Lignosulphonates are a useful byproduct recovered from the spent liquor in the sulphite process.

It is cooled by flash evaporation, the steam given off being used to heat spent liquor returning to digestion.

Spent liquor was discharged untreated into the Kapuskasing River.

In 1865 they patented a method for recovery of the cooking liquors by incineration of the spent liquor.

After conventional pickling, the spent liquor was discarded and the pickled stock was tanned with spent chrome liquor from the previous run after reconstitution.

But the forest products industry claims that most of energy used for producing virgin fibre normally comes from burning by-products of timber processing such as bark, wood waste and spent liquor.

Anaerobic treatment was found to be much less suitable as evidenced by severely inhibited methane production rates and impaired treatment efficiencies during batch serum bottle testing of 5-20% v/v spent liquor.