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STUDY OF THE EFFECT OF BORON TOXICITY ON AN ACTIVATED SLUDGE SYSTEM Wayne G. Webber, .Project Engineer Donald W. Kemp, Chemist Samuel E. Rice, Project Engineer Metcalf and Eddy, Inc. Boston, Massachusetts 02114 INTRODUCTION Boron levels in aqueous systems can vary widely depending on the water source and the effluent that is discharged to the receiving water. For surface waters the observed boron concentration ranges from 0.1 mg/l to 5 mg/l in lakes and streams and is relatively constant at 4.5 mg/l in sea water [1], Generally, boron levels in ground water exceed those of surface water but there is a wide variability due in part to the presence or absence of boron-containing minerals. The concentration of boron in the influents to municipal systems will vary depending on the boron levels contributed by industrial sources. The boron in aqueous systems originates from the leaching of naturally occurring boron deposits, effluents from industrial processing that utilizes boron compounds as raw material and wastes from boron-containing consumer products such as borate-based detergents. An increase in the consumption of these consumer products is expected to result in increased levels of boron in some receiving waters. The presence of boron in the water has both beneficial and detrimental effects, depending upon its relative concentration. For example, boron is a necessary micronutrient for some plants and algae species; however, toxic effects can result if certain minimum concentration levels are exceeded. These concentration limits vary with different plant systems. For example, plant crops have been categorized into three different groups with respect to toxicity levels: tolerant, 2 to 4 mg/l; semitolerant, 1 to 2 mg/l; and sensitive, < 1 mg/l [ 1 ]. The tolerant classification includes most of the root species, such as turnip, beet, and carrot, and some leaf species, such as cabbage and lettuce. The semitolerant toxic level includes the grains and most of the stalk vegetables, such as tomatoes, beans and peppers. Included in the sensitive class are citrus and fruit trees. Algae species show variable behavior with respect to boron. Some species, such as blue-green algae, absorb boron and show a growth response to boron, whereas some of the green algae species were observed to be neither stimulated nor inhibited by boron levels up to 10 mg/l [2,3]. Animal or human life has not been observed to be adversely affected by boron concentrations that one normally observes in water systems. Toxic effects, however, have been observed in certain biological processes. One study using a synthetic activated sludge derived from a yeast extract observed a toxic or inhibiting effect when the sludge was contacted with 1 mg/l solution of boron [4]. Based on these observed effects EPA has defined concentration limitations for the usage of boron-contaminated water sources [4J. Different standards ranging from 0.75 mg/l to 2 mg/l have been imposed for irrigation water depending upon which crop species are being irrigated. The standard given for raw water used as a public water supply is a maximum acceptable concentration of 1 mg/l [5]. The rationale given for this low limit is not because of the toxicity to humans, but because of the potential toxic effects that might result from watering home gardens, fruit trees and ornamental plants with concentrations of boron higher than 1 mg/l. No standard has been given for aquatic life or wildlife in fresh water, but in marine water the maximum concentration of boron has been set at 5 mg/l [6]. 743
Object Description
Purdue Identification Number | ETRIWC197666 |
Title | Study of the effect of boron toxicity on an activated sludge system |
Author |
Webber, Wayne G. Kemp, Donald W. Rice, Samuel E. |
Date of Original | 1976 |
Conference Title | Proceedings of the 31st Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://e-archives.lib.purdue.edu/u?/engext,27048 |
Extent of Original | p. 743-752 |
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 | 2009-07-08 |
Capture Device | Fujitsu fi-5650C |
Capture Details | ScandAll 21 |
Resolution | 300 ppi |
Color Depth | 8 bit |
Description
Title | page 743 |
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 | STUDY OF THE EFFECT OF BORON TOXICITY ON AN ACTIVATED SLUDGE SYSTEM Wayne G. Webber, .Project Engineer Donald W. Kemp, Chemist Samuel E. Rice, Project Engineer Metcalf and Eddy, Inc. Boston, Massachusetts 02114 INTRODUCTION Boron levels in aqueous systems can vary widely depending on the water source and the effluent that is discharged to the receiving water. For surface waters the observed boron concentration ranges from 0.1 mg/l to 5 mg/l in lakes and streams and is relatively constant at 4.5 mg/l in sea water [1], Generally, boron levels in ground water exceed those of surface water but there is a wide variability due in part to the presence or absence of boron-containing minerals. The concentration of boron in the influents to municipal systems will vary depending on the boron levels contributed by industrial sources. The boron in aqueous systems originates from the leaching of naturally occurring boron deposits, effluents from industrial processing that utilizes boron compounds as raw material and wastes from boron-containing consumer products such as borate-based detergents. An increase in the consumption of these consumer products is expected to result in increased levels of boron in some receiving waters. The presence of boron in the water has both beneficial and detrimental effects, depending upon its relative concentration. For example, boron is a necessary micronutrient for some plants and algae species; however, toxic effects can result if certain minimum concentration levels are exceeded. These concentration limits vary with different plant systems. For example, plant crops have been categorized into three different groups with respect to toxicity levels: tolerant, 2 to 4 mg/l; semitolerant, 1 to 2 mg/l; and sensitive, < 1 mg/l [ 1 ]. The tolerant classification includes most of the root species, such as turnip, beet, and carrot, and some leaf species, such as cabbage and lettuce. The semitolerant toxic level includes the grains and most of the stalk vegetables, such as tomatoes, beans and peppers. Included in the sensitive class are citrus and fruit trees. Algae species show variable behavior with respect to boron. Some species, such as blue-green algae, absorb boron and show a growth response to boron, whereas some of the green algae species were observed to be neither stimulated nor inhibited by boron levels up to 10 mg/l [2,3]. Animal or human life has not been observed to be adversely affected by boron concentrations that one normally observes in water systems. Toxic effects, however, have been observed in certain biological processes. One study using a synthetic activated sludge derived from a yeast extract observed a toxic or inhibiting effect when the sludge was contacted with 1 mg/l solution of boron [4]. Based on these observed effects EPA has defined concentration limitations for the usage of boron-contaminated water sources [4J. Different standards ranging from 0.75 mg/l to 2 mg/l have been imposed for irrigation water depending upon which crop species are being irrigated. The standard given for raw water used as a public water supply is a maximum acceptable concentration of 1 mg/l [5]. The rationale given for this low limit is not because of the toxicity to humans, but because of the potential toxic effects that might result from watering home gardens, fruit trees and ornamental plants with concentrations of boron higher than 1 mg/l. No standard has been given for aquatic life or wildlife in fresh water, but in marine water the maximum concentration of boron has been set at 5 mg/l [6]. 743 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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