The freezing causes the inactivation of the bacteria. In case of freezing the, bacterial enzymes are not able to function, this causes the inactivation of bacterial growth and function, but once the favourable circumstances are present, these enzymes get activated again, and the bacteria is fully functional.
So, saying that freezing kills all the bacteria is incorrect as it only deactivates the bacterial activity.
Shorter wavelengths are known to kill the bacteria more effectively, as it directly targets the genetic material of the bacteria. Ultraviolet radiations are used in many industries and laboratory processes to kill the bacteria.
The bacteria can also be filtered, if the pore size is smaller enough to inhibit the bacteria pass through it. Although, it is a little difficult, but it works.