This study investigated the effect of compositional differences in acid whey from cottage cheese (CAW), quark (QAW), lactose free skyr (LFAW) and normal skyr (NAW) on the rate and extension of deacidification, demineralisation and energy consumption during electrodialysis at 10 V for 180 min. The results showed that the presence of minor amounts of carbohydrates, proteins and salts in acid whey influenced both the removal of lactate and minerals. Under the same processing conditions, 91% of lactate was removed from CAW while only 78% from QAW, which had the highest phosphate concentration. 80% of K⁺ and 80% of Mg²⁺ and Ca²⁺ were removed faster in CAW likely due to the highest whey protein concentration. Furthermore, lower Mg²⁺ and Ca²⁺ were removed from whey with high concentrations of sugars (LFAW). The energy consumption was found to be most dependent on conductivity and therefore lowest for CAW and highest for QAW.