Rening av avloppsvatten är en viktig samhällsfunktion med höga krav på reningskapacitet och effektivitet, men traditionella reningsme- toder kräver mycket energi. Med anledning av detta har avloppsrening med mikrobiella bränsleceller (MFC) blivit ett stort forskningsområde. En MFC använder sig av nedbrytande mikroorganismer i en elektroke- misk redoxreaktion och kan därför användas för rening av avloppsvatten samtidigt som elektrisk energi kan utvinnas. I den här litteraturstudien sammanfattas den senaste forskningen kring hur de hinder som åter- står för storskalig avloppsrening med MFC kan överbryggas. Hindren är både ekonomiska och driftstekniska och tyngdpunkten i denna studie ligger på kostnadseffektivitet och ekologisk hållbarhet samt vilken roll det är rimligt att MFC kan anta i framtidens avloppsreningssystem. Det analyserade forskningsmaterialet antyder att den mest kostnadseffektiva grundkonfigurationen av MFC för avloppsrening är membranlös och fri från kostsamma katalysatorer. Att utnyttja biologiska sätt att underlätta redoxreaktionen, såsom att använda sig av bioanod, biokatod och luftka- tod, är både ekonomiskt och ekologiskt hållbart jämfört med traditionell MFC-teknik. Vidare har forskning kring användning av naturmaterial samt kol-, metalloxid- eller polymerbaserade nanomaterial visat på lo- vande resultat, men mycket arbete återstår innan MFC-tekniken till ful- lo är både driftsäker och kostnadseffektiv. Sammantaget visar resultaten att MFC-forskningen kring ekonomiskt och ekologiskt hållbara material och konfigurationer gjort vissa framsteg de senaste åren, samt att dessa bör utnyttjas i sammanhang där MFC integreras med beprövad renings- teknik, såsom membranbioreaktorer eller konstgjorda våtmarker, för att öka möjligheterna till att finna ett ekonomiskt och ekologiskt hållbart avloppsreningssystem. / Wastewater treatment is a crucial function in the urban society. With increasing population the need for energy efficient and ecologically sus- tainable solutions for water recovery will grow. Microbial Fuel Cells (MFC) are a promising technique with a potential to contribute to solv- ing this task, which is why they have been under extensive studies for several years in the context of wastewater treatment and energy recov- ery. A MFC designed for wastewater treatment consists of an electrolysis cell that uses wastewater as electrolyte, turning the chemical energy into electrical energy whilst microbes digests the nutrients and organic sub- stances. Some specific microbes, electrochemically active bacterias, are capable of anaerobic digestion and when the organic loadings are con- sumed, electrons and protons are released and a current can be collected from the fuel cell. This paper is a review of the most recent research focused on solving the critical problems that still prohibit a large scale usage of MFC for wastewater treatment. The most prominent issues are related to high initial costs och operational stability and the aim of this study is to summarize the state of art regarding cost effective materials and configurations and also to discuss what the future role of MFC in wastewater treatment might be. Due to the limited format only the eco- nomical and ecological aspects of sustainability is regarded. The results from this review indicates that the most cost effective basic configuration of MFC is membranless and free from expensive catalysts. Many studies show that the use of biological catalysts, such as microbial biofilm on the electrode surfaces, is a low-cost and effective way of stimulating the oxidation-reduction-reactions that drives the MFC. Also the use of air- cathodes, where the cathode is exposed to the air in order to stimulate oxygen reduction, instead of energy consuming air pump, is a promising way forward. Recently the use of natural materials, such as loofah and clay ware, have been studied with various results, and if the operational stability and overall performance could be enhanced this might well be a sustainable rout in research. Another strong trend is the use of cole-, metaloxide- or polymerbased nanomaterials which have a documented ability to increase both electric and purifying efficiencies, but the ecolog- ical sustainability regarding nanomaterials is a complex question which is not answered in this paper. Altogether, the research covered in this work shows that large scale wastewater treatment with MFC alone not at all is near at hand. However, some minor improvements have been made regarding cost effective and ecologically sustainable materials and con- figurations for MFC, and these findings could well be used in a context where MFC is integrated with other techniques, such as a Membrane Bio Reactor or Constructed Wetland, in order to take advantage of the syner- gistic effects that has been noticed in several studies. This might be the most reasonable role for MFC to play in the future wastewater treatment business, thereby contributing to the global strive for sustainability.
| Identifer | oai:union.ndltd.org:UPSALLA1/oai:DiVA.org:kth-189240 |
| Date | January 2016 |
| Creators | Lindvall, Sara |
| Publisher | KTH, Industriell ekologi |
| Source Sets | DiVA Archive at Upsalla University |
| Language | Swedish |
| Detected Language | English |
| Type | Student thesis, info:eu-repo/semantics/bachelorThesis, text |
| Format | application/pdf |
| Rights | info:eu-repo/semantics/openAccess |
| Relation | TRITA-IM-KAND 2016:26 |
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