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
Description of the technology
Urban waste waters present high concentrations of nitrogen and phosphorus that must be eliminated before discharge into rivers or the sea, in order to avoid problems of eutrophication with consequent degradation of environmental quality. Many procedures exist for removing these nutrients but they usually present problems in terms of high cost, complexity of operation and/or high energy consumption (which accounts for 60% to 80% of the total cost of the treatment process). Recently the cultivation of photosynthetic microorganisms, and particularly microalgae, in waste waters has attracted attention as a viable alternative technology, since it combines three significant advantages: elimination of excessive nutrients; production of useful biomass; and consumption of undesirable CO2.
Specifications
Researchers of the University of Cadiz working on the "photobiotreatment of waste waters” have developed a new procedure for elimination of the nutrients contained in urban waste waters by using microalgae. An important characteristic is that this new process takes place in two phases. The first phase is the elimination of nutrients in darkness and, in the second phase, the growth of biomass takes place in a photobioreactor. The innovation takes advantage of the capacity of microalgae to take up nutrients from waste waters without the presence of a light source. Among the principal advantages are the reduction of costs and the possibility of operating in conditions of darkness.
Main advantages of its use
Applications
The university of Cadiz is a state university with 4 campuses and more than 2,000 lecturers. It is located at South Spain and it is one of the nine state universities in Andalusia, Spain. We have in our portfolio more than 100 patents for licensing, looking for potential investors.
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