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[en] This paper presents a new control strategy which unifies the direct and indirect multi-scale control schemes via a double-loop control structure. This unified control strategy is proposed for controlling a class of highly nonminimum-phase processes having both integrating and unstable modes. This type of systems is often encountered in fed-batch fermentation processes which are very difficult to stabilize via most of the existing well-established control strategies. A systematic design procedure is provided where its applicability is demonstrated via a numerical example. (paper)
[en] Polyhydroxyalkanoates (PHAs) have been produced by various bacteria as natural polymers stored in bacterial cells as a source of carbon and energy. They are currently preferred biomaterials for use in many industrial fields instead of conventional non-degradable plastics. Due to their unique properties they can reduce pollution caused by the increasing global polymer demand. Pseudomonas species have been chosen as PHAs producers in many recent studies. Being metabolically versatile and possessing a remarkable tolerance to a wide range of carbon sources, these bacteria have become an efficient cell factory for PHAs production. Currently, attention is focused on the design of Pseudomonas strains to increase their ability to accumulate PHAs in the cell and modifying their biosynthetic pathways to obtain strains with modified compositions and improved properties. This article discusses the current state of knowledge of polyhydroxyalkanoates synthesized by Pseudomonas species which are industrially important microorganisms. This review provides an overview of recent trends towards PHA production, focusing on the utilization of low-cost carbon sources, fermentation strategies, PHAs properties and their uses as valuable bioproducts.
[en] The main concern of this study is to develop a feasible and economical technique to microbially recover metals from oxide low-grade ores. Owing to the significant quantities of metals that are embodied in low - grade ores and mining residues, these are considered new sources of metals. On the other hand, they potentially endanger the environment, as the metals they contain may be released to the environment in a hazardous form. Hence, mining industries are seeking an efficient technique to handle these ores. Pyrometallurgical and hydrometallurgical techniques are either very expensive, energy intensive or have a negative impact on the environment. For these reasons, biohydrometallurgical techniques are coming into perspective. In this study, by employing Aspergillus niger, the feasibility of recovery of metals from a mining residue is shown. A. niger exhibits good potential in generating a variety of organic acids effective for metal solubilization. Organic acid effectiveness was enhanced when sulphuric acid was added to the medium. Different agricultural wastes such as potato peels were tested. In addition to this, different auxiliary processes were tried in order to either elevate the efficiency or reduce costs. Finally, maximum solubilization of 68%, 46% and 34% were achieved for copper, zinc and nickel, respectively. Also iron codissolution was minimized as only 7% removal occurred. (author)
[en] Olive pomace, which is considered as one of the worst agro-industrial wastes in Mediterranean countries was tested for bioactive compounds production through the solid state fermentation of Kluyveromyces marxianus. Because they present potent biological activities, phenolic compounds from both unfermented and fermented pomace were extracted with simultaneous evaluation of their antioxidant and anticancer activities. Conditions for optimum total phenolic recovery with maximum antioxidant activity were optimized using methanol as the extracting solvent with a sample to solvent ratio of 1:10 at 50 °C for 2 hours. The in-vitro anticancer activity of both extracts was assessed against different human cancer cell lines. The results revealed that both extracts exerted anticancer effects close to the value of doxorubicin drug against liver HepG2 and breast MCF-7 cell lines, and moderate activity against prostate PC3 and colon HCT116 cell lines. Nevertheless, the fermented extract was more potent than the unfermented one. No effect against lung A549, cervix Hela cancer cell lines or normal HFB4 cells was observed for both extracts. A GC/MS analysis was carried out to determine the compounds responsible for antioxidant and anticancer activities. The results showed the presence of methyl palmitate, methyl oleate, and ethyl oleate in the methanolic extract of unfermented olive pomace, while that of the fermented one showed the production of carvacrol, thymol, eugenol, caryophyllene oxide and methyl isopalmitate.
[es]El orujo de oliva considerado como uno de los peores residuos agroindustriales en los países mediterráneos fue ensayado para la producción de compuestos bioactivos mediante fermentación en estado sólido de Kluyveromyces marxianus. Se extrajeron los compuestos fenólicos de orujos fermentados y no fermentados ambos con potentes actividades biológicas y se evaluaron sus actividades antioxidantes y anticancerígenas. Se optimizaron las condiciones para la recuperación fenólica óptima con actividad antioxidante máxima, estas se lograron usando metanol como disolvente de extracción con una relación de muestra a disolvente de 1:10 a 50 °C durante 2 horas. La actividad anticancerígena in vitro de ambos extractos se evaluó frente a diferentes líneas celulares de cáncer humano. Los resultados revelaron que ambos extractos ejercen un efecto anticancerígeno cercano al valor del fármaco doxorrubicina contra líneas celulares hepáticas HepG2 y MCF-7 de mama, y actividad moderada contra líneas celulares de PC3 de próstata y HCT116 de colon, sin embargo, el extracto fermentado fue más potente que el no fermentado. No se observó ningún efecto contra las líneas celulares A549 de cáncer el pulmón, de cuello de útero o células HFB4 normales, para ambos extractos. El análisis GC/MS se llevó a cabo para determinar los compuestos responsables de las actividades antioxidantes y anticancerígenas. Los resultados mostraron la presencia de palmitato de metilo, oleato de metilo y oleato de etilo en el extracto metanólico de orujo de oliva no fermentado, mientras que el fermentado mostró la producción de carvacrol, timol, eugenol, óxido de cariofileno e isopalmitato de metilo
[en] Highlights: • The life-cycle performance of 10 co-digestion substrates were compared. • AD performance is sensitive to co-substrate properties and management strategy. • High loading rates are economically favorable yet increase farm-level emissions. • Co-digestion lowers total environmental impacts compared to manure-only digestion. • Economic profitability of the AD system is driven primarily by gate-fee revenue. - Abstract: Anaerobic digestion systems on dairy farms in New York State rely on gate-fee revenues from co-digestion to ensure economic viability. Yet, because gate fees are paid on a volumetric (or weight) basis, farmers have been compelled to accept large waste volumes. When these wastes are co-digested at rates exceeding the design capacity of the digester, potentially significant technical, environmental, and economic consequences may arise. To better understand these trade-offs, we performed a combined environmental life-cycle and economic assessment with uncertainty analysis. We used the Anaerobic Digestion Model N1 to simulate the co-digestion process for 10 potential co-substrates that were hypothetically mixed with dairy manure throughout a range of loading rates. These simulation results demonstrated the need to include a robust anaerobic digestion model to capture complex process dynamics and loading limits. Results also showed that while higher loading rates were more economically favorable, they caused considerable reductions in the degree of waste stabilization during the digestion process, which dramatically increased downstream methane emissions (e.g., >450%) on the farm compared to manure-only digestion. Regardless, most co-digestion scenarios led to a net reduction in total life-cycle emissions compared to manure only and not digesting the co-substrate due mainly to greater electric power production and synthetic fertilizer replacement. Economically, gate-fee revenue was the most important contributor to profitability, substantially outweighing the revenue from electric power production, while also compensating for the increased handling costs of the added waste volume. Ultimately, the model clearly demonstrated the important environmental and economic implications arising from current anaerobic digestion implementation practices and policy in New York State. In addition, the model highlighted key stages in the system life-cycle, which was used to instruct and recommend immediately actionable policy changes.
[en] The discussion following presentations on financing landfill gas projects for power generation and the quality of landfill gas for utilisation in internal combustion engines is reported. Topics covered include the use of landfill gas in external combustion engines, the use of oil-free engines, such as gas turbines, and guarantees required by financiers. (UK)
[en] The anaerobic digestion of solid wastes is now a widely-used technology in Europe with more than 50 full-scale plants operating. However, anaerobic solid waste digestion is still used to only a limited extent in North America with only three facilities in Canada. Because of the expected importance of anaerobic digestion in the future for energy recovery, reliable tools are required to evaluate the different available technologies, as well as the feed stocks that are suitable for treatment. Therefore, this paper presents a framework that has been developed for evaluating anaerobic solid waste digestion. To develop the framework, a review of the performance of digestion processes was first conducted. Because the data presented were for very different operational parameters (retention time, temperature, configuration set up, mixing, etc.) as well as substrates used for digestion, a standard method of comparison was developed. Gas production per Mg input, organic loading rate and percent volatile solids removal were identified as useful standard parameters for evaluating the performance of different technologies. This framework was constructed as a spread sheet and can be used for different set ups (configuration, organic loading rate, etc.) and with different substrates. It can predict, based on the input and using mass balances, the mass of products of the digester including biogas, treated solids and water. This framework provides a useful tool for evaluating the technical capabilities of different technologies, predicting the quantity of the products, and ultimately, making decisions as to which technologies best meet local needs. (author)
[en] Irradiation has been recognized as a highly suitable tool to aid in the formation of hydrogel. The radiation process has various advantage, such as easy process control and the lack of necessity for initiators and crosslinker. In this study, the hydrogel containing the citrus fermentation gel for the wound healing were successfully synthesized. The strength of hydrogel was increased as a function of a increasing the concentration of citrus and the irradiation doses. In addition, this hydrogel have been evaluated by the cytotoxicity and animal experiment