Removal of anionic surfactant in a sequential batch fluidized bed biological reactor filled with polymeric hydrochar

Abstract

Biological fluidized bed systems can be used to treat effluent contaminated with linear alkylbenzene sulfonate (LAS) and can also be made up of support materials produced from spent ion exchange resin residues. Therefore, the objective of this study was to evaluate the removal of anionic surfactants, specifically LAS, in a fluidized bed system filled with polymeric hydrochar and a consortium of microorganisms. For this purpose, the methodology was developed in the following phases: (I) production and characterization of the support medium; (II) implementation of the system in sequential batches and hydrodynamic tests; (III) inoculation, synthetic substrate supplementation, and adaptation of the inoculum to the system’s LAS in sequential batches; and (IV) operation of the system in sequential batches to determine the LAS manipulation kinetics for three initial LAS concentrations from 17.51 to 41.89 mg L-1. In phase I, polymeric hydrochar was obtained with an average diameter of 0.715 mm, an acidic surface, a low specific surface area, high sphericity, and characteristics of a nonporous or macroporous solid. The hydrodynamic tests resulted in a minimum fluidization velocity of 0.49 cm-1 in phase II. For the biological treatment system, the inoculation, feeding, and adaptation trials were extended for 29 days in Phase III. From the LAS treatment in the system in sequential batches, in Phase IV, removal efficiencies greater than 80.0% were obtained for both concentrations evaluated after 48 h of operation, and the degradation rate coefficients (kLAS) decreased with increasing LAS concentration in the system.