Product quality, such as purity and particle size distribution (PSD), is one of the most important process metrics. These are also defined as some of the critical quality attributes (CQAs) for formulated products in the pharmaceutical and food industries. Crystallization process development, at the R&D stage, is usually carried out by utilizing pure solutions, when the emphasis is on the process development, yield optimization, and growth kinetic parameters estimation. However, in manufacturing and real-life scenarios, there are many different impurities present in the mother liquor, which impact the performance of the crystallizer, and product quality and other CQAs. In addition, the isolation step includes crystallization, filtration and drying stages, in which the filtration and drying also impact the CQAs of the product.
In this research, impurity inclusion, crystallization and filtration performance were studied for acid whey solution in batch and continuous modes. Three different impurities, and different mechanisms of impurity inclusion were studied. Yield, distribution coefficient, PSD, process performance, and process stability were evaluated and compared for batch and continuous processes in pure and impure solutions.