One of the main irritants for me in this game is having to keep pollution under control, when I know that I'll eventually have Behemoths to deal with anyway. So I thought it would be cool if we could filter pollution out of the air. My idea has 2 parts to it:

Part 1: Filtration: The first building involved is the Air Filter. Feed it electricity and supply it with water, and it will pull pollution out of the atmosphere and dissolve it in the water. This polluted water could then be pumped into an Assembling Machine, along with Empty Barrels, and turned into Pollution Barrels. These pollution barrels can be loaded onto trains, and sent to part 2 of my idea.

Part 2: Disposing: The other new building I suggest is the Subterranean Drill. Basically, this is a drill that digs down into the planet. It ejects landfill, and maybe even Stone and/or Copper Ore and/or Iron Ore and/or Coal. The drill must be fed replacement drillbits, as every 100? metres, the drillbit breaks. When the drill is done, Pollution Barrels can be inserted into the drill, and it will place them in the hole, filling it. When the hole is completely filled up, the drill will retract, and it can be removed.

To stop this from becoming over-powered, I suggest that, if possible, the Pollution Barrels 'break down' over time, slowly releasing some of their pollution into the atmosphere. This would create an area of dense pollution.