Brown and Caldwell Home Page
Technical Papers RECENT PAPERS    ALL PAPERS

Brown and Caldwell engineers and scientists are technical and thought leaders in the environmental sector. Meet the people who have been advancing innovation for more than 70 years.
Author      Title/Abstract      


Algae Harvesting Using Flotation
Author: John Bratby
Date: 11/12
Preprint, IWA’s 6thInternational Conference on Flotation in Water and Wastewater Systems, New York, NY, October 29-31, 2012

This paper discusses dissolved-air flotation (DAF) applied to algae harvesting for the algae-to-biofuels industry. The DAF process is the most effective means of separating a relatively low concentration of algae from a large body of water. Some of the important design features of DAF that promote effective algae separation and harvesting, as well as thickening of the separated algae, are discussed. The efficiency of recovery is a significant issue because it relates to the economics of the separation technique. However, it is not necessarily of overriding importance since the water from the separation unit can be recycled back to the algae growth units. The efficiency of recovery and operation of the separation technique depends to a large extent on the means by which the algae is conditioned. The paper discusses various inorganic and organic chemicals for algae coagulation, to facilitate algae separation by DAF. Inorganic coagulants tend to be the most effective, although some natural and synthetic polymers are effective. Ideally the coagulant used should not detract from the animal feed option for the co-product from algae biofuel processing. Chitosan is discussed as one option, but other organic polymers that are GRAS certified should be used preferentially to those products that are not certified.

This library contains published materials for which copyrights may be owned by entities other than Brown and Caldwell, but which are stored for limited uses by BC employees. Technical papers authored by BC employees generally may be printed and shared electronically with clients and prospective clients outside BC. Technical papers cannot be sold, and technical papers shared outside BC must have proper attribution of the original sponsoring organization or conference where the paper was presented. This attribution is embedded in each technical paper file when it is loaded into this library. Published articles from magazines or trade journals which are stored in this library are FOR INTERNAL USE ONLY and SHOULD NOT be distributed to clients or others outside BC, without express permission of the copyright owner. For questions regarding copyrights associated with any document in this library, or questions regarding copyrights in general, contact the Legal Department.