Concentration and Dewatering of Micro-Algal Cultures with High Throughput Ceramic/Metal Membranes

Micro-algae have very high energy density and growth rate compared to other crops and plants.Harvesting it from very dilute culture solutions into biomass that is suitable for storage and transport is difficult and costly.Energy-efficient and low-cost technologies are needed to facilitate algal industry growth.A compact and high throughput membrane filtering unit employing thin ceramic/metal sheet membranes made by Molecule Works Inc.with its proprietary processes will be developed to lower the energy consumption by use of relatively small pumps and to reduce the harvesting cost by increasing flux and prolonging the membrane service time.The filtering unit can be used to harvest a variety of micro-algae species by excluding algae cells with the membrane of uniform and smaller pore sizes.High flux of MoleculeWorksTM thin ceramic/metal sheet membrane is shown with actual cultures and simulated model feeds at cross-flow velocity substantially lower than what was reported in other membrane filtration tests.It is confirmed that the membrane surface is resistant to algae and bacteria adhesion.A simple back-flushing method is identified for in situ cleaning of the membrane surface periodically.The feasibility of assembling 24 membrane sheets into a cross-flow membrane module of 1 m2 is shown that may be operated with low feed velocity and back-flushing.In Phase II, the membrane sheet production will be optimized and 20 m2 membrane modules will be assembled.A mobile, turnkey filter unit will be designed and built with algae processing capacity of about 1000 liter/h.The mobile unit will be tested at cultivation sites with different cultures for about one-year to demonstrate its performance advantages over existing harvesting tools in terms of energy consumption, harvesting efficiency, productivity, versatility, and overall cost.A versatile membrane filter unit will be built based on Phase II results for commercial demonstration.The membrane unit will be provided for algal cultivators as a new, handy harvesting tool useful for any microalgae species.In addition, the filter unit will be marketed to address the application needs that could not be well met with existing membrane products, such as, grey water treatment and re-use, and one-step removal of particulates and bacteria from seawater and industrial cooling water.