Sunday, May 4, 2008
1-14

Conversion of Kraft Paper Mill Sludges into Ethanol by Simultaneous Saccharification and Fermentation

Li Kang, Wei Wang, and Y.Y. Lee. Chemical Engineering, Auburn University, 212 Ross Hall, Auburn, AL 36849

Paper mill sludge is a solid waste material composed of pulp residues coming out of paper machine and inorganic additives associated with paper making. The carbohydrate portion of the sludge has chemical and physical characteristics similar to pulp. Because of high carbohydrate content and well dispersed structure, paper sludges can easily be converted into value-added products without a costly pretreatment process, which is a significant economic benefit. The sludges also contain high level of ash content originated from additives used in paper making. This adversely affects enzyme activity and the bioconversion process. In this study, the sludges were de-ashed and put through Simultaneous Saccharification and Co-Fermentation (SSCF) using cellulase (Spezyme-CP) and recombinant E. coli (KO-11), and also Simultaneous Saccharification and Fermentation (SSF) using Spezyme-CP and Saccharomyces cerevisiae (D5A). The ethanol yield in the SSCF was 70-80% of theoretical maximum on the basis of total carbohydrates and 90-100% on the basis of glucan alone. The ethanol yield in the SSF was 70-80% on the basis of glucan. The SSCF and SSF proceeded well without pH control using the deashed sludges. The ash content, which contains calcium carbonate, clay and titanium dioxide, was partially neutralized by the acids produced from the SSCF and SSF acting as a buffer to stabilize the pH during fermentation. When the SSCF and SSF were operated in fed-batch mode, the ethanol concentration in the broth was increased to 50g/L and 65g/L, respectively.

See more of Poster Session One
See more of General Submissions

See more of The 30th Symposium on Biotechnology for Fuels and Chemicals (May 4 -- 7, 2008)