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The Fate of Phosphorus in Waste Treatment Processes: The Enhanced Removal of Phosphate by Activated Sludge ARNOLD B. MENAR, Graduate Student DAVID JENKINS, Assistant Professor Department of Civil Engineering University of Calif ornia Berkeley, California INTRODUCTION In the considerable body of literature concerning the fate of phosphate in the activated sludge process, there appear to be two distinct schools of thought. The first viewpoint, represented in papers by Sawyer (1), Sekikawa etal. (2), Hall and Engel- brecht (3), and Jenkins and Menar (4), can be summarized as follows: 1) The volatile mass of activated sludge contains between two and three per cent by weight of biologically incorporated phosphorus; 2) the amount of phosphate incorporated biologically into activated sludge is not affected by the growth rate of the sludge, or by process operating parameters such as organic loading, MLSS concentration, aeration rate, or mixed liquor DO concentration; and 3) phosphate removal is proportional to the net sludge growth. With activated sludge P contents of two to three per cent, domestic sewage P contents of ten mg P/1, and substrate removal rates in the standard-rate range (0.4- 1.0 lb COD removed/lb MLVSS-day), biological removal of phosphate can only account for a maximum of 20 to 30 per cent of the influent phosphate or about two to three mg P/l of an influent ten mg P/l. The second point of view, expounded in papers by Levin and Shapiro (5), Borchardt and Azad (6), and Connell and Vacker (7), embodies the idea that under certain conditions activated sludge is capable of removing more than the two to three per cent phosphate-P that it requires for growth. The biological uptake of excess phosphate has been termed "luxury uptake." According to these authors phosphate removal by this mechanism is enhanced by high DO concentrations and, conversely, phosphate that has been incorporated into sludges by the luxury uptake mechanism can be released easily under anoxic conditions and conditions of low pH, such as those that might be encountered in the sludge blanket at the bottom of a secondary clarifier or in an anaerobic digester. Further, luxury uptake of phosphate leads to sludges with phosphate contents two to three times greater than "normal" sludges and consequently, treatment of domestic sewage at standard organic loading rates can lead to phosphate removals of 60 to 90 per cent of an influent ten mg P/l. A mechanism for the enhanced removal of phosphate must be consistent with these observations and in addition must provide satisfactory interpretation of the following observations made at the Rilling Road Plant, San Antonio, Texas - a plant that has experienced phosphate removals as high as 90 per cent: 1) At a point about -655-
Object Description
Purdue Identification Number | ETRIWC1969043 |
Title | Fate of phosphorus in waste treatment processes : the enhanced removal of phosphate by activated sludge |
Author |
Menar, Arnold B. Jenkins, David |
Date of Original | 1969 |
Conference Title | Proceedings of the 24th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,16392 |
Extent of Original | p. 655-674 |
Series | Engineering extension series no. 135 |
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 | 2009-05-21 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 655 |
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 | The Fate of Phosphorus in Waste Treatment Processes: The Enhanced Removal of Phosphate by Activated Sludge ARNOLD B. MENAR, Graduate Student DAVID JENKINS, Assistant Professor Department of Civil Engineering University of Calif ornia Berkeley, California INTRODUCTION In the considerable body of literature concerning the fate of phosphate in the activated sludge process, there appear to be two distinct schools of thought. The first viewpoint, represented in papers by Sawyer (1), Sekikawa etal. (2), Hall and Engel- brecht (3), and Jenkins and Menar (4), can be summarized as follows: 1) The volatile mass of activated sludge contains between two and three per cent by weight of biologically incorporated phosphorus; 2) the amount of phosphate incorporated biologically into activated sludge is not affected by the growth rate of the sludge, or by process operating parameters such as organic loading, MLSS concentration, aeration rate, or mixed liquor DO concentration; and 3) phosphate removal is proportional to the net sludge growth. With activated sludge P contents of two to three per cent, domestic sewage P contents of ten mg P/1, and substrate removal rates in the standard-rate range (0.4- 1.0 lb COD removed/lb MLVSS-day), biological removal of phosphate can only account for a maximum of 20 to 30 per cent of the influent phosphate or about two to three mg P/l of an influent ten mg P/l. The second point of view, expounded in papers by Levin and Shapiro (5), Borchardt and Azad (6), and Connell and Vacker (7), embodies the idea that under certain conditions activated sludge is capable of removing more than the two to three per cent phosphate-P that it requires for growth. The biological uptake of excess phosphate has been termed "luxury uptake." According to these authors phosphate removal by this mechanism is enhanced by high DO concentrations and, conversely, phosphate that has been incorporated into sludges by the luxury uptake mechanism can be released easily under anoxic conditions and conditions of low pH, such as those that might be encountered in the sludge blanket at the bottom of a secondary clarifier or in an anaerobic digester. Further, luxury uptake of phosphate leads to sludges with phosphate contents two to three times greater than "normal" sludges and consequently, treatment of domestic sewage at standard organic loading rates can lead to phosphate removals of 60 to 90 per cent of an influent ten mg P/l. A mechanism for the enhanced removal of phosphate must be consistent with these observations and in addition must provide satisfactory interpretation of the following observations made at the Rilling Road Plant, San Antonio, Texas - a plant that has experienced phosphate removals as high as 90 per cent: 1) At a point about -655- |
Resolution | 300 ppi |
Color Depth | 8 bit |
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