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Froth Flotation for Harvesting Algae and Its Possible Application to Sewage Treatment GILBERT B. LEVIN, Director of Special Research JOHN M. BARNES, Plant Pathologist Bioengineering Department Hazleton Laboratories, Inc. Falls Church, Virginia INTRODUCTION The modified froth flotation process previously reported (1) as promising economic harvesting of algae has been further developed. In addition to bringing a practicable algal harvesting system nearer, the new work indicates that the method may also be useful in the treatment of sewage. The fact that laboratory- grown cultures of algae frothed without the addition of flotants indicates that a frothing agent was produced by the cultures themselves. A high-temperature strain of Chlorella pyrenoidosa was initially selected for use in the studies because its adaptability to the conditions of laboratory culture and its relatively high reproductive rate make it desirable for mass culturing as a food source or for gas exchange in closed systems. Following acid pH adjustment of the feed culture, it was placed in a glass cylinder equipped with a porous diffusion plate at the bottom. Air was forced through the plate, creating fine bubbles in the liquid above. A stable foam, highly concentrated in algae, formed at the liquid surface and rose up the column; the foam was collected at a discharge orifice. The feed solution was virtually clarified by this process which harvested almost all of the suspended cells (Figure 1). Hydrochloric acid was used to lower the pH of the harvest feed cultures and sodium hydroxide for subsequent neutralization. It was found that aeration rate and pH level influenced the degree of concentration obtained. Subsequent work has considered the desirability of harvesting only a portion of the algae and recycling the remaining culture in a continuous growth system. Successful operation of such a system requires that the algae remain viable despite exposure to the low pH condition in the harvester. Investigations were directed toward determination of viability of cells repeatedly exposed to harvesting conditions; and their subsequent growth in fresh media, supplemented, unsupple- mented, and diluted harvest liquor. EXPERIMENTAL PROCEDURES AND RESULTS Viability of Cells In order to determine the viability of cells which were continuously recycled, and resuspended in fresh medium, the following determinations were made. Seven hundred ml of urea medium (Composition in mg/1 deionized-distilled water: MgS04-7H2O, 1, 000; KH2PO4, 250; Urea, 1,000; iron sequestrine, 35; manganese sequestrine, 3; and sequestrines of copper, zinc and cobalt, 1.) were - 421
Object Description
Purdue Identification Number | ETRIWC196436 |
Title | Froth flotation for harvesting algae and its possible application to sewage treatment |
Author |
Levin, Gilbert B. Barnes, John M. |
Date of Original | 1964 |
Conference Title | Proceedings of the nineteenth Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,11114 |
Extent of Original | p. 421-434 |
Series |
Engineering extension series no. 117 Engineering bulletin v. 49, no. 1(a)-2 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Date Digitized | 2009-05-19 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 421 |
Collection Title | Engineering Technical Reports Collection, Purdue University |
Repository | Purdue University Libraries |
Rights Statement | Digital object copyright Purdue University. All rights reserved. |
Language | eng |
Type (DCMI) | text |
Format | JP2 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Transcript | Froth Flotation for Harvesting Algae and Its Possible Application to Sewage Treatment GILBERT B. LEVIN, Director of Special Research JOHN M. BARNES, Plant Pathologist Bioengineering Department Hazleton Laboratories, Inc. Falls Church, Virginia INTRODUCTION The modified froth flotation process previously reported (1) as promising economic harvesting of algae has been further developed. In addition to bringing a practicable algal harvesting system nearer, the new work indicates that the method may also be useful in the treatment of sewage. The fact that laboratory- grown cultures of algae frothed without the addition of flotants indicates that a frothing agent was produced by the cultures themselves. A high-temperature strain of Chlorella pyrenoidosa was initially selected for use in the studies because its adaptability to the conditions of laboratory culture and its relatively high reproductive rate make it desirable for mass culturing as a food source or for gas exchange in closed systems. Following acid pH adjustment of the feed culture, it was placed in a glass cylinder equipped with a porous diffusion plate at the bottom. Air was forced through the plate, creating fine bubbles in the liquid above. A stable foam, highly concentrated in algae, formed at the liquid surface and rose up the column; the foam was collected at a discharge orifice. The feed solution was virtually clarified by this process which harvested almost all of the suspended cells (Figure 1). Hydrochloric acid was used to lower the pH of the harvest feed cultures and sodium hydroxide for subsequent neutralization. It was found that aeration rate and pH level influenced the degree of concentration obtained. Subsequent work has considered the desirability of harvesting only a portion of the algae and recycling the remaining culture in a continuous growth system. Successful operation of such a system requires that the algae remain viable despite exposure to the low pH condition in the harvester. Investigations were directed toward determination of viability of cells repeatedly exposed to harvesting conditions; and their subsequent growth in fresh media, supplemented, unsupple- mented, and diluted harvest liquor. EXPERIMENTAL PROCEDURES AND RESULTS Viability of Cells In order to determine the viability of cells which were continuously recycled, and resuspended in fresh medium, the following determinations were made. Seven hundred ml of urea medium (Composition in mg/1 deionized-distilled water: MgS04-7H2O, 1, 000; KH2PO4, 250; Urea, 1,000; iron sequestrine, 35; manganese sequestrine, 3; and sequestrines of copper, zinc and cobalt, 1.) were - 421 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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