The influence of upflow velocity and hydraulic retention time changes on taxonomic and functional characterization in Fluidized Bed Reactor treating commercial laundry wastewater in co-digestion with domestic sewage.

A large-scale (19.8L) Fluidized Bed Reactor (FBR) operated for 592 days was used to assess the removal performance of linear alkylbenzene sulfonate (LAS). Adjustments in hydraulic retention time (HRT) (18 and 30 h), ethanol (50, 100, 200 mg L-1) and linear alkylbenzene sulfonate (LAS) concentration (6.3-24.7 mg L-1) with taxonomic and functional characterization of biomass using Whole Genome Shotgun Metagenomic (WGSM) represented a major step forward for optimizing biological treatments of LAS. In addition, the variation of the upflow velocity (0.5, 0.7 and 0.9 cm s-1) was investigated, which is a parameter that had not yet been correlated with the possibilities of LAS removal in FBR. Lower Vup (0.5 cm s-1) allied to higher ethanol concentration (200 mg L-1) resulted in lower LAS removal (29%) with predominance of methanogenic archaea and genes related to methanogenesis, while higher Vup (0.9 cm s-1) led to aerobic organisms and oxidative phosphorylation genes. An intermediate Vup (0.7 cm s-1) and higher HRT (30 h) favored sulfate reducing bacteria and genes related to sulfur metabolism, which resulted in the highest LAS (83%) and COD (77%) removal efficiency.