There are many different purification methods. Which method/process to choose depend on the purpose of your protein and final purity requied. And some technology are suitable only for research, some are better for scale up. Chromatography is a key technology in protein purification both in labs and drug manufacture.
Normally for a best process, different purification or seperation steps need to be used in serial. e.g. for seperation of solid and liquid components, centrifugation, depth filtration and some precipatation methods should be considered; for seperation of molecules with different properties, such as the charge, size, hydrophobicity, affinity, chromatography normally is most effective, and Ultrafiltration is also a widely used technology to seperation molecules with different size.