Rotary Drum Bioreactor Research Articles

Changes in bioactive and volatile aroma compounds in vinegar fermented in a rotary drum bioreactor

Changes in bioactive and volatile aroma compounds in vinegar fermented in a rotary drum bioreactor

Fungal bioremediation of agricultural wastewater in a long-term treatment: biomass stabilization by immobilization strategy

Fungal bioremediation emerges as an effective technology for pesticide treatment, but its successful implementation depends on overcoming the problem of microbial contamination. In this regard, fungal immobilization on wood seems to be a promising strategy, but there are two main drawbacks: the predominant removal of pesticides by sorption and fungal detachment. In this study, agricultural wastewater with pesticides was treated by Trametes versicolor immobilized on wood chips in a rotary drum bioreactor (RDB) for 225 days, achieving fungal consolidation and high pesticide biodegradation through two main improvements: the use of a more favorable substrate and the modification of operating conditions. Fungal community dynamic was assessed by denaturing gradient gel electrophoresis (DGGE) analysis and subsequent prominent band sequencing, showing a quite stable community in the RDB, mainly attributed to the presence of T. versicolor. Pesticide removals were up to 54 % diuron and 48 % bentazon throughout the treatment. Afterwards, pesticide-contaminated wood chips were treated by T. versicolor in a solid biopile-like system. Hence, these results demonstrate that the microbial contamination constraint has definitely been overcome, and fungal bioremediation technology is ready to be implemented on a larger scale.

Maturity and stability assessment of composted tomato residues and chicken manure using a rotary drum bioreactor

ABSTRACT The efficiency of the composting process for tomato residues and chicken manure was estimated after monitoring of the rotary composting system. Physicochemical parameters and Compost Quality Index were evaluated. The tomato residues (leaves, stems, and some green and damaged fruits) were collected, cut into small pieces, moistened approximately (60–65%), and mixed with 20% chicken manure then distributed into three rotary drum bioreactors. The obtained results showed that, the temperature above 50°C was maintained for more than two days. Carbon: nitrogen (C:N) ratio was reduced from 30:1 to 19.13:1. The pH value ranged between 7 and 8.80 during the composting process, while the electrical conductivity (EC) ranged between 2.67 to 4.53 dS/m. Both compost quality parameters (Dewar and germination index) and (Solvita-CO2 and Solvita-NH3) indicated that, the final compost is stable and mature. Implications: The idea of this research revolves around assessing the maturity and stability of the compost resulting from mixing tomato residues with chicken manure, using a rotary drum bioreactor which is characterized by reducing the time of the active phase to several hours or days instead of weeks or months. Several tests related to the maturity and stability of mixture have been used to judge its quality. Also, many parameters related to this topic were monitored and discussed with many previous researches to determine the importance of benefiting from mixing the different wastes together and obtaining a good fertilizer ready for application as an agricultural substrate or a soil conditioner.

Case Study of Anaerobic Digestion Process Stability Detected by Dissolved Hydrogen Concentration

The paper presents the results of a laboratory experiment of mesophilic single-stage anaerobic digestion performed to verify the possibility of early detection of process instability and reactor overload by evaluating the course of dissolved hydrogen concentration of the main intermediate. The digestion process was run in a Terrafors IS rotary drum bioreactor for 230 days. The substrate dosed on weekdays was food leftovers from the university canteen. At an average temperature of 37 °C, an organic loading of volatiles of 0.858 kg m−3 day−1 and a theoretical retention time of 259 days, biogas production of 0.617 Nm3 kg VS−1 was achieved with a CH4 content of 51.7 vol. %. The values of the established FOS/TAC stability indicator ranged from 0.26 to 11.4. The highest value was reached when the reactor was overloaded. The dissolved hydrogen concentration measured by the amperometric microsensor ranged from 0.039–0.425 mg dm−3. Data were statistically processed using Pearson’s correlation coefficient. The correlation of the hydrogen concentration with other parameters such as the concentration of organic acids was evaluated. The value of Pearson’s correlation coefficient was 0.331 and corresponded to a p-value of 0. The results confirmed a very low limit of the hydrogen concentration at which the microbial culture, especially methanogens, was already overloaded. The amperometric microsensor proved to be rather unsuitable for operational applications due to insufficient sensitivity and short service life. The newly designed ratio of dissolved hydrogen concentration to neutralizing capacity was tested but did not work significantly better than the established FOS/TAC stability indicator.

Bioremediation by Cupriavidus metallidurans Strain MSR33 of Mercury-Polluted Agricultural Soil in a Rotary Drum Bioreactor and Its Effects on Nitrogen Cycle Microorganisms.

Nitrogen cycle microorganisms are essential in agricultural soils and may be affected by mercury pollution. The aims of this study are to evaluate the bioremediation of mercury-polluted agricultural soil using Cupriavidus metallidurans MSR33 in a rotary drum bioreactor (RDB) and to characterize the effects of mercury pollution and bioremediation on nitrogen cycle microorganisms. An agricultural soil was contaminated with mercury (II) (20–30 ppm) and subjected to bioremediation using strain MSR33 in a custom-made RDB. The effects of mercury and bioremediation on nitrogen cycle microorganisms were studied by qPCR. Bioremediation in the RDB removed 82% mercury. MSR33 cell concentrations, thioglycolate, and mercury concentrations influence mercury removal. Mercury pollution strongly decreased nitrogen-fixing and nitrifying bacterial communities in agricultural soils. Notably, after soil bioremediation process nitrogen-fixing and nitrifying bacteria significantly increased. Diverse mercury-tolerant strains were isolated from the bioremediated soil. The isolates Glutamicibacter sp. SB1a, Brevundimonas sp. SB3b, and Ochrobactrum sp. SB4b possessed the merG gene associated with the plasmid pTP6, suggesting the horizontal transfer of this plasmid to native gram-positive and gram-negative bacteria. Bioremediation by strain MSR33 in an RDB is an attractive and innovative technology for the clean-up of mercury-polluted agricultural soils and the recovery of nitrogen cycle microbial communities.

Establishment and verification of a model for the movement of pulverized sweet sorghum stalks in a rotary drum bioreactor by discrete element method

The mixing of raw materials in a rotary drum bioreactor is important for advanced solid-state fermentation technology. However, the shape, size, and other properties of pulverized sweet sorghum stalk particles are more complicated than those of the spherical particles. In this study, a soft rod-shaped discrete particle model was established and verified to simulate the mixing behavior of sweet sorghum stalk particles in a rotary drum bioreactor. We were inspired by the particle shape and established a rod-shaped particle model by investigating the influence of the shape (length–diameter ratio) and size (diameter) on the particle packing (stack height and bed porosity). We used orthogonal simulations and extremum difference analysis to determine the main factors, optimum level, and groups of other parameters. Based on calibrated parameters, twelve sets of simulations of radial mixing in the drum were performed, and the results were compared with experiments conducted under identical operating conditions. The average relative error between the simulation and the experiment was 10.95%, which indicates that they agreed well and that the simulation could predict the mixing process well.

Manufacture of a novel anisotropic bacterial nanocellulose hydrogel membrane by using a rotary drum bioreactor

Since anisotropic hydrogel membranes have great potential in tissue engineering and bioseparation, the aim of this study was to produce an anisotropic BNC hydrogel membrane for the first time with enhanced BNC productivity by using a newly designed 30-L horizontal rotary drum bioreactor. As compared with the traditional tray static cultivation, the BNC hydrogel from the rotary drum bioreactor showed anisotropic morphology, sparser network, lower dry matter content of 0.16 w/w%, thicker fiber diameter, and lower degree of polymerization that was still 1.8 times higher than cotton, and featured with much higher ultraviolet-visible light transmittance, as well as demonstrated anisotropic tensile properties, lower Young’s modulus of 0.23 MPa and compressive modulus of 0.99 kPa. The productivity of dry and wet BNC was enhanced by 1.65 times and 3.73 times, respectively. The proposed technology may not only obtain anisotropic BNC hydrogel membranes with high transparency, but also promote the BNC productivity.

RANCANG BANGUN ROTARY DRUM BIOREACTOR UNTUK PRODUKSI MICROBIAL CELLULOSE

Microbial cellulose is the result of bacterial metabolism of Acetobacter xylinum in a liquid medium used. To grow and produce optimal microbial cellulose, Acetobacter xylinum bacteria requires oxygen for metabolism of glucose. Several studies conducted to obtain optimal results as a static method, RDR, bioreactor dye and spin reactor still has weakness in the tools design. To overcome this weakness a new tool called Rotary Drum Bioreactor (RDB) has been created. The design of Rotary Drum Bioreactor particularly aimed to overcome the weaknesses of the previous studies and to determine the best treatment using RDB in better producing of microbial cellulose. The study started on the selection tools and materials that will be used in designing the RDB tools, then proceed to design the tools to be able to work with four tools simultaneously that have different speeds in each fermentor including 2, 4,6 and 8 rpm, as the treatment with three replications and untreated comparison is static fermentation. The third phase was testing tools in producing microbial cellulose and then the data were analyzed statistically using analysis of variance followed by further test of Duncan’s New Multiple Range Test (DNMRT) at 5% level. The analysis showed that the speed of 2 rpm for 6 days of fermentation gave the best results including 95.02% moisture content, wet weight of 0.62 gr/ cm2 and yield 9.92%.

Energy Analysis of a Rotary Drum Bioreactor for Composting Tomato Plant Residues

Energy produced from plant residue composting has stimulated great interest in heat recovery and utilization. Composting is an exothermic process often controlled through temperature measurements. However, energy analysis of the overall composting system, especially the rotary bioreactors, is generally not well known and very limited. This study presents detailed energy analysis in a laboratory-scale, batch-operated, rotary bioreactor used for composting tomato plant residues. The bioreactor was considered as a thermodynamic system operating under unsteady state conditions. The composting process was described, the input generated and lost energy terms as well as the relative importance of each term were quantitatively evaluated, and the composting phases were clearly identified. Results showed that the compost temperature peaked at 72 h of operation reaching 66.7 °C with a heat generation rate of 9.3 W·kg−1 of organic matter. During the composting process, the accumulated heat generation was 1.9 MJ·kg−1 of organic matter; only 4% of this heat was gained by the composting material, and 96% was lost outside the bioreactor. Contributions of thermal radiation, aeration, cylindrical, and side-walls surfaces of the reactor on the total heat loss were 1%, 2%, 69%, and 28%, respectively. The information obtained is applicable in the design, management, and control of composting operations and in improvement of bioreactor effectiveness and productivity.

Effect of passive transport of water through plasma membrane in production of extracellular enzyme.

In this article, availability and control of water in solid-state fermentation (SSF) were investigated. Based on passive transport of water through plasma membranes, a new model was proposed for calculation and control of water activities in the mixture of solids. The validity of theoretical model and accuracy of the proposed model were proved by experimental data. This model was used for production of pectinases via mixed-SSF with the aid of a rotary drum bioreactor. It was found that in case of extracellular enzyme production, the new model is in good agreement with experimental data for the control of water activities in the mixed-SSF. Exact control of water activity in SFF, the production of endo- and exo-pectinases was relatively enhanced. Based on theoretical view point, the prominence of this new model in control of water activity was also proved.

Statistical optimization of enzymatic degradation process for oil palm empty fruit bunch (OPEFB) in rotary drum bioreactor using crude cellulase produced from Aspergillus niger EFB1

Oil palm empty fruit bunch (OPEFB) was pretreated with 2% (v/v) HNO3 and degraded by Aspergillus niger EFB1 crude cellulase. Through 2 Level Factorial Design (2LFD), it was found that OPEFB concentration, temperature, incubation time, concentration of Tween 80 and agitation speed have significant effect in reducing sugar production. A standard Response Surface Methodology (RSM) design known as Central Composite Design (CCD) was used to optimize the enzymatic degradation condition of OPEFB in rotary drum bioreactor. Reducing sugar level of 1.183g/L was obtained with the following optimized degradation conditions: 1.95% (w/v) OPEFB, 0.5% (v/v) Tween 80, 55°C, 87.5rpm in the incubation period of 3 days and 16h. The optimal degradation condition improved reducing sugar production by 1.07 fold compared to that before optimization in shake flasks culture. The optimization strategy of enzymatic degradation of OPEFB inside rotary drum bioreactor led to increase in glucose, xylose, arabinose, galactose and mannose production by 3, 2.5, 1.64, 19.37 and 22.52 fold, respectively. The improvement in reducing sugar and polyoses production were comparable with the reduction in OPEFB cellulose and hemicellulose content by 89.32% and 48.17% respectively after enzymatic degradation in optimized condition.

Solid state bioconversion of oil palm empty fruit bunches for cellulase enzyme production using a rotary drum bioreactor

Bioconversion of oil palm lignocellulosic biomass in the form of empty fruit bunches (EFB) as the major substrate into cellulase enzyme was studied in the laboratory. A fungal strain, Trichoderma harzianum T2008 was used to evaluate the solid state bioconversion of EFB for cellulase production. The study was conducted in two systems: an Erlenmeyer flask (EF, 500 mL) and a horizontal rotary drum bioreactor (RDB, 50 L), designed and fabricated locally. The highest cellulase activity on the fourth day of fermentation in the EF was 8.2 filter paper activity (FPA)/gram dry solids (gds) of EFB, while its activity from the RDB was 10.1 FPA/gds on the second day of fermentation. Glucosamine, reducing sugar and pH were also determined to evaluate the substrate uptake and growth conditions during the entire fermentation period.

Solid-substrate fermentation of soybeans with Rhizopus spp.: Comparison of discontinuous rotation with stationary bed fermentation

Tempe is a soybean food obtained by stationary solid-substrate fermentation using moulds (mainly Rhizopus spp.) as starter organism. Traditionally, tempe is fermented in static layer trays or wrapped packages. Due to heat and mass transfer limitations, gradients of temperature and gas atmosphere will result. Agitated fermentation can help to level heat and mass gradients, yielding better homogeneity. This type of process will not result in traditional tempe, but in individually fermented soybeans that could be processed into food ingredients. This report deals with the comparative effect of stationary versus agitated solid-substrate fermentation of soybeans on some chemical indices of substrate modification. For agitated solid-substrate fermentation, a 450- l size rotary-drum bioreactor was designed and constructed. Of two Rhizopus spp. tested, R. microsporus tolerated agitation quite well, as judged by changes of pH, amino nitrogen, ammonia, and soluble dry matter. The other species, R. oligosporus was strongly affected by agitation. This resulted in less pH increase (difference approx. 1.5 units), lower amino nitrogen levels (30–50% of levels in static fermentation), and lower levels of water-soluble non-lipid dry matter (30–50% of levels in static fermentation) with R. oligosporus agitated fermentation of soybeans controlled at 30 and 37°C, compared to static fermentation at temperatures ranging between 25–35 and 30–40°C, respectively.