Biogas is a biofuel with a high energy value and basically consisting of methane, which can be used as a renewable energy source as a substitute for natural gas or liquefied petroleum gas. It can be produced by anaerobic digestion of agricultural organic waste or manure in rural areas, where it can be used to generate electric, thermal or mechanical energy. It can also be generated in landfills from the organic fraction of municipal solid wastes and used as an alternative energy source in urban areas. Industrialized and urbanized areas are afflicted by serious environmental problems associated with the generation of organic residues. Anaerobic microorganisms can degrade pollutants resulting in two kinds of products, i.e., digested sludge and biogas, which can be exploited as a soil fertilizer and a renewable energy source, respectively. The correct management of residual waste involves high costs, and inadequate treatment and storage can compromise its quality. Environmental agencies have been encouraging the dissemination of anaerobic digesters to produce biogas from organic residues and the use of the resulting sludge as fertilizer since it is able to destroy pathogenic agents and reduce the humidity level. This review aims to evaluate the production capability of biogas and its application as an alternative energy source in rural and urban areas. Clean EnergyEnergy has been the sustaining basis of civilization, because it has historically promoted the economic, social and cultural development of mankind. Nowadays, renewable energy sources are gaining significant interest, because they promise to be a feasible alternative to the problems relating to future oil shortage, the difficulty of setting up hydroelectric and thermoelectric powers, and the so-called "dirty energies", e.g., mineral coal, oil shale, etc. Energy demand has been increasing as the worlds' economies grow, bringing an associated change in consumption patterns, which in turn, vary depending on the source and availability of the energy source, conversion loss and end use efficiency.The term "alternative energy source" is used not only to indicate an efficient alternative; it is also synonymous with clean, pure, non-polluting energy, which is, in principle, inexhaustible and can be found everywhere. The electric energy generated by clean and renewable sources is the result of the environmentally friendly exploitation of abundant natural resources. Moreover, the use of clean energies such as solar and wind energies, biomass, biogas and hydroelectric power would allow the diversification of the supply, ensuring long term energy availability, reducing the emissions of greenhouse gases, and increasing the employment opportunities in both rural and urban areas.In recent years, public and political sensitivities to environmental issues and energy security have led to the promotion of renewable energy resources. Among these resources, biomass could play a substantial role in a more diverse and sustainable mix of energies, and biogas can be produced by u...

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Industrial effluents from the pharmaceutical industry often contain high concentrations of phenolic compounds. The presence of "anthropogenic" organic compounds in the environment is a serious problem for human health; therefore, it merits special attention by the competent public agencies. Different methods have been proposed in the last two decades for the treatment of this kind of industrial residues, the most important of which are those utilizing absorption columns, vaporization and extraction, and biotechnological methods. Biofiltration is a method for the removal of contaminants present in liquid or gaseous effluents by the use of aerobic microorganisms, which are immobilized on solid or porous supports. Although several bacteria can utilize aromatic compounds as carbon and energy source, only a few of them are able to make this biodegradation effectively and with satisfactory rate. For this reason, more investigation is needed to ensure an efficient control of process parameters as well as to select the suited reactor configuration. The aim of this work is to provide an overview on the main aspects of biofiltration for the treatment of different industrial effluents, with particular concern to those coming from pharmaceutical industry and laboratories for the production of galenicals.

A strain of genetically modified Saccharomyces cerevisiae (S. cerevisiae) W303 181 was used to improve glucose-6-phosphate dehydrogenase (G6PDH) production in aerobic culture. Fed-batch cultures were carried out in a 5 L fermentor at variable values of the parameter K, namely, 0.2, 0.3, 0.5, 0.7, and 0.8 h(-)(1). The highest G6PDH production (1164 U/L) and specific activity (517 U/g(cell)) were obtained using the following conditions: glucose, 5.0 g/L; adenine, 8 microg/mL; histidine, 8 microg/mL; tryptophan, 8 microg/mL; temperature, 30 degrees C; inoculum, 1.28 g/L; pH, 5.7; agitation, 400 rpm; aeration, 2.2 vvm; and K, 0.2 h(-)(1). The exponential feeding pattern increased cell density (2.14 g/L), enzyme productivity (149.27), and biomass yield (0.18 g(glu)/g(cell)( )(mass)). The level of G6PDH in the genetically modified S. cerevisiae was approximately 4.1-fold higher than that found in a commercial strain.