Reduction of microalgae harvesting costs via the development of an ultrasound flow cell to provide pre-concentration

[EU] The worldwide production of microalgae is currently around 7,000 tons/year of dry algal biomass, used for a wide variety of applications including livestock feed, aquaculture, functional foods, cosmetics or pharmaceuticals. In addition, microalgae contain around 30% by weight of lipids, being regarded as a highly promising feedstock for biofuels, primarily biodiesel.

Microalgae are commercially grown in open ponds of bioreactors, and then harvested using a centrifuge separator. However, the centrifuge step is highly energy intensive (up to 50% of the total processing energy) due to the properties of microalgae and their low concentration in the growing medium, representing a major obstacle to the economic viability of microalgae biodiesel production. The capital investment required for the centrifuge is also a barrier for widespread SME entry to the sector. The ALGAEMAX project aims to address these issues via the development and demonstration of an ultrasound based flow-cell to concentrate the microalgae. The technology will be integrated into harvesting systems, reducing investment and operational costs and helping SMEs grow their business to address larger markets.

The ultimate goal of the project is to reduce the high energy cost of the dewatering step while ensuring the high quality and long shelf life of the microalgae products.

Project Results:

CRIC (Centre for Research and Innovation of Catalonia), NPL (National Physical Laboratory) and Fraunhofer (Fraunhofer Institute for Interfacial Engineering and Biotechnology) started to collaborate in October 2012 with a core group of European small and medium enterprises (SMEs). The work performed by the ALGAMEAX R&D organizations observes the specifications provided by microalgae production experts CDU (Turkey) and Algaelink N.V. (The Netherlands) and has the technical support from technology manufacturers Sonic Systems Ltd. (UK) and Hakki Usta (Turkey).

During the first 9 months of the project, a collaborative partnership has been forged in which companies and research centers with highly distant areas of expertise have worked together to develop a suitable solution for an emerging sector. The multidisciplinary character of the consortium has boosted the organization of training activities, which in the first period have mostly taken the shape of training seminars. Starting on the second year of the project training activities will progressively focus on technology demonstration.

A high effort was invested during the first months in defining the specifications of the ALGAEMAX flow cell. The process was led by the SMEs in the microalgae producing sector (ÇAGLAR and ALGAELINK), which provided the requirements of the sector. SONIC Systems, as specialists in the design and manufacturing of ultrasonic systems, contributed advice on the limitations and requirements for the design and assembly of the ultrasound chamber. Finally, HAUS provided expertise in the field of separation technology.

NPL has led the design process of the ultrasound chamber (WP2) by identifying the relevant parameters and developing a theoretical model to describe the behavior of the microalgae particles under the effect of an acoustic standing wave. NPL’s modeling work has been supported by CRIC, which has performed fluidics simulations to predict the effect of a fluid flow in the flow cell and by Fraunhofer, where preliminary tests to evaluate the effect of specific parameters such as temperature changes due to the ultrasound power being applied on cell quality have been carried out.

NPL subsequently built different bench scale set ups to experimentally test the results of simulations. Preliminary tests with those bench scale set ups have demonstrated the successful flocculation of a Chlorella suspension.

Tests were also successful with other synthetic particles simulating microalgae cells (e.g. rice starch). Based on theoretical modeling and preliminary experimental results, at the end of M9 two demonstration prototypes with different configurations have been designed by NPL. These will allow validation of the preliminary results by testing different conditions on real microalgae cultures, providing experimental data for the characterization of the microalgae behavior under the effect of acoustic standing waves. The best flow cell configuration will be selected for the final prototype based on the experimental results. The testing will start in September 2013 with a more advanced prototype capable of processing higher flowrates under continuous flow conditions expected to be ready for testing in early 2014.

During the first project period the consortium has created a visual identity for the project that will become a platform for the diffusion of all the news related to the project and its results. The increasing presence of the ALGAEMAX consortium members in scientific conferences, trade fairs and other events will contribute to disseminate the work among the scientific community and the specialized industry.

Potential Impact:

The reduction of production costs is critical for algae biomass producing SMEs in order to progress from the now saturated high-value products market (livestock, nutraceuticals, pharmaceuticals, specialty chemicals), with an estimated size of €1 billion, to the €50 billion market of low-value products like algae biomass for CO2 capture or the much anticipated third generation biofuels market, with a potential size of €1 Trillion.

The efforts of the scientific community are diversified in 3 directions: (i) selection and optimization of microalgae strains, (ii) optimization of cultivation technologies, e.g. improving the design of photobioreactors and (iii) optimization of the downstream process, reducing harvesting time and costs (both investment costs and operational costs).

The ALGAEMAX project has put together a group of SMEs with a common interest in developing an efficient technology to reduce microalgae harvesting costs and a group of RTDs with wide experience in the fields of acoustics, microalgae production and process optimization.

End users of the technology, primarily European SMEs producing microalgae for different applications, will directly benefit from an expected 67% reduction in harvesting costs and 20% reduction in total production costs. Moreover, the overall impact of the project for the players of the European microalgae producing industry will be to gain highly competitive positions in European and international markets, creating jobs, increasing revenues and contributing to a sustainable environment.

ALGAEMAX will also generate additional social and economic benefits deriving from the development of a widely accessible, cost-effective solution for small-scale algae growing.

 

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