Saving water in a volume-decreasing diafiltration process

The aim of this work is to improve a mathematical model to describe the volume-decreasing diafiltration process by including macrosolute rejection. Water consumption in this continuous process was analyzed and a significant advantage when comparing both the classical diafiltration process and multi-stage diafiltration processes was noticed. For whey protein, a relative volume was used continuously. A decreasing diafiltration process was estimated at a level of 1.36, while the corresponding values of fresh water relative volumes were reported as follows: 5.4 for the classical process, 2.9 for the two-stage process and 1.5 for the six-stage diafiltration process.

Fig. 3. Comparison of water consumption in the volume-decreasing diafiltration process with water consumption in classical (one-stage), two-stage and sixstage diafiltration processes. The process model of volume-decreasing diafiltration was improved by including the rejection of both macrosolutes and microsolutes, necessary in any real diafiltration process. Thus, the approach given by Jaffrin and Charrier [2] was improved, getting a more realistic character. It was also demonstrated that the analyzed volume-decreasing diafiltration process consumes much less fresh water than classical diafiltration as well as the multi-stage diafiltration processes. There is no doubt that the continuous process deserves attention and offers some opportunities that should be investigated in more detail.