Renewable Sources of Energy Technology Offers Page 5

Universidad de Cádiz posted this:

UCA researchers have developed a new process for the treatment of waste waters by using microalgae, specifically for the removal of nitrogen and phosphorus. This process is based on applying three fundamental findings made by the research group: • Before the microalgae start to grow, they are already consuming nitrogen and phosphorus when cultivated in waste waters. • The microalgae accumulate nutrients internally in such a way that the assimilation of nutrients commences before the growth phase, and at a rate that is considerably faster than the rate during the generation of biomass. • The initial elimination of nutrients prior to the growth of biomass takes place at a similar rate both in darkness and in the presence of light. To exploit this phenomenon, a procedure has been designed in which the two phases take place separately in two reactors: the first phase for elimination of nutrients from the waste water in darkness (known as ‘luxury uptake’) and the second for the growth of biomass under illumination. What this achieves is not only the efficient removal of the nutrients from the waste water but also, by means of a simple change of the mode of operation of the process, nutrients can be eliminated at night using the excess of biomass generated during daylight hours. To implement this advance, the research group has conceived a process for the separation of the biomass from the culture medium in both phases, by means of membrane technologies. The treatment plant can operate with cellular retention times very much longer than the hydraulic residence times. This, in turn, allows the same flow volumes of waste water to be treated in smaller reactors. • It enables waste waters to be treated at night without the need for a luminous phase. This cannot currently be done with the processes that employ existing photosynthetic organisms. • Simplicity of operation and reduction of costs in comparison with conventional technologies. It avoids the production of more solid residues, i.e. sludges, which require disposal. • The use of microalgae allows the treatment of waste waters with high levels of nitrogen and phosphorus but low content of organic matter (a characteristic of the waste waters of steelworks), since autotrophic organisms are involved. Thus the proposed process avoids the need to add organic matter from an external source, as is the case of other biological processes. • With the possibility of generating energy and capturing CO2, the biomass generated in the process represents value added in terms of energy consumption and environmental protection

xrqtc posted this:

Current polymorphism studies are being carried out using one of the following three alternatives: atom-atom potentials, DFT (Density Functional Theory) calculations and ad-hoc potentials. However, all of them have serious disadvantatges. 1) with software that uses atom-atom potentials: Advantages: fast and capable of working with large molecules. Disadvantages: the "blind tests" carried out by the "Cambridge Crystallographic Data Centre" are giving a 50% maximum success in the predictions. 2) with software based on DFT calculations: Advantages: good results Disadvantages: they are computationally very slow, so they are only used for very simple molecules compared with drug molecules. In addition, they have errors predicting van der Waals interactions and weak hydrogen bridges if not corrected empirically. 3) with software using ad hoc potentials for each molecule obtained from systematic exploration of the surface potential of intermolecular interactions: Advantages: efficient and faster. Disadvantages: some potentials should be calculated for each molecule studied, which are complex and slow, and is not general. The approach presented here is new and unique because the potential Pixel has never been used before for drawing polymorphic predictions and it has shown to present the advantages of all the alternatives combined. This is the first research group which has brought the potential Pixel to this level of calculation. The potential calculations and the applicability of the methode based on pixels have the same quality that the sophisticated ab initio based potential calculations. Besides, this is much faster than DFT (Functional-Based Theory)-based and ad hoc potentials ..