Continuous conversion of CO2/H2 with Clostridium aceticum in biofilm reactors

Experimental investigations on the kinetics of wastewater treatment processes in biofilms were performed in a laboratory reactor. Parallel with the kinetic experiments, the influence of the biofilm kinetics on the biofilm structure was studied at macroscopic and microscopic levels. The close interrelationship between biofilm kinetics and structural changes caused by the kinetics is illustrated by several examples. From the study, it is evident that the traditional modelling of wastewater treatment processes in biofilm reactors based on substrate removal kinetics alone will fail in many cases, due to the inevitable changes in the biofilm structure not taken into consideration. Therefore design rules for substrate removal in biofilms used for wastewater treatment must include correlations between the removal kinetics and the structure and development of the biological film.

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Phosphorus Release Kinetics in Biofilm Reactors

Water Science & Technology ◽

10.2166/wst.1992.0436 ◽

1992 ◽

Vol 26 (3-4) ◽

pp. 567-576 ◽

Cited By ~ 2

Author(s):

F. A. Ruiz-Treviño ◽

S. González-Martínez ◽

C. Doria-Serrano ◽

M. Hernández-Esparza

Keyword(s):

Phosphorus Removal ◽

Release Kinetics ◽

Phosphorus Release ◽

Organic Substrate ◽

Biofilm Reactor ◽

Substrate Uptake ◽

Biofilm Reactors ◽

Initial Substrate ◽

Linear Behaviour ◽

Substrate Concentrations

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.

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Cometabolism in biofilm reactors

Water Science & Technology ◽

10.2166/wst.1995.0048 ◽

1995 ◽

Vol 31 (1) ◽

pp. 215-225 ◽

Cited By ~ 7

Author(s):

Gerald E. Speitel ◽

Robert L. Segar

Keyword(s):

Chlorinated Solvents ◽

Packed Bed ◽

Operating Conditions ◽

Mixed Cultures ◽

Treatment Technology ◽

Hydraulic Residence Time ◽

Slow Growth Rate ◽

Biofilm Reactors ◽

Aerobic Cometabolism ◽

Degrading Bacteria

Aerobic cometabolism of chlorinated aliphatic solvents in biofilm reactors is a potential treatment technology for contaminated water and air streams. This research investigated cometabolism by pure and mixed cultures of methanotrophs and mixed cultures of phenol-degrading bacteria. Initial experiments with continuous-flow, packed-bed bioreactors proved unsuccessful; therefore, the major focus of the work was on sequencing biofilm reactors, which cycle between two modes of operation, degradation of chlorinated solvents and rejuvenation of the microbial population. Particular success was obtained with a mixed culture of phenol degraders in the treatment of chlorinated ethenes (e.g., trichloroethylene - TCE). Under the best operating conditions, 90% removal of TCE occurred at a 14-minute packed-bed hydraulic residence time. The bioreactors required only two, 1.5 h biomass rejuvenation periods per day to sustain this removal. Experiments with Methylosinus trichosporium OB3b were less successful because of the organism's slow growth rate, relatively poor ability to attach to surfaces, and its inability to successfully compete with other methanotrophs in the bioreactor environment. Overall, however, the research demonstrated the potential attractiveness of sequencing biofilm reactors in treating water contaminated with chlorinated solvents.

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Biodegradation rates of aromatic contaminants in biofilm reactors

Water Science & Technology ◽

10.2166/wst.1995.0027 ◽

1995 ◽

Vol 31 (1) ◽

pp. 117-128 ◽

Cited By ~ 8

Author(s):

Jean-Pierre Arcangeli ◽

Erik Arvin

Keyword(s):

Aromatic Hydrocarbons ◽

Competitive Inhibition ◽

Removal Rate ◽

First Order ◽

Biofilm Reactors ◽

First Order Kinetics ◽

Reducing Conditions ◽

Low Concentrations ◽

Degradation Rates ◽

Order Surface

This study has shown that microorganisms can adapt to degrade mixtures of aromatic pollutants at relatively high rates in the μg/l concentration range. The biodegradation rates of the following compounds were investigated in biofilm systems: aromatic hydrocarbons, phenol, methylphenols, chlorophenols, nitrophenol, chlorobenzenes and aromatic nitrogen-, sulphur- or oxygen-containing heterocyclic compounds (NSO-compounds). Furthermore, a comparison with degradation rates observed for easily degradable organics is also presented. At concentrations below 20-100 μg/l the degradation of the aromatic compounds was typically controlled by first order kinetics. The first-order surface removal rate constants were surprisingly similar, ranging from 2 to 4 m/d. It appears that NSO-compounds inhibit the degradation of aromatic hydrocarbons, even at very low concentrations of NSO-compounds. Under nitrate-reducing conditions, toluene was easily biodegraded. The xylenes and ethylbenzene were degraded cometabolically if toluene was used as a primary carbon source; their removal was influenced by competitive inhibition with toluene. These interaction phenomena are discussed in this paper and a kinetic model taking into account cometabolism and competitive inhibition is proposed.

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Modelling of experiments with colloidal organic matter in biofilm reactors

Water Science & Technology ◽

10.2166/wst.1994.0795 ◽

1994 ◽

Vol 29 (10-11) ◽

pp. 479-486 ◽

Cited By ~ 4

Author(s):

T. A. Larsen ◽

P. Harremoës

Keyword(s):

Mathematical Model ◽

Organic Matter ◽

Bulk Liquid ◽

Native Starch ◽

Trickling Filters ◽

Biofilm Reactors ◽

Removal Capacity

A mathematical model for the degradation of colloidal organic matter in biofilm reactors has been developed. Contradictory to existing theories, the model includes bulk liquid hydrolysis as the first important step in the degradation sequence. This leads to unexpected effects of different reactor configurations. The model was successfully verified with native starch as a model substrate. Observed differences in colloid removal capacity between trickling filters and RBC-reactors are well explained by the model.

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Hydrolysis of organic wastewater particles in laboratory scale and pilot scale biofilm reactors under anoxic and aerobic conditions

Water Science & Technology ◽

10.2166/wst.1998.0805 ◽

1998 ◽

Vol 38 (8-9) ◽

pp. 179-188 ◽

Cited By ~ 4

Author(s):

K. F. Janning ◽

X. Le Tallec ◽

P. Harremoës

Keyword(s):

Organic Matter ◽

Mass Balance ◽

Particulate Organic Matter ◽

Removal Rate ◽

Pilot Scale ◽

Laboratory Scale ◽

Synthetic Wastewater ◽

Aerobic Conditions ◽

Biofilm Reactors ◽

Hydrolysis Of

Hydrolysis and degradation of particulate organic matter has been isolated and investigated in laboratory scale and pilot scale biofilters. Wastewater was supplied to biofilm reactors in order to accumulate particulates from wastewater in the filter. When synthetic wastewater with no organic matter was supplied to the reactors, hydrolysis of the particulates was the only process occurring. Results from the laboratory scale experiments under aerobic conditions with pre-settled wastewater show that the initial removal rate is high: rV, O2 = 2.1 kg O2/(m3 d) though fast declining towards a much slower rate. A mass balance of carbon (TOC/TIC) shows that only 10% of the accumulated TOC was transformed to TIC during the 12 hour long experiment. The pilot scale hydrolysis experiment was performed in a new type of biofilm reactor - the B2A® biofilter that is characterised by a series of decreasing sized granular media (80-2.5 mm). When hydrolysis experiments were performed on the anoxic pilot biofilter with pre-screened wastewater particulates as carbon source, a rapid (rV, NO3=0.7 kg NO3-N/(m3 d)) and a slowler (rV, NO3 = 0.3 kg NO3-N/(m3 d)) removal rate were observed at an oxygen concentration of 3.5 mg O2/l. It was found that the pilot biofilter could retain significant amounts of particulate organic matter, reducing the porosity of the filter media of an average from 0.35 to 0.11. A mass balance of carbon shows that up to 40% of the total incoming TOC accumulates in the filter at high flow rates. Only up to 15% of the accumulated TOC was transformed to TIC during the 24 hour long experiment.

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The Dynamic Response of Nitrogen Transformation to the Dissolved Oxygen Variations in the Simulated Biofilm Reactor

International Journal of Environmental Research and Public Health ◽

10.3390/ijerph18073633 ◽

2021 ◽

Vol 18 (7) ◽

pp. 3633

Author(s):

Qianqian Lu ◽

Nannan Zhang ◽

Chen Chen ◽

Miao Zhang ◽

Dehua Zhao ◽

...

Keyword(s):

Dissolved Oxygen ◽

Copy Number ◽

Stable State ◽

Quantitative Relationship ◽

Nitrogen Transformation ◽

Biofilm Reactor ◽

Short Term ◽

Nirs Gene ◽

Biofilm Reactors ◽

Recovery Times

Lab-scale simulated biofilm reactors, including aerated reactors disturbed by short-term aeration interruption (AE-D) and non-aerated reactors disturbed by short-term aeration (AN-D), were established to study the stable-state (SS) formation and recovery after disturbance for nitrogen transformation in terms of dissolved oxygen (DO), removal efficiency (RE) of NH4+-N and NO3−-N and activity of key nitrogen-cycle functional genes amoA and nirS (RNA level abundance, per ball). SS formation and recovery of DO were completed in 0.56–7.75 h after transition between aeration (Ae) and aeration stop (As). In terms of pollutant REs, new temporary SS formation required 30.7–52.3 h after Ae and As interruptions, and seven-day Ae/As interruptions required 5.0% to 115.5% longer recovery times compared to one-day interruptions in AE-D and AN-D systems. According to amoA activity, 60.8 h were required in AE-D systems to establish new temporary SS after As interruptions, and RNA amoA copies (copy number/microliter) decreased 88.5%, while 287.2 h were required in AN-D systems, and RNA amoA copies (copy number/microliter) increased 36.4 times. For nirS activity, 75.2–85.8 h were required to establish new SSs after Ae and As interruptions. The results suggested that new temporary SS formation and recovery in terms of DO, pollutant REs and amoA and nirS gene activities could be modelled by logistic functions. It is concluded that temporary SS formation and recovery after Ae and As interruptions occurred at asynchronous rates in terms of DO, pollutant REs and amoA and nirS gene activities. Because of DO fluctuations, the quantitative relationship between gene activity and pollutant RE remains a challenge.

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