預臭氧程序提升綜合性工業廢水生物可分解性之研究; Study of Biodegradability Enhancement for Industrial Wastewater by Preozonation Process

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Title:	預臭氧程序提升綜合性工業廢水生物可分解性之研究;Study of Biodegradability Enhancement for Industrial Wastewater by Preozonation Process
Authors:	范姜仁茂;Jen-Mao Fanchiang
Contributors:	環境工程研究所
Keywords:	預臭氧程序;綜合性工業廢水;生物可分解性;分子量分佈;脫色;preozonation process;industrial wastewater
Date:	2001-07-17
Issue Date:	2009-09-21 12:13:46 (UTC+8)
Publisher:	國立中央大學圖書館
Abstract:	本研究以預臭氧程序(preozonation process)處理中壢工業區綜合性工業廢水，並探討臭氧劑量、預臭氧反應時間與初始pH值等操作因子，對廢水水質之生物可分解性的影響。此外，並就廢水的BOD曲線、COD組成及分子量分佈等，評估預臭氧程序提升廢水生物可分解性的成效。同時，本研究亦探討預臭氧處理程序對原廢水之真色色度的去除效果，並就臭氧脫色後之水質的生物可分解性，加以進一步的討論。研究結果顯示，原廢水中約有50%的有機物為生物難分解有機物(BOD5/COD約為0.27)，並含高濃度硫酸鹽(236mg/L)與氯離子(764mg/L)。預臭氧氧化處理結果顯示，臭氧劑量為116.2mg/min時，廢水COD會有明顯的礦化現象，使得COD減少而BOD5增加，此有助於提升廢水的生物可分解性。另外，在120分鐘的預臭氧反應時間內，廢水之BOD5/COD比值均可提升，但是最適的反應時間與BOD5/COD比值增加的原因，需視水質pH而定。其中，在中性水質情況下，BOD5/COD增加的主要原因，係臭氧產生局部氧化反應(partial oxidaton)，轉化難分解有機物，成為生物可分解有機物；在酸性水質條件下，BOD5/COD提升原因，除臭氧局部氧化反應外，尚發生COD礦化反應；至於在鹼性水質條件下，則發現反應初期，廢水中可生物分解的有機物(BOD5)會有礦化的現象，故不利生物可分解性的提升，但反應時間延長至120分鐘後，預臭氧化仍可破壞難分解有機物，增加水質的生物可分解性。此外，藉由廢水之BOD曲線與COD組成的評估，獲知在中性水質、低臭氧劑量條件下，預臭氧反應以礦化顆粒性難分解有機物為主，且提高臭氧劑量後，則可使其形成溶解性可分解有機物。在酸性水質條件下，臭氧可使難分解有機物同時轉化成顆粒性與溶解性可分解有機物。至於在鹼性水質條件下，廢水之有機物組成的變化，則與在中性水質條件時相似。又根據分子量分佈的分析結果發現，廢水生物可分解性提高的原因，主要與大分子量(約500kD)之DOC，被臭氧破壞成小分子量有機物有關。預臭氧脫色的結果指出，預臭氧反應在各不同初始pH情況下，均能有效地破壞色度，當臭氧劑量與預臭氧反應時間，分別大於42mg/min與60 分鐘時，真色色度去除率，均可達到90%以上，且值得注意的是，隨著色度去除率的增加，廢水的生物可分解性，亦隨之提升，此顯示廢水中的色度，即為難分解有機物的來源之一。 The objectives of this study are aimed to investigate the performance of biodegradability enhancement in an industrial wastewater by preozonation process. Effect of ozone dosage, reaction time of preozonation and initial pH was studied. The biodegradability of wastewater was evaluated by BOD curve, COD fractionation and dissolved organic carbon molecular weight (DOC MW) distribution. This study also investigated the color removal in this wastewater by preozonation process and corresponding variation in biodegradability. Experimental results showed that this industrial wastewater contains 50% biorefracotry organic compounds and the value of BOD5/COD was 0.27. Moreover, the average concentration of sulfate and chloride are as high as 236mg/L and 764mg/L respectively. The biodegradability of wastewater could be enhanced apparently with 116.2 mg/min of ozone dosage due to the mineralization of COD and the increase of BOD5. However, within 120min of preozonation time, biodegradability enhancement in this wastewater was also observed, but the optimal reaction time of preozonation and the increase of BOD5/COD were depended on the initial pH of wastewater. The value of BOD5/COD increased at 7.5 of initial pH as a result of the partial oxidations of biorefractory organic compounds and the generation of biodegradable organic compounds. When the initial pH was controlled at 5.0, the phenomena of partial oxidation and COD mineralization occurred simultaneously. In addition, although the BOD5 of wastewater was mineralized in the initial preozonation time at 9.0 of initial pH, but the biodegradability of wastewater could be eventually enhanced as the reaction time of preozonation approached 120 minutes. The analysis of COD fractionation and BOD curve showed the particulate biorefractory organic compounds were mineralized at low ozone dosage when initial pH was at 7.5 and 9.0 respectively, but could be converted to soluble biodegradable organic compounds with the increase of ozone dosage. Also, the biorefractory organic compounds were converted to particulate and soluble biodegradable organic compounds when initial pH was maintained at 5.0. Additionally, biodegradability enhancement in this wastewater was primarily resulted from the conversion of high MW DOC (>500kD) to low MW DOC by means of DOC MW distribution analysis. Results also revealed that color of wastewater could be effectively removed by preozonation, and the color removal could be over 90% when ozone dosage and preozonation time was 42.0mg/min and 60min respectively. In particular, biodegradability enhancement in this wastewater was obtained along with the color removal. This implied that the color of this wastewater was one source of biorefractory organic compounds.
Appears in Collections:	[Graduate Institute of Environmental Engineering ] Electronic Thesis & Dissertation

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