This may not be great dinner-table conversation but simply separating urine from excreta can make a huge difference to how we approach the issue of human waste. Wost Man Ecology, a firm run by Swedish farmer Ingvar-Nilsson, makes separating toilets that are now selling all across the world. Essentially, the urine can be directly used as a source of urea while the solid waste composts (and turns into fertiliser) much quicker when it’s dry.