Described herein are one or more implementations for transforming DRM-protected digital media content while retaining associated DRM-information. The wastewater is purified in an aeration tank in which a low oxygen concentration of less than 1. The method includes adding a surfactant to the mixture to prevent or decrease flocculation of the solid particle additives. A thermoplastic film bag is placed on the heated sealing bar and a movable sealer jaw is lowered on top of the bag.