Case Study: Fluoride reduction system for the removal of fluorides from industrial wastewaters.
| Client:
Major semiconductor manufacturer in the southwest United States.
Industry: Semiconductor Manufacturing. Installation Date: June 2008. Objective: To remove fluoride and neutralize hydrofluoric acid and fluoride laden wastewater. Criteria and Limitations: Influent flow is relatively constant and ranges from 150 to 175 GPM with fluoride levels ranging from 0 - 5000 ppm. Fluoride effluent limit is 17ppm of total fluoride and effluent pH range is 6.0 < pH < 9.0 |
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| Overview:
The extensive use of hydrofluoric acid (HF) and buffered oxide etches (BOE)
for the use of silica substrate etching requires the use of fluoride
reduction system throughout the industry to remove fluorides from the
wastewater stream. Free fluorides in industrial wastewater can be very
corrosive and very toxic to both aquatic and terrestrial life, therefore
fluorides must be removed. .
In a typical application fluorides are removed from wastewater via Calcium Fluoride (CaF2) precipitation and subsequent pH neutralization. The fluorides, once properly treated, are handled as a completely inert, non-hazardous dry sludge cake with resale / recycle value. In this example we examine a 200 GPM fluoride reduction and pH neutralization system designed to remove fluorides from levels as high as 5,000 ppm to less than 17 ppm of total fluoride. The system is installed outdoors in a hurricane prone region in the vicinity of a chemical production classified as hazardous (Class 1, Division 1, group C&D). |
Solution: A modular continuous flow through fluoride reduction system was developed and installed by DAC to handle flows up to 200 GPM of acidic fluoride laden wastewaters. The major stages of this system include:
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| The Process: Digital Analysis Corp. has developed a unique process for reducing fluorides in semiconductor fab operations. This process allows for the totally automated reduction in total fluorides. Fluoride levels as low as 2ppm can be reliably attained. |
Conclusion: Digital Analysis was contracted to design, build, install, and commission a fluoride reduction and pH neutralization system as outlined above. This system, as with many industrial wastewater treatment systems, was constrained by time, space and money with special emphasis on space. This fluoride removal system was installed outdoors in a hurricane prone region near a chemical process that was classified as hazardous necessitating an explosion proof design and installation.
The project, as with many wastewater treatment systems, was
constrained by time, space, and money. The use of a standard
packaged system at the center of the treatment process allowed us
to offer the customer a very capable system with a good delivery
time, very competitive price, and minimal installation since the
entire treatment system was fabricated in our shop prior to
shipping.
The fluoride system performance has exceeded all specified and published requirements and has run continuously for over three years and has been very well maintained by the end user .
Description: The
system supplied for this application utilizes our unique process
for reduction and removal of fluoride from semi-conductor
wastewater streams as non-hazardous calcium fluoride (CaF2).
The process we employ is totally automated, requires no operator
intervention (other than periodic maintenance and calibrations),
is safe and can yield total fluoride levels as low as 2 ppm,
depending on configuration.
The system
featured in this case review is a continuous flow through four stage fluoride
reduction and pH adjustment system capable of handling peak flows to 200 GPM.
Critical component redundancy is provided in those areas identified as
vulnerable.
This package was
totally fabricated in our facility and shipped as several
subsystems, including a catwalk for servicing equipment at higher
elevations. Installation was minimized by the fact that the
entire system was fabricated in our shop prior to shipping.
A Supervisory
Control And Data Acquisition (SCADA)
system is installed that monitors the entire system. All of the
programmable parameters, tuning variables, and setpoints are
available through the SCADA system. All process variables and
system performance are monitored continuously via the SCADA
system. Historical logging will maintain a continuous stream of
data that may span several years.
A remote connection is available via MODEM that allows us to monitor the system from anywhere in the world. We are able to troubleshoot, modify tuning parameters, or conduct training via this phone line connection.
For additional information request our white paper Fluoride Reduction in Industrial Waste Streams via email: support@digital-analysis.com and see our technical paper: Fluoride Removal from Industrial Wastewaters
Digital
Analysis Corporation
PO Box 95
716 Visions Drive
Skaneateles, NY 13152
315-685-0760
315-685-0766(fax)
For Product Information : Email : info@digital-analysis.com
For Service & Support :Email : support@digital-analysis.com
