Algae Harvesting with Flexidisks® Membrane Filtration System Algae are highly efficient lipid producers. As a matter of fact, most of the oil we use today as fuels came from ancient algal blooms. They are by far the most productive species for oil production, many hundred times higher than soybean or rapeseed oil. Many exhibited properties make algae an excellent candidate for commercial scale biofuel production. Furthermore, algae can also recycle and absorb waste nutrients and CO2 emissions, making them an excellent solution for waste management. Beside many promises inherent in algal biomass Flexidisks® system with algae cultivating production, there are still several technological panels in the background challenges to overcome. These include consistent production with high lipid content, economical algae harvesting techniques, and cost‐effective lipid extraction. Centrifugation is the most common technique for algae harvesting. However, high energy consumption and loss of algal cells in supernatant are typical problems for this harvesting method. Membrane filtration is an ideal solution because it provides well‐defined pore openings to separate algal cells from the culture. While conventional spiral or tubular membrane filtration systems are subject to rapid membrane fouling and flux decline due to increased concentration of algal cells, there are other types of proprietary membrane filtration systems in the markets which utilize added shear forces to slow down fouling. While these systems stave off fouling for a longer period of time, the energy consumption is very high and the applied shear forces often rupture algal cell walls. Structure of Flexidisks® membrane element Copyright © 2010 Avanti Membrane Technology, Inc. All rights reserved. www.avantimembrane.com Page 1 of 2 AMT Doc. A‐008 v 2.0 August 16, 2011 Standing in contrast to both of these methods is Flexidisks®. Flexidisks® is a cutting edge membrane filtration technology that retains the advantages of conventional membrane filtration technologies while eliminating their shortcomings. Flexidisks® offers you  Low initial capital investment and operating costs  Proprietary membrane bonding technology and patented interlocking cams make flexible membrane disks, which can be backwashed and/or air‐scrubbed  Unique stacking membrane disks provide a larger membrane surface area with a smaller footprint compared to other membrane systems  Larger spacing between membrane disks reduces fouling and caking, increasing backwash, air‐scrubbing, and CIP efficiency  Circular disk design can be spun or scrapped to remove cake layers when necessary.  No pretreatment required  Submersible membrane elements operated with negative feed pressure can be easily maintained or replaced At the beginning of 2010, a Flexidisks® industrial scale pilot system was installed and commissioned in a semiconductor plant in Northern Taiwan. The semiconductor plant invested in a trial process to investigate algae’s ability to absorb CO2 emissions from the plant’s production line. The process produces a diluted algae stream at a flow rate of 6.8 m3/day (1800 gallons per day). A submersible ultra‐filtration Flexidisks® membrane system with 4 m2 (43 ft2) of surface area was installed to harvest algae. The trial unit easily achieved a 95% recovery rate (volumetrically) while maintaining an average flux rate of 70 LMH (41 GFD). A submersed Flexidisks® membrane element shown at the end of batch The fouling prevention and cleaning routine for this specific system is very straightforward. Air scrubbing is used constantly to vibrate each membrane disk so it’s kept free of suspended particles, mainly algal cells. The entire membrane element is always spun at low speed to minimize the possibility of algal cake formation. The membrane element control system is also programmed to be backwashed at 0.2 kg/cm2 once an hour to maximize the performance. Once the batching tank reaches a 95% volume reduction, the concentrated algal solution is then drained into the collection tank. The batch tank is then filled with diluted algae biomass solution and the process begins anew. As the technologies of cultivating algae for fuel sources, nutrients removal, and carbon reductions mature, the key lies in how to efficiently and economically harvest algae. Flexidisks® membrane filtration system with its low initial capital and operating costs can provide the missing link for cost‐effective continuous algal cultivation. Copyright © 2010 Avanti Membrane Technology, Inc. All rights reserved. www.avantimembrane.com Page 2 of 2 AMT Doc. A‐008 v 2.0 August 16, 201