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EXTRACTION OF METALS AND PHOSPHORUS FROM INCINERATED MUNICIPAL SEWAGE SLUDGE Robert C. Gabler, Jr., Research Chemist David L. Neylan, Chemist College Park Metallurgy Research Center Bureau of Mines U.S. Department of the Interior College Park, Maryland 20740 INTRODUCTION In the U.S. approximately 9.3 million dry tons [ 1 ] of municipal sewage sludge is generated annually, of which 35% is incinerated. As an extension of the Bureau of Mines program to convert waste materials from a disposal problem into a secondary resource, studies were undertaken to determine if the metals and phosphorus can be removed prior to disposal of the ash. By this approach, the ash is converted into an environmentally acceptable material while valuable resources are conserved. Although this secondary source of metals and phosphorus will probably not be economically competitive with conventional ores, part of the extraction-recovery cost could be borne as a disposal expense. This resource recovery study, being conducted at the Bureau of Mines College Park Metallurgy Research Center, has two objectives—detailed characterization of incinerated sludge ashes from representative U.S. cities, and evaluation of low-cost extraction processes. Various investigators have shown an increasing interest in both the quantity of metals present in sludge ash and the most efficient means of extracting these metals and phosphorus. Furr and co-workers [2] and Salotto, Grossman and Farrell [3] determined the metals in sludge samples from many municipal wastewater treatment plants. The disposition of the metals, phosphorus, pesticides and polychlorinated biphenyls during the incineration of sludges was studied by Farrell and Salotto [4]; Other researchers [5-9] investigated the extraction of metals and phosphorus from both sludges and sludge ash. Diosady [6] was of the opinion that "only phosphate recovery seems economically warranted." However, most of the previous investigators are in agreement that further investigations into extraction processes are necessary because environmental considerations may ultimately require the removal of toxic metals from the sludge ash prior to disposal. In addition, the sludge ash from one of the U.S. cities investigated in this study contained concentrations of precious metals that may justify removal and recovery. Previous characterization studies by the authors [10] on incinerated sludge ash are summarized in Table I. Samples were obtained from 14 incinerators serving 11 U.S. localities that range from cities with heavy industry such as Detroit, Michigan, Cleveland, Ohio, and St. Louis, Missouri, to cities with small specialized industries and large residential areas such as San Mateo and Palo Alto, California. The analytical data on these samples showed significant variations between cities in the major constituents, possible reflecting the various reagents-iron and aluminum slats, and lime-used to remove phosphorus from the sewage stream. As expected, there were also large variations in trace and minor elements between cities. 39
Object Description
Purdue Identification Number | ETRIWC1977006 |
Title | Extraction of metals and phosphorus from incinerated municipal sewage sludge |
Author |
Gabler, Robert C. Neylan, David L. |
Date of Original | 1977 |
Conference Title | Proceedings of the 32nd Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,26931 |
Extent of Original | p. 39-49 |
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 | 2009-06-30 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page039 |
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 | EXTRACTION OF METALS AND PHOSPHORUS FROM INCINERATED MUNICIPAL SEWAGE SLUDGE Robert C. Gabler, Jr., Research Chemist David L. Neylan, Chemist College Park Metallurgy Research Center Bureau of Mines U.S. Department of the Interior College Park, Maryland 20740 INTRODUCTION In the U.S. approximately 9.3 million dry tons [ 1 ] of municipal sewage sludge is generated annually, of which 35% is incinerated. As an extension of the Bureau of Mines program to convert waste materials from a disposal problem into a secondary resource, studies were undertaken to determine if the metals and phosphorus can be removed prior to disposal of the ash. By this approach, the ash is converted into an environmentally acceptable material while valuable resources are conserved. Although this secondary source of metals and phosphorus will probably not be economically competitive with conventional ores, part of the extraction-recovery cost could be borne as a disposal expense. This resource recovery study, being conducted at the Bureau of Mines College Park Metallurgy Research Center, has two objectives—detailed characterization of incinerated sludge ashes from representative U.S. cities, and evaluation of low-cost extraction processes. Various investigators have shown an increasing interest in both the quantity of metals present in sludge ash and the most efficient means of extracting these metals and phosphorus. Furr and co-workers [2] and Salotto, Grossman and Farrell [3] determined the metals in sludge samples from many municipal wastewater treatment plants. The disposition of the metals, phosphorus, pesticides and polychlorinated biphenyls during the incineration of sludges was studied by Farrell and Salotto [4]; Other researchers [5-9] investigated the extraction of metals and phosphorus from both sludges and sludge ash. Diosady [6] was of the opinion that "only phosphate recovery seems economically warranted." However, most of the previous investigators are in agreement that further investigations into extraction processes are necessary because environmental considerations may ultimately require the removal of toxic metals from the sludge ash prior to disposal. In addition, the sludge ash from one of the U.S. cities investigated in this study contained concentrations of precious metals that may justify removal and recovery. Previous characterization studies by the authors [10] on incinerated sludge ash are summarized in Table I. Samples were obtained from 14 incinerators serving 11 U.S. localities that range from cities with heavy industry such as Detroit, Michigan, Cleveland, Ohio, and St. Louis, Missouri, to cities with small specialized industries and large residential areas such as San Mateo and Palo Alto, California. The analytical data on these samples showed significant variations between cities in the major constituents, possible reflecting the various reagents-iron and aluminum slats, and lime-used to remove phosphorus from the sewage stream. As expected, there were also large variations in trace and minor elements between cities. 39 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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