Lignocellulosic structural changes of Spartina alterniflora after anaerobic mono- and co-digestion

摘要

Lignocellulosic structural changes of Spartina alterniflora after anaerobic digestion were investigated by Fourier transform infrared (FTIR) spectroscopy, X-ray diffractometry (XRD), and scanning electron microscopy (SEM). Batch experiments for anaerobic mono-digestion of S. alterniflora and co-digestion with potato at S. alterniflora to potato (SA:P) of 4:1 and 6:1 (based on volatile solids [VS]) were performed at 35 +/- 1 [degree]C at initial VS of 6%. FTIR spectroscopy study showed that the ratio of lignin to carbohydrate peak area for digested S. alterniflora was more than twice that for the undigested one, and the ratio of lignin to hemicellulosic peak area of samples from co-digestion was approximately twice that from mono-digestion, indicating co-digestion improved hemicellulosic degradation of S. alterniflora. This should attribute to the concentration increase of volatile fatty acids with a peak of about 11 g Ae l[super]-1 for co-digestion compared with 5 g Ae l[super]-1 for mono-digestion. XRD analysis indicated that anaerobic digestion decreased the crystallinity of S. alterniflora by 6.1-8.6%, but the degree of crystallinity decrease for co-digestion was slightly different from that of mono-digestion. SEM observation showed that physical structural destruction of S. alterniflora caused by co-digestion was similar to that caused by mono-digestion, and the degradation of S. alterniflora stem occurred mainly in vascular bundle tissue, whereas the degradation of parenchyma cells was not obvious.