To qualify for the tax credit, paper companies started adding diesel fuel to “black liquor”, a pulp-making byproduct that they were already using to generate electricity on its own.

Sodium carbonate for example, is recovered from black liquor in soda pulp mills.

The study probe into the separation of lignin from pulp waste liquor, the condition and measure of lignin modification, and the influence of lignin on non-biological stability of beer.