I recommend reading the article again. They got anything but the tritium out of the water. Which is comparable easy to accomplish, and also important. The remaining tritium is as harmless as radioactive things can get in the first place.
A radiation scientist here reminded people of those radium-based glow-in-the-dark wrist watches, and compared the radiation caused by this wastewater release to adding about 70 to 80 of those watches to the pacific ocean.