Use of the freeze salting-out method for reducing dosage of salting-out agent and salinity in wastewater from carmine production

A novel technology named the freeze salting-out method was developed as an improvement to the traditional salting-out method, which requires a large amount of the salting-out agent and generates a large volume of high-salinity wastewater. Using the freeze salting-out method, the dosage of salting-out agent is only 5 wt%, compared to 20 wt% for the traditional approach. The electrical conductivity of the freeze salting-out effluent was 35.7 ms/cm, far lower than that generated by the traditional approach (330 ms/cm). Overall, 182 g of carmine with a high purity of 93.7% was produced from a 2 L crude carmine solution. The salting-out action enacted through freeze-concentration played a crucial role in the freeze salting-out process. The cost of carmine production using freeze salting-out technology was lower than that of the conventional salting-out method. Thus, this new method offers an alternative approach for extracting carmine and improving other salting-out processes.