Process intensification of sulfate pulp production with lignin recovery by pressure-assisted forward osmosis (PAFO)

Biofuels in the form of lignin bio-oil can be produced from sulfate pulp mill lignin. However, the current process developed by SunCarbon extracts lignin from black liquor by membrane filtration resulting in low lignin filtrate. This project thus aims to intensify the sulfate pulp production process with lignin recovery by enhancing the lignin recovery combined with the recycling of water and cooking chemicals. The posi-tive impacts from this processes are: 1) an increased lignin production, 2) energy savings of up to 110 kWh/m3 recycled water and 3) a boost in green electricity production. The new innovative process pro-posed integrates the available streams and utilizes the osmotic pressure potential of the concentrated salt stream from the cooking liquid preparation. Adding a novel membrane step with the concentrated salt stream as draw on the backside of the membranes removes the water from the black liquor while simulta-neously concentration and thus recovering the lignin.