It looks like standard industrial bearings (not a cartridge bottom bracket!) press fitted into the frame. You remove those bearings by protecting the end of the axle with a piece of wood and then whacking the axle axially with a big hammer. Bearings should come out to either side. Replacements are hammered in (first one) with a protective piece of wood and (the second one) with a socket over the axle.
Should be a fun job - only semi brutal force and no special tools needed!