An efficient treatment technique for TMAH wastewater by catalytic oxidation

Developers used in photolithography contain toxic tetramethylammoniumhydrox ide (TMAH) and this creates a problem of how to properly treat developer wa stewater. We have developed a TMAH wastewater treatment technique that cons ists of a combination of two novel decomposition processes: pyrolyzing TMAH to TMA and decomposing TMA to N-2, H2O, and CO2 by means of a selective ox idation catalyst for nitrogenous compounds. We have tested a system using t his technique in long-term treatment of the actual wastewater and have foun d it to be sufficiently practical. The running cost of a treatment system u sing our technique would be about one-ninth that of disposing of the wastew ater as industrial waste but about 2.3 times that of biological treatment. Compared with biological treatment, however, our system is tolerant to many treatment conditions and operation management is much easier. Furthermore, it occupies only about one-sixth the area of a biological treatment system .