Treatment technologies and mechanisms for tetramethylammonium hydroxide (TMAH) wastewater from micro-electronic industry: A review

With the advent of Industry 4.0, the micro-electronic industry has become one of the fastest-growing industries worldwide. As a result, tetramethylammonium hydroxide (TMAH) wastewater, as the typical wastewater from the micro-electronic industry, has been dramatically increasing. The efficient treatment of TMAH wastewater has attracted growing attention due to its toxicity to the eco-environment and human health. However, the review of the mechanisms of TMAH wastewater treatment is still lacking. This paper systematically reviewed the mechanisms of TMAH treatment using various processes, including recovery processes and degradation processes. The recovery mechanisms of TMAH included cation exchange under the electrostatic attraction for adsorption, directed migration of TMA+ and OH− driven by electrodes for electrodialysis, etc. The degradation mechanisms of TMAH included methanogenic TMAH degradation, TMAH-oxidative methylotrophic degradation, and demethylation and oxidation. The results highlighted that both hybrid recovery and treatment processes exhibited the most efficient recovery and removal of TMAH. Future research on TMAH wastewater treatment should focus on energy metabolism, electron transfer, and co-digestion of biodegradation, efficient novel materials for TMAH recovery and degradation, and appropriate hybrid recovery and treatment processes for resource reuse of TMAH wastewater. Ultimately, the possible pathways for the resource reuse of TMAH wastewater were also proposed.