In-depth analysis of biological regulation and process characteristics in the treatment of bath wastewater using oxic-anoxic biological magnetically suspended fluidized bed reactor (O-ABMSFBR)

Abstract

This study proposes an Oxic-Anoxic Biological Magnetically Suspended Fluidized Bed Reactor (O-ABMSFBR) for the treatment of bath wastewater containing high concentrations of linear alkylbenzene sulfonates (LAS) and low levels of organic matter and nutrients. The results indicate that when the inflow rate is maintained between 5.2 and 6.0 mL/min, the removal rates of LAS, turbidity, and Chemical Oxygen Demand with Dichromate (CODcr) exceed 94%, 90%, and 83%, respectively. Combined with high-throughput sequencing, it was found that under aerobic conditions, LAS can be degraded into sulfates and sulfites; under anoxic conditions, sulfates and sulfites are reduced to lower valence states and ultimately converted into organic sulfur for microbial metabolism. The magnetic field assists microorganisms in resisting the toxicity of LAS, enhances their biological activity, promotes bacterial adaptation to LAS stress, and strengthens bioflocculation, thereby improving the removal efficiency of various pollutants by the O-ABMSFBR. The magnetic levitation layer facilitates the formation of both the activated sludge layer and the biofilm layer, fostering the establishment of an aerobic-anoxic environment within the reactor, enhancing the removal of LAS and their degradation products, and demonstrating greater resilience to fluctuations in organic load. The O-ABMSFBR effectively enhances mixing efficiency and mass transfer capacity between the liquid phase and activated sludge, characterized by a relatively short hydraulic retention time (HRT). The effluent concentrations of LAS, CODcr, and turbidity meet greywater reuse standards and exhibit significant potential for treating low-pollution wastewater.