運用產鹼型微生物燃料電池進行阿莫西林水解效果評估

Abstract

微生物燃料電池（Microbial Fuel Cell, MFC）為一種新興的綠色能源技術，陽極微生物利用廢水中的有機物作為養分，代謝有機物的同時產生電子與質子，電子藉由外部電路將電子輸送到陰極產生電流，質子透過溶液傳輸到陰極以達到電中性，在降解污染物的同時也能夠產出電力進行利用。在質子傳輸過程中若陽極含有高濃度的陽離子，其會取代質子穿透陽離子交換膜通往陰極，並和陰極產生的氫氧根離子生成如氫氧化鈉、氫氧化鉀等腐蝕性強鹼之有價物質；過去研究發現阿莫西林抗生素在鹼性條件下能夠更好的被水解，而水解後之阿莫西林能夠降低抗生素對環境的影響，因此本研究利用陰極產生鹼度的特性對阿莫西林抗生素進行降解，未來能夠應用在製藥廢水或是醫療廢水的相關處理。 本研究使用採自於台北市迪化污水廠之厭氧污泥作為微生物來源，利用H-type雙槽式微生物燃料電池進行實驗，所使用之電極為經過酸熱前處理和活性碳改質之碳氈電極，實驗分為兩個階段，第一階段使用合成NaCl溶液作為陰極溶液，第二階段使用實際藥廠廢水作為陰極溶液。分別添加阿莫西林進行實驗，實驗中設計不同溫度條件以及實驗組進行比對，定時採樣檢測阿莫西林之殘留量，並對水質進行監測。第一階段結果顯示以合成NaCl溶液作為陰極溶液具有最佳產鹼效果，pH最高值達到10，在閉路組的阿莫西林降解最快，其次是開路組和空白組，閉路組在不同溫度下皆在4小時內達到100%的降解率；第二階段結果顯示以藥廠廢水作為陰極溶液的實驗仍然具有產鹼效果但較NaCl溶液來的差，pH上升幅度較小，阿莫西林降解速率依然是閉路組最快，開路組其次，最慢為空白組。相較於第一階段，第二階段閉路組在不同溫度下耗費8-16小時才達到100%降解率，並且和開路組的降解速率差異縮小，根據pH變化分析和阿莫西林測定得出在使用該藥廠廢水作為陰極基質時產鹼效果下降，進而影響了阿莫西林的鹼水解速率。

Microbial Fuel Cells (MFCs) is an emerging green energy technology. The microorganisms in anode utilize organic matters in wastewater. Electrons and protons are produced during the metabolism of the organic matters. Electrons are transferred to the cathode through an external circuit, producing an electric current, while protons are transported through the cation exchange membrane (CEM) to the cathode to maintain electrical neutrality. This process allows for the degradation of pollutants while generating usable electricity. If the anolyte contains a high concentration of cations, they would penetrate CEM toward the cathode instead of protons, reacting with hydroxide ions generated at the cathode to form caustic bases such as sodium hydroxide and potassium hydroxide. Previous research has found that amoxicillin can be hydrolyzed more efficiently under alkaline conditions, and reduces environmental impact. Therefore, this study aims to utilize alkaline produced MFCs to remove amoxicillin antibiotics, which could be applied in the treatment of pharmaceutical or medical wastewater in the future. In this study, anaerobic sludge was collected from the Dihua Wastewater Treatment Plant in Taipei city and used as the source of anodic microorganism source. The experiment was conducted using H-type dual-chamber microbial fuel cells. The electrodes were carbon felt electrodes, which went through acid and heat pretreatment and were coated with activated carbon. The experiment was divided into two stages. In the first stage, NaCl solution was used as the catholyte, and in the second stage, actual pharmaceutical wastewater was used as the catholyte. Amoxicillin was added in catholyte in both stages, and different temperature conditions and experimental groups were designed for comparison. Sampling was conducted at designed time intervals to determine the residual concentration of amoxicillin, and water quality parameters were also monitored during experiment.

Results from the first stage indicated that using NaCl solution as the catholyte had the best alkaline production efficiency, with the highest pH reaching 10. Amoxicillin was degraded fastest in the closed circuit group, followed by the open circuit group, and lastly, the blank group. The closed circuit group achieved 100% hydrolysis rate within 4 hours under different temperature conditions. Results from the second stage showed that using pharmaceutical wastewater as the catholyte could still produce alkalinity but showed less efficiency compared to the first stage with a lower increase in pH. The closed circuit group still had the fastest hydrolysis of amoxicillin, followed by the open circuit group, and the slowest blank group. Compared to the first stage, the closed circuit group took 8-16 hours to reach 100% hydrolysis rate under different temperature conditions, and the difference in hydrolysis rate between the closed and open circuit groups wasn’t obvious as the first stage. The pH variation and amoxicillin residual analysis indicated that the alkalinity production decreased while using the pharmaceutical wastewater as the catholyte, thereby affecting the alkaline hydrolysis rate of amoxicillin.