There were certain waste products they could not deal with.
Heavy oil, then available as a waste product, was used for firing.
For the most part, they have been a waste product.
The waste products of rich people were sold at higher prices because their diet was better.
You must also provide customers with information on how they can return waste products, and keep records.
"In effect, what you saw was a waste product of the process."
In either case, the waste products must be dealt with.
"And we do what with our waste products in the meantime?"
This allowed him to turn a waste product into a source of income.
Various systems of the body, after performing their functions, give off waste products.