The focus of this study investigation was laid on the plant-specific applicability of a NaOH and thermal pretreatment of activated sludge AS with following mesophilic digestion and the influence on the biomethane potential BMP. Firstly, the hydrolysis of activated sludge from the granular sludge process of the Nereda technology, which differs from conventional activated sludge in terms of sludge formation, sludge stabilization, and sludge age, was investigated for the first time. A higher dose of NaOH (0.02 - 0.08 g NaOH per gVS, 70 °C) raised the COD and phosphate degree of digestion and the digester gas yield by 22 - 47 %. Different hydrolysis temperatures (50 - 90 °C, 0.05 g NaOH per gVS) also increased the sludge parameters. However, the BMP only enhanced by 12 % at temperatures higher than 70 °C. With increasing hydrolysis temperature, the digestion time was reduced by 2 - 5 days. Despite the process-related differences between conventional AS (from the Stahnsdorf wastewater treatment plant) and AS from the granular sludge processing, comparable results were obtained in the BMP test, with and without pretreatment. Due to a lack of time, the experiments could only be carried out once or twice. As there are currently no further experience and references on this subject, additional attempts for achieving significant results will follow. In the second part, sludges from the Waßmannsdorf sewage treatment plant were used. Laboratory tests have shown that primary sludge has no influence on the digestion process. The calculated BMP of 176.5 NmL/gCSB deviates by 3% from the value of 181.9 NmL/gCSB measured in the laboratory test. It is directly related to the ratio of the used sludges. Hydrolysis according to PONDUS (70 °C; 2 h; 2.5 mL NaOH 50 % per L AS) at laboratory revealed a comparable influence on the sludge parameters as with hydrolysis on a pilot scale. During the BMP test, the laboratory sample achieved a maximum gas yield of 143 NmL/gCSB, which is a 9 % higher BMP in comparison to the pilot sample with 132 NmL/gCSB. The laboratory results can, therefore, be transferred to the pilot scale, so that the effects of changes in operation can be reliably assessed by cost, time and effort saving laboratory tests. This thesis was written within the framework of the project “Evaluation of process options for the reduction of energy consumption and greenhouse gas emissions of Berlin sewage treatment plants" at the Berlin Centre of Competence for Water.