When I empty my loo and those buckets I use for compost and gray water they sometimes end up smelling, well, rather unpleasant. Even after rinsing them thoroughly.
The solution is to simply let them stay out in the sun some hours. If I let them dry indoors nothing exiting happens, and they continue to smell. If they dry in the sun, all odor disappears.
It turns out I'm hardly the first one to discover solar disinfection.
If only everything had been this easy.