Feasibility of NaOH-treatment for improving biogas production of digested Spartina alterniflora

order to improve the biotransformation rate of Spartina alterniflora (SA) and evaluate the feasibility of NaOH-treatment as a pretreatment of digested SA (DSA) for advanced anaerobic biogasification, two experiments were conducted under lab-scale conditions. First, SA was directly digested under 35 +/- 1 degrees C with initial total solid (TS) loading of 20% (the first stage). After 90 day's reaction, cumulative biogas yield of SA and average methane content were 388 22 ml g(-1) TSadded and 59.62 +/- 1.88%, respectively. Then the DSA was treated with 5% NaOH solution and was used for advanced biogasification (the second stage). The cumulative biogas yield of NaOH-treatment and control were 210 +/- 11 ml g(-1) TSadded and 103 +/- 16 ml g(-1) TSadded, respectively, with 70.78 +/- 2.11% and 76.92 +/- 1.94% of average methane content. The total cumulative biogas yield (sum of the first stage and the second stage of NaOH-treatment) and TS removal rate of SA were 495 24 ml g(-1) TSadded and 76.85 +/- 1.94%. After NaOH treatment, surface lignin and some carbohydrate of DSA were destructed into lignin fragment, organic acids, and some other small molecular organic matter; while the skeleton structure of lignin and cellulose were not destructed significantly. The results of C-13 NMR showed that methyl and carboxylic C groups of DSA were decomposed significantly. The results indicated that NaOH-treatment was a good pretreatment for DSA. (C) 2014 Published by Elsevier Ltd.