CIRCUBLACK. Back to the Black Liquor. New concept of biorefinery integrated in the paper sector through the direct valorization of black liquor.

Europe, as the world’s second-largest producer of pulp and paper, generates 25 to 35 million tons of black liquor annually as a byproduct of the Kraft process, with a high lignin content. Despite its significant antioxidant potential, lignin recovery remains a challenge due to the lack of viable technologies. Currently, most black liquor is burned as fuel, leading to biogenic CO₂ emissions and the loss of valuable compounds.

The CIRCUBLACK project aims to change this paradigm through two key strategies. First, the development of an innovative membrane-based pretreatment that enables direct lignin extraction from black liquor without generating acidic effluents or disrupting the chemical balance of the pulping process. Second, the transformation of the recovered lignin into high-value products using two groundbreaking technologies:

1. OHRIGINS, a patented technology developed by CENER for producing natural antioxidants from lignin, with applications in food, cosmetics, rubber, and biofuels.
2. Hydrothermal Liquefaction (HTL), adapted to produce advanced biofuels with properties similar to crude oil but with lower environmental impact.

The consortium, which includes leading companies from various sectors (Oleofat, Urzante, Nucaps, Única), will validate the feasibility of these products for industrial applications. CIRCUBLACK represents a major step toward a circular economy in the pulp and paper industry, reducing emissions, revalorizing byproducts, and promoting sustainable alternatives to fossil-based compounds.

CENER will act as the scientific leader of the project, conducting laboratory-scale research on three key technologies. First, a membrane-based pretreatment process, and second, two proprietary technologies: OHRIGINS (lignin depolymerization and fractionation) and HTL (hydrothermal liquefaction), both crucial for the proper valorization of black liquor from the pulp industry. To achieve this, CENER will work closely with the project coordinator and black liquor producer, SMURFIT WESTROCK NAVARRA, as well as with other partners responsible for assessing the technical feasibility of the obtained products in various industrial sectors, including food, nutraceuticals, rubber, and bioenergy. CENER’s critical role in the project includes coordinating Activities 2 and 3 and leading key tasks within Activities 4 and 6.