In this experiment, sodium bicarbonate solution (5 g·L-1, 60 mmol·L-1) was used to simulate the digestate. The alkalinity was equivalent to 2976 mg CaCO3·L-1. Wet resin (5 ml) was used to treat the sodium bicarbonate solution and this was found to decrease the pH of 150 ml sodium bicarbonate solution to about 6.0, which would meet the demand of the integrated process (Fig. 2)