Alkalinization of acid whey by means of electrodialysis with bipolar membranes and analysis of induced membrane fouling

Abstract

An issue of acid whey processing, well known in the dairy industry, is its high amount of lactic acid, a key feature that hampers acid whey industrial utilization. As a result, dried products of acid whey treatment possess a number of undesirable properties such as elevated acidity, hygroscopicity and caking. In the present study, electrodialysis with bipolar membranes (EDBM) was used to alkalinize acid whey at laboratory scale. Two alternative configurations of electrodialysis cells were designed, where the whey stream was directly connected to the bipolar membrane generating hydroxide ions. pH of acid whey was raised up to 6.5. The above said pH adjustment corresponded to 25% lactic acid removal rate and 24-34% demineralization rate. The operation of EDBM, although efficient, induced fouling on the anion-exchange side of bipolar membranes after acid whey alkalinization. A complex analysis of membranes after whey processing was conducted. The analysis of whey precipitate and membrane fouling revealed 13 and 7% protein content in respective dried samples. Membrane fouling displayed minor protein content; thus, mineral fraction was likely to be dominant in the fouling matter