When we are milling out on the farms the sawdust just gets left behind. Because we a moving the mill around it's just a thin layer where each log was, it rots down and the grass grows up through it pretty quickly. Next year you would never know where we had been.
The shavings and sawdust I make in the workshop when planing down the rough sawn boards get used for bedding for friends horses or garden mulch. Offcuts are firewood.
Not much gets wasted