The effect of overliming on the toxicity of dilute acid pretreated lignocellulosics: the role of inorganics, uronic acids and ether-soluble organics

• Published in: Enzyme and microbial technology Vol. 27; no. 3; pp. 240 - 247
• Main Authors: Ranatunga, Thilini D, Jervis, Judith, Helm, Richard F, McMillan, James D, Wooley, Robert J
• Format: Journal Article
• Language: English
• Published: Amsterdam Elsevier Inc 01.08.2000; Elsevier Science
• Subjects: Acids; Biochemical engineering; Biofuel production; Biological and medical sciences; Biotechnology; calcium carbonate; calcium hydroxide; Energy; Enzymes; Ethanol; Ether-soluble organics; Fundamental and applied biological sciences. Psychology; Industrial applications and implications. Economical aspects; lignocellulose; Lignocellulosics; Microorganisms; Overliming; pH effects; Sulfur compounds; Toxicity; uronic acid; Uronic acids; Zymomonas; Lignocellulosics; Uronic acids; Ethanol; Ether-soluble organics; Overliming; Zymomonas; Toxicity; Industrial application; Detoxication; Biofuel; Inorganic compound; Calcium Hydroxides; Hydrolysate; Biotransformation; Uronic acid; Chemical composition; Pretreatment
• ISSN: 0141-0229; 1879-0909
• DOI: 10.1016/S0141-0229(00)00216-7

Although the treatment of dilute acid pretreated lignocellulosics with calcium hydroxide or carbonate (overliming) is known to improve the fermentability of carbohydrate-rich hydrolyzate streams, a firm understanding of the chemistry behind the process is lacking. Quantitative evaluation of inorganics, uronic acids, and non-polar organics indicates that only a portion of the improvement can be ascribed to these materials. Upon overliming the concentrations of inorganics either increase (Ca, Mg), decrease (Fe, P, Zn, K) or remain relatively the same (Al, Na). Furthermore, organic compounds that are not extractable with tert-butyl methyl ether (MTBE) are toxic to Zymomonas mobilis CP4(pZB5). Overliming and direct neutralization are somewhat effective in removing sulfate anions, although sulfate toxicity is considerably less than that of acetic acid. Uronic acids were found to be non-toxic under pH controlled conditions.