Robustness and Microbial Diversity of a Fluidized Bed Reactor Employed for the Removal and Degradation of an Anionic Surfactant from Laundry Wastewater

Abstract

A fluidized bed reactor (FBR) was employed to evaluate the removal and degradation of linear alkylbenzene sulfonate (LAS) from laundry wastewater without supplementary feeding. After immobilizing the biomass on the support material, the reactor was operated in two stages: Stage I, fed with a synthetic substrate, and Stage II, fed with laundry wastewater with a LAS concentration generally reported as being process disturbing in anaerobic systems to treat LAS (21.7±5.3 mg/L) and sodium bicarbonate as a buffering agent. Despite the low chemical oxygen demand (COD) in the influent during Stage II (74±26 mg/L), the observed proportions of LAS (80±11%) and COD (91±9%) removed were high. The microbiological analysis of samples collected from different regions of the FBR during Stages I and II suggests that the composition of the laundry wastewater may have also contributed to the biomass differentiation and that the environmental conditions in the different parts of the reactor affected the microbial composition. A remarkable proportion of genera capable of degrading aromatic compounds, including LAS, was observed in the upper compartments of the reactor, which was related to a facultative environment.