Cleanup of industrial effluents containing heavy metals : a new opportunity of valorising the biomass produced by brewing industry

Heavy metal pollution is a matter of concern in industrialised countries. Contrary to organic pollutants, heavy metals are not metabolically degraded. This fact has two main consequences: its bioremediation requires another strategy and heavy metals can be indefinitely recycled. Yeast cells of Saccharomyces cerevisiae are produced at high amounts as a by-product of brewing industry constituting a cheap raw material. In the present work, the possibility of valorising this type of biomass in the bioremediation of real industrial effluents containing heavy metals is reviewed. Given the auto-aggregation capacity (flocculation) of brewing yeast cells, a fast and off-cost yeast separation is achieved after the treatment of metal-laden effluent, which reduces the costs associated with the process. This is a critical issue when we are looking for an effective, eco-friendly, and low-cost technology. The possibility of the bioremediation of industrial effluents linked with the selective recovery of metals, in a strategy of simultaneous minimisation of environmental hazard of industrial wastes with financial benefits from reselling or recycling the metals, is discussed

Synchronous equatorial satellites

It is shown that the equilibrium positions of a synchronous equatorial satellite are situated in the directions of the extreme positions of the radius of the equatorial section of the synchronous, and not the Earth's geoid. It is further established that the motion of13; a synchronous equatorial satellite is best explained on the basis of a much-more-than elliptically longitudinally heterogeneous shape of the curve of Earth's equator, and with the inclusion of more harmonics of the Earth's gravitational potential in the analysis. The accuracy and adequacy of the known geopotential constants, called for in the numerical determination of the locations of the equilibrium positions of the satellite, is examined13; next. The paper concludes with a discussion of the stability of the satellite around an equilibrium position, subject to an orbital injection error from the uncertainty in the knowledge of exact location of the equilibrium position. It is found that the stable geostationary equilibrium position in the East, south of West Coast of India, above the Indian Ocean, is better suited for experiments towards exact determination of the locations of equilibrium positions of the satellite

Bioremediation of industrial effluents containing heavy metals using brewing cells of Saccharomyces cerevisiae as a green technology : a review

The release of heavy metals into the environment, mainly as a consequence of anthropogenic activities, constitutes a worldwide environmental pollution problem. Unlike organic pollutants, heavy metals are not degraded and remain indefinitely in the ecosystem, which poses a different kind of challenge for remediation. It seems that the "best treatment technologies" available may not be completely effective for metal removal or can be expensive; therefore, new methodologies have been proposed for the detoxification of metal-bearing wastewaters. The present work reviews and discusses the advantages of using brewing yeast cells of Saccharomyces cerevisiae in the detoxification of effluents containing heavy metals. The current knowledge of the mechanisms of metal removal by yeast biomass is presented. The use of live or dead biomass and the influence of biomass inactivation on the metal accumulation characteristics are outlined. The role of chemical speciation for predicting and optimising the efficiency of metal removal is highlighted. The problem of biomass separation, after treatment of the effluents, and the use of flocculent characteristics, as an alternative process of cell-liquid separation, are also discussed. The use of yeast cells in the treatment of real effluents to bridge the gap between fundamental and applied studies is presented and updated. The convenient management of the contaminated biomass and the advantages of the selective recovery of heavy metals in the development of a closed cycle without residues (green technology) are critically reviewed.The authors thank to the Fundacao para a Ciencia e a Tecnologia (FCT) from Portuguese Government for the financial support of this work with FEDER founds, by the Project POCTI/CTA/47875/2002 and through the grants PEST-OE/EQB/LA0023/2011 (IBB) and PEST-C/EQB/LA0006/2011 (REQUIMTE)