I'd heard (3rd-hand information, don't know how reliable it is) that aspirin (Bayer's original brand) can be used as a suitable substitute for campden tablets. Does anyone know how well this works? I ask because I need some campden tablets and the brewing supply store near me is closed for renovations, and won't open for a while. Are there other easy-to-get alternatives to campden?
I'm HIGHLY suspicious of substituing aspirin for metasulfate (the active compound in Campden tablets). Different chemicals and I've never heard of aspirin being effective against yeasts at normal concentrations. Certainly not a single tablet or two (or more). Aspirin is not an effective antimicrobial in the concentrations that you would want to drink. It appears that you would need a concentration of 400 micrograms per milliliter to see an effect and that translates to 3.5 lbs of pure aspirin in a 5 gal batch (see http://gut.bmj.com/content/52/4/490).
You could burn sulfur and bubble the gas through your solution, but this really wouldn't be very effective and it really stinks.
The easiest way to remove the potentially problematic yeasts is to pasteurize. This is accomplished by bringing your solution to 145F for at least 30 minutes (or 165F for 1 minute, AKA HTST pasteurization - see http://www.dairyeng.com/applejuice.asp). This is what was done historically to kill bacteria and yeast. People who are potentially allergic to sulfites use this method instead of metasulfate. And I do this when I don't have Campden handy. Cheers.