以TiO2/UV光反應器處理養殖及染整廢水之研究

Treatment of aquaculture and dye wastewaters using TiO2/UV photoreactors

郭佳婷(Kuo Chia-Ting)

指導教授 ： 林耀堅

國立屏東科技大學/工學院/環境工程與科學系所/碩士(2008年)

https://doi.org/10.6346/NPUST.2008.00183

摘要

研究中將TiO2覆鍍於玻璃管上，作為異相光催化劑，利用TiO2 /UV光反應器對養殖廢水進行處理，取代傳統廢水過濾方式，應可節省使用過濾綿與活性碳之成本，更可減少保養與汰換的工作與人力支出。由於染料造成廢水顏色過深，故針對染整廢水進行脫色處理，即使在廢水濃度低的情形，亦不會造成環境污染。本研究以自製TiO2-玻璃管/UV光催化反應系統，搭配不同氧化程序對染料廢水及養殖廢水進行降解處理，並探討不同實驗因子對不同水樣之降解、礦化、脫色等作用以及毒性之影響。
以不同製備方法所研發之TiO2-玻璃管，結果顯示樣品於W-2-玻璃管300 min光照時間下可以完全被降解，效果最好，故後續所有實驗均以此條件下進行測試。光觸媒玻璃管與黑管比較結果顯示，黑管效果較差，表示光遮蔽對反應有所影響。添加0.25 M H2O2於反應中，可在30分鐘內達100 %脫色，但若添加過多的H2O2，有過量的氧分子存在時，則會影響光催化之效率。將水溶液之pH調整為3時，可提升光催化反應效率，因二氧化鈦於酸性條件下會支持電子間的吸引力而增加吸收反應，另一方面，水樣pH為3但不添加過氧化氫情形下，效果反而不理想，原因可能以鹽酸調整pH時，因氯離子捕捉氫氧自由基而導致廢水去除效率變低。若將反應系統與0.25 M H2O2及pH 3條件結合，脫色率於反應20分鐘即達100 %；而將pH調整為9，反應則需40分鐘才達100 %。由此可知，在不同pH下，過氧化氫的添加是有助益的。由BET之結果發現以W法鍛燒400℃之TiO2光觸媒其比表面積為134.88 m2/g，但於高溫下其比表面積卻降低，推測觸媒在高溫鍛燒過程中，TiO2表面的OH官能基會互相縮合鍵結，再進行成核、長晶等反應，故造成觸媒之比表面積降低。XRD分析W方法製備之二氧化鈦光觸媒具有較佳之光催化活性，且大多以鋭鈦礦晶型存在。
水族箱水樣處理前之SS與濁度分別為3.1 mg/L及3.87 NTU，反應後SS降為1.6 mg/L，濁度降為2.71 NTU。養殖廢水SS反應前為76 mg/L，濁度為9.99 NTU，反應後SS為7 mg/L，濁度則為2.67 NTU；實際養殖廢水反應前後差距較大，顯示光催化可有效淨化水質，使懸浮固體明顯減少。而水族箱水樣及養殖廢水初始DO分別約為6.1 mg/L及6.8 mg/L，BOD5分別為3.9 mg/L及56 mg/L，養殖廢水之生化需氧量較高，推測該養殖廢水有機質濃度含量高，有機水體成分較水族箱水樣複雜。氨氮在反應前後效果並不明顯，可能於此系統對於氨氮的去除機制不理想。而不論何種水樣，系統進行光催化反應對COD的去除皆有良好的效果。養殖水樣照光8小時後之DOC去除率為34.45 %，而在其他不同水樣（亞甲基藍水樣、水族箱水樣）測試之結果顯示，於短時間內之DOC並無降解效果，而需將光照時間延長，其降解效果才會出現。養殖水樣光照8小時後，毒性抑制率反而增加，推測產生有毒中間產物；染整水樣於光照5小時候毒性抑制率明顯降低，效果較好。再利用測試方面，紫外燈之光強度並無明顯衰減，二氧化鈦光觸媒玻璃管重複使用50次以上，其光觸媒玻璃管降解效率依然良好。

關鍵字

光催化 ； 二氧化鈦 ； 紫外光 ； 亞甲基藍 ； 養殖廢水

並列摘要

TiO2 coated on a glass tube was used as a hetero-catalyst. The TiO2/UV photoreactor was used to treat aquaculture wastewater to replace the traditional method. It is expected to save the cost of using filters and active carbon. Time and cost may be minimized and to maintain the water quality. When the color of wastewater becomes darker, the dye wastewater required treatment. With the low concentration of treated dye wastewater, the environment is not seriously polluted. Self-produced TiO2-glass tubes were assembled , and UV photocatalytic system with different procedures were tested to treat dye and aquaculture wastewaters. Toxicity, mineralization, and decoloration were discussed under different conditions with various wastewater samples.
At different experimental settings, the TiO2-glass tube results showed that wastewater samples can be completly treated in 300 min using W-2-glass tube. In order to understand the effect of UV light on TiO2 glass tube, the experiment using a black tube was conducted to compare with UV light. The result showed that the effect of black tube was negligible. W-2-glass tube was effective to increase photocatalytical efficiency with 0.25 M H2O2. Decoloration can reach 100 % in 30 min. However, too much H2O2 had adverse effect on the reaction efficiency. When pH was adjusted to 3, the reaction efficiency significantly improved. It is because that acidic conditions would boost the electrostatic attraction between the positively charged TiO2 surface and the reactant dyes. To combine 0.25 M H2O2 and pH 3, the decoloration can achieve 100 % in 20 min. If the pH was adjusted to 9, results showed that decoloration achieved 100 % in 40 min. The modification of pH conditions increased H2O2 effectiveness to assist photocatalyst reaction. Results of BET showed that using W-method TiO2 at 400℃ calcination, the specific surface area was 134.88 m2/g. The specific surface area was decreased as the temperature increased. At high temperature, the OH functional group on TiO2 could form mutual condensation bonding and nucleation reactions. XRD showed that the major form of TiO2 crystallization were anatase which showed that W-method possess was a better photocatalytic method.
For the treatment of fish tank water sample in photocatalytic reaction, the SS of a fish tank water samples were reduced from 3.1 to 1.6 mg/L, and the turbidity were reduced from 3.87 to 2.71 NTU. For the treatment of aquaculture wastewater in the same conditions, the SS were from 76 to 7 mg/L, and the turbidity were from 9.99 to 2.67 NTU. The result showed that the photocatalytical reaction was efficient to treat related wastewater. Results of BOD study, the fish tank water sample and the aquaculture wastewater showed that original DO were 6.1 mg/L and 6.8 mg/L, and the BOD5 were 3.9 mg/L and 56 mg/L, respectively. The aquaculture wastewater had higher concentration of organic matter than that of fiah tank water. The photocatalysis did not demonstrate the degrading effect on NH4+. No matter what kind of wastewaters, COD showed significant degradation in this treatment. DOC removal rate of 34.45 % was detected in aquaculture wastewater after 8-hr of irradiation. Toxicity increased due to the formation of by-products in the water sample after 8-hr of irradiation. Contrarily, toxicity was decreased for dye wastewater after 5-hr of irradiation. Reusability of TiO2 was tested. The results showed that the intensity of UV lamp remained constant, and the TiO2 glass tube was still effective even used more than 50 times.

並列關鍵字

photocatalysis ； titanium dioxide ； UV ； methylene blue ； aquaculture wastewater

參考文獻

林垂鈺 (2002) 養殖漁業生產區公共給排水模式及其優選方法之研究。中原大學土木工程研究所碩士論文。

張英詩 (2004) 奈米二氧化鈦光催化微粒之合成及其在有機廢水處理應用。元智大學化學工程學系碩士論文。

曾聖倫 (2004) 貴金屬提高二氧化鈦對五氯酚光催化效應之研究。國立屏東科技大學環境工程與科學系碩士論文。

廖毓鈴、董正鈦、高志明 (2002) 二氧化鈦光催化分解水中氯化三丁基錫污染物之反應行為研究，第一屆海峽兩岸土壤與地下水污染整治研討會，C-260-C-273。

Anderson, M. A., A. Yamazaki-Nishida, and S. Cervera-March (1993) Photodegradation of trichloroethylene in the gas phase using TiO2 porpous ceramic membranes. Photocatalytic Purification and Treatment of Water and Air. 820 : 405-420.