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Microelectronics Manufacturer Reduces Rinse Line Water Disposal Costs and Sludge with Vacuum Evaporation

Introduction:

A top manufacturer of TFT-LCD panels needed to reduce its sludge production and wastewater disposal costs at two of its plants—complying with local environmental legislation. This sludge and water waste was produced in both of the plants’ rinse lines, as part of their copper(Cu) etching production process.

The Solution

Because no two wastewater streams are exactly alike, in order to find the best solution to meet the plant’s goals for each specific plant application, a careful review of their processes were completed, along with a thorough testing and analysis of the wastewater of each plant’s rinsing line. It was then determined that a PRAB EVALED® Vacuum Evaporator would be the best solution for each rinse line process.


Plant-1 Treatment Solution

At plant-1 a model RV F 15 AA vacuum evaporator was the solution for effectively cleaning the wastewater coming from their Cu-etching rinsing process and the new process was implemented.

New Wastewater Treatment Process Implemented

Diagram - Cu Etching Line to IER Regeneration with pH Adjustment that sends 13-15 tons per day to a PRAB EVALED Vacuum Evaporator RV F 15 AA which generates 11-14 tons per day of distillate that is resent to WWTP and 1-2 tons per day of concentrate that is disposed of
Front View - Evaled Vacuum Evaporator installed for Copper Etching Rinse Water LineSide View - Evaled Vacuum Evaporator installed for Copper Etching Rinse Water Line

PRAB EVALED Vacuum Evaporator
Model RV F 15 AA (113 sq/ft footprint)

Plant-1 Wastewater Treatment Results

Parameters u.m. Waste In Distilled Out Concentrate Out
pH 6-6.5 9
TDS ppm 4,000-50,000 <10
Conductivity µS/cm <8,000 <30
TS at 105˚C % 0.6-5
30
Chloride ppm <500 <300
Ammonium ppm 500-5,000 <500

Plant-2 Treatment Solution

Two model RV F 30 AA vacuum evaporators were determined to be the solution for effectively cleaning the wastewater coming from the rinsing lines at plant 2. One evaporator was implemented into the L7A Rinsing Line, and the other was installed as part of the L6B Rinsing Line.

New Wastewater Treatment Process Implemented

Diagram - Spent Bath (Rinsing Cu-Etching) to IER Regeneration with H2O2 Reduction and pH Adjustment which is sent to 2 separate lines with PRAB EVALED Vacuum Evaporators (model RV F 30 AA) that generate distillate and concentrate

Plant-2 Wastewater Treatment Results

Parameters u.m. Waste In Distilled Out Concentrate Out
pH 6-6.5 9
COD ppm 80,000 <4,000
Conductivity µS/cm <50,000 <20
TS at 105˚C % 5-9
30
Chloride ppm <500 <300
Ammonium ppm 5,000-15,000 <500

Summary

After adding PRAB EVALED® Vacuum Evaporator’s to the manufacturer’s rinsing line processes, each plant saw a significant reduction in sludge and disposal costs. Now, 70-90% of distillate is recovered and reused in the production processes—which has resulted in system paybacks within 8-months of installation.

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