A study was carried out in an electronic wafer manufacturer which uses Hydrofluoric (HF) acid for their wafer production lime. This process known as wafer etching contributes not only acidic pH value, but also high fluoride content in their wastewater. On average, the production line discharge 10m³/day of HF waste into their wastewater treatment system. As the HF wastewater is being discharge, it contains an average of 15,000ppm of fluoride in the wastewater which is 7,500 times more than DOE Standard A Discharge Limit. 

 

This HF wastewater will go through a series of chemical treatment, particularly using conventional method (Lime) to reduce the fluoride level and increase its pH. However, after using the conventional method, the fluoride level at the final discharge level is recorded at 9ppm. The discharge level does not meet the DOE Standard A level which is 2ppm. 

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In order to solve this issue, Watterson had conducted a study on the wastewater. We maintain the usage of Lime to act as a primary reducer for the fluoride while adding Hyfor as a polishing chemical to bring down the Fluoride level down to DOE Standard A discharge limit. As a result of using both Lime and Hyfor as coagulants, we managed to bring the Fluoride level down to 0.636ppm which is much lower than DOE Standard A discharge limit.