This work describes the production of polyhydroxyalkanoates (PHAs) as a side stream process on a municipal waste water treatment plant (WWTP) at different operation conditions. Therefore various tests were conducted regarding a high PHA production and stable PHA composition. Influence of substrate concentration, temperature, pH and cycle time of an installed feast/famine-regime were investigated. The results demonstrated a strong influence of the operating conditions on the PHA production. Lower substrate concentration, 20 degrees C, neutral pH-value and a 24 h cycle time are preferable for high PHA production up to 28.4% of cell dry weight (CDW). PHA composition was influenced by cycle time only and a stable PHA composition was reached. (C) 2014 Elsevier Ltd. All rights reserved.