Working utilities

harrawaffa:
Animal byproducts from abattoirs that are not fit for human consumption and bulk fallen stock animals (animals that have died/been killed at the farm)
I mainly do tanker work on blood collection now but we run a fleet of bulk tippers for the majority of the work
The material eventually gets burned to produce electricity after it’s been through the plants my employer operates

I’m just interested now. Why the exemption for that? Is it because it’s a potential environmental/biological hazard so a trailer full of animal blood doesn’t need to be sat in services or a lay-by for 45 mins?