Instagram recently (I believe) implemented a personal filter that lets you put in keywords. Comments that contain these keywords are hidden from you. I feel like Twitter could greatly benefit from this.
Sadly, while their actions are in no way excusable, you are never going to get rid of internet trolls without cracking down on the freedom many of us enjoy on the internet and I am sure none of us want that. That said, all trolls really want is a reaction from you. I’ve heard most people say “just ignore them” and while that is true it is often a lot easier said than done, and some trolls are just relentless.
With the above mentioned feature I think this will make it a lot easier to ignore them. Out of sight, out of mind.