Electrodialysis Process for the Recycling and Concentrating of Tetramethylammonium Hydroxide (TMAH) from Photoresist Developer Wastewater

A large amount of developer wastewater containing tetramethylammonium hydroxide (TMAH) is discharged from semiconductors and photoelectric industries. The electrodialysis technique was employed for the recovering and concentrating of TMAH from developer wastewater. The effect of current density on the recovery process was investigated by considering the stability of membranes and process cost. Results indicated that the optimal current density was chosen at 30 mA•cm–2. TMAH can be concentrated in the range of 7.45%–8.33%. The used membranes in the experiments were stable and suitable for this wastewater treatment. The total process cost was estimated to be 36.4 $/t without considering the profit of the recovered TMAH. Naturally, electrodialysis is a cost-effective and environmentally friendly technology for treating developer wastewater.