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The Effect of Temperature on High-Rate Digestion of Activated Sludge J. F. MALINA, JR. Assistant Professor of Civil Engineering University of Texas Austin, Texas The high-rate digestion of decomposable solids is of primary concern because of the large volume of activated sludge resulting from the treatment of waste waters. Information dealing with the effect of temperature on high-rate digestion processes currently employed in the treatment of waste waters is almost nonexistent. It is generally accepted that careful control of the temperature is imperative for efficient operation of the anaerobic digestion process. The information included in this paper presents an evaluation of the effect of temperatures greater than 30 C on the high-rate digestion of activated sludge. LITERATURE REVIEW The processes employed in primary treatment of waste water are designed in part to separate a portion of the suspended particulate materials from colloidal and dissolved matter. In secondary treatment processes the colloidal and dissolved substances are converted microbially into suspended material which can be separated by gravity sedimentation. The solids separated in these processes require additional treatment, and in many treatment works are partially decomposed by an anaerobic microbial population in a sludge digestion tank. In current practice the anaerobic fermentation of the sewage solids has been carried out in what is generally referred to as either conventional sludge digestion tanks or high-rate sludge digestion tanks. The conventional tank is one in which the contents are unmixed, and the loading to these digesters was about 0.05 lbs of volatile material per cu ft of capacity per day. The detention time was usually in excess of 30 days. However, within the past decade high-rate digestion systems have been developed. The results of studies conducted in the laboratory in pilot units and in field installations indicate that loadings of volatile material up to 0.35 lbs of volatile material per cu ft of digester capacity per day could be digested in less than 15 days at temperatures near 30 c. Laboratory and pilot investigations by Fuhrman (3), Morgan (10), Sawyer, (11), and Torpey (14) indicate that up to seven times the conventional loading to the digester are successfully treated in about one-third the conventional detention time. Table I summarizes these early studies. Successful plant-scale high-rate digestion units have been installed employing both gas circulation and draft-tube mixers. The results obtained at these Field installations confirm the results of the laboratory and pilot-plant studies discussed above. - 232 -
Object Description
Purdue Identification Number | ETRIWC196123 |
Title | Effect of temperature on high-rate digestion of activated sludge |
Author | Malina, Joseph F., 1935- |
Date of Original | 1961 |
Conference Title | Proceedings of the sixteenth Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/cdm4/document.php?CISOROOT=/engext&CISOPTR=7917&REC=15 |
Extent of Original | p. 232-250 |
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 | 2008-09-22 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 232 |
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 Effect of Temperature on High-Rate Digestion of Activated Sludge J. F. MALINA, JR. Assistant Professor of Civil Engineering University of Texas Austin, Texas The high-rate digestion of decomposable solids is of primary concern because of the large volume of activated sludge resulting from the treatment of waste waters. Information dealing with the effect of temperature on high-rate digestion processes currently employed in the treatment of waste waters is almost nonexistent. It is generally accepted that careful control of the temperature is imperative for efficient operation of the anaerobic digestion process. The information included in this paper presents an evaluation of the effect of temperatures greater than 30 C on the high-rate digestion of activated sludge. LITERATURE REVIEW The processes employed in primary treatment of waste water are designed in part to separate a portion of the suspended particulate materials from colloidal and dissolved matter. In secondary treatment processes the colloidal and dissolved substances are converted microbially into suspended material which can be separated by gravity sedimentation. The solids separated in these processes require additional treatment, and in many treatment works are partially decomposed by an anaerobic microbial population in a sludge digestion tank. In current practice the anaerobic fermentation of the sewage solids has been carried out in what is generally referred to as either conventional sludge digestion tanks or high-rate sludge digestion tanks. The conventional tank is one in which the contents are unmixed, and the loading to these digesters was about 0.05 lbs of volatile material per cu ft of capacity per day. The detention time was usually in excess of 30 days. However, within the past decade high-rate digestion systems have been developed. The results of studies conducted in the laboratory in pilot units and in field installations indicate that loadings of volatile material up to 0.35 lbs of volatile material per cu ft of digester capacity per day could be digested in less than 15 days at temperatures near 30 c. Laboratory and pilot investigations by Fuhrman (3), Morgan (10), Sawyer, (11), and Torpey (14) indicate that up to seven times the conventional loading to the digester are successfully treated in about one-third the conventional detention time. Table I summarizes these early studies. Successful plant-scale high-rate digestion units have been installed employing both gas circulation and draft-tube mixers. The results obtained at these Field installations confirm the results of the laboratory and pilot-plant studies discussed above. - 232 - |
Resolution | 300 ppi |
Color Depth | 8 bit |
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