André Mota

Continuous cultivation of photosynthetic microorganisms: Approaches, applications and future trends.

The possibility of using photosynthetic microorganisms, such as cyanobacteria and microalgae, for converting light and carbon dioxide into valuable biochemical products has raised the need for new cost-efficient processes ensuring a constant product quality. Food, feed, biofuels, cosmetics and pharmaceutics are among the sectors that can profit from the application of photosynthetic microorganisms. Biomass growth in a photobioreactor is a complex process influenced by multiple parameters, such as photosynthetic light capture and attenuation, nutrient uptake, photobioreactor hydrodynamics and gas-liquid mass transfer. In order to optimize productivity while keeping a standard product quality, a permanent control of the main cultivation parameters is necessary, where the continuous cultivation has shown to be the best option. However it is of utmost importance to recognize the singularity of continuous cultivation of cyanobacteria and microalgae due to their dependence on light availability and intensity. In this sense, this review provides comprehensive information on recent breakthroughs and possible future trends regarding technological and process improvements in continuous cultivation systems of microalgae and cyanobacteria, that will directly affect cost-effectiveness and product quality standardization. An overview of the various applications, techniques and equipment (with special emphasis on photobioreactors) in continuous cultivation of microalgae and cyanobacteria are presented. Additionally, mathematical modeling, feasibility, economics as well as the applicability of continuous cultivation into large-scale operation, are discussed.

Formation of flavor-active compounds during continuous alcohol-free beer production : the influence of yeast strain, reactor configuration, and carrier type

The aim of this study is to demonstrate the influence of production strains (bottom-fermenting Saccharomyces pastorianus and S. cerevisiae with disruption in the KGD2 gene), carrier materials (spent grains and corncobs), reactor arrangements (packed-bed and gas-lift reactors), and mixing regimes (ideally mixed and plug flow) on the formation of flavor-active compounds during alcohol-free beer production. In addition, the composition of alcohol-free beer produced on a laboratory scale was compared with those of commercial products. The results confirmed the influence of each component of the production system (yeast strain, reactor, and carrier) on flavor formation, but their individual importance was case specific. The results indicate that the interplay between the appropriate production strain, carrier material, and bioreactor design is very important in continuous immobilized cell reactors and that suitable combinations could be used to improve both system performance and product quality.

Fermentation pH in stirred tank and air-lift bioreactors affects phytase secretion by Aspergillus japonicus differently but not the particle size

Abstract Phytases are mainly produced by filamentous fungi and have great potential for biotechnological use in animal feed treatment, because this enzyme hydrolyzes ester bonds of the phytic acid releasing inositol and inorganic phosphate. The aim of this work was to evaluate the effect of pH on the production of phytase by Aspergillus japonicus in two different bioreactors, known to have different mixing patterns—stirred tank and air-lift bioreactors. The maximum phytase production—53 U/mL—was obtained at 120 h in the stirred tank while in the air-lift the maximum value was 41 U/mL, observed at 144 h. In fermentations evaluated at controlled pH values (3.5, 6.0, and 7.5), the stirred tank was more efficient for production of phytase than the air-lift. Under these conditions, the highest value was measured at 24 h and pH 3.5. These results were not closely related to fungi particle size, because hyphae with a similar diameter (0.51–0.63 mm) and sphericity (0.78–0.87 mm) secreted different amounts of phytase under the conditions studied.

Lead (II) Removal from Contaminated Soils by Electrokinetic Remediation Coupled with Modified Eggshell Waste

Electrokinetic remediation deserves particular attention in soil treatment due to its peculiar advantages, including the capability of treating fine and low permeability materials, and achieving consolidation, dewatering and removal of salts and inorganic contaminants like heavy metals in a single stage. In this study, the remediation of artificially lead (II) contaminated soil by electrokinetic process, coupled with Eggshell Inorganic Fraction Powder (EGGIF) permeable reactive barrier (PRB), was investigated. An electric field of 2 V cm-1was applied and was used an EGGIF/soil ratio of 30 g kg-1 of contaminated soil for the preparation of the permeable reactive barrier (PRB) in each test. It was obtained high removal rates of lead in both experiments, especially near the cathode. In the normalized distance to cathode of 0.2 it was achieved a maximum removal rate of lead (II) of 68, 78 and 83% in initial lead (II) concentration of 500 mg-1, 200 mg-1 and 100 mg-1, respectively. EGGIF (Eggshell Inorganic Fraction) proved that can be used as permeable reactive barrier (PRB) since in all the performed tests were achieved adsorptions yields higher than 90%.

Development of Bioplastic Film for Application in the Footwear Industry

There is a growing interest in the use of biodegradable polymers that can help minimize the environmental impact of plastics. Biopolymers have been considered the most promising materials for this purpose. However, they generally have poorer mechanical properties. Starch is a low-cost polysaccharide derived from agricultural plants. To improve starch processing, the molecular order within the granules must be destroyed. This is generally achieved by heating the granular starch mixed with plasticizers. With this process, a conversion of the biopolymer’s molecular structure into thermoplastic starch is obtained. In this way, much of the starch changes from a crystalline structure to an amorphous structure. Of the various plasticizers used, the most common are polyols, in which glycerol is included, allowing a good structuring, although it induces the phenomenon of recrystallization. Four bioplastics were developed, based on corn flour, which differed in thickness (0.25 mm and 0.45 mm, on average), with and without a natural pine resin. Regarding the tests carried out in bioplastics, it was concluded that the bioplastic with 0.25 mm and with resin is the one that presents a greater transparency and a greater tensile strength. In turn, the bioplastic with the highest elongation was the one presenting 0.45 with resin. It was also concluded that up to a certain thickness of bioplastic (0.34 mm), the resin adds a certain resistance, from which it withdraws. Through the FTIR analysis, it was confirmed that the resin provides transparency to the bioplastic and that it causes interference in the bonds between the starch and the glycerol.

Waste-to-Energy Technologies Applied for Refuse Derived Fuel (RDF) Valorisation

Refuse Derived Fuel (RDF) is a solid fuel made after basic processing steps or techniques that increase the calorific value of municipal solid waste (MSW), commercial or industrial waste materials. Therefore, energy production from RDF can provide economic and environmental benefits as it reduces the amount of wastes sent to landfill and allows the energy recovery from a renewable source.

Potential of exhausted olive pomace for gasification

The research work here presented is related to the activities included in the project proposal ELAC2014/BEE0364, with the acronym SUMO - Sustainable Use of bioMass from Oleaginous processing, insert in an ERANet-LAC program and financed by FCT - Fundacao para a Ciencia e a Tecnologia.

Fundamentals of Bio-reaction Engineering

To fully understand biotechnology and bioengineering it is essential to apprehend the fundamentals of bio-reaction engineering. Bioprocesses have been applied for thousands of years, but only in the past century did they become the target of research studies that established the basis of biocatalysis mechanisms. These studies boosted the biotechnology industry over the past half-century, fostering the implementation of new, sustainable, and efficient bioprocesses all over the world. Contained in this chapter are the basic concepts of biocatalyst (cell and enzymes) kinetics and the main bioreactor types and their operation modes, presenting also a comprehensive approach to various bio-reaction monitoring and control strategies.

Nonmechanically Agitated Bioreactors

Bubble column and airlift reactors are normally the first choice in many applications, especially ones involving biomaterials. Their popularity is essentially related to the simple design, nonmechanical agitation, and satisfactory heat and mass transfer properties. However, problems related to poor mixing, scale-up, product quality, and process reproducibility are typically reported. To overcome some of these limitations, oscillatory flow reactors (OFR) have been studied. These reactors, located on the frontier of mechanically and nonmechanically agitator reactors, will be explored in this chapter. The following sections present the two most common reactors (bubble column and airlift) used in bioprocesses as well as OFRs, highlighting the advantages and limitations of these reactors and their possible contribution to future developments in biotechnology and bioengineering.

Characterization of Industrial Bioreactors (Mixing, Heat, and Mass Transfer)

Abstract Multiphase contactors are intensively used in chemical, biochemical, pharmaceutical, petrochemical, and others industries. The complexity and diversity of industrial processes implies that different types of gas–liquid contactors have been developed and constructed, such as bubble columns, airlifts, oscillatory flow reactors, pipes and tubes, mechanical agitated tanks, packed columns, plate and tray columns, spray towers, jet (loop) reactors, tubular Venturi ejectors, and motionless mixers. Mixing, heat, and mass transfer performance characterize the different reactors, and choosing the best reactor for a certain application is not an easy task. System characteristics such as viscosity, surface tension, density, and the presence or absence of solids, among others, have a high influence on the mixing process as well as heat and mass transfer. This chapter provides a general introduction to mixing, heat, and mass transfer in bioreactors. An analogy is also explored between these properties and reactor design, in particular for bubble column, airlift, and stirred-tank reactors.