Removal from ips.backscatter.org is extremely strict. Upon detection, your IP address will be listed for 4 weeks from the point of last seen abuse. If no further abuse is seen, your IP address will expire in exactly 4 weeks. If 4 weeks is too long for your organization to wait, there is a process called "expressdelisting", which is explained when you lookup your IP within the ips.backscatter.org IP lookup tools. Not all IP addresses are eligible for expressdelisting.