The Land of Israel: Terumah, Ma'aser, Shmittah and Yovel, Kilayim: Terumah and Maaser Nowadays:
What is done with terumah and maaser nowadays?
Nowadays the Levites' tithe is separated and kept (since anyone can eat it); the kohanim's 1% (plus a token amount for terumah) is separated and destroyed
(because it can only be eaten in a state of ritual purity, which is no longer possible); the second tithe is redeemed for a token amount, which is destroyed, or in the third and sixth years its value is given to charity.
Ask a follow-up question