Microbial Identification and Extracellular Polymeric Substances Characterization of Aerobic Granules Developed in Treating Rubber Processing Wastewater

The goal of this study was to investigate the species of the abundance microbial in seed sludge and aerobic granular sludge. Experiments were carried out in a sequencing batch reactor with a working volume of 1.6 L. During the start-up period, the reactor was inoculated with 800 mL of sludge from a municipal sewage treatment plant plus 800 mL of rubber processing wastewater. Further investigation by Illumina high-throughput sequencing was performed to analyze the microbial diversity and phylogenetic structures during the granulation of seed sludge to aerobic granules. A diversity of microorganisms was identified from the seed sludge and aerobic granular sludge. Seed sludge consisted of 96.4% bacteria, 1.7% eukaryote, 1.2% archaea, and 0.7% viruses. Aerobic granular sludge consisted of 97.8% bacteria, 1.0% eukaryote, 0.8% archaea, and 0.4% viruses. As the granulation process succeeded in SBR, distinct differences of the microbial community in the seed sludge and aerobic granular sludge were observed, which suggested that there was high microbial selection pressure during granulation in the system. The most abundance species in seed sludge was Dechloromonas aromatica, while Pseudomonas fluorescens was the most abundance species in aerobic granular sludge.