In nano-electronics manufacturing, tetramethylammonium hydroxide (TMAH) is extensively used in the photo-lithography and etching processes, leading to a waste disposal issue. The present study focuses on TMAH wastewater treatment in nano-electronics industries by using membrane distillation technology. Actual TMAH wastewater samples were collected at imec, Belgium. An air gap membrane distillation bench unit was employed to perform the experiments for different operating conditions i.e., feed temperatures and flow rates. High quality water is recovered after reducing the TMAH concentration to 1 ppm and lowering the TOC to 0.8 ppm from 8 ppm. For the industrial scale TMAH wastewater treatment, industrial waste heat driven and district heating driven membrane distillation systems are designed and analyzed. It is determined that 14 GWh thermal energy is required annually to treat 20,000 m3 of TMAH wastewater/year while considering 65 °C as the membrane distillation feed temperature. Expected unit water treatment cost is found as low as 16 $/m3 of TMAH wastewater, roughly 80% lower than current disposal costs.
Noor, I. e., Coenen, J., Martin, A., Dahl, O., & Åslin, M. (2019). Experimental investigation and techno-economic analysis of tetramethylammonium hydroxide removal from wastewater in nano-electronics manufacturing via membrane distillation. Journal of Membrane Science, 579, 283–293. https://doi.org/10.1016/j.memsci.2019.02.067