Assuming that they are poor though otherwise functional (capable of work), then in order to make money from them you take advantage of them, knowing that poor people desperate for money to support their families will put up with more shit.
Have a "recycling" company and need somebody to man one of the electronics burning pits? Get one of those poor guys in they alley to do it. What are his other options?
You may need to bribe others to get away with this, but if those people are also relatively poor, the bribes should be affordable.