Purification is one of the most important steps in downstream processing as it separates the product of interest from other contaminants in the fermentation or cell culture broth. There are several unit operations used for purification including centrifugation, flocculation, micro/ultrafiltration, and chromatography. https://www.zupyak.com/p/4487116/t/downstream-processing-important-steps-for-purification-and-recovery-of-biopharmaceutical-products