Agostinho,
I'll answer your question as it was posed.
"I want to know what is the best solution , 24 VDC or 220 VAC detector swich, in terms of interference noise and fiability."
If you are NOT using shielded wiring for your sensors, then they are subject to noise. Noise is usually in the form of low, stray voltages that have some effect on the measured effect.
Six-Volts of noise on a 24-Volt system presents 25%-Noise. That could cause a problem. Six-Volts of noise on a 220 VAC system presents 2.7%-Noise. That will NOT cause a problem.
I think the correct answer, in terms of your posed question, is clear.
In terms of your question, as it was posed, the answer is... "Use the 220 VAC".
Since we are working with electricity, which, in some forms, can KILL, there is no reason to make anyone feel comfortable with it. I am an Electrician as well as a Process Control Engineer - I don't want to, nor will I ever, find myself too comfortable with that KILLER!
Using 24-VDC certainly is safer than 220-VAC, or 440-VAC, and much more certainly safer than 15,700-VAC, but no one should ever get the idea that "Hey! It's only 24-VDC Electricity, it can't hurt me!" Everyone that works with Electricity should have the "Electrician's-Shake".
If the world was based on 24-VDC, that would be one thing... but, I guarantee you, the world ain't based on 24-VDC!