Activated sludge microbiome in a membrane bioreactor for treating Ramen noodle-soup wastewater

Population shifts in the activated sludge microbiome of a membrane bioreactor (MBR) during the treatment of Ramen noodle-soup wastewater were analyzed by high-throughput sequencing. An MBR underwent stable treatment of wastewater containing increasing oil concentrations (from 135 to 1,350 mg/L) for 26 days; however, after feeding with wastewater containing 2,700 mg/L of oil, the mixed liquor suspended solids and transmembrane pressure exhibited gradual and rapid increases, respectively, leading to clogging of the membrane. Phylogenetic analysis revealed an oil supply-dependent increase in the abundance of Cupriavidus gilardii (relative abundance of 26.2% at Day 30) in the sludge together with Parasegetibacter terrae (9.9%) and Ferruginibacter yonginensis (9.4%). These dominant species may play important roles in noodle-soup wastewater treatment.