Toward a Sustainable Approach for Dairy Waste Management: The Integration of Filtration, Ion Exchange, and Electrodialytic Processes for Whey Demineralization

The disposal of salt-rich waste streams, such as salty whey, remains an intractable issue in the dairy industry, as there is no environmentally acceptable mechanism for the disposal of sodium chloride. In this work, two different processes are integrated at a pilot scale to provide a solution. Electrodialysis with bipolar membranes (EDBM) is used to convert sodium chloride in salty whey into sodium hydroxide (NaOH) and hydrochloric acid (HCl). The HCl generated from this EDBM operation is then utilized directly during the electrodialysis (ED) of sweet whey to prevent scaling, for the production of demineralized whey (D70). The HCl and NaOH produced from the EDBM are also used in the clean-in-place procedures of the pilot plant. This novel integration enables the recovery of both byproducts as valuable resources. No significant fouling is noted in either EDBM or ED studies, illustrating the satisfactory quality of the chemicals produced for onsite consumption. The inclusion of an upstream ion exchange step also improves the ED current efficiency from 69 to 85% for a 90% reduction in sweet whey conductivity, with no significant change in ED energy consumption.