Our apartment has one of those all-enclosed glass showers that allows absolutely no ventilation. And the bathroom is so tiny that it's just not possible to leave the glass door open after a shower to air it out. It's absurd. So, of course, we now have a mold and mildew problem.
We've been trying to deal with it in a green way. Vinegar. Borax. Non-cholorine bleach. Ecover (suggested by a clerk at Whole Foods). But no luck yet. We're tempted to just give in and buy the darn toxic Scrubbing Bubbles, but we just refuse until we've tried everything green that might work.
Maybe try a mix of water and an oxygen bleach like oxyclean?
I too have a no-window bathroom. The main thing I do is run a small floor fan at the threshold after I shower; it drys out the bathroom much quicker and has greatly reduced the skankiness. When I do get gross growing stuff i cave in and use diluted bleach (4:1) in a spray bottle. I only have to do that 2-3 times a year.
http://www.eartheasy.com/live_nontoxic_solutions.htm
Lemon juice is a great cleaner. You can also use an orange citurs cleaner as well...
Borax solutions left to dry in place work well on walls and ceilings, but for an enclosed shower you're probably gonna have to resort to bleach from time to time. Either that or sprinkle the shower down with borax after each shower. It won't remove mold and mildew, but it can prevent their growth.
You will always be amazed at what baking soda and vinegar can remove. Best on hard water spots-but could put a good dent in your mold. I make a paste out of the baking soda with a tiny bit of water, apply it and then spray vinegar on it. "Green" scrubbing bubbles!
i had the same problem with my shower enclosure. Straight tee tree oil would always remove the surface mold, and even after a thourough drying for a week (I took showers at the gym) and then resealing, the mold would slowly return. Apparently the spores are in the grout....and killing the surface stuff is just palliation.
So we chipped out the old grout and regrouted and sealed. and of course got better bathroom ventiliation and that solved the problem.
Tea Tree Oil is one of the few substances that will actually KILL mold, bacteria, and fungi, as opposed to just bleaching them out (which is about all those toxic bathroom cleaners are really doing). It's expensive, and will make your bathroom smell funny for a while, but if you follow the good cleaning with daily use of one of those shower sprays (Method makes one, I'm sure there's some home-grown recipe for it somewhere too)maybe you won't have to repeat the process very often.
Put hydrogen peroxide from the pharmacy in a spray bottle and spray liberally on the grout (no pun intended.) leave undisturbed for an hour. It will bleach out the grout and kill the mold, and degenerates into harmless oxygen and water. Effective and cheap too!