Bottle Reactor Research Articles

Mild solar photo-Fenton: An effective tool for the removal of Fusarium from simulated municipal effluents

In this work, the efficacy of natural solar radiation (up to 21.1kJ/L of UV energy dose) combined with homogeneous iron (5 and 10mg/L Fe2+) and/or hydrogen peroxide (10 and 20mg/L) to treat a simulated municipal effluent in a solar bottle reactor was assessed. Emphasis was given on the inactivation of resistant spores with Fusarium solani serving as the test species in a matrix containing 25mg/L of dissolved organic carbon, 65mg/L of inorganic carbon and pH about 8. Processes like dark Fenton oxidation (5mg/L Fe2+ and 10mg/L H2O2 at pH 3), solar radiation alone (at 21.1kJ/L and pH 3–8) and H2O2 oxidation alone (up to 20mg/L in the dark) led to no or inadequate disinfection, thus showing the resistance of F. solani. Solar irradiation in the presence of 10mg/L peroxide led to complete inactivation (i.e. ≤2CFU/mL which is the detection limit) with 11.9kJ/L at pH 3 and 16.9kJ/L at pH 4–8, but no mineralization occurred. When the process was added 5mg/L Fe2+, complete inactivation required 17.1kJ/L at pH 3 but this was accompanied by 36% mineralization. Interestingly, doubling the concentration iron and peroxide hindered inactivation but promoted mineralization; these results demonstrate a competitive effect between spores and the effluent organic matter for hydrogen peroxide, hydroxyl radicals and other ROS and highlight the importance of the nature of the microorganism. Finally, the implications for wastewater treatment are also discussed.

Solar disinfection of fungal spores in water aided by low concentrations of hydrogen peroxide

Our previous contribution showed that Fusarium solani spores are inactivated by low amounts of hydrogen peroxide (lower than 50 mg L(-1)) together with solar irradiation in bottles. The purpose of the current study was to evaluate the effectiveness of solar H(2)O(2)/UV-Vis in distilled water and simulated municipal wastewater treatment plant effluent (SE) contaminated with chlamydospores of Fusarium equiseti in a 60 L solar CPC photo-reactor under solar irradiation. This study showed that F. equiseti chlamydospores in distilled and simulated municipal wastewater effluent were inactivated with 10 mg L(-1) of H(2)O(2) in a 60 L CPC photoreactor. F. equiseti chlamysdospore concentration decreased from 325 (±70) CFU mL(-1) to below the detection limit (DL=2 CFU mL(-1)) within five hours of solar exposure in a solar bottle reactor and from 180 (±53) CFU mL(-1) to below the detection limit in distilled water within two hours of solar irradiation in the solar CPC reactor. These results demonstrate that the use of low concentrations of hydrogen peroxide and CPC systems may be a good alternative for disinfection of resistant microorganisms in water.

Resistance of Fusarium sp spores to solar TiO2 photocatalysis: influence of spore type and water (scaling‐up results)

AbstractBACKGROUND: Common irrigation water disinfection methods, which may be unable to inactivate all types of pathogens or even become phytotoxic themselves, are not very effective in controlling phytopathogens. Water disinfection by photocatalysis is a promising irrigation‐water treatment for destroying phytopathogens without the drawbacks of conventional disinfection methods. Previous research has shown that solar photocatalytic technology can be used in the disinfection treatment of bacteria, protozoa and fungi, either through solar disinfection only. The purpose of this work was evaluate the TiO2 photocatalysis process to inactivate Fusarium spores in distilled and well water.RESULTS: This paper reports on the ability of solar photocatalysis to inactivate Fusarium spores in a solar bottle reactor and in a new 60 L compound parabolic collector (CPC) prototype reactor. Inactivation of Fusarium sp spores by titanium dioxide (Degussa P25) was evaluated in distilled and natural well water. The experiments were carried out using 5 or 6 h exposure to natural sunlight at the Plataforma Solar de Almeria (Southeast Spain). The highest Fusarium spore inactivation rate during experiments was achieved with a 30 L min−1 flow rate and 100 mg L−1 TiO2 concentration. Three different Fusarium spores (microconidia, macroconidia and chlamydospores) were individually evaluated to determine whether there were differences in resistance to the photocatalytic treatment. The results showed that chlamydospores were the most resistant, followed by macroconidia, and finally microconidia were the most sensitive.CONCLUSIONS: Microconidia, macroconidia and chlamydospores in distilled and well water were inactivated with TiO2 slurry in a 60 L CPC photoreactor, demonstrating for the first time that it is possible to scale‐up photocatalytic treatment for use and reuse of water for irrigation. Copyright © 2010 Society of Chemical Industry

Laboratory-scale method for enzymatic saccharification of lignocellulosic biomass at high-solids loadings.

BackgroundScreening new lignocellulosic biomass pretreatments and advanced enzyme systems at process relevant conditions is a key factor in the development of economically viable lignocellulosic ethanol. Shake flasks, the reaction vessel commonly used for screening enzymatic saccharifications of cellulosic biomass, do not provide adequate mixing at high-solids concentrations when shaking is not supplemented with hand mixing.ResultsWe identified roller bottle reactors (RBRs) as laboratory-scale reaction vessels that can provide adequate mixing for enzymatic saccharifications at high-solids biomass loadings without any additional hand mixing. Using the RBRs, we developed a method for screening both pretreated biomass and enzyme systems at process-relevant conditions. RBRs were shown to be scalable between 125 mL and 2 L. Results from enzymatic saccharifications of five biomass pretreatments of different severities and two enzyme preparations suggest that this system will work well for a variety of biomass substrates and enzyme systems. A study of intermittent mixing regimes suggests that mass transfer limitations of enzymatic saccharifications at high-solids loadings are significant but can be mitigated with a relatively low amount of mixing input.ConclusionEffective initial mixing to promote good enzyme distribution and continued, but not necessarily continuous, mixing is necessary in order to facilitate high biomass conversion rates. The simplicity and robustness of the bench-scale RBR system, combined with its ability to accommodate numerous reaction vessels, will be useful in screening new biomass pretreatments and advanced enzyme systems at high-solids loadings.

Photocatalytic disinfection of natural well water contaminated by Fusarium solani using TiO 2 slurry in solar CPC photo-reactors

Phytopathogenic infection of food crops with fungi such as Fusarium spp. is a major problem faced by the farming industry and it has a major economic impact through the reduction in crop yields and through the need to use chemical pesticides to control the problem. As fungi are resistant to many disinfecting agents, which may also be phytotoxic or create environmental problems, more and more effort is being invested in the development of new control techniques for phytopathogenic fungi. It has recently been demonstrated on a small scale that the Fusarium, and within it, Fusarium solani, a plant and human pathogen, is susceptible to solar photocatalytic disinfection with TiO 2 in distilled water.We report on disinfection of water contaminated by F. solani spores using a solar bottle reactor and a 14-L CPC solar photoreactor with distilled and also with natural well water. It was possible to reach high disinfection yields with different TiO 2 concentrations (from 10 to 500 mg L −1) and state flow conditions (20 L/min), at these volumes, not only in distilled, but also in natural well water. We also give the inactivation rate constant for the first stage of photocatalysis under the various experimental conditions, for selection of the best parameters for disinfecting water with phytopathogenic fungi in a future pilot treatment plant.

Effect of UV solar intensity and dose on the photocatalytic disinfection of bacteria and fungi

The purpose of this work was to study the dependence of solar photocatalytic and solar water disinfection on solar irradiation conditions under natural sunlight. This dependency was evaluated for solar photocatalysis with TiO 2 and solar-only disinfection of three microorganisms, a pure E. coli K-12 culture and two wild strains of the Fusarium genus, F. solani and F. anthophilum. Photocatalytic disinfection experiments were carried out with TiO 2 supported on a paper matrix around concentric tubes, in compound parabolic collectors (CPCs) or with TiO 2 as slurry in bottle reactors, under natural solar irradiation at the Plataforma Solar of Almería (Spain). The experiments were performed with different illuminated reactor surfaces, in different seasons of the year, and under changing weather conditions (i.e., cloudy and sunny days). All results show that once the minimum solar dose has been received, the photocatalytic disinfection efficacy is not particularly enhanced by any further increase. The solar-only disinfection turned out to be more susceptible to changes in solar irradiation, and therefore, only took place at higher irradiation intensities.

Photocatalyzed N-demethylation and degradation of methylene blue in titania dispersions exposed to concentrated sunlight

S imulated wastewaters that con tain methylene blue (MB) were bleached in a photocatalytic aqueous TiO2 dispersion illuminated by concentrated sunlight using a parabolic round concentrator reactor (PRCR). The kinetic analysis was carried out well when the temporal concentration variation was a function of the concentrated light energy irradiated. The p hotocatalyzed N-demethylation of MB takes place concurrently with photocatalytic decomposition of MB by pseudo- first-order kinetics. The dependence of the photo- decomposition kinetics on the initial concentration of MB is consistent with the Langmuir– Hinshelwood model. Elimination of TOC (total organic carbon) also occurs by pseudo- first-order kinetics prior to full bleaching of the aqueous TiO2 dispersion, after which the TOC level decreases only slightly. Also, compared with the open to air, the photodegradation of MB is not influenced by molecular oxygen bubbl ing continuously through the reactant suspensions during illumination . TiO2 loadings and flow rates markedly a ffect the degradation o f MB. Under concentrated sunlight, t he relative photonic efficiency of MB photodegradation i s ζrel=0.49 (relative to phenol) . T he efficiency ζrel for the degradation of MB is independent of photoreactor geometry (cylindrical bottle reactor versus round-bot tomed flask), of light sources (solar light concentrator versus a Hg lamp) and of the operating mode used (flow versus batch operation).

Enhanced mixing and mass transfer in a recirculation loop results in high cell densities in a roller bottle reactor.

A recirculation loop added to a large-scale roller bottle reactor resulted in high cell densities as compared to standard roller bottles. Four different mammalian cell lines reached an average maximum density equal to 5.4 x 10(6) cells /mL (sigma = 0.263), which was between 2.13 and 2.95 times greater than the densities in roller bottles without recirculation using the same cell lines. The high densities were maintained over long durations (>25 days) while the reactor operated with continuous perfusion. The increased densities are attributed to enhanced liquid mixing and oxygen transfer that occur as a result of the recirculation loop. Models were developed that describe axial liquid flow and oxygen transfer in both the sample loop and the reactor growth chamber. Axial dispersion and oxygen transfer coefficients are presented for a variety of operating conditions. The increased oxygen transfer characteristics of the reactor allow for easy scale-up of roller bottle cultures by operating at larger volumes with greater liquid depths than conventional roller bottles permit. The surface-area-to-volume ratio in the tests performed was 0.206 versus 1.16 cm(-1) in a standard roller bottle.

Effect of particle size and sodium ion concentration on anaerobic thermophilic food waste digestion

Serial basic tests were conducted for the determination of fundamental kinetics and for the actual application of kinetic parameters to food waste digestion with precise measurement of methane production. The effects of food particle size and sodium ion concentration on the anaerobic thermophilic food waste digestion process were investigated. Results of serial tests for the determination of fundamental kinetic coefficients showed the value of k (maximum substrate utilization rate coefficient) and KS (half-saturation coefficient) as 0.24 hr-1 and 700 mg/L, respectively, for non-inhibiting organic loading range. The substrate inhibition coefficient (Ki) was 1000 mg/L for inhibiting organic loading range. No inhibition effect was shown until 5 g/L of sodium ion concentration was applied to the serum bottle reactor. However, the volume of methane gas was decreased gradually to the concentrations of more than 5 g/L of sodium ion applied. All sizes of food waste particle had the same constants (A: 0.45) but the maximum substrate utilization rate constant (kHA) was inversely proportional to particle size. As average particle size increased from 1.02 mm to 2.14 mm, kHA decreased from 0.0033 hr-1 to 0.0015 hr-1. Result reveals that particle size is one of the most important factors in anaerobic food waste digestion.

Inhibition kinetics for propionate degradation using propionate-enriched mixed cultures

To study propionate inhibition kinetics, seed cultures for the experiment were obtained from a propionate-enriched steady-state anaerobic Master Culture Reactor (MCR) operated under a semi-continuous mode for over six months. The MCR received a loading of 1.0 g propionate COD/l-day and was maintained at a temperature of 35±1°C. Tests using serum bottle reactors consisted of four phases. Phase I tests were conducted for measurement of anaerobic gas production as a screening step for a wide range of propionate concentrations. Phase II was a repeat of phase I but with more frequent sampling and detailed analysis of components in the liquid sample using gas chromatography. In phase III, different concentrations of acetate were added along with 1.0 g propionate COD/l to observe acetate inhibition of propionate degradation. Finally in phase IV, different concentrations of propionate were added along with 100 and 200 mg acetate/l to confirm the effect of mutual inhibition. Biokinetic and inhibition coefficients were obtained using models of Monod, Haldane, and Han and Levenspiel through the use of non-linear curve fitting technique. Results showed that the values of kp, maximum propionate utilization rate, and Ksp, half-velocity coefficient for propionate conversion, were 0.257 mg HPr/mg VSS-hr and 200 mg HPr/l, respectively. The values of kA, maximum acetate utilization rate, and KsA, half-velocity coefficient for acetate conversion, were 0.216 mg HAc/mg VSS-hr and 58 mg HAc/l, respectively. The results of phase III and IV tests indicated there was non-competitive inhibition when the acetate concentration in the reactor exceeded 200 mg/l.

Hydrolysis of (ligno)cellulosic materials under sulfidogenic and methanogenic conditions

A Biochemical methane potential (BMP) test and Serum Bottle Reactor (SBR) test were used to compare hydrolysis (mineralization) of lignocellulosic materials under sulfidogenic and methanogenic conditions. Lignocellulosic carbon mineralization under sulfidogenic conditions was found to be more than 2 times higher than under methanogenic conditions. The percentages of lignocellulosic carbon mineralized under methanogenic condition were 18.0% and 10.71% while under sulfidogenic conditions 36.69% and 27.44% for office paper and newspaper, respectively. Although a poor linear relationship between the percentage of carbon mineralization and percentage lignin content was observed, but in general a decrease in mineralization of lignocellulosic carbon was observed with the increase in lignin content. A method based on selective inhibition of microorganism activity, by 3% toluene, was used to measure the initial rate of lignocellulosic material mineralization and the accumulation of mineralized products (i. e. sugars). Sugars linearly accumulated over time and the accumulation rates of glucose and xylose were calculated. The accumulation rates of glucose under methanogenic condition were 1.302, μM/g-dry wt hr and 0.004, μM/g-dry wt hr while under sulfidogenic condition they were 2.624, μM/g-dry wt hr and 2.279 μM/g-dry wt hr for offce and newspaper, respectively.

Improved oxygen delivery in a continuous-roller-bottle reactor

Variations to the original aeration system in a continuous roller bottle reactor of novel design have been tested and compared for optimal oxygen (O) delivery. Reactor operating parameters that affect O transfer are rotation rate, liquid-volume level, fresh-feed rate, and supplementary-aeration rate. Design modifications to enhance gas-liquid O transfer include the addition of wall baffles and center baffles. The number and location of each of these baffles are compared for their effect on k(L)a values in the reaction chamber. The liquid feed into the system has been modified to improve the axial liquid mixing and O transfer.

Inhibition kinetics for propionate degradation using propionateenriched mixed cultures

To study propionate inhibition kinetics, seed cultures for the experiment were obtained from a propionateenriched steady-state anaerobic Master Culture R°eactor (MCR) operated under a semi-continuous mode for over six months. The MCR received a loading of 1.0 g propionate COD/1-day and was maintained at a temperature of 35±1°C. Tests using serum bottle reactors consisted of four phases. Phase I tests were conducted for measurement of anaerobic gas production as a screening step for a wide range of propionate concentrations. Phase II was a repeat of phase I but with more frequent sampling and detailed analysis of components in the liquid sample using gas chromatography. In phase III, different concentrations of acetate were added along with 1.0 g propionate COD/I to observe acetate inhibition of propionate degradation. Finally in phase IV, different concentrations of propionate were added along with 100 and 200 mg acetate/l to confirm the effect of mutual inhibition. Biokinetic and inhibition coefficients were obtained using models of Monod, Haldane, and Han and Levenspiel through the use of non-linear curve fitting technique. Results showed that the values of kp, maximum propionate utilization rate, and Ksp, half-velocity coefficient for propionate conversion, were 0.257 mg HPr/mg VSS-hr and 200 mg HPr/l, respectively. The values of kA, maximum acetate utilization rate, and Ksp, half-velocity coefficient for acetate conversion, were 0.216 mg HAc/mg VSS-hr and 58 mg HAM, respectively. The results of phase III and IV tests indicated there was non-competitive inhibition when the acetate concentration in the reactor exceeded 200 mg/l.

Hydrolysis of (ligno)cellulosic materials under sulfidogenic and methanogenic conditions

A Biochemical methane potential (BMP) test and Serum Bottle Reactor (SBR) test were used to compare hydrolysis (mineralization) of lignocellulosic materials under sulfidogenic and methanogenic conditions. Lignocellulosic carbon mineralization under sulfidogenic conditions was found to be more than 2 times higher than under methanogenic conditions. The percentages of lignocellulosic carbon mineralized under methanogenic condition were 18.0% and 10.71% while under sulfidogenic conditions 36.69% and 27.44% for office paper and newspaper, respectively. Although a poor linear relationship between the percentage of carbon mineralization and percentage lignin content was observed, but in general a decrease in mineralization of lignocellulosic carbon was observed with the increase in lignin content. A method based on selective inhibition of microorganism activity, by 3% toluene, was used to measure the initial rate of lignocellulosic material mineralization and the accumulation of mineralized products (i. e. sugars). Sugars linearly accumulated over time and the accumulation rates of glucose and xylose were calculated. The accumulation rates of glucose under methanogenic condition were 1.302, μM/g-dry wt hr and 0.004, μM/g-dry wt hr while under sulfidogenic condition they were 2.624, μM/g-dry wt hr and 2.279 μ M/g-dry wt hr for offce and newspaper, respectively.

Biotransformation rates of chloroform under anaerobic conditions—II. Sulfate reduction

Biotransformation of chloroform (CF) was studied in a sulfate-reducing culture utilizing acetic acid as the primary substrate. In a chemostat, CF and its biotransformation product, dichloromethane (DCM) were transformed and CF removal efficiency of more than 96% was achieved, with influent CF concentrations up to 16.74 μM. Serum bottle reactor tests were conducted using the culture from the chemostat with an average VSS concentration of 259 mg/l. These tests showed that the culture exhibited a maximum rate of CF transformation of 16.3 μM/h corresponding to an initial CF concentration of 22.6 μM. The culture degraded CF primarily by reductive dehalogenation leading to the formation of DCM which degraded at a very slow rate compared to CF. No inhibition of acetic acid utilization was observed in the culture for CF concentrations as high as 29.3 μM. Compared to no acetic acid addition, acetic acid at 50 mg/l considerably increased the rate of CF transformation but further increase in acetic acid concentration to 200 mg/l did not affect the rate of CF biotransformation. Additional acclimation of the culture for 1 yr did not affect the rate of transformation of CF. The results indicate that the sulfate-reducing culture has much higher rates of CF transformation than a methanogenic culture, also grown on acetic acid at the same concentration.

Repression of mycelia extension from a support carrier containing immobilized growing Aspergillus oryzae

The rolling of carrier particles containing immobilized Aspergillus oryzae by rotation of the bioreactor (roller bottle reactor and roller drum reactor) resulted in the mycelial strands extending from the carrier surface being wound around the carrier particles. The prevention of mycelial extension from the support carrier led to a decrease in the viscosity of the culture broth, which subsequently resulted in improvement of the oxygen transfer rate within the beads.

Treatment of coffee waste by slurry-state anaerobic digestion

Slurries containing 20% (w/v) coffee waste solids were treated anaerobically in one- and two-phase thermophilic methane fermentation systems (53°C) with or without pH control. In one-phase methane fermentation using a roller bottle reactor, the maximum gas evolution rate of 0.87 l/l·d was achieved during treatment for 91 d. However, this one-phase methane fermentation did not yield reproducible data. In a two-phase methane fermentation system consisting of a completely stirred tank reactor type (CSTR-type) liquefaction reactor without pH control and an anaerobic fluidized bed type gasification reactor, three-repetitions of treatment were conducted. Each treatment was very stable and the average gas evolution rate per volume of the gasification reactor was about 2.4 l/l·d. Two-repetitions of treatment were then done while controlling pH in the liquefaction at more than 6. The average gas evolution rate per volume of gasification reactor was found to have increased to 10.2 l/l·d, a value which corresponded to 0.84 l/l·d per total volume, including the liquefaction reactor. It was observed that treatment in a two-phase methane fermentation could be repeated in a stable fashion even in the closed system without discharging anything but the coffee waste residues.