In the black

Black liquor, a by-product of the pulping process is sometimes referred to as ‘black gold’ because of the high levels of energy it contains.

Globally, over 65% of Sappi’s renewable energy use is from its own black liquor.

Black liquor is formed when pulp is washed to separate spent cooking chemicals and dissolved wood solids from pulp fibres.

Sappi is the co-lead of the committee operating under the auspices of the Alliance for Pulp and Paper Technology Innovation (APPTI) to demonstrate and deploy membrane-based technology for black liquor. Other members of the committee include the Georgia Institute of Technology (Georgia Tech), members of the US forest products industry, and membrane system/process developers.

Resource scarcity and growing concern for natural capital

Membrane-based kraft black liquor dewatering is a highly desirable technology for the US forest products sector but challenging to develop and deploy.

The goal: enhanced energy efficiency

Specifically, the committee is involved in developing a modular graphene oxide (GO) membrane system, and membrane-based process, that substantially improves the energy efficiency of concentrating kraft black liquor. Robust, high-performance GO membrane technology can have impacts in many applications such as biorefining and water treatment, not only black liquor concentration. Should the project be successful, it would also have important impacts in enabling membrane technology in other biomass pretreatment and water recycling schemes.

The team is now ready to commence initial mill piloting of tubular GO membrane technology. Given that approximately 164 trillion British Thermal Units (BTU) per year is used in black liquor concentration in US kraft mills, this could have important implications for enhancing energy efficiency.