Researchers Develop Scheme to Turn Bamboo into High-grade Dissolving Pulp and Ethanol

Bamboo is an underutilized biomass source despite being similar to wood. The main challenge for the industrial processing of bamboo is the high level of silica, which negetively affects the process. A scheme for the production of pulp from bamboo needs a process for silica removal as well as to fully utilize all of the materials in the process, including lignin, and cellulosic and hemicellulosic sugars.

Zhaoyang Yuan from the University of British Columbia, United Kingdom, used alkaline pretreatment on bamboo to extract silica before the pulping process. Pretreatment at 95°C with 12% NaOH for 150 min extracted all the silica and about 30% of the hemicellulose from bamboo. The silica-free substrate was then used to produce high-grade dissolving pulp. Meanwhile, the dissolved silica, lignin, hemicellulosic sugars, and degraded cellulose in the liquors from the pretreatment and pulping process were used to produce bio-based chemicals and fuel.

After kraft pulping, xylanase treatment and cold caustic extraction, the team obtained pulp with hemicellulose content of about 3.5%. On the other hand, hydrolysis and fermentation of the liquor showed an ethanol recovery of 0.46 g/g sugar, achieved with 93.2% of hydrolyzed sugars consumed.

This work presents a process that contains alkaline pretreatment, kraft pulping, enzyme treatment and cold caustic extraction for the production of high-grade dissolving pulp and recovery of silica, lignin, and hemicellulose from bamboo. This process could alleviate the silica-associated challenges and provide feedstocks for bio-based products, allowing bamboo use in industrial processes.