how does one go about cleaning a used mattress? are there ways to disinfect it?

I ask because buying a new mattress is not a viable option for me right now. I have been buying air mattress’ but it seems I have to buy a new one every three months, which gets to be costly. So is there a way to clean, deodorize, disinfect a used mattress? or if it’s dirty it’s just dirty and you have no recourse but to buy a new one?