Absolutely, one sump with one return pump into one UV then the return line splits into 3, one for each tank. Because the tanks are such different sizes (2 small, one bigger) combine your desired flow (after taking into account head pressure) for all three tanks to get your return pump size. That will dictate your UV model. Then put a ball valves, or better yet gate valves, on the 2 20's returns and let the return to the 55 be open to help reduce back pressure on the pump. You could put a valve on the 55's line for safety but try to leave it open.
If you can post a pic of your set up I might be able to make an educated guess on a return pump and set up in general. If the tanks are close together it helps, farther apart = more elbows and fittings = more head pressure, its a killer ($$ pumps). That's the other consideration, UV's that can handle high flow and remain effective are not cheap either.
Chris