https://en.m.wikipedia.org/wiki/Bioremediation this should deserve a look. How many interested in this field?

MOD EDIT: I have edited this post to active the link for you, you can do this in future by wrapping the URL in < URL >. - Jason Rainbow Dec 22 @ 22:00

Also, know some cellular lines to use?

I agree with the Bioremediation method of breaking down toxic substances into less toxic substances through the use of microbes that feed on toxic substances. Left over materials can also be used for compost.

You can do everything with fluid wastes, if we can reproduce methane cycle with that we can produce fuel too (and become energetically a bit more indipendent)

i think human waste is usefull to fertilize the soil we bring to asgardia ,sound crazy but shypon the water and heat up the waste can be the good option i think

Bioremediation will have to be one of the many tools in the toolbox to manage all the waste from a future self-sustaining space habitat.

The natural environment on Earth has evolved in a manner where the waste of one organism is a resource for another. Except for one species, there are no examples in natural biological systems where an organism produces waste that is either toxic by its nature or by the amount discharged into the environment over a prolonged period. Can you guess the one species that is the exception? :)

Even though space is (for all intents and purposes) infinite, future Asgardians will have to refuse the temptation to just "shove the waste out an airlock". We have to be better than that and make sustainable decisions on what we use, how we use it and how we manage any wastes. That is one way you can guarantee the long term sustainability of a large scale space habitat.