Concentration of Potato Fruit Juice From the Starch Industry Using Nanofiltration Membranes as Pretreatment Process Upstream an Evaporator for Energy Savings

ABSTRACT In a potato starch factory, potato proteins can also be obtained alongside the main product starch. After the denatured proteins have been withdrawn, the remaining potato fruit juice (PFJ) can be further concentrated through evaporation and used as a fertilizer. However, evaporators are highly energy‐intensive. Instead, membrane filtration presents a more energy‐efficient alternative for this process. In this study, the possibility of reducing energy consumption by preconcentrating the PFJ using nanofiltration (NF) before the evaporator was investigated. The results identified the MPS 34 NF membrane as the most promising candidate, achieving an average flux of 28 L/m 2 h during the concentration of the PFJ to 53% volume reduction. It was also possible to reach retentions of total solids, total nitrogen, and Brix between 83% and 89%. Even though the membrane fouled severely during the concentration, it was possible to recover the filtration capacity up to 77% of the initial pure water flux by using only one alkaline cleaning step. A pretreatment step to the NF using centrifugation was also evaluated, but no major improvements could be observed. A techno‐economic analysis of implementing a continuous NF membrane plant before the evaporator indicated a potential payback period of 2.3 years.