Utilisation of microwave-NaOH pretreatment technology to improve performance and l-lactic acid yield from vinasse

Jianguo Liu, Qunhui Wang, Shuang Wang, Dexun Zou, Kenji Sonomoto

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Pretreatment of vinasse is necessary to break down its complex wooden structure, improve the efficiency of enzymolysis, and provide an adequate substrate for fermentation during l-lactic acid production. Independent microwave and NaOH pretreatment processes were carried out in an earlier study. Here a two-way microwave-NaOH coupled method, was investigated to determine the effects of simultaneous saccharification and fermentation (SSF) of vinasse on l-lactic acid production. Compared with the former individual microwave and NaOH pretreatment methods, hemicellulose and lignin in vinasse were more significantly reduced using microwave-NaOH coupled pretreatments, reducing crystallinity to 14.77%. l-lactic acid yield was also higher in the coupled method than the sum of the yields from the independent pretreatment processes. The optimal conditions for the coupled pretreatment method were: 0.06 g g -1 (vinasse dry weight) NaOH; 523 W microwave power; 1:2 solid-liquid ratio; and 8 min microwave pretreatment time. These conditions resulted in an 86.0 mg g -1 l-lactic acid yield. The microwave power and the amount of alkali used were approximately 25% lower than those used prior to the optimisation process. The reduced values indicate that optimisation can significantly decrease energy and reagent consumptions. Thus, microwave-NaOH coupled pretreatment exhibits a synergistic effect for improving l-lactic acid production.

Original languageEnglish
Pages (from-to)6-13
Number of pages8
JournalBiosystems Engineering
Issue number1
Publication statusPublished - May 1 2012


All Science Journal Classification (ASJC) codes

  • Control and Systems Engineering
  • Food Science
  • Animal Science and Zoology
  • Agronomy and Crop Science
  • Soil Science

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