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Biological Treatment of Acid Mine Water CHIN - CHIEN HSU, Graduate Student PHILIP A. RICE, Assistant Professor Department of Chemical Engineering and Metallurgy Syracuse University Syracuse, New York INTRODUCTION Acid mine drainage is a serious pollutant in all states in which coal mining is important. The drainage is thought to be generated by action of the iron bacteria on the pyrite deposits in the presence of air and water (1). The iron bacteria oxidize the pyrite, forming in the process iron sulfate and sulfuric acid. Thus acid mine drainage is characterized by a low pH, 3.5; high sulfate ion content, from a few hundred to several thousand ppm, and a high iron content, with both ferrous and ferric ions of about 10 to 500 mg/1. The water is unfit for recreational use, it cannot support fish life, and is corrosive to industrial piping and highway bridges. Several types of treatment of prevention processes are under investigation (1,2). These include mine sealing, neutralization with lime and limestone, and biological treatment. The purpose of mine sealing is to prevent the acid mine water from forming by eliminating the oxygen from the vicinity of the coal surface and to reduce the flow of polluted water from the mine. Typical ways of accomplishing this are to flood the mine with water or to displace the air in the mine with inert nitrogen. This process cannot be used in active mines and sealing is often difficult to accomplish completely because of underground streams, rock fissures, and the natural permeability of the overburden. Neutralization with lime and limestone removes or reduces the acidity of the stream and may remove some of the iron. It does not remove the sulfate, however, and the addition of calcium adds to the hardness of the water. In addition, continuous additions are required, implying continuous operating costs. A biological treatment process seemed desirable since no addition of chemicals to the water except organic substrate to serve as a carbon source for the bacteria would be necessary. This carbon source could be provided cheaply, possibly in the form of municipal sludge or sawdust. A particularly suitable bacteria for this purpose is the sulfate reducing bacteria, Desulfovibrio desulfuricans. This bacteria is a strict anaerobe, using sulfur compounds alone as its oxygen source or electron acceptor. This bacteria, in the presence of a carbon source at low oxidation potentials reduces sulfate ion to sulfide (3,4).The sulfide produced then combines with ferrous ion in the solution to form ferrous sulfide precipitate. Additional sulfide produced is released in the form of hydrogen sulfide gas, removing in the process hydrogen ion from the solution. Thus, if the reactor can be properly operated, both the sulfate and the iron will be removed from the drainage and the pH also increased. This process would require the additional treatment of the hydrogen sulfide gas. -662-
Object Description
Purdue Identification Number | ETRIWC197070 |
Title | Biological treatment of acid mine water |
Author |
Hsu, Chin-Chien Rice, Philip A. |
Date of Original | 1970 |
Conference Title | Proceedings of the 25th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,18196 |
Extent of Original | p. 662-672 |
Series | Engineering extension series no. 137 |
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 | 2009-06-09 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page662 |
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 | Biological Treatment of Acid Mine Water CHIN - CHIEN HSU, Graduate Student PHILIP A. RICE, Assistant Professor Department of Chemical Engineering and Metallurgy Syracuse University Syracuse, New York INTRODUCTION Acid mine drainage is a serious pollutant in all states in which coal mining is important. The drainage is thought to be generated by action of the iron bacteria on the pyrite deposits in the presence of air and water (1). The iron bacteria oxidize the pyrite, forming in the process iron sulfate and sulfuric acid. Thus acid mine drainage is characterized by a low pH, 3.5; high sulfate ion content, from a few hundred to several thousand ppm, and a high iron content, with both ferrous and ferric ions of about 10 to 500 mg/1. The water is unfit for recreational use, it cannot support fish life, and is corrosive to industrial piping and highway bridges. Several types of treatment of prevention processes are under investigation (1,2). These include mine sealing, neutralization with lime and limestone, and biological treatment. The purpose of mine sealing is to prevent the acid mine water from forming by eliminating the oxygen from the vicinity of the coal surface and to reduce the flow of polluted water from the mine. Typical ways of accomplishing this are to flood the mine with water or to displace the air in the mine with inert nitrogen. This process cannot be used in active mines and sealing is often difficult to accomplish completely because of underground streams, rock fissures, and the natural permeability of the overburden. Neutralization with lime and limestone removes or reduces the acidity of the stream and may remove some of the iron. It does not remove the sulfate, however, and the addition of calcium adds to the hardness of the water. In addition, continuous additions are required, implying continuous operating costs. A biological treatment process seemed desirable since no addition of chemicals to the water except organic substrate to serve as a carbon source for the bacteria would be necessary. This carbon source could be provided cheaply, possibly in the form of municipal sludge or sawdust. A particularly suitable bacteria for this purpose is the sulfate reducing bacteria, Desulfovibrio desulfuricans. This bacteria is a strict anaerobe, using sulfur compounds alone as its oxygen source or electron acceptor. This bacteria, in the presence of a carbon source at low oxidation potentials reduces sulfate ion to sulfide (3,4).The sulfide produced then combines with ferrous ion in the solution to form ferrous sulfide precipitate. Additional sulfide produced is released in the form of hydrogen sulfide gas, removing in the process hydrogen ion from the solution. Thus, if the reactor can be properly operated, both the sulfate and the iron will be removed from the drainage and the pH also increased. This process would require the additional treatment of the hydrogen sulfide gas. -662- |
Resolution | 300 ppi |
Color Depth | 8 bit |
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