Robust removal of phenolic compounds from coal pyrolysis wastewater using anoxic carbon-based fluidized bed reactor

Coal industry provided various carbon derived products, but it also caused serious environmental pollution by phenolic wastewater emission. By in-situ applications of coal-derived carriers, carbon-based fluidized bed reactors established a sustainable system that realized byproducts recycling and waste elimination, contributing to cleaner production of coal industry. Benefitted from adsorption capacity, powdered activated carbon/lignite activated coke-based fluidized bed reactors significantly promoted start-up and recovery efficiency with higher phenolic degradation rate than activated sludge reactor (avg. 90% vs 70%) when total phenols ranged at 250–350 mg/L, whereas iron-carbon (Fe–C)-based reactor showed the highest stability (70 ± 5%) under supreme phenolic impact (450 mg/L). Combined with adsorption capacity and activated sludge properties, resilient adsorption benefited lignite activated coke-based reactor with toxicity alleviating while intensified sludge flocs equipped Fe–C-based reactor with superior resistance. Moreover, Brachymonas genus provided microbial basis for robust performance of carbon-based systems in methylphenolic degradation. Higher abundance of functional genes for demethylation and cleavage of aromatic ring contributed to superior methylphenolic degradation for fluidized bed reactors in contrast to activated sludge reactor, while up-regulated oxidative stress evidenced superior oxidative resistance of Fe–C-based reactor. In summary, carbon-based fluidized bed reactors provided a cost-efficient and sustainable way for coal pyrolysis wastewater treatment.