I don't want to mislead you, but I believe that when you install Trisquel it
creates a partition used for swap. I don't think you can wipe it.
You can however use the "memory" option and the "free space" option, which
would in theory wipe all traces left behind of anything you might have been
doing. HOWEVER!!! Keep in mind that "memory" option is unstable and might
harm your system. Also, free space does takes a lot of time (depending on how
much free space you have on your HD).
I am not saying it will clean the swap partition, but it is a good start.
I use Bleachbit, with everything on except those two, due to the reasons I
stated above.
Hope it helps in some way.