以電氧化法處理養豬廢水 : 操作條件測試

養豬廢水中含有大量的有機與氨氮污染物，如果未進行有效處理，會造成環境污染。本研究探討養豬廢水電高級氧化處理的較佳操作條件(電流密度、陰陽極材料面積、陽極材料、陰陽極間距及放大試驗測試)並且使用氨氣分析儀分析水中及空氣中氨氮濃度變化。而林可黴素(lincomycin, LIN)為畜牧業常用的一種抗生素，是一種環境新興汙染物。因此，本研究亦依得到之較佳操作條件進行其在配製LIN溶液與添加LIN之養豬廢水中的降解實驗，探討其電氧化降解之效能及有機物去除效率。另外使用紫外-可見分光光度法(UV-Vis)及螢光激發/放射光譜進行分析，並利用液相層析質譜儀(LC-MS)及高效能液相層析儀(HPLC)分析鑑定其中間產物及提出電氧化降解解。研究結果顯示，較佳的操作條件為4 cm2摻硼鑽石(boron-doped diamond (BDD)) 陽極、4 cm2鈦板陰極、添加0.05 M NaCl、較大陰陽極間距、電流密度0.25 A/cm2及溫度25°C。電氧化降解養豬廢水實驗結果顯示，COD、TOC、BOD、氨氮及氯離子濃度會隨電解時間增加而降低，而大腸桿菌群可降至ND。各批次亞硝酸鹽氮濃度有些為ND、先升後降或升後未降，而硝酸鹽氮濃度大都先升後降。電降解養豬廢水時，水中氨氮濃度下降，空氣中氨濃度快速上升，而當水中氨氮濃度下降至低於 0.01 mg/L時，空氣中氨濃度也會隨之下降。在氫氧自由基濃度分析中，有添加0.05 M NaCl電解質者，螢光強度比未添加高出許多，但兩者皆能證明本電解程序可產生氫氧自由基。使用BDD電極，進行循環伏安法實驗，可發現LIN的氧化峰，但無還原峰出現，故LIN在BDD電極上的電化學反應特性為不可逆。LIN去除率隨電解時間增加而上升。養豬廢水及LIN配置溶液之UV-Vis分析結果顯示，吸收峰強度會隨電解時間增加而下降且最終消失。在螢光特性分析中，各養豬廢水皆會於區域I(類酪氨酸)/區域Ⅱ(類色氨酸)及區域Ⅳ(可溶性微生物副產物)出現螢光峰；LIN配置溶液於跨區域II (類色氨酸)/區域IV (可溶性微生物副產物)有一螢光峰，其強度皆會隨電解時間增加而變弱且最終消失。LIN經電降解生成的中間產物有質荷比(m/z) = 377、359及126化合物，另有(2,4,5,6-四羥基己-5-烯-3-基)吡咯烷-2-甲酰胺)、(E)-N(4,5-二氧代己-2-烯-3-基)-1-甲基-4-丙基吡咯啉-2-甲酰胺、單羥基化林可黴素、三羥基化林可黴素、N-去甲基林可黴素及2-丙基-N-甲基脯胺酸。關鍵字：養豬廢水、林可黴素、摻硼鑽石電極、電高級氧化、氨氣分析儀、氫氧自由基、紫外-可見分光光譜分析、螢光激發/放射光譜、液相層析質譜分析

關鍵字

養豬廢水；林可黴素；摻硼鑽石電極；電高級氧化；氨氣分析儀；氫氧自由基

並列摘要

Swine wastewater contains considerable amounts of organic and ammonia nitrogen pollutants. It may cause environmental pollution, if not effectively treated. This study explores the suitable operating conditions (current density, anode and cathode material area, anode material, anode-anode distance, and equipment amplification) for the electrochemical treatment of swine wastewater. For comparison, an ammonia analyzer was used to simultaneously analyze the concentrations of ammonia nitrogen in water and air. Lincomycin (LIN), one of the most commonly used antibiotics in animal husbandry, is one of the emerging environmental pollutants. Therefore, we also conducted degradation experiments in the prepared solution and swine wastewater spiked with LIN operated at the suitable operating conditions. Liquid chromatography-mass spectrometry (LC-MS), high performance liquid chromatography (HPLC), and ion chromatography (IC) analyses were performed to identify the intermediates (products) and pathways of TC electro-degradation. Moreover, Ultraviolet-visible (UV-Vis) and fluores- cence excitation-emission matrix (EEM) tests were conducted to evaluate the electro-degradation characteristics of water matrices during operations. The results show that the suitable operating conditions were obtained using boron-doped diamond (BDD) anode (4 cm2) and Ti cathode (4 cm2),addition of sodium chloride = 0.05 M, current density = 0.25 A / cm2, and temperature = 25 °C. The results of electro-oxidation degradation of swine wastewater showed that the concentrations of COD, TOC, BOD, ammonia nitrogen, and chloride decreased with the increase of electrolysis time, while that of E. coli group decreased to ND. Moreover, the concentrations of nitrite nitrogen were lowered to ND, initially increased and then decreased or did not, while those of nitrate nitrogen mostly increased and then decreased in the tests. During electrolysis, the ammonia nitrogen concentration in water decreased while that in air increased rapidly; however, when the ammonia nitrogen concentration in water was lower than 0.01 mg/L, that in air also decreased. In the analysis of hydroxyl radical, the fluorescence intensity was much higher for the solution with 0.05 M NaCl addition than for that without adding the electrolyte, but hydroxyl radicals were indirectly identified in both solutions, suggesting that hydroxyl radicals were produced in the tested electrochemical advanced oxidation process. According to cyclic voltammetric analysis using the BDD electrode, an oxidation peak of LIN appeared without any corresponding reduction peak, revealing that its electrochemical behavior was totally irreversible and LIN could be directly electro-oxidized on the surface of BDD. The degradation efficiency of LIN increased with the increase of electrolysis time. The intensities of absorption peaks of prepared solution and swine wastewater spiked with LIN decreased with the increase of electrolysis time and eventually disappeared in UV-Vis analysis. In fluorescence analysis, swine wastewater showed fluorescence peaks in regions I (tyrosine-like)/region II (tryptophan-like) and IV (soluble microbial by-products), while the prepared LIN solution had a fluorescence peak with a wavelength range across regions II and IV. The intensities of these peaks decreased with the increase of electrolysis time and they disappeared finally. The LIN in prepared solution was electrochemically degraded to unknown intermediates with m/z =377, 359, and 126 and (2,4,5,6-tetrahydroxyhex-5-en-3-yl)pyrrolidine-2-carboxamide, (E)-N(4,5dioxohex-2-en-3-yl)-1-methyl-4-propylpyrrolodine-2-carboxamide, mono-hydroxylated lincomycin, tri-hydroxylated lincomycin, N-De-methyl-lincomycin, and 2-propyl-N-methylproline. Keyword :Swine wastewater, Lincomycin(LIN), Boron dopeddiamond(BDD) electrode, Electrochemical advanced oxidation, Ammonia Analyzer, Hydroxyl radical, Ultraviolet-visible (UV-Vis) analysis, Fluorescence excitation-emission matrix (EEM) spectrum, Liquid chromatography-mass spectrometry (LC-MS)