The objective of this study was to optimize membrane systems applied for wastewater reuse in breweries in consideration of economic efficiency and safety of operation by defining and adjusting the wastewater matrix. With the help or extensive quantitative and qualitative analyses of relevant process water flows from several breweries with similar product ranges and different wastewater treatment concepts, the following process water flows were identified as critical regarding membrane filtration: polyvinylpolypyrrolidone regeneration lye, cleaning and rinsing lyes from cleaning in place systems as well as effluents from the bottle washing machine and conveyor belts. Their negative effects on the filtration performance of low pressure membranes were shown in laboratory-scale tests. In addition, treatment concepts of recycling the alkaline process water flows (polyvinylpolypyrrolidone regeneration lye, cleaning in places lyes) were developed and investigated with regard to technical, ecological and economic aspects. As secondary objectives, the reduction of inert organic substances, the recovery of valuables (polyphenols, sodium hydroxide solution) and the substitution of critical substances (lubricants for conveyor belts) were pursued. (C) 2014 Elsevier B.V. All rights reserved.