高級氧化處理兩種工業廢水效率之探討

Abstract

本研究即利用臭氧曝氣管柱反應器對模擬製漿廢水及科學工業園區廢水進行臭氧高級氧化處理與臭氧、活性碳及過氧化氫聯合處理，以廢水之化學需氧量(Chemical oxygen demand，COD)、生物需氧量(Biochemical oxygen demand，BOD)及色度去除效果探討臭氧處理進一步降低廢水污染量的可行性。實驗結果顯示臭氧處理法對科學工業園區綜合污水處理廠廢水之COD及BOD有良好的處理效果，但無法增加廢水之生物可分解性。隨著臭氧濃度增加，廢水中污染物去除效果越高。以放流水而言6 g/hr臭氧對COD及BOD之去除效果最佳，可去除45 %之COD及 58 %之BOD。但若以單位(mg)臭氧可去除COD量來判斷臭氧之處理效率則可發現隨著臭氧濃度之下降，單位臭氧可去除之COD量則會增加但隨著處理時間之增長，單位臭氧處理之效果會隨之下降，而COD及BOD之去除速度會在臭氧處理10分鐘後漸趨緩慢。利用活性碳、過氧化氫與臭氧聯合處理放流水，可得到更佳的COD及BOD去除效果。以臭氧/活性碳/過氧化氫聯合處理，在經過18 min處理後，COD增加27 %之去除效果，BOD則增加36 %之去除率。 在模擬製漿廢水方面，臭氧對於廢液的去色效果極佳。COD 50 mg/L之模擬製漿廢水在經過6 g/hr臭氧處理30min之色度去除率達98.8 %，唯1 g/hr除色效率較差，30分鐘處理僅去除10.1 %。隨著臭氧濃度之增加，廢水COD去除效果越好，50mg/L模擬製漿廢水經由6 g/hr臭氧處理15 min後可有效去除66 %之COD，其次依序為3 g/hr及1 g/hr臭氧處理。以每單位(mg)臭氧去除COD來判斷臭氧之處理效率則可發現隨著臭氧濃度之下降，每單位臭氧可去除之COD量随之增加。而隨時間之增長，每單位臭氧對模擬製漿廢水的處理效果隨之上升，這一點與科學園區放流水的趨勢不同。最後同樣以臭氧、活性碳、過氧化氫三物質聯合模擬廢水，發現聯合處理可可得到更佳的COD去除效果。以臭氧/活性碳/過氧化氫聯合處理，在經過30 min處理後，COD增加21 %。 用凝膠色層分析法探討COD 150 mg/L模擬廢水中木質素衍生物受6 g/hr 臭氧處理後降解之情形，可發現不論是木質素成份之平均分子量或主要成分之分子量，都有下降的情形發生，原COD 150 mg/L模擬廢水之平均分子量為30733.1，在經過臭氧處理30分鐘後，其平均分子量下降為17482.7。

Feasibility on further pollutant reduction by ozone and related advanced oxidation technologies was investigated in this study with a bubble-column reactor. Simulated pulping effluents and effluents from a science park (SP) were employed. Activated carbon and hydrogen peroxide were combined with ozone treatment. Chemical oxygen demand (COD), Biochemical oxygen demand (BOD) and color reduction were investigated. Overall, ozone treatment could effectively reduce BOD and COD for effluents from integrated wastewater treatment plant of a science park. But it failed to increase biodegradability of the effluents. Higher ozone dosages treatment can lead to better treatment efficiencies. For the final efluent wastewater, treatment by 6 g ozone/hr for 15 minutes reduced 45 % COD and 58 % BOD. The result is better than 3 g ozone/hr and 1 g ozone/hr treatment. In contrast, lower applied ozone dosages demonstrated higher treatment efficiencies per unit weight of applied ozone, defined by ratios of mg COD removed/mg ozone applied. Furthermore, the treatment efficiencies per unit ozone weight applied decreased with increasing duration of ozone application. Better COD and BOD removals from effluents were achieved by combination of ozone/activated carbon/hydrogen peroxide treatments. After 18 minutes, additional 27% of COD and 36% of BOD were achieved by the combined treatments. For simulated pulping effluents, ozone demonstrated significant decolorization. For 50 mg COD/L simulated effluent, 98.8 % decolorization were achieved by applying 6 g ozone/hr for 30 minutes. Increasing applied ozone dosage could increase COD removals. Again, treatment efficiencies per unit ozone weight applied decreased with increasing applied ozone dosages. Contrast to SP effluents, longer durations led higher treatment efficiencies per unit ozone weight applied. Better COD removals from simulated pulping effluents were achieved by combination of ozone/activated carbon/hydrogen peroxide treatments. After 30 minutes, additional 21% of COD were removed by the combined treatments. Molecular weight distributions of lignin fragments before and after ozonation were monitored by gel permeation chromatography. Weight averaged molecular weight (Mw) for untreated COD 150 mg/L wastewater is 30733 After 30 minutes of ozonation, Mw was reduced to 17482.