The anammox house

Abstract

In biofilms, microorganisms are embedded in a hydrated matrix that provides a stable structure and protection against influences fromthe environment. Thismatrix is formed by extracellular polymeric substances (EPS) that are produced by the microorganisms of the biofilm. A major part of the microorganisms in nature lives in aggregated forms like biofilms. Yet, knowledge about biofilm formation, composition and structure is limited. A specific formof biofilm is granular sludge. A granule is a spherical biofilmthat is not attached to a surface or carrier. In wastewater treatment, granular sludge systems are used for efficient wastewater treatment. Due to the high settling velocity of granules, granular sludge-based plants can be built smaller, compared to conventional plants (with flocculent sludge). Anaerobic ammonium oxidizing (anammox) bacteria are applied in granular sludge systems in wastewater treatment. Anammox bacteria are important players in the nitrogen cycle in wastewater treatment, as well as in the natural environment. Although the formation of granular sludge is not completely understood, EPS are the key components in the formation of the matrix that provides a stable structure wherein the bacteria are embedded. The aim of this thesis was to characterize the EPS composition of anammox granular sludge.