Enhancing operational stability and pollutants removal in dynamic membrane bioreactors via granular activated carbon for landfill leachate treatment

Abstract

Polymeric membrane-based technology has been widely engineered to facilitate efficient treatment of landfill leachate. However, low membrane filtration flux and severe membrane fouling greatly hampered its low-cost application. In this study, a dynamic membrane bioreactor (DMBR) integrated with granular activated carbon (GAC) was proposed to enhance both filtration performance and pollutants removal from high-strength landfill leachate. Under influent COD and NH₄⁺-N were 3522 ± 264 and 983 ± 36 mg/L, GAC-DMBR achieved effluent COD and total nitrogen of 367 ± 45 and 114 ± 20 mg/L, respectively. A dynamic membrane (DM) layer was rapidly formed within 0.5 h and sustained stable operation for a cycle of about 33 days at a constant flux of 10 LMH. GAC addition facilitated the formation of a thicker but more permeable DM layer through enhanced sludge aggregation and significant reduction in extracellular polymeric substances (EPS). Microbial analysis revealed GAC-induced enrichment of nitrifiers (e.g., Nitrosomonas, Nitrobacter) and organic degraders (e.g., Candidatus Promineifilum), alongside reduced abundance of EPS-producing genera (e.g., Anaerolinea) and denitrifiers (e.g., Thauera, Ottowia). These community shifts aligned with the higher abundances of genes involved in nitrification, anammox, along with the lower abundances of denitrification and EPS biosynthesis. All these changes promoted a transition toward autotrophic nitrogen removal (ANR) and effectively mitigated membrane fouling. This study offers a promising approach for improving the efficiency and operational sustainability of landfill leachate treatment systems using GAC-mediated DMBR technology.