Keywords: ash solid fraction, calcium, cryosection, EPS, extracellular polymeric substances, phosphorus removal, spatial distribution, porous structure, spatial characteristics, aerobic granules, porosity, microstructure, microorganisms, wastewater treatment
Porous structure and spatial characteristics of aerobic granules
Cryosectioned granules were observed in microstructure, Extracellur Polymeric Substances (EPS) and metal distribution. Aerobic granules composed of pores and channels that were not plugged by EPS, with rather open structure. Microorganisms proliferated mainly on the surface of granule and on the wall of channels, carbohydrate EPS mainly distributed on the surface of granules, and protein EPS mainly distributed in the interior part of granules. Also, aerobic granules accumulated considerable calcium and phosphorus, which increase the ash solid fraction of granules and thus improve the settleability. Additionally, iron was neither temporally accumulated nor heterogeneously spatially distributed.