How do I build a filter to remove artefacts from EMG signal?

I am working on EMG signal and I have bursts of artefacts at 50Hz (see picture).

I would like to remove these artefacts, keeping the meaningful information that overlaps (sometimes).

First, I usually do a Butterworth filter [50 500]. After I tried a notch filter or a comb notch filter to remove the artefacts, but it did not work. I have the same signal at 30kHz and 2kHz. In the .mat file, I saved one signal at 30kHz and the same at 2kHz.

Could you help me understand how to remove it?

Thanks, Flavio