Batch and semi-continuous experiments examining the sludge mesophilic anaerobic digestive performance with different...

Anaerobic co-digestion of excess sludge (ES) and different varieties of rice straw including indica rice straw (IRS), japonica rice straw (JRS) and glutinous rice straw (GRS) was investigated in batch and semi-continuous experiments. The batch experiment results showed that the GRS addition presents the highest hydrolysis and methanogenesis rates, its cumulative methane yield (CMY) was 305.75 mL/g VS and its average methane content was 60.56%. After digestion, the structure of GRS was almost completely destroyed, which was beneficial to the degradation of lignocellulose. The digestive process is affected by the abundance of Actinobactereria, Proteobacteria, Methanosaetae and Methanosarcina. The results of semi-continuous digestion were similar to batch digestion. In addition, the addition of GRS increased TN concentration in biogas residue and TP concentration in biogas slurry, but was not conducive to the subsequent dehydration of sludge.