Filterability and extracellular polymeric substances of aerobic granules for AGMBR process

Extracellular polymeric substances (EPS) are a major component of aerobic granules. This work cultivated aerobic granules in sequencing batch reactor (SBR) using EPS-free pellets as seed sludge and glucose as sole carbon source. Mature aerobic granules were cultivated in 25 d. Then the granules were tested in aerobic granule membrane bioreactor (AGMBR) to treat glucose-containing synthetic wastewater. The AGMBR experienced a lower trans-membrane pressure drop than the conventional MBR with activated sludge flocs as seed sludge. In situ EPS fluorescent staining, EPS fractionation protocol and microscopic observation characterized the structure and chemical components of aerobic granules. The secreted EPS, including proteins and polysaccharides, were largely bound with cells hence leaving low quantity of free EPS in supernatant for membrane fouling.