• Universitat de València
• Universitat Politècnica de València

• José Ferrer Polo
• Ángel Robles Martínez
• Freddy Durán Pinzón
• Ana Ruiz Martínez
• Alexandre Viruela Navarro
• Tao Antonio Gómez Gil

In recent years, one of the methods of obtaining biofuels that is attracting a great deal of attention is the cultivation and harvesting of microalgae. Once the microalgae have been cultivated and harvested, it is possible to convert the biomass obtained into different value-added products such as biofuels in a clean, reproducible and sustainable way. In the systems known to date, microalgae cultivation is mainly carried out either in open ponds or in closed photobioreactors. The main advantages of open ponds are their ease of operation and low investment and operating costs, but they are very sensitive to contamination and have low automation capacity. Photobioreactors, on the other hand, have high investment costs, but solve the problems associated with contamination and automatic control of the reactors. However, despite the great interest and development of microalgae cultivation, there are still a number of challenges that need to be overcome for microalgae cultivation to become a viable technology as a source of energy and products on a large scale. These challenges include: improving algal biomass productivity and the harvesting process, and proposing an integrated, detailed (instrumentation, indicative operating values) and proven technology that facilitates its implementation on an industrial scale.

Researchers from the Universitat de València and the Universitat Politècnica de València have developed a new algae cultivation and harvesting method that significantly increases the yield compared to current systems. The method developed is an integrated system that allows the entire process (cultivation and harvesting) to be carried out continuously and uninterruptedly, minimising installation and operating costs. Furthermore, as the method has two filtration units (one for pre-harvesting and one for harvesting), it is possible to make the concentration of solids maintained in the photobioreactors independent of the concentration purged from the system, allowing the concentration in each unit to be optimised to achieve higher biomass productivity and facilitate the harvesting process. Therefore, the developed system overcomes the disadvantages of the methods known so far.

The invention is applicable in the industrial-scale production of algal biomass. This biomass could be used for one or more of the following applications:

• As a CO2 sink.
• As a raw material for the production of lipids, proteins and other value-added products associated with the agri-food industry.
• As a raw material for the production of biodiesel and biofertilisers.
• As a carbon source in biogas production plants.
• As a sustainable treatment system for the recovery of nutrients in wastewater.

The process of the invention has the following advantages:

• It allows the production of algal biomass in an efficient way, minimising the associated production costs, reducing energy consumption and, therefore, the environmental impact associated with this type of process.
• It is possible to maximise the recovery of nutrients in the case of operating with wastewater and the obtaining of a liquid stream with characteristics that make its subsequent reuse possible.
• The production of a concentrated algal biomass that can be used later in the form of commercial products.

• Patent granted