Within the 3.5 year ENREM project (Enhanced Nutrient REmoval in Membranebioreactors) in Berlin-Margaretenhöhe a novel and patented process was investigated to demonstrate the feasibility of a semi-decentralised solution reaching high effluent requirements set by the water authority of Berlin. This novel process could be a solution for suburban areas of Berlin which are not connected to central sewer system. The biological process combines enhanced biological phosphorus removal (EBPR) with post denitrification in MBR technology without dosing of any carbon sources. The process configuration of this demonstration plant enables advanced wastewater nutrients removal (C, P and N) and could be a promising option for wastewater treatment wherever high effluent qualities are required. A second prototype MBR system was operated in parallel, applying a different biological process, e.g. without biological phosphorus removal, enabling a comparison of these different technological approaches. The demonstration plant showed high elimination rates for COD (>95%), phosphorus (>99%) and nitrogen (up to 98%) when operated within the appropriate range of design conditions. The operational experience within the first years showed that there is a possibility for process stabilisation by changing the ratio of the process steps. For this reason the volume of the anoxic zone was enlarged by reducing the aerobic volume in Feb 2008. The positive effects could be seen on the basis of the effluent concentrations after a short period of adaptation. The membrane filtration performance was very reliable with a new cleaning strategy: Two membranes were operated alternating with an operational flux of 15 – 20 L/m²/h and a maintenance cleaning with low chemical concentration. Different cleaning agents were used in order to evaluate the cleaning efficiencies. An economical evaluation of the demonstration plant was performed in comparison to the existing wastewater treatment costs of app. 7 €/m3 by trucking away and the prototype MBR plant. Operated on the same site, the two MBR systems were used to calculate the actual costs, in relation to the effluent quality, and to perform a scale-up up to 5000 pe considering four different effluent quality classes. The results showed that the ENREM process applied in the demonstration plant is economically an alternative for plant sizes of 5000 pe and larger. For plant sizes smaller than 5000 pe, the prototype MBR system equipped with precipitation and a downstream adsorption filter for enhanced phosphorus removal proofed to be the more viable solution.