Bio-enhanced Granular-Activated Carbon Dynamic Biofilm Reactor for Greywater Treatment: Biofilm Growth, Performance and Mechanisms

Abstract The potential of source-diverted greywater (GW) reuse mainly rely on the efficiency and cost of GW treatment technology. Oxygen (O2) supply and utilization rate directly determines the energy consumption and pollutants removal rate in the biological GW treatment. This study developed an effective, gravity flow self-supplying O2 and easy-to-maintain bio-enhanced granular-activated carbon dynamic biofilm reactor (BhGAC-DBfR) for on-site GW treatment. Results showed that increasing of saturated/unsaturated ratio led to the continuous growth of biomass on GAC surface. Division of saturated and unsaturated zones favors the formation of aerobic-anoxic-anaerobic biofilm in the reactor. A saturated/unsaturated ratio of 1:1.1 achieved the maximum removal rate of chemical oxygen demand (COD), linear alkylbenzene sulfonates (LAS), ammonia nitrogen and total nitrogen at 98.3, 99.4, 99.8 and 83.5%, respectively. Key is that adsorption and biodegradation play important and distinct roles in the quick uptake and continuous removal of both organics and N in the system. The related genus and enzymes functional for LAS mineralization, deamination of organic N, ammonium oxidation, and nitrate respiration enabled the efficient and simultaneous removal of organics and N in the BhGAC-DBfR. This study offers a promising engineering alternative technology with great potential to achieve efficient and low-energy-input GW treatment.