A case study for integrated forest biorefinery: Recovery of manool from evaporator condensate of a kraft pulp mill

• Recovery of manool from kraft black liquor evaporator condensate was showcased as an Integrated Forest Biorefinery approach.
• Adsorption of Manool onto Talc was effective for its recovery from the very diluted waste stream.
• An overall process, including talc adsorption, desorption, solvent recovery, and further upgrading, was proposed.

The integrated forest biorefinery concept teaches the opportunity in producing value-added products from the pulp and paper manufacturing processes, in addition to the traditional pulp and paper products. Manool is a plant extractive that is available in many wood species, in particular, softwood, and can find high value applications, such as in the perfumery industry. The evaporator condensate from the kraft black liquor recovery process contains manool and can be a potential source for this valuable product. In this paper, the recovery of manool from the evaporator condensate that was further concentrated in a reverse osmoses (RO) process (known as the RO concentrate) in a kraft mill in Eastern Canada, was investigated. The results showed the manool content in the RO concentrate is in the range of 300–1500 mg/L for samples collected. A novel process was developed in recovering manool from the RO concentrate, which consists of (1) adsorption of manool (together with other organics) into absorbent, such as talc, (2) desorption from the adsorbent and (3) further upgrading of manool. About 90% of the manool from the RO concentrate can be adsorbed onto the talc under the optimal conditions. The adsorbed manool on talc can be subsequently regenerated by extraction using ethanol or dichloromethane, resulting in the crude manool product. The purity of this crude manool product was about 25%, which was further purified to 86% based on the chromatographic separation technology.