Nitrogen pollution of water bodies causes eutrophication, a serious problem in many areas. As part of current governmental policies in Sweden to control nitrogen pollution, removal of nitrogen has been implemented in wastewater treatment plants (WWTP). This is commonly achieved on a two-step microbiological process, using nitrification (ammonium to nitrate) and denitrification (nitrate to nitrogen gas). A large input of energy is however required for this process and furthermore it’s associated with emission of Nitrous Oxide and Carbon Dioxide, two greenhouse gases.
An alternative for nitrogen removal of wastewater is the use of the recently discovered anammox bacteria. They use nitrite and ammonium as substrates, converting it to nitrogen gas. The anammox process involves first the partial conversion of ammonium on the wastewater to nitrate, using aerobic Ammonia Oxidizing Bacteria (AOB); which require oxygen. Anammox bacteria and AOB are often grown together, with AOB providing the nitrite anammox bacteria require and creating anoxic niches where anammox bacteria can thrive.
Anammox are slow growing bacteria, and the anammox process can be sensitive and unstable. An approach to increase biomass and the retention time of the slow growing anammox bacteria are the MBBR (Moving Bed Biofilm Reactors). Here plastic carriers are used, which allow AOB-anammox communities to attach and form a biofilm. However our knowledge of the biology of anammox bacteria and the ecology of the ecology of the mixed AOB-anammox biofilms is still limited. Our project aims to use molecular- and advanced microscopic techniques and image analysis to study those biofilms. Research on the topic is needed to improve carriers design and reactor operations, thus achieving a better performance of the process.
|Projekt titel:||Sustainable removal of nitrogen in wastewater. A closer look to anammox bacteria|
|Handledare:||Malte Hermansson, GU|
|Bihandledare:||Frank Persson, Chalmers|
|Adress:||Box 462, SE 405 30 Göteborg|
|Tidplan:||January 2013 – december 2016|
|Tid för Licentiat examen|
|Tid för disputation:||December 2016|