以生物處理法降解含TMAH廢水之研究

Abstract

近年來，高科技產業為台灣很蓬勃的經濟產業，其製造程序中常使用許多含有高毒性及生物抗性的化學藥劑，增加有機廢水處理之困難性，例如：四甲基氫氧化銨（Tetra-methyl ammonium hydroxide ,TMAH）、異丙醇(Isopropyl alcohol,Isopropanol,IPA)、單乙醇胺(Monoethanolamine, MEA)等。該類有機廢水具有強鹼性及高氮特性，若未能有效處置即排入河川則將會危害人體健康及造成環境失衡，因此，提升含TMAH有機廢水之有機物及氮處理實有研究之必要。 本研究使用無氧/好氧（anoxic-aerobic process）程序之連續式活性污泥處理系統針對含TMAH廢水進行生物降解、去氮試驗，以期找到最適處理之實驗條件及探討廢水成份改變對去除成效之影響。 由實驗結果顯示，以連續式無氧/好氧反應處理系統處理合成式TMAH廢水，去除TMAH之最適F/M為 0.29-0.37 Kg-COD/Kg-MLSS/day，TMAH本身及廢水TOC去除率分別可達95.7%和 98.5%；另由監測反應中得知：氮系化合物濃度之變化，乃隨著TMAH的分解而會釋放出氨且累積，總氮去除成效僅29.2%，且好氧槽中之硝化作用並不顯著。 但當應用出流水循環結合曝氣系統於後；廢水不需調整pH即可直接處理，可節省酸液用量及提高氨氮轉化率；當以循環系統分別處理TMAH 、TAMH/IPA、TMAH/MEA，結果顯示TMAH/ MEA廢水對系統效能未造成衝擊；反之，TMAH/ IPA廢水，則因微生物先分解IPA，而令使TMAH之分解率明顯下降。 由TMAH廢水之去氮試驗顯示，硝化作用於鹼度充足下，F/M範圍介於 0.2-0.23 Kg-COD/Kg-MLSS/day間時硝化反應最完全，脫硝作用則以TOC/T-N = 15時脫硝效率最佳。考量總碳源及僅考量TMAH之 F/M分別為0.55-0.59及0.21-0.22 Kg-COD/Kg-MLSS/day有最佳總氮去除率，可達99.4%。總之，以食微比介於0.55-0.59 Kg-COD/Kg-MLSS/day之操作狀況下，以好氧/無氧處理法處理半導體實廠之有機廢水，其結果顯示總氮及TOC去除率可高達99.4%及99.8%，而TMAH本身則幾乎完全去除，顯示本研究所設計之生物處理程序未來極具實際應用前景。

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. The 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.