Using Process Simulation to Predict Wastewater Treatment Outcomes

摘要

Changes occur rapidly in the semiconductor industry. New tools, new processes and the need to increase process capacity greatly impact downstream activities, notably wastewater treatment. The ability to predict how process changes affect water treatment will help to drive better wastewater handling methods, as critical areas of concern are identified aprioi. This paper examines the outcome of four waste treatment applications designed on the computer using real-solution aqueous process simulation. First, two typical fluoride waste water streams were treated with either Ca(OH)_2 or Process simulation was used to predict the chemical addition rate, and the clean water composition following CaF_2 removal. The predictions favorably compared to results achieved in the lab on synthetic wastewater samples; differences were attributed to limitations in the lab experimental procedures. Next, the effect of neutralization on dilute acid waste composition was explored by process simulation. It was shown that subtle changes can cause huge swings in species concentrations of wastewater. Third, the alumina and silica solubility in CMP waste was predicted, and it was pointed out how the data could be used to design a full-scale system. Lastly, it was determined how pH and ligand concentrations affected copper solubility in Cu CMP wastewater. Simulation predicted that 1,000 ppm of ammonia in the waste would cause the treated water to exceed discharge limitation unless a very high pH set point was used. The process simulation software was used to support the development and design of a process to treat Cu CMP wastewater, which was successfully piloted and commercialized.