A Study on the Degradation of TMAH-containing Wastewater by Biological Treatment
Date Issued
2009
Date
2009
Author(s)
Hwang, Shean-Harn
Abstract
With the development of the high-tech industry (i.e., semiconductor industry), many toxic and bio-resistant compounds, such as TMAH, IPA and MEA, are used largely in the manufacturing process, resulting in the difficulty in treat the organic wastewater. The organic wastewater from manufacturing process is characterized by by high basicity and nitrogen. This nitrogenous wastewater may not onlycause the unbalance ecosystem and also threaten the human beingsdanger the health .Therefore it is necessary to develop an effective treatment for the removing of the nitrogen. The main objective of this research was to develop the optimal operating condition in treating this kind of wastewater and determine the influence on TOC、TMAH and nitrogen removal efficiency by varying the waste water compositon The TMAH-containing wastewater was investigated in biodegradability and the nitrogen was removed by acontinuous anxic/aerobic bioreactor. he optimal operating condition for decomposing the synthetic TMAH wastewaterwas F/M = 0.29-0.32 Kg-COD/Kg-MLSS/day in this research. The TMAH and TOC removal efficiency was 95.7% and 98.5%, respectively. With the TMAH degradation, ammonia, whose concentration was detected by the transformation of nitrogen within the reaction, was then released. However, nitrification processes did not perform well as expected in the aerobic bioreactor, the the total nitrogen removal efficiency was only 29.2%. By circulating the effluent partially and using the air stripping system simultaneously for treating TMAH, the level of ammonium ion in the effluent was decreased effectively without adjusting the pH of the influent.. For treating TMAH, TMAH/IPA and TMAH/MEA by circulating the effluent, the existence of MEA will not restrain the biodegradability of TMAH. On the contrary, the existence of IPA can lower the TMAH removal efficienc due to the fact that the IPA biodegradation was prior to TMAH. Based on the experimental results of TMAH denitrification, nitrification occurred completely in sufficient alkalinity and F/M was between 0.2-0.23 Kg-COD/Kg-MLSS/day , resulting in the optimal denitrification efficiency with TOC/T-N = 15. The optimal operating condition for the total nitrogen removal ratio was 99.4% with F/M = 0.55-0.59 Kg-COD/Kg-MLSS/day (F/M =0.21-0.22 Kg-COD/Kg -MLSS /day, calculating TMAH source only) between. Additionally, actual semiconductor wastewatwe was treated by using the anxic/aerobic bioreactor with F/M = 0.55-0.59 Kg-COD/Kg-MLSS/day and sufficient alkalinity. The total nitrogen removal ratio and TOC were 99.4% and 99.8%, respectively. The TMAH removal efficiency was up to 100%. To sum up, according to the results discussed above, this biological treatment process is feasible for treating the organic wastewater from manufacturing process.
Subjects
Anxic/aerobic
TMAH
IPA
MEA
Type
thesis
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