雙槽平板式微生物燃料電池產能和磷回收研究

Abstract

隨著全球人口快速增加，能源的使用大幅提升，導致全球暖化的現象，因此再生能源和水資源處理技術逐年受到重視。微生物燃料電池(Microbial Fuel Cell, MFC)為一種生物電化學技術，此技術在運行時，能同時有產電和廢水處理的功能，可用於作為生質能和降解廢水中之有機質。另外，由於製造肥料所需，全球磷礦的開採量增加，又加上磷礦自然形成速度緩慢，導致磷礦資源消耗逐年加劇。近年，科學家嘗試從人類尿液中，以沉澱的方式回收一種磷的礦物進行再利用，此磷礦沉澱物為鳥糞石(struvite, NH4MgPO4·6H2O)，而沉澱反應需在鹼性環境下進行，當雙槽式MFC在運行時，其陰極槽的部分為鹼性環境，可以進行鳥糞石沉澱。因此本研究主要探討MFC處理人工尿液時，其有機質降解成效、產電效能和磷回收的效果。 本研究不同於以往文獻中使用單槽式MFC來進行尿液中的磷回收，改使用平板雙槽式MFC處理人工尿液，槽體分為陽極槽和陰極槽，兩槽中間以薄膜進行區隔。陽極進行微生物降解有機質的反應，陰極進行曝氣和鳥糞石沉澱之反應。兩槽中的電極皆使用石墨氈。本研究同時比較陰極電極改質與不同薄膜對產電效果之影響，此改質為電極進行催化塗層，使用的催化劑為鈦菁鐵(iron phthalocyanine, FePc)，薄膜則分為陽離子交換膜、陰離子交換膜和質子交換膜。本實驗在水質、產能和磷回收部分進行探討。結果顯示化學需氧量之去除率最高可達93.7%。而使用質子交換膜時可以獲得較高之電壓，並產生最高功率密度78.14 mW/m2。使用質子交換膜時，成功地在陰極槽中獲得鳥糞石沉澱。

The potential of two-chambers microbial fuel cells (MFCs) for treating synthetic human urine has been investigated. In the treatment, there are not only the degradation of organic matter but also the recycling of phosphate as struvite (magnesium ammonium phosphate, NH4MgPO4·6H2O). In this study, we used the flat plate MFC (FPMFC), which was made up of an anode and a cathode. The two chambers were separated by the membrane. The anode with channel, where the microorganism degrade substrate, was operated as a plug flow reactor, and the anode was inoculated with anaerobic sludge obtained from a wastewater treatment plant. The cathode without channel was continuously aerated, and the precipitation of struvite will occur with the alkaline environment in the cathode. We adopted graphite felt for the electrode and investigated supported iron phthalocyanine (FePc) as the catalyst for the oxygen reduction reaction (ORR). Cation exchange membrane, anion exchange membrane and proton exchange membrane were used in the FPMFC to test which one is good for electricity production. Organic matter can be degraded effectively by using FPMFC and the maximum removal efficiency is 93.7%. When we use the proton exchange membrane, the FPMFC have the high voltage output and the maximum power density is 78.14 mW/m2. By adding magnesium dichloride, we got the struvite in the cathode from synthetic urine.