Combine the juice, grated ginger, and kombucha in a large glass pitcher (this may need to be done in batches depending on the size of your pitcher). Stir well and pour into sanitized flip-cap bottles, filling the bottles 3/4 of the way up.

Add several frozen blueberries to each bottle and before sealing them. Place bottles in a dark, warm place for 2 to 4 days to allow for secondary fermentation.

Move bottles to your refrigerator and chill before opening. Note that the kombucha will continue to ferment while in the refrigerator, although the process will slow down.

When ready to drink, carefully open a bottle (DO NOT SHAKE!), pointing the opening away from your face. Using a fine mesh strainer, strain the ginger and blueberry pulp prior to drinking.

Store kombucha in your refrigerator for up to 1 month.