Method for purifying target substance

A method for purifying a composition comprising water, a target substance, impurities and optionally cells, the method comprising steps (A) and (B): (A) preparing a liquid raw material by subjecting the composition to steps (Ai) and/or (Aii); (Ai) removing at least some of the cells from the composition; (Aii) concentrating the composition by removing water therefrom; and (B) passing the liquid feedstock through an instrument comprising at least two processing units, each such unit producing a product stream containing the purified target substance and optionally a waste stream comprising at least some of the impurities, where each unit comprises defined components (i) to (v). In addition to the devices that they contain, the units may be substantially identical, resulting in advantages in simplicity, cost and ease of operation, lower risk of operator errors, easier maintenance, and lower inventory of spare parts. 用于纯化包含水、目标物质、杂质和任选的细胞的组合物的方法，所述方法包括步骤(A)和(B)：(A)通过对所述组合物进行步骤(Ai)和/或(Aii)来制备液体原料；(Ai)从所述组合物中去除至少一