Fermentation and bioprocesses in which various metabolites from food to pharmaceutics are produced are constantly evolving. This section is devoted to contamination risks and their eliminations, media preparation, decontamination, and sterilization methods for such processes. For contamination, sources of microbial contaminations and decontamination (physical and chemical) practices are discussed. In addition, sterilization methods (heat, filtration, chemical, and radiation) that are applied for the removal of microorganisms from small-scale to large-scale instruments, gases, and liquids are explained. In the preparation of the media, the batching area, developed equipment, and methods for large-scale reactors are mentioned. In summary, the preparation and sterilization of the media in bioprocesses from laboratory-scale reactors to industrial-scale reactors are evaluated.