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74 TECHNIQUES FOR FLUORIDE REMOVAL IN INDUSTRIAL WASTEWATERS C. Peter Varuntanya, Project Manager Dennis R. Shafer, Project Engineer Chester Environmental Pittsburgh, Pennsylvania 15244 INTRODUCTION Generation of fluoride containing wastes from the semiconductor industry is a result of chemical etching in which hydrofluoric acid is used. Fluoride containing wastes from the steel or metal processing industries are a result of pickling by utilizing a mixture of nitric and hydrofluoric acid. Industries, such as electroplating, glass manufacturing, and the aluminum industry typically generate fluoride containing wastes as well. For discharges resulting from the manufacture of semiconductors, U.S. Environmental Protection Agency (U.S. EPA) has proposed the fluoride effluent limitations for any existing point source subject to best available technology (BAT) and new sources subject to new source performance standards (NSPS) in 40 CFR 469.17 as 32.0 mg/L for the daily maximum and 17.4 mg/L for the average of daily values for 30 consecutive days, respectively. As for discharges resulting from the manufacture of non-ferrous metals for surface treatment rinses in 40 CFR 471.92, BAT standards for fluoride are 52.9 mg/off-Kg (daily maximum) and 23.5 mg/off-Kg (average of daily values for 30 consecutive days). [The term "off-Kg" means the mass of metal or metal alloy removed from a forming operation at the end of a process cycle for transfer to a different machine or process.) Most of the state regulatory agencies have subscribed to a uniform limitation of 1 mg/L for the concentration of fluoride ion in surface waters to prevent mottling of teeth. Therefore, regulatory agencies will be driven to allocate limitations to industrial facilities that will ensure a 1 mg/L fluoride concentration in surface waters. This paper discusses treatability studies utilizing several techniques for reducing fluoride-laden industrial wastewaters based on limited plant operating data. The treatability studies were conducted on the wastewaters of a semiconductor manufacturing facility and of a zirconium tube manufacturer. BACKGROUND As specified by its NPDES (National Pollutant Discharge Elimination System) permit, the zirconium manufacturer was required to meet a discharge limit for fluoride of 18.9 lb/day as a daily maximum and 8.4 lb/day as a monthly average. The average flow from the facility was 0.07 MGD. The maximum flow from the facility was 0.10 MGD. Based on a maximum flow, a concentration limit of 10.1 mg/L was established as the objective for fluoride reduction in the treatability studies. The semiconductor facility was under agreement with its permitting authority to limit its discharge to 22.6 lb/day. The flow from this facility was 0.6 MGD. Therefore the objective of treatability studies for this waste was to reduce the fluoride concentration to a maximum of 4.5 mg/L. Both facilities generate wastewaters containing roughly 25 mg/L fluoride. The treatability studies showed that fluoride can be reduced to nearly 1 mg/L using conventional treatment processes. The treatability studies conducted in the laboratory were based on lime precipitation which is the first stage of chemical addition. Upon formation of the calcium fluoride precipitate, other chemicals were added sequentially; i.e., calcium chloride, alum, alum/sodium hexametaphosphate, and phosphoric acid. Use of lime precipitation followed by activated alumina was also performed. 48th Purdue Industrial Waste Conference Proceedings, 1993 Lewis Publishers, Chelsea, Michigan 48118. Printed in U.S.A. 743
Object Description
Purdue Identification Number | ETRIWC199374 |
Title | Techniques for fluoride removal in industrial wastewaters |
Author |
Varuntanya, C. Peter Shafer, Dennis R. |
Date of Original | 1993 |
Conference Title | Proceedings of the 48th Industrial Waste Conference |
Conference Front Matter (copy and paste) | http://earchives.lib.purdue.edu/u?/engext,21159 |
Extent of Original | p. 743-750 |
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 |
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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 | 74 TECHNIQUES FOR FLUORIDE REMOVAL IN INDUSTRIAL WASTEWATERS C. Peter Varuntanya, Project Manager Dennis R. Shafer, Project Engineer Chester Environmental Pittsburgh, Pennsylvania 15244 INTRODUCTION Generation of fluoride containing wastes from the semiconductor industry is a result of chemical etching in which hydrofluoric acid is used. Fluoride containing wastes from the steel or metal processing industries are a result of pickling by utilizing a mixture of nitric and hydrofluoric acid. Industries, such as electroplating, glass manufacturing, and the aluminum industry typically generate fluoride containing wastes as well. For discharges resulting from the manufacture of semiconductors, U.S. Environmental Protection Agency (U.S. EPA) has proposed the fluoride effluent limitations for any existing point source subject to best available technology (BAT) and new sources subject to new source performance standards (NSPS) in 40 CFR 469.17 as 32.0 mg/L for the daily maximum and 17.4 mg/L for the average of daily values for 30 consecutive days, respectively. As for discharges resulting from the manufacture of non-ferrous metals for surface treatment rinses in 40 CFR 471.92, BAT standards for fluoride are 52.9 mg/off-Kg (daily maximum) and 23.5 mg/off-Kg (average of daily values for 30 consecutive days). [The term "off-Kg" means the mass of metal or metal alloy removed from a forming operation at the end of a process cycle for transfer to a different machine or process.) Most of the state regulatory agencies have subscribed to a uniform limitation of 1 mg/L for the concentration of fluoride ion in surface waters to prevent mottling of teeth. Therefore, regulatory agencies will be driven to allocate limitations to industrial facilities that will ensure a 1 mg/L fluoride concentration in surface waters. This paper discusses treatability studies utilizing several techniques for reducing fluoride-laden industrial wastewaters based on limited plant operating data. The treatability studies were conducted on the wastewaters of a semiconductor manufacturing facility and of a zirconium tube manufacturer. BACKGROUND As specified by its NPDES (National Pollutant Discharge Elimination System) permit, the zirconium manufacturer was required to meet a discharge limit for fluoride of 18.9 lb/day as a daily maximum and 8.4 lb/day as a monthly average. The average flow from the facility was 0.07 MGD. The maximum flow from the facility was 0.10 MGD. Based on a maximum flow, a concentration limit of 10.1 mg/L was established as the objective for fluoride reduction in the treatability studies. The semiconductor facility was under agreement with its permitting authority to limit its discharge to 22.6 lb/day. The flow from this facility was 0.6 MGD. Therefore the objective of treatability studies for this waste was to reduce the fluoride concentration to a maximum of 4.5 mg/L. Both facilities generate wastewaters containing roughly 25 mg/L fluoride. The treatability studies showed that fluoride can be reduced to nearly 1 mg/L using conventional treatment processes. The treatability studies conducted in the laboratory were based on lime precipitation which is the first stage of chemical addition. Upon formation of the calcium fluoride precipitate, other chemicals were added sequentially; i.e., calcium chloride, alum, alum/sodium hexametaphosphate, and phosphoric acid. Use of lime precipitation followed by activated alumina was also performed. 48th Purdue Industrial Waste Conference Proceedings, 1993 Lewis Publishers, Chelsea, Michigan 48118. Printed in U.S.A. 743 |
Resolution | 300 ppi |
Color Depth | 8 bit |
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