Quarantine USB Drives

I work for a company that provides managed IT services for our clients. Recently we've had increased response to ransomware and other malicious viruses on our clients PC's.

When we send engineers to site to disinfect and investigate the issue, we supply them with a USB stick with several on demand Anti-Malware products (ClamWin, EET, HitmanPro, Malwarebytes and the client's paid antivirus)

The last incident we faced infected the USB stick and was transferred onto our network.

We're now looking at enforcing a policy that all foreign storage devices get quarantined and thoroughly scaed on a PC coected to a DMZ away from any of our production equipment.

Is there any software that you'd recommend for thoroughly scaing these usb's and making sure they're safe to coect back to our network to be reused. Free software is preferable but of there's software that is worth the price.

If there's no data we want back from the USB, would formatting using a live CD be safe enough to completely disinfect it?