dealing with wast

I have two questions.
1.  I live in the country and have a septic tank.  Do I have to do =
anything to treat my septic tank when I pour the wast water into my =
septic system that I used to wash my bio diesel?
2.  A while ago I wrote about my wash test when I used 100ml processed =
bio and 100ml water and ended up with a white film between the two. I =
was advised to freeze it.  Freezing was supposed to get rid of the soap, =
which it did. Freezing also cleard up the foggy bio to a clear golden =
color.  Why did my finnished bio become so clear when it was frozen?  =
What does this tell me about my test bio?