Yes, there are two main methods.
Bromine: Bromine can be used as a substitute of cholorine.
Salt cholorine generators: In this, the salts which ar produced as a byprodut of choolrine, choloramines, are regenerated back into chlorine so that it can be sued again. It is these chloramines which accumulate in the pool and which cause all the disagreeable effects of cholorine.
Please check out these two sites:
http://www.citrus-iberia.com/salt-chlorine-generators-spain.htmlhttp://wiki.answers.com/Q/Can_you_sanitize_your_pool_without_chlorineI hope this answer was helpful. If you need more information, feel free to ask. For accepting this answer, please click on the green 'accept' button below. Feedback/Bonus will be warmly appreciated.