The key is in the ecosystem you're taking with you.

#Organic tech.

The floor is a [Tapestry Lawn][1]:

[![enter image description here][2]][2]

<sup>_Attribution: grassfreelawns.co.uk_</sup>

The various species of bee and other insect that you'll no doubt be wanting to take with you to populate your new world will love it, as will the worms and soil bacteria. (Moles, gophers, well - that's your choice)

- The ivy that you decorate the walls with acts as fine self-repairing handholds and homes for insects (a food source for the many birds/bats that are part of your habitat). 

- While there might be some large common areas for trees, most of the oxygen production can be from wheat/barley and other food crops in your farming bays. 

- Solid human-waste composted with dead plant matter would of course be used as fertilizer, as would urea, trace salts and water from the liquid waste to grow the plants necessary for life.

- Larger mammals (including the aquatic ones) may not be practical in terms of the required space to house and feed them, cryo-preservation of eggs for eventual regrowth in artificial wombs would be the preferred option.

- Your aquaculture bays would house and produce fish, oyster shrimp, algae and various plants, as well as more varied marine habitats for transplantation to the new world.

All this would require maintenance by; gardeners, arborealists, microbiologists, chemists, habitat management specialists, waste recycling engineers ... etc. This would provide rich educational opportunities for the future children, helping to maintain hands-on skills throughout the voyage necessary for populating the destination-world.

  [1]: https://en.wikipedia.org/wiki/Tapestry_lawn
  [2]: https://i.sstatic.net/7gnix.jpg