Rotating Drum Bioreactor Research Articles

Combining fungal bioremediation and ozonation for rinse wastewater treatment

In this work, agricultural rinse wastewater, which is produced during the cleaning of agricultural equipment and constitutes a major source of pesticides, was treated by fungal bioremediation and ozonation, both individually and combined in a two-stage treatment train. Three major pesticides (thiacloprid, chlortoluron, and pyrimethanil) were detected in rinse wastewater, with a total concentration of 38.47 mg C L−1. Comparing both technologies, ozonation in a stirred reactor achieved complete removal of these pesticides (720 min) while proving to be a more effective approach for reducing colour, organic matter, and bacteria. However, this technique produced transformation products and increased toxicity. In contrast, fungal bioremediation in a rotating drum bioreactor attenuated toxicity levels and did not produce such metabolites, but only removed approximately 50 % of target pesticide - hydraulic retention time (HRT) of 5 days - and obtained worse results for most of the general quality parameters studied. This work also includes a preliminary economic assessment of both technologies, revealing that fungal bioremediation was 2 times more cost-effective than ozonation. The treatment train, consisting of a first stage of fungal bioremediation followed by ozonation, was found to be a promising approach as it synergistically combines the advantages of both treatments, achieving high removals of pesticides (up to 100 %) and transformation products, while reducing operating costs and producing a biodegradable effluent. This is the first time that fungal bioremediation and ozonation technologies have been compared and combined in a treatment train to deal with pesticides in agricultural rinse wastewater.

Effect of dissolved oxygen on the degradation activity and consumption capacity of white-rot fungi

In recent decades, bioremediation using white rot fungi (WRF) has become an attractive alternative for the removal of xenobiotics from water. However, WRF are aerobic microorganisms whose degradative capacity may be reduced when operating in oxygen-restricted environments. This work determines the limiting dissolved oxygen level of Trametes versicolor in terms of degradation of two target micropollutants: bentazon and tributyl phosphate. When the dissolved oxygen concentration was set below 15 % saturation (1.3 mg O2·L−1), the results revealed a considerable decrease in degradation capacity and laccase synthesis. Hence, 15 % dissolved oxygen was established as a reference value of aerobic conditions to assess dissolved oxygen profiles in both a rotating drum bioreactor (RDB) and a fixed-bed bioreactor (FBB). Restrictive oxygen conditions were achieved after an operating period of 24 h in the RDB and an empty bed contact time of 44 min in the FBB. In addition, growth kinetics on Q. ilex wood and organic matter removal (in terms of COD) were studied, obtaining 0.059 mg ergosterol·g wood DW−1·day−1 and 16.23 mg O2·L−1·h−1, respectively. Therefore, T. versicolor has demonstrated a remarkable ability to assimilate complex carbon sources and a high micropollutant degradation activity, especially when operating in non-limiting oxygen regimes.

Fungal treatment of agricultural washing wastewater: Comparison between two operational strategies

Agricultural washing wastewater (AWW) is an important source of pesticides that, given its intrinsic characteristics, has a high potential to be treated by fungal bioremediation using white rot fungi. In the present study, two AWW treatment strategies were compared: a fluidized-bed reactor (FBR) with T. versicolor pellets and a rotating drum bioreactor (RDB) with T. versicolor immobilized on wood. The RDB effluent showed better results in all studied parameters compared to those of the FBR, including pesticide removal (87%), toxicity, laccase activity, COD, absorbance and microbial communities. Additionally, the fungal assemblage showed that T. versicolor was successfully immobilized in the RDB, which triggered a major shift in the initial community. Afterwards, solid by-products were treated in a fungal biopile-like system reaching high biodegradation rates. Therefore, this study validates the fungal RDB as a viable alternative for AWW treatment, opening up the possibility of a further in-situ and full-scale application.

Inoculation conditions improved the pectinase productivity in Aspergillus niger LB-02-SF solid-state cultivation

In this work, the pectinase production by Aspergillus niger LB-02-SF was evaluated in relation to the inoculation conditions of solid-state cultivations carried out in Becher flasks and in rotating drum bioreactor. From the inoculation by spore suspension in the concentration of 7 × 107 spore/100 g of wet medium (gwm), which is standard inoculum condition, were evaluated: different concentrations of spore suspension (from 7 × 104 to 7 × 108 spore/100 gwm), solid vegetative inoculum using 50 and 100 gwm of fermented solid medium (obtained from 48 h of A. niger cultivation in Becher flasks, in a humidified atmosphere, 30 °C) and liquid vegetative inoculum in the proportions of 5 and 10% (v/w) (obtained from 18 h of A. niger cultivation at 300 rpm, 28 °C). In comparison to the standard condition, with the use of the lowest spore concentration (7 × 104 spore/100 gwm), 100 gwm of solid vegetative inoculum and 10% (v/w) of liquid vegetative inoculum, higher pectinases productivities were observed, around 48, 42 and 85%, respectively. The results obtained indicate that the three inoculation strategies defined are alternatives to increase the enzyme productivity and to facilitate the inoculum preparation stage aimed at applying this process on an industrial scale.

Performance analysis of a laboratory scale rotating drum bioreactor for production of rhamnolipid in solid-state fermentation using an agro-industrial residue

Performance analysis of a laboratory scale rotating drum bioreactor for production of rhamnolipid in solid-state fermentation using an agro-industrial residue

Biodegradability of di-(2-ethylhexyl) phthalate by a newly isolated bacterium Achromobacter sp. RX

Di-(2-ethylhexyl) phthalate (DEHP) is a chemical plasticizer that has been commonly used in the manufacture of polyvinyl chloride. DEHP is one of the environmental pollution sources. In this study, a gram-negative strain RX bacterium utilizing DEHP as sole carbon source was isolated from activated sludge through screening test. This strain RX was identified as Achromobacter sp. RX based on its morphology, physiological properties and 16S rRNA gene sequence analysis. The results showed that the optimal conditions for the DEHP degradation were 30.0 °C and pH 7.0. The DEHP degradation induced by strain RX demonstrated nitrogen source dependent, while followed a decreasing degradation rate under the source of: NO3− > NH4+ > NO2−. The biodegradability of Achromobacter sp. RX was enhanced with Masson pine seed powder as a co-metabolic substrate and Tween-80 as a solubilizing agent. Meanwhile, the degrading kinetics analysis was performed in the condition of DEHP as sole carbon source. The DEHP degradation curves fitted well with the first-order kinetic model at 50–300 mg/L of DEHP, with the half-life ranging from 13.0 to 16.4 h. During the biodegradation of DEHP, mono-(2-ehtylhexyl) phthalate (MEHP) was firstly generated through de-esterification, followed by the formation of phthalic acid and benzoic acid after further de-esterification of MEHP. Benzoic acid was finally mineralized to CO2 and H2O. The decontamination of DEHP-contaminated soil by Achromobacter sp. RX was investigated using a rotating-drum bioreactor. Evolution of total organic carbon from the contaminated soil showed that 86.4%–91.7% of DEHP was mineralized at pH 7.0 and 30.0 °C within 96 h. Reusability of Achromobacter sp. RX and its lifetime were observed over six consecutive cycles. Thus, Achromobacter sp. RX possessed high DEHP biodegradability, which provided a good potential in dealing with DEHP-contaminated soil.

The removal of diuron from agricultural wastewaters by Trametes versicolor immobilized on pinewood in simple channel reactors

The presence of pesticides in agricultural wastewater entails harmful risks to both the environment and public health. In this study, two channel-type bioreactors with Trametes versicolor immobilized on pinewood chips were evaluated in terms of the removal efficiency of diuron from agricultural wastewater under non-sterile conditions. First, both single and successive sorption processes of diuron on pinewood chips were evaluated. The Freundlich model showed the best correlation in the sorption isotherm study (R2 = 0.993; Δq = 5.245), but according to repeated sorption experiments, the Langmuir model (R2 = 0.993; Δq = 5.757) was considered more representative. Equilibrium was reached after approximately 48 h, and the Elovich kinetic model gave the best fit with the experimental data. A packed-bed channel bioreactor (PBCB) was found to be a remarkable alternative able to remove up to 94% diuron from agricultural wastewater during 35 d. However, periodic manual mixing was required to guarantee an aerobic process, and a rotating drum bioreactor (RDB) was subsequently proposed as an enhanced version. The RDB removed up to 61% diuron during 16 d using almost 7 times lower wood dose (152 g wood·L−1) than in the PBCB (1000 g wood·L−1).

Lipase production by Aspergillus brasiliensis in solid-state cultivation of malt bagasse in different bioreactors configurations.

We evaluated the conditions to produce lipase in solid-state cultivation using a recently isolated strain of Aspergillus brasiliensis 157f in bioreactors of different configurations: static flat-bed, plugged-flow bed with forced water-saturated aeration, and pilot-scale rotating drum bioreactor, using malt bagasse as substrate. Lipase production was optimized applying experimental design analysis, which showed optima parameters defined as pH 7.7, addition of 11.3 % of soybean oil to the medium, and culture temperature of 32.7 oC, in static flat-bed. The highest enzyme activity (9.8 U.g-1 substrate) was obtained in the plugged-flow bed with forced water-saturated aeration. The fermented culture medium was lyophilized to create a solid enzymatic preparation (SEP), which was used to test the possibility of using this cheap biocatalyst in bioreactors to mediate esterification and transesterification reactions. SEP presented lipase activities of 7.35 U.g-1 substrate, indicating the possibility of further enhancing aspects of the use of such biocatalyst.

Bioconversion of agroindustrial wastes to pectinases enzyme via solid state fermentation in trays and rotating drum bioreactors

Abstract In this work, production of polygalacturonases through solid-state fermentation of orange pomace by A. niger was studied. Bench-scale pectinase productions in tray and rotating-drum bioreactors were compared. Tray bioreactor was more suitable for pectinases production; despite the fact that moisture control was much better in rotating-drum bioreactor, while agitation and watering was carried out in the fermentation. Exo- and endo-pectinases production yields in tray bioreactor were 45 and 37% higher than rotating-drum bioreactor, respectively. Moreover, to solve dryness in tray bioreactor, sugarcane bagasse was studied as a water preservative material. Comparing the obtained water sorption isotherms for bagasse and orange pomace indicated that addition of bagasse to orange pomace for preservation of water in the fermentation was a great help. This issue was experimented in tray bioreactor and it was proved that bagasse enhanced pectinases production from orange pomace. The percentage of bagasse for preservation of moisture in pectinases production was optimized. The obtained results demonstrated that addition of bagasse (40 g bagasse. g−1dry solid) to orange pomace led to 17 and 23% enhancement in exo- and endo-pectinase activities, respectively. Finally, enzyme kinetics for exo- and endo-pectinases were investigated.

Determination of Effective Parameters for Alpha-Amylase Production in a Modified Rotating Drum Bioreactor

In this study, rotating drum bioreactor (RDB), one of the most important bioreactors, used in the solid substrate fermentation was designed by adapting to slurry fermentation. Although conventional RDB is an important microbial production system in terms of preventing heat accumulation and having low shear stress on microorganisms, it is not completely adequate due to heat and mass transfer limitations and low working volume requirement. In order to minimize these problems, ceramic micro-air diffuser was used in modified RDB design. Dissolved oxygen concentration, pH, temperature, oxygen, and carbon dioxide were measured as online. Effects of seven operation parameters such as rotation speed, aeration rate, working volume, diffuser’s pore diameter, baffle size, temperature, and inoculum size on the $$\alpha $$ -amylase production in modified RDB were determined by Plackett–Burman design. The rotation speed, aeration rate, and baffle size were statistically significant parameters with low p values ( $$p < 0.05$$ ) calculated by ANOVA. The maximum value of the specific productivity ( $$50.86\,\hbox {IU\,g}^{-1}\,\hbox {h}^{-1}$$ ) was obtained at the high point ( $$+$$ 1) of the significant parameters. As a result, it has been improved an important bioreactor for the cheap enzyme production using agricultural wastes by modified RDB that can be operated at high working volumes.

Degradation of Adsorbed Azo Dye by Solid-State Fermentation: Improvement of Culture Conditions, a Kinetic Study, and Rotating Drum Bioreactor Performance

The presence of synthetic dyes in effluents leads to an environmental imbalance characterized by a decrease in photosynthetic activity and, therefore, a reduction of available oxygen, which affects all living aquatic species. To reduce this problem, a combination adsorption and biodegradation treatment strategy is proposed. In this work, Red 40 dye was adsorbed onto a low-cost waste product, followed by degradation by Trametes versicolor under solid state fermentation conditions. The principal aim of this research was to establish the best fermentation conditions using a kinetic evaluation of both degradation and laccase enzyme activity. The process was scaled-up using a rotating drum bioreactor. The best process conditions were a carbon:nitrogen ratio of 30:1, a moisture percentage of 75%, and an inductor concentration of 0.5 mM; the maximum dye degradation was 96.04%. Under these optimized conditions, the highest enzymatic activity was 8.49 U/gdm after 14 days of culture at the flask scale. Using a rotating drum bioreactor, 630 mg of azo dye was degraded after 30 days of culture. Red 40 dye degradation was confirmed using infrared spectroscopy Fourier transform infrared spectrometer and HPLC-MS techniques. The results show that the degradation percentage has a direct relation with laccase activity, and the obtained efficiency in the rotating drum bioreactor confirms the potential of this methodology for implementation at the industrial level.

The influence of biomass agitation on biogas and methane production using the high-solids thermophilic anaerobic digestion

Abstract In this study, we tested the high-solids thermophilic anaerobic digestion of separated cattle slurry solids inoculated by liquid digestate collected from the 1st stage of the wet process operated in an agricultural mesophilic biogas plant. The process without batch agitation (stirring) was carried out in a barrel bioreactor located in the incubator, whereas the process with batch agitation was carried out in a rotating drum bioreactor (rotation speed: 0.1 min−1). In both cases, the biomass batch was non-liquid and the content of total solids was 18.8 wt%. The processes were conducted discontinuously without any addition for 21 days. The total solids content of both batches decreased to about 15 wt%, with only slight liquefaction. The bulk density increased from 500 to 750 kg m−3. The highest biogas production was achieved consistently on the 7th day. During the 21-day period, the unagitated batch produced 0.120 mN 3 of biogas, and the agitated batch produced 32.5% extra. The average CH4 content in biogas from the unstirred batch amounted to 47.7 vol.%, and biogas from the stirred batch reached 46.2 vol.%. The cumulative methane production rates from the unagitated and agitated batches were 0.095 and 0.121 mN 3 kgVS −1, respectively. Thus, the agitation resulted in 28.5% higher methane yield.

Evaluation of the operating conditions for the solid-state production of pectinases by Aspergillus niger in a bench-scale, intermittently agitated rotating drum bioreactor

Pectinase production by Aspergillus niger LB-02-SF was studied in a bench-scale rotating drum bioreactor. With 30% of the bioreactor volume occupied, agitation promoted increasing fungal growth and decreasing enzyme production, whereas with 50% occupation, an opposite trend occurred. The interval between agitation events was evaluated for an occupation volume of 70%, and no difference in enzyme production was observed for the 90 and 120 min intervals; for the 60 min intervals, however, the activity was reduced. Cultivations performed without temperature control attained 45 °C and showed maximum enzyme activity almost four times superior to cultivations controlled at 30–37 °C. Air flow rates between 0.18 and 0.90 L of air per kilogram of medium per minute were evaluated for 30 and 50% of the occupation volume. Fungal growth and pectinase production were favoured by the smallest and largest occupation volumes, respectively, with an intermediate air flow. The results of this work indicate that the best conditions for biomass growth are not the best for the production of pectinases.

Mass production of Ajmalicine by bioreactor cultivation of hairy roots of Catharanthus roseus

Catharanthus roseus has been known to produce Ajmalicine which is used for treatment of circulatory disorders. Significantly low content of the drug in the natural plant necessitates development of alternative production protocols. Hairy root propagation was considered as a viable alternative. Mass cultivation of the hairy root culture was attempted in several bioreactor configurations; Bubble column, Rotating drum bioreactor, Modified Bubble column with polypropylene (PP) mesh support and Modified Bubble column with Polyurethane foam (PUF) support. Important factors like medium composition, inoculum density, illumination period and aeration rates were optimized before mass propagation of hairy roots. From the data gleaned, the cultivation in rotating drum bioreactor resulted in ajmalicine content of only 4.6±0.4mg/l. However, the ajmalicine concentration surpassed even that obtained in shake flask (with 34±2.3mg/l) in a customized bioreactor wherein the hairy roots were anchored onto a polyurethane foam, the highest reported in this scale of cultivation.

Valorization of By-Products from Palm Oil Mills for the Production of Generic Fermentation Media for Microbial Oil Synthesis.

This study demonstrates the production of a generic nutrient-rich feedstock using by-product streams from palm oil production that could be used as a substitute for commercial fermentation supplements. Solid-state fermentations of palm kernel cake (PKC) and palm-pressed fiber (PPF) were conducted in tray bioreactors and a rotating drum bioreactor by the fungal strain Aspergillus oryzae for the production of crude enzymes. The production of protease was optimized (319.3U/g) at an initial moisture content of 55%, when PKC was used as the sole substrate. The highest free amino nitrogen (FAN) production (5.6mg/g) obtained via PKC hydrolysis using the crude enzymes produced via solid-state fermentation was achieved at 50°C. Three initial PKC concentrations (48.7, 73.7, and 98.7g/L) were tested in hydrolysis experiments, leading to total Kjeldahl nitrogen to FAN conversion yields up to 27.9%. Sequential solid-state fermentation followed by hydrolysis was carried out in the same rotating drum bioreactor, leading to the production of 136.7U/g of protease activity during fermentation and 196.5mg/L of FAN during hydrolysis. Microbial oil production was successfully achieved with the oleaginous yeast strain Lipomyces starkeyi DSM 70296 cultivated on the produced PKC hydrolysate mixed with commercial carbon sources, including glucose, xylose, mannose, galactose, and arabinose.

Simultaneous Production of Amyloglucosidase and Exo-Polygalacturonase by Aspergillus niger in a Rotating Drum Reactor.

Simultaneous production of amyloglucosidase (AMG) and exo-polygalacturonase (exo-PG) was carried out by Aspergillus niger in substrate of defatted rice bran in a rotating drum bioreactor (RDB) and studied by a 31×22 factorial experimental design. Variables under study were A. niger strains (A. niger NRRL 3122 and A. niger t0005/007-2), types of inoculum (spore suspension and fermented bran), and types of inducer (starch, pectin, and a mix of both). Solid-state fermentation process (SSF) was conducted at 30°C under 60-vvm aeration for 96h in a pilot scale. Production of AMG and exo-PG was significantly affected by the fungal strain and the type of inoculum, but inducers did not trigger any significant effect, an evidence of the fact that these enzymes are constitutive. The maximum activity of exo-PG was 84Ugdm-1 whereas the maximum yield of AMG was 886.25Ugdm-1.

Phytase Production of Aspergillus Niger on Soybean Meal by Solid-State Fermentation Using a Rotating Drum Bioreactor

Abstract Soybean meal is an agro-industrial residue which is used as a substrate to produce the enzyme phytase by Aspergillusniger in solid-state fermentation. Phytase is a biocatalytic enzyme widely used in the animal feed industry. The aim of this study was to investigate the growth of A. niger and its production of phytase in two systems: 500 mL Erlenmeyer flasks (EF) and a 600 L rotating drum bioreactor (RDB). The highest phytase activity found was about 1,200 unit/g substrate dry weight in EF and 580 unit/g substrate dry weight in RDB. In solid-state fermentation it is necessary to control temperature and substrate moisture content to optimize A. niger growth and its production of phytase. This study confirmed that temperature and moisture content of substrate could be controlled to optimize the result during fermentation in a 600 L RDB. In this study, inlet air velocity was controlled at 1.5 m/s and the rotational speed at 1.0 rpm in solid-state fermentation. The crude enzyme produced by A. niger in solid-state fermentation was achieved in a 600 RDB after 36 h of fermentation. This crude enzyme was dried in a hot air oven at 50oC for 3 d prior to use in animal feed. Phytase activity was found to be 1.5-fold lower than the activity obtained before drying the crude enzyme.

Analytical Expressions of the Concentrations of Substrate, Biomass, and Ethanol for Solid‐State Fermentation in Biofuel Production

AbstractMathematical and kinetic models are discussed for anaerobic solid‐state fermentation (SSF) in rotating‐drum bioreactors (RDBs). In this study, a simple approximate analytical expression pertaining to the concentration of substrate, biomass, and ethanol is derived in terms of all parameters. These analytical results were found to be in good agreement with numerical solutions (MATLAB/SCILAB) and experimental results.

Research on the characteristic of power consumption in a novel rotating drum bioleaching reactor of different sizes

A novel rotating drum bioreactor (RDB) with the volume of 18L and 96L in our previous work has shown the potential for bioleaching processes with high solid concentration. In this paper, a larger RDB with a volume of 703L was scaled up, and effect of operation condition and baffle parameters on power consumption in the 96L and 703L RDBs was investigated. The results showed that the specific power consumption increased with the rotation speed and was insensitive to aeration rate. Meanwhile, the specific power consumption was negatively related to loading coefficient and was positively related to diameter of RDB. It was found that the power consumption increased with the increase of number and width of baffles. The mass transfer performance was most economic, when the 703L RDB was equipped with 8 baffles with a 0° angle. The mass transfer performance of the 703L RDB at the same specific power was close to that of a stirred tank bioreactor (STB) commercially used. For the Al2O3 slurry system, the specific power consumption in the 703L RDB was less than 1/3 of that in the traditional STB with the same diameter.

Fuzzy Logic Control of Rotating Drum Bioreactor for Improved Production of Amylase and Protease Enzymes by Aspergillus oryzae in Solid-State Fermentation

In this study, we compared the performance of two control systems, fuzzy logic control (FLC) and conventional control (CC). The control systems were applied for controlling temperature and substrate moisture content in a solidstate fermentation for the biosynthesis of amylase and protease enzymes by Aspergillus oryzae. The fermentation process was achieved in a 200 L rotating drum bioreactor. Three factors affecting temperature and moisture content in the solid-state fermentation were considered. They were inlet air velocity, speed of the rotating drum bioreactor, and spray water addition. The fuzzy logic control system was designed using four input variables: air velocity, substrate temperature, fermentation time, and rotation speed. The temperature was controlled by two variables, inlet air velocity and rotational speed of bioreactor, while the moisture content was controlled by spray water. Experimental results confirmed that the FLC system could effectively control the temperature and moisture content of substrate better than the CC system, resulting in an increased enzyme production by A. oryzae. Thus, the fuzzy logic control is a promising control system that can be applied for enhanced production of enzymes in solidstate fermentation.