
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Cooke, A. J., R. K. Rowe, B. E. Rittmann i I. R. Fleming. "Modeling biochemically driven mineral precipitation in anaerobic biofilms". Water Science and Technology 39, nr 7 (1.04.1999): 57–64. http://dx.doi.org/10.2166/wst.1999.0328.
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A numerical model links the build-up of mineral precipitate (primarily CaCO3) and the anaerobic activity of biofilms, which occur in granular material permeated with leachate from a municipal solid waste landfill. The model represents the porous-media flow system as a collection of elements in which each element acts as a separate, fixed-film reactor. The model represents biofilm growth for microorganisms carrying out acetogenesis of propionate and methanogenesis of acetate. It also directly links substrate utilization to mineral precipitation and accounts for the accumulation of inert biomass on the porous media at any time or position along the length of the column. Thus, the model describes the ecological interactions among fermenters, methanogens, inert biomass, and mineral precipitate. Although substrate utilization by the active microorganisms drives the entire system, mineral precipitate becomes a dominant component in the biofilm.
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Helness, H., i H. Ødegaard. "Biological phosphorus and nitrogen removal in a sequencing batch moving bed biofilm reactor". Water Science and Technology 43, nr 1 (1.01.2001): 233–40. http://dx.doi.org/10.2166/wst.2001.0053.
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Biological phosphorus and nitrogen removal in biofilm processes have a potential advantage compared to activated sludge processes, because of less vulnerability with respect to sludge loss and because biofilm processes, in general, are more compact with a smaller footprint. Experiments have been carried out in a moving bed biofilm reactor operated as a sequencing batch reactor (SBR), with simultaneous nitrification, phosphorus uptake and denitrification in the aerobic phase. In order to achieve good phosphorus and nitrogen removal, the length of the anaerobic period should be tuned to achieve near complete removal of easily biodegradable COD in the anaerobic period, and the length of the aerobic period should be long enough for complete nitrification. The total COD-loading rate must be at the same time be kept high enough to achieve a net growth of biomass in the reactor.
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Sarti, A., A. W. Lamon, A. Ono i E. Foresti. "A new device to select carriers for biomass immobilization and application in an aerobic/anaerobic fixed-bed sequencing batch biofilm reactor for nitrogen removal". Water Science and Technology 74, nr 11 (20.09.2016): 2666–74. http://dx.doi.org/10.2166/wst.2016.410.
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This study proposes a new approach to selecting a biofilm carrier for immobilization using dissolved oxygen (DO) microsensors to measure the thickness of aerobic and anaerobic layers in biofilm. The biofilm carriers tested were polyurethane foam, mineral coal (MC), basaltic gravel, and low-density polyethylene. Development of layers in the biofilm carrier surface was evaluated using a flow cell device, and DO profiles were conducted to determine the size of the layers (aerobic and anaerobic). MC was the biofilm carrier selected due to allowing the development of larger aerobic and anaerobic layers in the biofilm (896 and 1,058 μm, respectively). This ability is supposed to improve simultaneous nitrogen removal by nitrification and denitrification biological processes. Thus, as a biofilm carrier, MC was used in a fixed-bed sequencing batch biofilm reactor (FB-SBBR) for treatment of wastewater with a high ammonia concentration (100–400 mgNH4+-N L−1). The FB-SBBR (15.0 L) was filled with matrices of the carrier and operated under alternating aeration and non-aeration periods of 6 h each. At a mean nitrogen loading rate of 0.55 ± 0.10 kgNH4+-N m−3 d−1, the reactor attained a mean nitrification efficiency of 95 ± 9% with nitrite as the main product (aerobic period). Mean denitrification efficiency during the anoxic period was 72 ± 13%.
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Rim, J. M., i D. J. Han. "Process development for nitrogen removal of swine waste". Water Science and Technology 42, nr 3-4 (1.08.2000): 239–46. http://dx.doi.org/10.2166/wst.2000.0386.
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This research aims to effectively remove nutrients in swine waste by a combined process of upflow anaerobic sludge blanket (UASB) and biofilm process. For effective removal of nutrients, both anaerobic and anoxic reactors were constructed consecutively within a single anaerobic/denitrification (SAD) reactor to which aerobic reactor for nitrification was connected. The total reactor was operated within range of 0.4 to 3.1 kg COD/m3/d of organics volumetric loading rate (VLR) and the removal rates of TCOD were 80 to 95%. Ammonia nitrogen was removed over 90% in VLR of less than 0.1 kg N/m3/d but removal rate was reduced to 70% in VLR of over 0.6 kg N/m3/d. However, complete denitrification was observed in all VLRs, which might be due to the maintenance of optimal temperature, sufficient inner carbon source, and use of NOx as an electron acceptor by anaerobic and anoxic microorganisms.
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Gaul, T., S. Märker i S. Kunst. "Start-up of moving bed biofilm reactors for deammonification: the role of hydraulic retention time, alkalinity and oxygen supply". Water Science and Technology 52, nr 7 (1.10.2005): 127–33. http://dx.doi.org/10.2166/wst.2005.0191.
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Aerobic and anaerobic ammonium oxidation can be combined in a completely mixed moving bed biofilm reactor, allowing for single-stage ammonium removal from wastewater with low COD/N ratio unsuitable for conventional nitrification/denitrification processes (‘deammonification’). Mandatory preconditions are: (a) a low hydraulic retention time to wash out suspended cells competing with mass transfer limited biofilm cells for alkalinity as limiting substrate; and (b) an oxygen flux adapted to the surface loading rate to prevent complete nitrification to nitrate. pH control or ‘NH3 inhibition’ of nitrite oxidation are neither useful nor necessary. By this strategy, oxygen limited biofilms with simultaneous presence of NH4-N and NO2-N were enriched, which allowed for growth of anaerobic ammonium oxidizers. It could be demonstrated that a deammonifying reactor can be purposefully started up within a reasonable span of time and without prior inoculation, if this explicitly described strategy is applied. Depending on surface loading and air flow rate, N removal rates of 4–5 g N/m2 d could be achieved at DO concentrations between 1.0 and 4.0 mg/l.
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Nandy, T., i S. N. Kaul. "Biofilm Loss in Anaerobic Immobilized Fixed Bed Reactor System". Environmental Technology 23, nr 4 (kwiecień 2002): 413–19. http://dx.doi.org/10.1080/09593332508618399.
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La Motta, Enrique J., i Patricio Cascante. "Substrate Consumption Kinetics in Anaerobic Biofilm Fluidized Bed Reactor". Journal of Environmental Engineering 122, nr 3 (marzec 1996): 198–204. http://dx.doi.org/10.1061/(asce)0733-9372(1996)122:3(198).
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Ehlinger, F., J. M. Audic i G. M. Faup. "Influence of Seeding Conditions on Initial Biofilm Development during the Startup of Anaerobic Fluidized Bed Reactors". Water Science and Technology 21, nr 4-5 (1.04.1989): 157–65. http://dx.doi.org/10.2166/wst.1989.0219.
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The characterization of the biofilm of an anaerobic fluidized-bed reactor was completed under standard conditions. The distribution of the fixed protein concentration depended on the level in the reactor. The protein concentration reached 1520 µg.g−1 of support at the top of the reactor and only 1200 µg.g−1 at the bottom after 504 hours of operation but the specific activity of the biofilm was 33×10−4 µM acetate.h−1.mg−1 proteins at the bottom and only 26×10−4 µM.h−1.mg−1 at the top. The efficiency of a fluidized bed reactor and the composition of the biofilm changed with an increase of the pH from 7 to 8.5 during the seeding of the support material. Future development of the biofilm and the specific activity of the support were affected.
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Heijnen, J. J., A. Mulder, R. Weltevrede, J. Hols i H. L. J. M. van Leeuwen. "Large Scale Anaerobic-Aerobic Treatment of Complex Industrial Waste Water Using Biofilm Reactors". Water Science and Technology 23, nr 7-9 (1.04.1991): 1427–36. http://dx.doi.org/10.2166/wst.1991.0595.
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Warm concentrated industrial wastewaters are preferably treated in an anaerobic reactor for reasons of energy generation and low surplus sludge production. Problems to be solved in the practical application concern a low growth rate of the micro-organisms, their low settling rate process instability, and the need for after-treatment of the noxious anaerobic effluent which often contains NH4+ and HS−. The use of biomass immobilized on small suspended carriers (< 0.5 mm) has proven to be a suitable mean to overcome most of these problems. Results are presented on–pilot and full-scale pretreatment of industrial wastewater in an anaerobic 2-stage fluidized bed reactor for CH.-production.–laboratory and pilot scale post-treatment of the anaerobic effluent, which contains NH4+. and HS2− in an aerobic air-lift suspension reactor for the production of NO3− and SO4−.