Bubbleless aerated-biological activated carbon as a superior process for drinking water treatment in rural areas

Drinking water supply in rural areas remains a substantial challenge due to complex natural, technical and economic conditions. To provide safe and affordable drinking water to all, as targeted in the UN Sustainable Development Goals (2030 Agenda), low-cost, efficient water treatment processes suitable for rural areas need to be developed. In this study, a bubbleless aeration BAC (termed ABAC) process is proposed and evaluated, involving the incorporation of a hollow fiber membrane (HFM) assembly within a slow-rate BAC filter, to provide dissolved oxygen (DO) throughout the BAC filter and an increased DOM removal efficiency. The results showed that after a 210-day period of operation, the ABAC increased the DOC removal by 54%, and decreased the disinfection byproduct formation potential (DBPFP) by 41%, compared to a comparable BAC filter without aeration (termed NBAC). The elevated DO (> 4 mg/L) not only reduced secreted extracellular polymer, but also modified the microbial community with a stronger degradation ability. The HFM-based aeration showed comparable performance to 3 mg/L pre-ozonation, and the DOC removal efficiency was four times greater than that of a conventional coagulation process. The proposed ABAC treatment, with its various advantages (e.g., high stability, avoidance of chemicals, ease of operation and maintenance), is well-suited to be integrated as a prefabricated device, for decentralized drinking water systems in rural areas.