LAUSR

The influence of micron-sized silica particles on the distribution of organic matters in sludge and anaerobic degradation of macromolecular organic components (MOCs) in sludge was investigated. With the addition of micron-sized particles in the influent (VS/TS decreased gradually from 90.46 ± 0.21 % to 33.36 ± 0.17 %), the protein degradation percentage was significantly promoted while the polysaccharides degradation percentage was largely inhibited, resulting in the total MOCs degradation and methane production increasing firstly (with the promotion extent within 10 %) and then declining slightly, with the peak value at VS/TS of 56.03 ± 0.21 %. The shifted degradation percentage of protein and polysaccharides were caused by the significant changed distribution of organic matters in sludge. With the addition of micron-sized silica particles, the MW of EPS and secondary structure of protein in EPS changed little, which brought about little influence. While, the promoted extracellular protein content (so that the total protein content) and declined extracellular carbohydrates content (so that the total polysaccharides content), were found to be strongly correlated to the enhanced protein degradation and inhibited polysaccharides degradation. The results suggested that large amounts of grit in sludge might not be the main reason for lower degradability of sewage sludge in China.